Chemical thermodynamics
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Chemical thermodynamics is the study of the interrelation of heat and work with chemical reactions or with physical changes of state within the confines of the laws of thermodynamics. Chemical thermodynamics involves not only laboratory measurements of various thermodynamic properties, but also the application of mathematical methods to the study of chemical questions and the spontaneity of processes.
The structure of chemical thermodynamics is based on the first two laws of thermodynamics. Starting from the first and second laws of thermodynamics, four equations called the "fundamental equations of Gibbs" can be derived. From these four, a multitude of equations, relating the thermodynamic properties of the thermodynamic system can be derived using relatively simple mathematics. This outlines the mathematical framework of chemical thermodynamics.[1]
Contents
[hide]
* 1 History
* 2 Overview
* 3 Chemical energy
* 4 Chemical reactions
o 4.1 Gibbs function
o 4.2 Chemical affinity
o 4.3 Solutions
* 5 Non equilibrium
o 5.1 System constraints
* 6 See also
* 7 References
* 8 Further reading
* 9 External links
[edit] History
J. Willard Gibbs - founder of chemical thermodynamics
In 1865, the German physicist Rudolf Clausius, in his Mechanical Theory of Heat, suggested that the principles of thermochemistry, e.g. such as the heat evolved in combustion reactions, could be applied to the principles of thermodynamics.[2] Building on the work of Clausius, between the years 1873-76 the American mathematical physicist Willard Gibbs published a series of three papers, the most famous one being the paper On the Equilibrium of Heterogeneous Substances. In these papers, Gibbs showed how the first two laws of thermodynamics could be measured graphically and mathematically to determine both the thermodynamic equilibrium of chemical reactions as well as their tendencies to occur or proceed. Gibbs’ collection of papers provided the first unified body of thermodynamic theorems from the principles developed by others, such as Clausius and Sadi Carnot.
During the early 20th century, two major publications successfully applied the principles developed by Gibbs to chemical processes, and thus established the foundation of the science of chemical thermodynamics. The first was the 1923 textbook Thermodynamics and the Free Energy of Chemical Substances by Gilbert N. Lewis and Merle Randall. This book was responsible for supplanting the chemical affinity for the term free energy in the English-speaking world. The second was the 1933 book Modern Thermodynamics by the methods of Willard Gibbs written by E. A. Guggenheim. In this manner, Lewis, Randall, and Guggenheim are considered as the founders of modern chemical thermodynamics because of the major contribution of these two books in unifying the application of thermodynamics to chemistry.[1]
[edit] Overview
The primary objective of chemical thermodynamics is the establishment of a criterion for the determination of the feasibility or spontaneity of a given transformation.[3] In this manner, chemical thermodynamics is typically used to predict the energy exchanges that occur in the following processes:
1. Chemical reactions
2. Phase changes
3. The formation of solutions
The following state functions are of primary concern in chemical thermodynamics:
* Internal energy (U)
* Enthalpy (H).
* Entropy (S)
* Gibbs free energy (G)
Most identities in chemical thermodynamics arise from application of the first and second laws of thermodynamics, particularly the law of conservation of energy, to these state functions.
The 3 laws of thermodynamics:
1. The energy of the universe is constant.
2. In any spontaneous process, there is always an increase in entropy of the universe
3. The entropy of a perfect crystal at 0 kelvins is zero
[edit] Chemical energy
Chemical energy is the potential of a chemical substance to undergo a transformation through a chemical reaction or to transform other chemical substances. Breaking or making of chemical bonds involves energy, which may be either absorbed or evolved from a chemical system.
Energy that can be released (or absorbed) because of a reaction between a set of chemical substances is equal to the difference between the energy content of the products and the reactants. This change in energy is called the change in internal energy of a chemical reaction. Where \Delta {U_f^\circ}_{\mathrm {reactants}} is the internal energy of formation of the reactant molecules that can be calculated from the bond energies of the various chemical bonds of the molecules under consideration and \Delta {U_f^\circ}_{\mathrm {products}} is the internal energy of formation of the product molecules. The internal energy change of a process is equal to the heat change if it is measured under conditions of constant volume, as in a closed rigid container such as a bomb calorimeter. However, under conditions of constant pressure, as in reactions in vessels open to the atmosphere, the measured heat change is not always equal to the internal energy change, because pressure-volume work also releases or absorbs energy. (The heat change at constant pressure is called the enthalpy change; in this case the enthalpy of formation).
Another useful term is the heat of combustion, which is the energy released due to a combustion reaction and often applied in the study of fuels. Food is similar to hydrocarbon fuel and carbohydrate fuels, and when it is oxidized, its caloric content is similar (though not assessed in the same way as a hydrocarbon fuel — see food energy).
In chemical thermodynamics the term used for the chemical potential energy is chemical potential, and for chemical transformation an equation most often used is the Gibbs-Duhem equation.
[edit] Chemical reactions
In most cases of interest in chemical thermodynamics there are internal degrees of freedom and processes, such as chemical reactions and phase transitions, which always create entropy unless they are at equilibrium, or are maintained at a "running equilibrium" through "quasi-static" changes by being coupled to constraining devices, such as pistons or electrodes, to deliver and receive external work. Even for homogeneous "bulk" materials, the free energy functions depend on the composition, as do all the extensive thermodynamic potentials, including the internal energy. If the quantities { Ni }, the number of chemical species, are omitted from the formulae, it is impossible to describe compositional changes.
[edit] Gibbs function
For a "bulk" (unstructured) system they are the last remaining extensive variables. For an unstructured, homogeneous "bulk" system, there are still various extensive compositional variables { Ni } that G depends on, which specify the composition, the amounts of each chemical substance, expressed as the numbers of molecules present or (dividing by Avogadro's number), the numbers of moles
G = G(T,P,\{N_i\})\,.
For the case where only PV work is possible
dG = -SdT + VdP + \sum_i \mu_i dN_i \,
in which μi is the chemical potential for the i-th component in the system
\mu_i = \left( \frac{\partial G}{\partial N_i}\right)_{T,P,N_{j\ne i},etc. } \,.
The expression for dG is especially useful at constant T and P, conditions which are easy to achieve experimentally and which approximates the condition in living creatures
(dG)_{T,P} = \sum_i \mu_i dN_i\,.
[edit] Chemical affinity
Main article: Chemical affinity
While this formulation is mathematically defensible, it is not particularly transparent since one does not simply add or remove molecules from a system. There is always a process involved in changing the composition; e.g., a chemical reaction (or many), or movement of molecules from one phase (liquid) to another (gas or solid). We should find a notation which does not seem to imply that the amounts of the components ( Ni } can be changed independently. All real processes obey conservation of mass, and in addition, conservation of the numbers of atoms of each kind. Whatever molecules are transferred to or from should be considered part of the "system".
Consequently we introduce an explicit variable to represent the degree of advancement of a process, a progress variable ξ for the extent of reaction (Prigogine & Defay, p. 18; Prigogine, pp. 4–7; Guggenheim, p. 37.62), and to the use of the partial derivative ∂G/∂ξ (in place of the widely used "ΔG", since the quantity at issue is not a finite change). The result is an understandable expression for the dependence of dG on chemical reactions (or other processes). If there is just one reaction
(dG)_{T,P} = \left( \frac{\partial G}{\partial \xi}\right)_{T,P} d\xi.\,
If we introduce the stoichiometric coefficient for the i-th component in the reaction
\nu_i = \partial N_i / \partial \xi \,
which tells how many molecules of i are produced or consumed, we obtain an algebraic expression for the partial derivative
\left( \frac{\partial G}{\partial \xi} \right)_{T,P} = \sum_i \mu_i \nu_i = -\mathbb{A}\,
where, (De Donder; Progoine & Defay, p. 69; Guggenheim, pp. 37,240), we introduce a concise and historical name for this quantity, the "affinity", symbolized by A, as introduced by Théophile de Donder in 1923. The minus sign comes from the fact the affinity was defined to represent the rule that spontaneous changes will ensue only when the change in the Gibbs free energy of the process is negative, meaning that the chemical species have a positive affinity for each other. The differential for G takes on a simple form which displays its dependence on compositional change
(dG)_{T,P} = -\mathbb{A}\, d\xi \,.
If there are a number of chemical reactions going on simultaneously, as is usually the case
(dG)_{T,P} = -\sum_k\mathbb{A}_k\, d\xi_k \,.
a set of reaction coordinates { ξj }, avoiding the notion that the amounts of the components ( Ni } can be changed independently. The expressions above are equal to zero at thermodynamic equilibrium, while in the general case for real systems, they are negative because all chemical reactions proceeding at a finite rate produce entropy. This can be made even more explicit by introducing the reaction rates dξj/dt. For each and every physically independent process (Prigogine & Defay, p. 38; Prigogine, p. 24)
\mathbb{A}\ \dot{\xi} \le 0 \,.
This is a remarkable result since the chemical potentials are intensive system variables, depending only on the local molecular milieu. They cannot "know" whether the temperature and pressure (or any other system variables) are going to be held constant over time. It is a purely local criterion and must hold regardless of any such constraints. Of course, it could have been obtained by taking partial derivatives of any of the other fundamental state functions, but nonetheless is a general criterion for (−T times) the entropy production from that spontaneous process; or at least any part of it that is not captured as external work. (See Constraints below.)
We now relax the requirement of a homogeneous “bulk” system by letting the chemical potentials and the affinity apply to any locality in which a chemical reaction (or any other process) is occurring. By accounting for the entropy production due to irreversible processes, the inequality for dG is now replace by an equality
dG = - SdT + VdP -\sum_k\mathbb{A}_k\, d\xi_k + W'\,
or
dG_{T,P} = -\sum_k\mathbb{A}_k\, d\xi_k + W'.\,
Any decrease in the Gibbs function of a system is the upper limit for any isothermal, isobaric work that can be captured in the surroundings, or it may simply be dissipated, appearing as T times a corresponding increase in the entropy of the system and/or its surrounding. Or it may go partly toward doing external work and partly toward creating entropy. The important point is that the extent of reaction for a chemical reaction may be coupled to the displacement of some external mechanical or electrical quantity in such a way that one can advance only if the other one also does. The coupling may occasionally be rigid, but it is often flexible and variable.
[edit] Solutions
In solution chemistry and biochemistry, the Gibbs free energy decrease (∂G/∂ξ, in molar units, denoted cryptically by ΔG) is commonly used as a surrogate for (−T times) the entropy produced by spontaneous chemical reactions in situations where there is no work being done; or at least no "useful" work; i.e., other than perhaps some ± PdV. The assertion that all spontaneous reactions have a negative ΔG is merely a restatement of the fundamental thermodynamic relation, giving it the physical dimensions of energy and somewhat obscuring its significance in terms of entropy. When there is no useful work being done, it would be less misleading to use the Legendre transforms of the entropy appropriate for constant T, or for constant T and P, the Massieu functions −F/T and −G/T respectively.
[edit] Non equilibrium
Main article: non-equilibrium thermodynamics
Generally the systems treated with the conventional chemical thermodynamics are either at equilibrium or near equilibrium. Ilya Prigogine developed the thermodynamic treatment of open systems that are far from equilibrium. In doing so he has discovered phenomena and structures of completely new and completely unexpected types. His generalized, nonlinear and irreversible thermodynamics has found surprising applications in a wide variety of fields.
The non equilibrium thermodynamics has been applied for explaining how ordered structures e.g. the biological systems, can develop from disorder. Even if Onsager's relations are utilized, the classical principles of equilibrium in thermodynamics still show that linear systems close to equilibrium always develop into states of disorder which are stable to perturbations and cannot explain the occurrence of ordered structures.
Prigogine called these systems dissipative systems, because they are formed and maintained by the dissipative processes which take place because of the exchange of energy between the system and its environment and because they disappear if that exchange ceases. They may be said to live in symbiosis with their environment.
The method which Prigogine used to study the stability of the dissipative structures to perturbations is of very great general interest. It makes it possible to study the most varied problems, such as city traffic problems, the stability of insect communities, the development of ordered biological structures and the growth of cancer cells to mention but a few examples.
[edit] System constraints
In this regard, it is crucial to understand the role of walls and other constraints, and the distinction between independent processes and coupling. Contrary to the clear implications of many reference sources, the previous analysis is not restricted to homogenous, isotropic bulk systems which can deliver only PdV work to the outside world, but applies even to the most structured systems. There are complex systems with many chemical "reactions" going on at the same time, some of which are really only parts of the same, overall process. An independent process is one that could proceed even if all others were unaccountably stopped in their tracks. Understanding this is perhaps a “thought experiment” in chemical kinetics, but actual examples exist.
A gas reaction which results in an increase in the number of molecules will lead to an increase in volume at constant external pressure. If it occurs inside a cylinder closed with a piston, the equilibrated reaction can proceed only by doing work against an external force on the piston. The extent variable for the reaction can increase only if the piston moves, and conversely, if the piston is pushed inward, the reaction is driven backwards.
Similarly, a redox reaction might occur in an electrochemical cell with the passage of current in wires connecting the electrodes. The half-cell reactions at the electrodes are constrained if no current is allowed to flow. The current might be dissipated as joule heating, or it might in turn run an electrical device like a motor doing mechanical work. An automobile lead-acid battery can be recharged, driving the chemical reaction backwards. In this case as well, the reaction is not an independent process. Some, perhaps most, of the Gibbs free energy of reaction may be delivered as external work.
The hydrolysis of ATP to ADP and phosphate can drive the force times distance work delivered by living muscles, and synthesis of ATP is in turn driven by a redox chain in mitochondria and chloroplasts, which involves the transport of ions across the membranes of these cellular organelles. The coupling of processes here, and in the previous examples, is often not complete. Gas can leak slowly past a piston, just as it can slowly leak out of a rubber balloon. Some reaction may occur in a battery even if no external current is flowing. There is usually a coupling coefficient, which may depend on relative rates, which determines what percentage of the driving free energy is turned into external work, or captured as "chemical work"; a misnomer for the free energy of another chemical process.
[edit] See also
* Thermodynamic databases for pure substances
[edit] References
1. ^ a b Ott, Bevan J.; Boerio-Goates, Juliana (2000). Chemical Thermodynamics – Principles and Applications. Academic Press. ISBN 0-12-530990-2.
2. ^ Clausius, R. (1865). The Mechanical Theory of Heat – with its Applications to the Steam Engine and to Physical Properties of Bodies. London: John van Voorst, 1 Paternoster Row. MDCCCLXVII.
3. ^ Klotz, I. (1950). Chemical Thermodynamics. New York: Prentice-Hall, Inc.
[edit] Further reading
* Herbert B. Callen (1960). Thermodynamics. Wiley & Sons. The clearest account of the logical foundations of the subject. Library of Congress Catalog No. 60-5597
* Ilya Prigogine & R. Defay, translated by D.H. Everett; Chapter IV (1954). Chemical Thermodynamics. Longmans, Green & Co. Exceptionally clear on the logical foundations as applied to chemistry; includes non-equilibrium thermodynamics.
* Ilya Prigogine (1967). Thermodynamics of Irreversible Processes, 3rd ed.. Interscience: John Wiley & Sons. A simple, concise monograph explaining all the basic ideas. Library of Congress Catalog No. 67-29540
* E.A. Guggenheim (1967). Thermodynamics: An Advanced Treatment for Chemists and Physicists, 5th ed.. North Holland; John Wiley & Sons (Interscience). A remarkably astute treatise. Library of Congress Catalog No. 67-20003
* Th. De Donder (1922). Bull. Ac. Roy. Belg. (Cl. Sc.) (5) 7: 197, 205.
[edit] External links
* Chemical Thermodynamics - University of North Carolina
* Chemical energetics (Introduction to thermodynamics and the First Law)
* Thermodynamics of chemical equilibrium (Entropy, Second Law and free energy)
[hide]v · d · eChemical Engineering Topics
History
History of Chemical Engineering
Chemicals in flasks.jpg
Concepts
Unit operations · Unit processes · Chemical engineer · Chemical process
Unit operations
Momentum transfer · Heat transfer · Mass transfer · Mechanical operations
Unit process
Chemical reaction engineering · Chemical kinetics · Chemical process modeling · chemical technology
Branches
Process design (chemical engineering) · Fluid mechanics · Chemical plant Design · Chemical thermodynamics · Transport phenomena · *More*
Others
Outline of chemical engineering · Index of chemical engineering articles · Education for Chemical Engineers · List of chemical engineers · List of chemical engineering societies · List of chemical process simulators
Category · Portal:Engineering
Retrieved from "http://en.wikipedia.org/wiki/Chemical_thermodynamics"
Categories: Thermodynamics | Chemical thermodynamics | Physical chemistry | Branches of thermodynamics
Personal tools
* Log in / create account
Namespaces
* Article
* Discussion
Variants
Views
* Read
* Edit
* View history
Actions
Search
Search
Navigation
* Main page
* Contents
* Featured content
* Current events
* Random article
* Donate to Wikipedia
Interaction
* Help
* About Wikipedia
* Community portal
* Recent changes
* Contact Wikipedia
Toolbox
* What links here
* Related changes
* Upload file
* Special pages
* Permanent link
* Cite this page
Print/export
* Create a book
* Download as PDF
* Printable version
Languages
* Български
* Galego
* Bahasa Melayu
* Nederlands
* Polski
* Русский
* Svenska
* Українська
* This page was last modified on 20 January 2011 at 00:12.
* Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. See Terms of Use for details.
Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
* Contact us
* Privacy policy
* About Wikipedia
* Disclaim
Monday, January 24, 2011
solar energy
From Wikipedia, the free encyclopedia
Jump to: navigation, search
Page semi-protected
This article is about all uses of solar energy. For generation of electricity using solar energy, see Solar power.
Nellis Solar Power Plant in the United States, the largest photovoltaic power plant in North America.
Renewable energy
Wind Turbine
Biofuel
Biomass
Geothermal
Hydroelectricity
Solar energy
Tidal power
Wave power
Wind power
v · d · e
Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available renewable energy on earth. Only a minuscule fraction of the available solar energy is used.
Solar powered electrical generation relies on heat engines and photovoltaics. Solar energy's uses are limited only by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes.To harvest the solar energy, the most common way is to use solar panels.
Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.
Contents
[hide]
* 1 Energy from the Sun
* 2 Applications of solar technology
o 2.1 Architecture and urban planning
o 2.2 Agriculture and horticulture
o 2.3 Solar lighting
o 2.4 Solar thermal
+ 2.4.1 Water heating
+ 2.4.2 Heating, cooling and ventilation
+ 2.4.3 Water treatment
+ 2.4.4 Cooking
+ 2.4.5 Process heat
o 2.5 Electrical generation
+ 2.5.1 Experimental solar power
o 2.6 Solar chemical
o 2.7 Solar vehicles
* 3 Energy storage methods
* 4 Development, deployment and economics
* 5 ISO Standards
* 6 See also
* 7 Notes
* 8 References
* 9 External links
Energy from the Sun
Main articles: Insolation and Solar radiation
About half the incoming solar energy reaches the Earth's surface.
The Earth receives 174 petawatts (PW) of incoming solar radiation (insolation) at the upper atmosphere.[1] Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth's surface is mostly spread across the visible and near-infrared ranges with a small part in the near-ultraviolet.[2]
Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones.[3] Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14 °C.[4] By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived.[5]
Yearly Solar fluxes & Human Energy Consumption
Solar 3,850,000 EJ[6]
Wind 2,250 EJ[7]
Biomass 3,000 EJ[8]
Primary energy use (2005) 487 EJ[9]
Electricity (2005) 56.7 EJ[10]
The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 3,850,000 exajoules (EJ) per year.[6] In 2002, this was more energy in one hour than the world used in one year.[11][12] Photosynthesis captures approximately 3,000 EJ per year in biomass.[8] The amount of solar energy reaching the surface of the planet is so vast that in one year it is about twice as much as will ever be obtained from all of the Earth's non-renewable resources of coal, oil, natural gas, and mined uranium combined.[13]
From the table of resources it would appear that solar, wind or biomass would be sufficient to supply all of our energy needs, however, the increased use of biomass has had a negative effect on global warming and dramatically increased food prices by diverting forests and crops into biofuel production.[14] As intermittent resources, solar and wind raise other issues.
Solar energy can be harnessed in different levels around the world. Depending on a geographical location the closer to the equator the more "potential" solar energy is available.[15]
Applications of solar technology
Average insolation showing land area (small black dots) required to replace the world primary energy supply with solar electricity. 18 TW is 568 Exajoule (EJ) per year. Insolation for most people is from 150 to 300 W/m² or 3.5 to 7.0 kWh/m²/day.
Solar energy refers primarily to the use of solar radiation for practical ends. However, all renewable energies, other than geothermal and tidal, derive their energy from the sun.
Solar technologies are broadly characterized as either passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps, and fans to convert sunlight into useful outputs. Passive solar techniques include selecting materials with favorable thermal properties, designing spaces that naturally circulate air, and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy and are considered supply side technologies, while passive solar technologies reduce the need for alternate resources and are generally considered demand side technologies.[16]
Architecture and urban planning
Main articles: Passive solar building design and Urban heat island
Darmstadt University of Technology in Germany won the 2007 Solar Decathlon in Washington, D.C. with this passive house designed specifically for the humid and hot subtropical climate.[17]
Sunlight has influenced building design since the beginning of architectural history.[18] Advanced solar architecture and urban planning methods were first employed by the Greeks and Chinese, who oriented their buildings toward the south to provide light and warmth.[19]
The common features of passive solar architecture are orientation relative to the Sun, compact proportion (a low surface area to volume ratio), selective shading (overhangs) and thermal mass.[18] When these features are tailored to the local climate and environment they can produce well-lit spaces that stay in a comfortable temperature range. Socrates' Megaron House is a classic example of passive solar design.[18] The most recent approaches to solar design use computer modeling tying together solar lighting, heating and ventilation systems in an integrated solar design package.[20] Active solar equipment such as pumps, fans and switchable windows can complement passive design and improve system performance.
Urban heat islands (UHI) are metropolitan areas with higher temperatures than that of the surrounding environment. The higher temperatures are a result of increased absorption of the Solar light by urban materials such as asphalt and concrete, which have lower albedos and higher heat capacities than those in the natural environment. A straightforward method of counteracting the UHI effect is to paint buildings and roads white and plant trees. Using these methods, a hypothetical "cool communities" program in Los Angeles has projected that urban temperatures could be reduced by approximately 3 °C at an estimated cost of US$1 billion, giving estimated total annual benefits of US$530 million from reduced air-conditioning costs and healthcare savings.[21]
Agriculture and horticulture
Greenhouses like these in the Westland municipality of the Netherlands grow vegetables, fruits and flowers.
Agriculture and horticulture seek to optimize the capture of solar energy in order to optimize the productivity of plants. Techniques such as timed planting cycles, tailored row orientation, staggered heights between rows and the mixing of plant varieties can improve crop yields.[22][23] While sunlight is generally considered a plentiful resource, the exceptions highlight the importance of solar energy to agriculture. During the short growing seasons of the Little Ice Age, French and English farmers employed fruit walls to maximize the collection of solar energy. These walls acted as thermal masses and accelerated ripening by keeping plants warm. Early fruit walls were built perpendicular to the ground and facing south, but over time, sloping walls were developed to make better use of sunlight. In 1699, Nicolas Fatio de Duillier even suggested using a tracking mechanism which could pivot to follow the Sun.[24] Applications of solar energy in agriculture aside from growing crops include pumping water, drying crops, brooding chicks and drying chicken manure.[25][26] More recently the technology has been embraced by vinters, who use the energy generated by solar panels to power grape presses.[27]
Greenhouses convert solar light to heat, enabling year-round production and the growth (in enclosed environments) of specialty crops and other plants not naturally suited to the local climate. Primitive greenhouses were first used during Roman times to produce cucumbers year-round for the Roman emperor Tiberius.[28] The first modern greenhouses were built in Europe in the 16th century to keep exotic plants brought back from explorations abroad.[29] Greenhouses remain an important part of horticulture today, and plastic transparent materials have also been used to similar effect in polytunnels and row covers.
Solar lighting
Daylighting features such as this oculus at the top of the Pantheon, in Rome, Italy have been in use since antiquity.
The history of lighting is dominated by the use of natural light. The Romans recognized a right to light as early as the 6th century and English law echoed these judgments with the Prescription Act of 1832.[30][31] In the 20th century artificial lighting became the main source of interior illumination but daylighting techniques and hybrid solar lighting solutions are ways to reduce energy consumption.
Daylighting systems collect and distribute sunlight to provide interior illumination. This passive technology directly offsets energy use by replacing artificial lighting, and indirectly offsets non-solar energy use by reducing the need for air-conditioning.[32] Although difficult to quantify, the use of natural lighting also offers physiological and psychological benefits compared to artificial lighting.[32] Daylighting design implies careful selection of window types, sizes and orientation; exterior shading devices may be considered as well. Individual features include sawtooth roofs, clerestory windows, light shelves, skylights and light tubes. They may be incorporated into existing structures, but are most effective when integrated into a solar design package that accounts for factors such as glare, heat flux and time-of-use. When daylighting features are properly implemented they can reduce lighting-related energy requirements by 25%.[33]
Hybrid solar lighting is an active solar method of providing interior illumination. HSL systems collect sunlight using focusing mirrors that track the Sun and use optical fibers to transmit it inside the building to supplement conventional lighting. In single-story applications these systems are able to transmit 50% of the direct sunlight received.[34]
Solar lights that charge during the day and light up at dusk are a common sight along walkways.[citation needed]
Although daylight saving time is promoted as a way to use sunlight to save energy, recent research has been limited and reports contradictory results: several studies report savings, but just as many suggest no effect or even a net loss, particularly when gasoline consumption is taken into account. Electricity use is greatly affected by geography, climate and economics, making it hard to generalize from single studies.[35]
Solar thermal
Main article: Solar thermal energy
Solar thermal technologies can be used for water heating, space heating, space cooling and process heat generation.[36]
Water heating
Main articles: Solar hot water and Solar combisystem
Solar water heaters facing the Sun to maximize gain.
Solar hot water systems use sunlight to heat water. In low geographical latitudes (below 40 degrees) from 60 to 70% of the domestic hot water use with temperatures up to 60 °C can be provided by solar heating systems.[37] The most common types of solar water heaters are evacuated tube collectors (44%) and glazed flat plate collectors (34%) generally used for domestic hot water; and unglazed plastic collectors (21%) used mainly to heat swimming pools.[38]
As of 2007, the total installed capacity of solar hot water systems is approximately 154 GW.[39] China is the world leader in their deployment with 70 GW installed as of 2006 and a long term goal of 210 GW by 2020.[40] Israel and Cyprus are the per capita leaders in the use of solar hot water systems with over 90% of homes using them.[41] In the United States, Canada and Australia heating swimming pools is the dominant application of solar hot water with an installed capacity of 18 GW as of 2005.[16]
Heating, cooling and ventilation
Main articles: Solar heating, Thermal mass, Solar chimney, and Solar air conditioning
Solar House #1 of Massachusetts Institute of Technology in the United States, built in 1939, used seasonal thermal storage for year-round heating.
In the United States, heating, ventilation and air conditioning (HVAC) systems account for 30% (4.65 EJ) of the energy used in commercial buildings and nearly 50% (10.1 EJ) of the energy used in residential buildings.[33][42] Solar heating, cooling and ventilation technologies can be used to offset a portion of this energy.
Thermal mass is any material that can be used to store heat—heat from the Sun in the case of solar energy. Common thermal mass materials include stone, cement and water. Historically they have been used in arid climates or warm temperate regions to keep buildings cool by absorbing solar energy during the day and radiating stored heat to the cooler atmosphere at night. However they can be used in cold temperate areas to maintain warmth as well. The size and placement of thermal mass depend on several factors such as climate, daylighting and shading conditions. When properly incorporated, thermal mass maintains space temperatures in a comfortable range and reduces the need for auxiliary heating and cooling equipment.[43]
A solar chimney (or thermal chimney, in this context) is a passive solar ventilation system composed of a vertical shaft connecting the interior and exterior of a building. As the chimney warms, the air inside is heated causing an updraft that pulls air through the building. Performance can be improved by using glazing and thermal mass materials in a way that mimics greenhouses.[citation needed]
Deciduous trees and plants have been promoted as a means of controlling solar heating and cooling. When planted on the southern side of a building, their leaves provide shade during the summer, while the bare limbs allow light to pass during the winter.[44] Since bare, leafless trees shade 1/3 to 1/2 of incident solar radiation, there is a balance between the benefits of summer shading and the corresponding loss of winter heating.[45] In climates with significant heating loads, deciduous trees should not be planted on the southern side of a building because they will interfere with winter solar availability. They can, however, be used on the east and west sides to provide a degree of summer shading without appreciably affecting winter solar gain.[46]
Water treatment
Main articles: Solar still, Solar water disinfection, Solar desalination, and Solar Powered Desalination Unit
Solar water disinfection in Indonesia
Small scale solar powered sewerage treatment plant.
Solar distillation can be used to make saline or brackish water potable. The first recorded instance of this was by 16th century Arab alchemists.[47] A large-scale solar distillation project was first constructed in 1872 in the Chilean mining town of Las Salinas.[48] The plant, which had solar collection area of 4,700 m², could produce up to 22,700 L per day and operated for 40 years.[48] Individual still designs include single-slope, double-slope (or greenhouse type), vertical, conical, inverted absorber, multi-wick, and multiple effect.[47] These stills can operate in passive, active, or hybrid modes. Double-slope stills are the most economical for decentralized domestic purposes, while active multiple effect units are more suitable for large-scale applications.[47]
Solar water disinfection (SODIS) involves exposing water-filled plastic polyethylene terephthalate (PET) bottles to sunlight for several hours.[49] Exposure times vary depending on weather and climate from a minimum of six hours to two days during fully overcast conditions.[50] It is recommended by the World Health Organization as a viable method for household water treatment and safe storage.[51] Over two million people in developing countries use this method for their daily drinking water.[50]
Solar energy may be used in a water stabilisation pond to treat waste water without chemicals or electricity. A further environmental advantage is that algae grow in such ponds and consume carbon dioxide in photosynthesis, although algae may produce toxic chemicals that make the water unusable.[52][53]
Cooking
Main article: Solar cooker
The Solar Bowl in Auroville, India, concentrates sunlight on a movable receiver to produce steam for cooking.
Solar cookers use sunlight for cooking, drying and pasteurization. They can be grouped into three broad categories: box cookers, panel cookers and reflector cookers.[54] The simplest solar cooker is the box cooker first built by Horace de Saussure in 1767.[55] A basic box cooker consists of an insulated container with a transparent lid. It can be used effectively with partially overcast skies and will typically reach temperatures of 90–150 °C.[56] Panel cookers use a reflective panel to direct sunlight onto an insulated container and reach temperatures comparable to box cookers. Reflector cookers use various concentrating geometries (dish, trough, Fresnel mirrors) to focus light on a cooking container. These cookers reach temperatures of 315 °C and above but require direct light to function properly and must be repositioned to track the Sun.[57]
The solar bowl is a concentrating technology employed by the Solar Kitchen in Auroville, Pondicherry, India, where a stationary spherical reflector focuses light along a line perpendicular to the sphere's interior surface, and a computer control system moves the receiver to intersect this line. Steam is produced in the receiver at temperatures reaching 150 °C and then used for process heat in the kitchen.[58]
A reflector developed by Wolfgang Scheffler in 1986 is used in many solar kitchens. Scheffler reflectors are flexible parabolic dishes that combine aspects of trough and power tower concentrators. Polar tracking is used to follow the Sun's daily course and the curvature of the reflector is adjusted for seasonal variations in the incident angle of sunlight. These reflectors can reach temperatures of 450–650 °C and have a fixed focal point, which simplifies cooking.[59] The world's largest Scheffler reflector system in Abu Road, Rajasthan, India is capable of cooking up to 35,000 meals a day.[60] As of 2008, over 2,000 large Scheffler cookers had been built worldwide.[61]
Process heat
Main articles: Solar pond, Salt evaporation pond, and Solar furnace
STEP parabolic dishes used for steam production and electrical generation.
Solar concentrating technologies such as parabolic dish, trough and Scheffler reflectors can provide process heat for commercial and industrial applications. The first commercial system was the Solar Total Energy Project (STEP) in Shenandoah, Georgia, USA where a field of 114 parabolic dishes provided 50% of the process heating, air conditioning and electrical requirements for a clothing factory. This grid-connected cogeneration system provided 400 kW of electricity plus thermal energy in the form of 401 kW steam and 468 kW chilled water, and had a one hour peak load thermal storage.[62]
Evaporation ponds are shallow pools that concentrate dissolved solids through evaporation. The use of evaporation ponds to obtain salt from sea water is one of the oldest applications of solar energy. Modern uses include concentrating brine solutions used in leach mining and removing dissolved solids from waste streams.[63]
Clothes lines, clotheshorses, and clothes racks dry clothes through evaporation by wind and sunlight without consuming electricity or gas. In some states of the United States legislation protects the "right to dry" clothes.[64]
Unglazed transpired collectors (UTC) are perforated sun-facing walls used for preheating ventilation air. UTCs can raise the incoming air temperature up to 22 °C and deliver outlet temperatures of 45–60 °C.[65] The short payback period of transpired collectors (3 to 12 years) makes them a more cost-effective alternative than glazed collection systems.[65] As of 2003, over 80 systems with a combined collector area of 35,000 m² had been installed worldwide, including an 860 m² collector in Costa Rica used for drying coffee beans and a 1,300 m² collector in Coimbatore, India used for drying marigolds.[26]
Electrical generation
Main article: Solar power
The PS10 concentrates sunlight from a field of heliostats on a central tower.
Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power (CSP). CSP systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. PV converts light into electric current using the photoelectric effect.
Commercial CSP plants were first developed in the 1980s, and the 354 MW SEGS CSP installation is the largest solar power plant in the world and is located in the Mojave Desert of California. Other large CSP plants include the Solnova Solar Power Station (150 MW) and the Andasol solar power station (100 MW), both in Spain. The 80 MW Sarnia Photovoltaic Power Plant in Canada, is the world’s largest photovoltaic plant.
Experimental solar power
Main articles: Solar pond and Thermogenerator
Solar Evaporation Ponds in the Atacama Desert, South America
A solar pond is a pool of salt water (usually 1–2 m deep) that collects and stores solar energy. Solar ponds were first proposed by Dr. Rudolph Bloch in 1948 after he came across reports of a lake in Hungary in which the temperature increased with depth. This effect was due to salts in the lake's water, which created a "density gradient" that prevented convection currents. A prototype was constructed in 1958 on the shores of the Dead Sea near Jerusalem.[66] The pond consisted of layers of water that successively increased from a weak salt solution at the top to a high salt solution at the bottom. This solar pond was capable of producing temperatures of 90 °C in its bottom layer and had an estimated solar-to-electric efficiency of two percent.
Thermoelectric, or "thermovoltaic" devices convert a temperature difference between dissimilar materials into an electric current. First proposed as a method to store solar energy by solar pioneer Mouchout in the 1800s,[67] thermoelectrics reemerged in the Soviet Union during the 1930s. Under the direction of Soviet scientist Abram Ioffe a concentrating system was used to thermoelectrically generate power for a 1 hp engine.[68] Thermogenerators were later used in the US space program as an energy conversion technology for powering deep space missions such as Cassini, Galileo and Viking. Research in this area is focused on raising the efficiency of these devices from 7–8% to 15–20%.[69]
Solar chemical
Main article: Solar chemical
Solar chemical processes use solar energy to drive chemical reactions. These processes offset energy that would otherwise come from an alternate source and can convert solar energy into storable and transportable fuels. Solar induced chemical reactions can be divided into thermochemical or photochemical.[70]
Hydrogen production technologies been a significant area of solar chemical research since the 1970s. Aside from electrolysis driven by photovoltaic or photochemical cells, several thermochemical processes have also been explored. One such route uses concentrators to split water into oxygen and hydrogen at high temperatures (2300-2600 °C).[71] Another approach uses the heat from solar concentrators to drive the steam reformation of natural gas thereby increasing the overall hydrogen yield compared to conventional reforming methods.[72] Thermochemical cycles characterized by the decomposition and regeneration of reactants present another avenue for hydrogen production. The Solzinc process under development at the Weizmann Institute uses a 1 MW solar furnace to decompose zinc oxide (ZnO) at temperatures above 1200 °C. This initial reaction produces pure zinc, which can subsequently be reacted with water to produce hydrogen.[73]
Sandia's Sunshine to Petrol (S2P) technology uses the high temperatures generated by concentrating sunlight along with a zirconia/ferrite catalyst to break down atmospheric carbon dioxide into oxygen and carbon monoxide (CO). The carbon monoxide can then be used to synthesize conventional fuels such as methanol, gasoline and jet fuel.[74]
A photogalvanic device is a type of battery in which the cell solution (or equivalent) forms energy-rich chemical intermediates when illuminated. These energy-rich intermediates can potentially be stored and subsequently reacted at the electrodes to produce an electric potential. The ferric-thionine chemical cell is an example of this technology.[75]
Photoelectrochemical cells or PECs consist of a semiconductor, typically titanium dioxide or related titanates, immersed in an electrolyte. When the semiconductor is illuminated an electrical potential develops. There are two types of photoelectrochemical cells: photoelectric cells that convert light into electricity and photochemical cells that use light to drive chemical reactions such as electrolysis.[76]
A combination thermal/photochemical cell has also been proposed. The Stanford PETE process uses solar thermal energy to raise the temperature of a thermionic metal to about 800C to increase the rate of production of electricity to electrolyse atmospheric CO2 down to carbon or carbon monoxide which can then be used for fuel production, and the waste heat can be used as well.[77]
Solar vehicles
Main articles: Solar vehicle, Solar-charged vehicle, Electric boat, and Solar balloon
Australia hosts the World Solar Challenge where solar cars like the Nuna3 race through a 3,021 km (1,877 mi) course from Darwin to Adelaide.
Development of a solar powered car has been an engineering goal since the 1980s. The World Solar Challenge is a biannual solar-powered car race, where teams from universities and enterprises compete over 3,021 kilometres (1,877 mi) across central Australia from Darwin to Adelaide. In 1987, when it was founded, the winner's average speed was 67 kilometres per hour (42 mph) and by 2007 the winner's average speed had improved to 90.87 kilometres per hour (56.46 mph).[78] The North American Solar Challenge and the planned South African Solar Challenge are comparable competitions that reflect an international interest in the engineering and development of solar powered vehicles.[79][80]
Some vehicles use solar panels for auxiliary power, such as for air conditioning, to keep the interior cool, thus reducing fuel consumption.[81][82]
In 1975, the first practical solar boat was constructed in England.[83] By 1995, passenger boats incorporating PV panels began appearing and are now used extensively.[84] In 1996, Kenichi Horie made the first solar powered crossing of the Pacific Ocean, and the sun21 catamaran made the first solar powered crossing of the Atlantic Ocean in the winter of 2006–2007.[85] There are plans to circumnavigate the globe in 2010.[86]
Helios UAV in solar powered flight.
In 1974, the unmanned AstroFlight Sunrise plane made the first solar flight. On 29 April 1979, the Solar Riser made the first flight in a solar powered, fully controlled, man carrying flying machine, reaching an altitude of 40 feet (12 m). In 1980, the Gossamer Penguin made the first piloted flights powered solely by photovoltaics. This was quickly followed by the Solar Challenger which crossed the English Channel in July 1981. In 1990 Eric Raymond in 21 hops flew from California to North Carolina using solar power.[87] Developments then turned back to unmanned aerial vehicles (UAV) with the Pathfinder (1997) and subsequent designs, culminating in the Helios which set the altitude record for a non-rocket-propelled aircraft at 29,524 metres (96,864 ft) in 2001.[88] The Zephyr, developed by BAE Systems, is the latest in a line of record-breaking solar aircraft, making a 54-hour flight in 2007, and month-long flights are envisioned by 2010.[89]
A solar balloon is a black balloon that is filled with ordinary air. As sunlight shines on the balloon, the air inside is heated and expands causing an upward buoyancy force, much like an artificially heated hot air balloon. Some solar balloons are large enough for human flight, but usage is generally limited to the toy market as the surface-area to payload-weight ratio is relatively high.[90]
Solar sails are a proposed form of spacecraft propulsion using large membrane mirrors to exploit radiation pressure from the Sun. Unlike rockets, solar sails require no fuel. Although the thrust is small compared to rockets, it continues as long as the Sun shines onto the deployed sail and in the vacuum of space significant speeds can eventually be achieved.[91]
The High-altitude airship (HAA) is an unmanned, long-duration, lighter-than-air vehicle using helium gas for lift, and thin film solar cells for power. The United States Department of Defense Missile Defense Agency has contracted Lockheed Martin to construct it to enhance the Ballistic Missile Defense System (BMDS).[92] Airships have some advantages for solar-powered flight: they do not require power to remain aloft, and an airship's envelope presents a large area to the Sun.
Energy storage methods
Main articles: Thermal mass, Thermal energy storage, Phase change material, Grid energy storage, and V2G
Solar Two's thermal storage system generated electricity during cloudy weather and at night.
Solar energy is not available at night, and energy storage is an important issue because modern energy systems usually assume continuous availability of energy.[93]
Thermal mass systems can store solar energy in the form of heat at domestically useful temperatures for daily or seasonal durations. Thermal storage systems generally use readily available materials with high specific heat capacities such as water, earth and stone. Well-designed systems can lower peak demand, shift time-of-use to off-peak hours and reduce overall heating and cooling requirements.[94][95]
Phase change materials such as paraffin wax and Glauber's salt are another thermal storage media. These materials are inexpensive, readily available, and can deliver domestically useful temperatures (approximately 64 °C). The "Dover House" (in Dover, Massachusetts) was the first to use a Glauber's salt heating system, in 1948.[96]
Solar energy can be stored at high temperatures using molten salts. Salts are an effective storage medium because they are low-cost, have a high specific heat capacity and can deliver heat at temperatures compatible with conventional power systems. The Solar Two used this method of energy storage, allowing it to store 1.44 TJ in its 68 m³ storage tank with an annual storage efficiency of about 99%.[97]
Off-grid PV systems have traditionally used rechargeable batteries to store excess electricity. With grid-tied systems, excess electricity can be sent to the transmission grid. Net metering programs give these systems a credit for the electricity they deliver to the grid. This credit offsets electricity provided from the grid when the system cannot meet demand, effectively using the grid as a storage mechanism.[98]
Pumped-storage hydroelectricity stores energy in the form of water pumped when energy is available from a lower elevation reservoir to a higher elevation one. The energy is recovered when demand is high by releasing the water to run through a hydroelectric power generator.[99]
Development, deployment and economics
Main article: Deployment of solar power to energy grids
A parabolic dish and stirling engine system, which concentrates sunlight to produce useful solar power.
Beginning with the surge in coal use which accompanied the Industrial Revolution, energy consumption has steadily transitioned from wood and biomass to fossil fuels. The early development of solar technologies starting in the 1860s was driven by an expectation that coal would soon become scarce. However development of solar technologies stagnated in the early 20th century in the face of the increasing availability, economy, and utility of coal and petroleum.[100]
The 1973 oil embargo and 1979 energy crisis caused a reorganization of energy policies around the world and brought renewed attention to developing solar technologies.[101][102] Deployment strategies focused on incentive programs such as the Federal Photovoltaic Utilization Program in the US and the Sunshine Program in Japan. Other efforts included the formation of research facilities in the US (SERI, now NREL), Japan (NEDO), and Germany (Fraunhofer Institute for Solar Energy Systems ISE).[103]
Commercial solar water heaters began appearing in the United States in the 1890s.[104] These systems saw increasing use until the 1920s but were gradually replaced by cheaper and more reliable heating fuels.[105] As with photovoltaics, solar water heating attracted renewed attention as a result of the oil crises in the 1970s but interest subsided in the 1980s due to falling petroleum prices. Development in the solar water heating sector progressed steadily throughout the 1990s and growth rates have averaged 20% per year since 1999.[39] Although generally underestimated, solar water heating and cooling is by far the most widely deployed solar technology with an estimated capacity of 154 GW as of 2007.[39]
ISO Standards
The International Organization for Standardization has established a number of standards relating to solar energy equipment. For example, ISO 9050 relates to glass in building while ISO 10217 relates to the materials used in solar water heaters.
Jump to: navigation, search
Page semi-protected
This article is about all uses of solar energy. For generation of electricity using solar energy, see Solar power.
Nellis Solar Power Plant in the United States, the largest photovoltaic power plant in North America.
Renewable energy
Wind Turbine
Biofuel
Biomass
Geothermal
Hydroelectricity
Solar energy
Tidal power
Wave power
Wind power
v · d · e
Solar energy, radiant light and heat from the sun, has been harnessed by humans since ancient times using a range of ever-evolving technologies. Solar radiation, along with secondary solar-powered resources such as wind and wave power, hydroelectricity and biomass, account for most of the available renewable energy on earth. Only a minuscule fraction of the available solar energy is used.
Solar powered electrical generation relies on heat engines and photovoltaics. Solar energy's uses are limited only by human ingenuity. A partial list of solar applications includes space heating and cooling through solar architecture, potable water via distillation and disinfection, daylighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes.To harvest the solar energy, the most common way is to use solar panels.
Solar technologies are broadly characterized as either passive solar or active solar depending on the way they capture, convert and distribute solar energy. Active solar techniques include the use of photovoltaic panels and solar thermal collectors to harness the energy. Passive solar techniques include orienting a building to the Sun, selecting materials with favorable thermal mass or light dispersing properties, and designing spaces that naturally circulate air.
Contents
[hide]
* 1 Energy from the Sun
* 2 Applications of solar technology
o 2.1 Architecture and urban planning
o 2.2 Agriculture and horticulture
o 2.3 Solar lighting
o 2.4 Solar thermal
+ 2.4.1 Water heating
+ 2.4.2 Heating, cooling and ventilation
+ 2.4.3 Water treatment
+ 2.4.4 Cooking
+ 2.4.5 Process heat
o 2.5 Electrical generation
+ 2.5.1 Experimental solar power
o 2.6 Solar chemical
o 2.7 Solar vehicles
* 3 Energy storage methods
* 4 Development, deployment and economics
* 5 ISO Standards
* 6 See also
* 7 Notes
* 8 References
* 9 External links
Energy from the Sun
Main articles: Insolation and Solar radiation
About half the incoming solar energy reaches the Earth's surface.
The Earth receives 174 petawatts (PW) of incoming solar radiation (insolation) at the upper atmosphere.[1] Approximately 30% is reflected back to space while the rest is absorbed by clouds, oceans and land masses. The spectrum of solar light at the Earth's surface is mostly spread across the visible and near-infrared ranges with a small part in the near-ultraviolet.[2]
Earth's land surface, oceans and atmosphere absorb solar radiation, and this raises their temperature. Warm air containing evaporated water from the oceans rises, causing atmospheric circulation or convection. When the air reaches a high altitude, where the temperature is low, water vapor condenses into clouds, which rain onto the Earth's surface, completing the water cycle. The latent heat of water condensation amplifies convection, producing atmospheric phenomena such as wind, cyclones and anti-cyclones.[3] Sunlight absorbed by the oceans and land masses keeps the surface at an average temperature of 14 °C.[4] By photosynthesis green plants convert solar energy into chemical energy, which produces food, wood and the biomass from which fossil fuels are derived.[5]
Yearly Solar fluxes & Human Energy Consumption
Solar 3,850,000 EJ[6]
Wind 2,250 EJ[7]
Biomass 3,000 EJ[8]
Primary energy use (2005) 487 EJ[9]
Electricity (2005) 56.7 EJ[10]
The total solar energy absorbed by Earth's atmosphere, oceans and land masses is approximately 3,850,000 exajoules (EJ) per year.[6] In 2002, this was more energy in one hour than the world used in one year.[11][12] Photosynthesis captures approximately 3,000 EJ per year in biomass.[8] The amount of solar energy reaching the surface of the planet is so vast that in one year it is about twice as much as will ever be obtained from all of the Earth's non-renewable resources of coal, oil, natural gas, and mined uranium combined.[13]
From the table of resources it would appear that solar, wind or biomass would be sufficient to supply all of our energy needs, however, the increased use of biomass has had a negative effect on global warming and dramatically increased food prices by diverting forests and crops into biofuel production.[14] As intermittent resources, solar and wind raise other issues.
Solar energy can be harnessed in different levels around the world. Depending on a geographical location the closer to the equator the more "potential" solar energy is available.[15]
Applications of solar technology
Average insolation showing land area (small black dots) required to replace the world primary energy supply with solar electricity. 18 TW is 568 Exajoule (EJ) per year. Insolation for most people is from 150 to 300 W/m² or 3.5 to 7.0 kWh/m²/day.
Solar energy refers primarily to the use of solar radiation for practical ends. However, all renewable energies, other than geothermal and tidal, derive their energy from the sun.
Solar technologies are broadly characterized as either passive or active depending on the way they capture, convert and distribute sunlight. Active solar techniques use photovoltaic panels, pumps, and fans to convert sunlight into useful outputs. Passive solar techniques include selecting materials with favorable thermal properties, designing spaces that naturally circulate air, and referencing the position of a building to the Sun. Active solar technologies increase the supply of energy and are considered supply side technologies, while passive solar technologies reduce the need for alternate resources and are generally considered demand side technologies.[16]
Architecture and urban planning
Main articles: Passive solar building design and Urban heat island
Darmstadt University of Technology in Germany won the 2007 Solar Decathlon in Washington, D.C. with this passive house designed specifically for the humid and hot subtropical climate.[17]
Sunlight has influenced building design since the beginning of architectural history.[18] Advanced solar architecture and urban planning methods were first employed by the Greeks and Chinese, who oriented their buildings toward the south to provide light and warmth.[19]
The common features of passive solar architecture are orientation relative to the Sun, compact proportion (a low surface area to volume ratio), selective shading (overhangs) and thermal mass.[18] When these features are tailored to the local climate and environment they can produce well-lit spaces that stay in a comfortable temperature range. Socrates' Megaron House is a classic example of passive solar design.[18] The most recent approaches to solar design use computer modeling tying together solar lighting, heating and ventilation systems in an integrated solar design package.[20] Active solar equipment such as pumps, fans and switchable windows can complement passive design and improve system performance.
Urban heat islands (UHI) are metropolitan areas with higher temperatures than that of the surrounding environment. The higher temperatures are a result of increased absorption of the Solar light by urban materials such as asphalt and concrete, which have lower albedos and higher heat capacities than those in the natural environment. A straightforward method of counteracting the UHI effect is to paint buildings and roads white and plant trees. Using these methods, a hypothetical "cool communities" program in Los Angeles has projected that urban temperatures could be reduced by approximately 3 °C at an estimated cost of US$1 billion, giving estimated total annual benefits of US$530 million from reduced air-conditioning costs and healthcare savings.[21]
Agriculture and horticulture
Greenhouses like these in the Westland municipality of the Netherlands grow vegetables, fruits and flowers.
Agriculture and horticulture seek to optimize the capture of solar energy in order to optimize the productivity of plants. Techniques such as timed planting cycles, tailored row orientation, staggered heights between rows and the mixing of plant varieties can improve crop yields.[22][23] While sunlight is generally considered a plentiful resource, the exceptions highlight the importance of solar energy to agriculture. During the short growing seasons of the Little Ice Age, French and English farmers employed fruit walls to maximize the collection of solar energy. These walls acted as thermal masses and accelerated ripening by keeping plants warm. Early fruit walls were built perpendicular to the ground and facing south, but over time, sloping walls were developed to make better use of sunlight. In 1699, Nicolas Fatio de Duillier even suggested using a tracking mechanism which could pivot to follow the Sun.[24] Applications of solar energy in agriculture aside from growing crops include pumping water, drying crops, brooding chicks and drying chicken manure.[25][26] More recently the technology has been embraced by vinters, who use the energy generated by solar panels to power grape presses.[27]
Greenhouses convert solar light to heat, enabling year-round production and the growth (in enclosed environments) of specialty crops and other plants not naturally suited to the local climate. Primitive greenhouses were first used during Roman times to produce cucumbers year-round for the Roman emperor Tiberius.[28] The first modern greenhouses were built in Europe in the 16th century to keep exotic plants brought back from explorations abroad.[29] Greenhouses remain an important part of horticulture today, and plastic transparent materials have also been used to similar effect in polytunnels and row covers.
Solar lighting
Daylighting features such as this oculus at the top of the Pantheon, in Rome, Italy have been in use since antiquity.
The history of lighting is dominated by the use of natural light. The Romans recognized a right to light as early as the 6th century and English law echoed these judgments with the Prescription Act of 1832.[30][31] In the 20th century artificial lighting became the main source of interior illumination but daylighting techniques and hybrid solar lighting solutions are ways to reduce energy consumption.
Daylighting systems collect and distribute sunlight to provide interior illumination. This passive technology directly offsets energy use by replacing artificial lighting, and indirectly offsets non-solar energy use by reducing the need for air-conditioning.[32] Although difficult to quantify, the use of natural lighting also offers physiological and psychological benefits compared to artificial lighting.[32] Daylighting design implies careful selection of window types, sizes and orientation; exterior shading devices may be considered as well. Individual features include sawtooth roofs, clerestory windows, light shelves, skylights and light tubes. They may be incorporated into existing structures, but are most effective when integrated into a solar design package that accounts for factors such as glare, heat flux and time-of-use. When daylighting features are properly implemented they can reduce lighting-related energy requirements by 25%.[33]
Hybrid solar lighting is an active solar method of providing interior illumination. HSL systems collect sunlight using focusing mirrors that track the Sun and use optical fibers to transmit it inside the building to supplement conventional lighting. In single-story applications these systems are able to transmit 50% of the direct sunlight received.[34]
Solar lights that charge during the day and light up at dusk are a common sight along walkways.[citation needed]
Although daylight saving time is promoted as a way to use sunlight to save energy, recent research has been limited and reports contradictory results: several studies report savings, but just as many suggest no effect or even a net loss, particularly when gasoline consumption is taken into account. Electricity use is greatly affected by geography, climate and economics, making it hard to generalize from single studies.[35]
Solar thermal
Main article: Solar thermal energy
Solar thermal technologies can be used for water heating, space heating, space cooling and process heat generation.[36]
Water heating
Main articles: Solar hot water and Solar combisystem
Solar water heaters facing the Sun to maximize gain.
Solar hot water systems use sunlight to heat water. In low geographical latitudes (below 40 degrees) from 60 to 70% of the domestic hot water use with temperatures up to 60 °C can be provided by solar heating systems.[37] The most common types of solar water heaters are evacuated tube collectors (44%) and glazed flat plate collectors (34%) generally used for domestic hot water; and unglazed plastic collectors (21%) used mainly to heat swimming pools.[38]
As of 2007, the total installed capacity of solar hot water systems is approximately 154 GW.[39] China is the world leader in their deployment with 70 GW installed as of 2006 and a long term goal of 210 GW by 2020.[40] Israel and Cyprus are the per capita leaders in the use of solar hot water systems with over 90% of homes using them.[41] In the United States, Canada and Australia heating swimming pools is the dominant application of solar hot water with an installed capacity of 18 GW as of 2005.[16]
Heating, cooling and ventilation
Main articles: Solar heating, Thermal mass, Solar chimney, and Solar air conditioning
Solar House #1 of Massachusetts Institute of Technology in the United States, built in 1939, used seasonal thermal storage for year-round heating.
In the United States, heating, ventilation and air conditioning (HVAC) systems account for 30% (4.65 EJ) of the energy used in commercial buildings and nearly 50% (10.1 EJ) of the energy used in residential buildings.[33][42] Solar heating, cooling and ventilation technologies can be used to offset a portion of this energy.
Thermal mass is any material that can be used to store heat—heat from the Sun in the case of solar energy. Common thermal mass materials include stone, cement and water. Historically they have been used in arid climates or warm temperate regions to keep buildings cool by absorbing solar energy during the day and radiating stored heat to the cooler atmosphere at night. However they can be used in cold temperate areas to maintain warmth as well. The size and placement of thermal mass depend on several factors such as climate, daylighting and shading conditions. When properly incorporated, thermal mass maintains space temperatures in a comfortable range and reduces the need for auxiliary heating and cooling equipment.[43]
A solar chimney (or thermal chimney, in this context) is a passive solar ventilation system composed of a vertical shaft connecting the interior and exterior of a building. As the chimney warms, the air inside is heated causing an updraft that pulls air through the building. Performance can be improved by using glazing and thermal mass materials in a way that mimics greenhouses.[citation needed]
Deciduous trees and plants have been promoted as a means of controlling solar heating and cooling. When planted on the southern side of a building, their leaves provide shade during the summer, while the bare limbs allow light to pass during the winter.[44] Since bare, leafless trees shade 1/3 to 1/2 of incident solar radiation, there is a balance between the benefits of summer shading and the corresponding loss of winter heating.[45] In climates with significant heating loads, deciduous trees should not be planted on the southern side of a building because they will interfere with winter solar availability. They can, however, be used on the east and west sides to provide a degree of summer shading without appreciably affecting winter solar gain.[46]
Water treatment
Main articles: Solar still, Solar water disinfection, Solar desalination, and Solar Powered Desalination Unit
Solar water disinfection in Indonesia
Small scale solar powered sewerage treatment plant.
Solar distillation can be used to make saline or brackish water potable. The first recorded instance of this was by 16th century Arab alchemists.[47] A large-scale solar distillation project was first constructed in 1872 in the Chilean mining town of Las Salinas.[48] The plant, which had solar collection area of 4,700 m², could produce up to 22,700 L per day and operated for 40 years.[48] Individual still designs include single-slope, double-slope (or greenhouse type), vertical, conical, inverted absorber, multi-wick, and multiple effect.[47] These stills can operate in passive, active, or hybrid modes. Double-slope stills are the most economical for decentralized domestic purposes, while active multiple effect units are more suitable for large-scale applications.[47]
Solar water disinfection (SODIS) involves exposing water-filled plastic polyethylene terephthalate (PET) bottles to sunlight for several hours.[49] Exposure times vary depending on weather and climate from a minimum of six hours to two days during fully overcast conditions.[50] It is recommended by the World Health Organization as a viable method for household water treatment and safe storage.[51] Over two million people in developing countries use this method for their daily drinking water.[50]
Solar energy may be used in a water stabilisation pond to treat waste water without chemicals or electricity. A further environmental advantage is that algae grow in such ponds and consume carbon dioxide in photosynthesis, although algae may produce toxic chemicals that make the water unusable.[52][53]
Cooking
Main article: Solar cooker
The Solar Bowl in Auroville, India, concentrates sunlight on a movable receiver to produce steam for cooking.
Solar cookers use sunlight for cooking, drying and pasteurization. They can be grouped into three broad categories: box cookers, panel cookers and reflector cookers.[54] The simplest solar cooker is the box cooker first built by Horace de Saussure in 1767.[55] A basic box cooker consists of an insulated container with a transparent lid. It can be used effectively with partially overcast skies and will typically reach temperatures of 90–150 °C.[56] Panel cookers use a reflective panel to direct sunlight onto an insulated container and reach temperatures comparable to box cookers. Reflector cookers use various concentrating geometries (dish, trough, Fresnel mirrors) to focus light on a cooking container. These cookers reach temperatures of 315 °C and above but require direct light to function properly and must be repositioned to track the Sun.[57]
The solar bowl is a concentrating technology employed by the Solar Kitchen in Auroville, Pondicherry, India, where a stationary spherical reflector focuses light along a line perpendicular to the sphere's interior surface, and a computer control system moves the receiver to intersect this line. Steam is produced in the receiver at temperatures reaching 150 °C and then used for process heat in the kitchen.[58]
A reflector developed by Wolfgang Scheffler in 1986 is used in many solar kitchens. Scheffler reflectors are flexible parabolic dishes that combine aspects of trough and power tower concentrators. Polar tracking is used to follow the Sun's daily course and the curvature of the reflector is adjusted for seasonal variations in the incident angle of sunlight. These reflectors can reach temperatures of 450–650 °C and have a fixed focal point, which simplifies cooking.[59] The world's largest Scheffler reflector system in Abu Road, Rajasthan, India is capable of cooking up to 35,000 meals a day.[60] As of 2008, over 2,000 large Scheffler cookers had been built worldwide.[61]
Process heat
Main articles: Solar pond, Salt evaporation pond, and Solar furnace
STEP parabolic dishes used for steam production and electrical generation.
Solar concentrating technologies such as parabolic dish, trough and Scheffler reflectors can provide process heat for commercial and industrial applications. The first commercial system was the Solar Total Energy Project (STEP) in Shenandoah, Georgia, USA where a field of 114 parabolic dishes provided 50% of the process heating, air conditioning and electrical requirements for a clothing factory. This grid-connected cogeneration system provided 400 kW of electricity plus thermal energy in the form of 401 kW steam and 468 kW chilled water, and had a one hour peak load thermal storage.[62]
Evaporation ponds are shallow pools that concentrate dissolved solids through evaporation. The use of evaporation ponds to obtain salt from sea water is one of the oldest applications of solar energy. Modern uses include concentrating brine solutions used in leach mining and removing dissolved solids from waste streams.[63]
Clothes lines, clotheshorses, and clothes racks dry clothes through evaporation by wind and sunlight without consuming electricity or gas. In some states of the United States legislation protects the "right to dry" clothes.[64]
Unglazed transpired collectors (UTC) are perforated sun-facing walls used for preheating ventilation air. UTCs can raise the incoming air temperature up to 22 °C and deliver outlet temperatures of 45–60 °C.[65] The short payback period of transpired collectors (3 to 12 years) makes them a more cost-effective alternative than glazed collection systems.[65] As of 2003, over 80 systems with a combined collector area of 35,000 m² had been installed worldwide, including an 860 m² collector in Costa Rica used for drying coffee beans and a 1,300 m² collector in Coimbatore, India used for drying marigolds.[26]
Electrical generation
Main article: Solar power
The PS10 concentrates sunlight from a field of heliostats on a central tower.
Solar power is the conversion of sunlight into electricity, either directly using photovoltaics (PV), or indirectly using concentrated solar power (CSP). CSP systems use lenses or mirrors and tracking systems to focus a large area of sunlight into a small beam. PV converts light into electric current using the photoelectric effect.
Commercial CSP plants were first developed in the 1980s, and the 354 MW SEGS CSP installation is the largest solar power plant in the world and is located in the Mojave Desert of California. Other large CSP plants include the Solnova Solar Power Station (150 MW) and the Andasol solar power station (100 MW), both in Spain. The 80 MW Sarnia Photovoltaic Power Plant in Canada, is the world’s largest photovoltaic plant.
Experimental solar power
Main articles: Solar pond and Thermogenerator
Solar Evaporation Ponds in the Atacama Desert, South America
A solar pond is a pool of salt water (usually 1–2 m deep) that collects and stores solar energy. Solar ponds were first proposed by Dr. Rudolph Bloch in 1948 after he came across reports of a lake in Hungary in which the temperature increased with depth. This effect was due to salts in the lake's water, which created a "density gradient" that prevented convection currents. A prototype was constructed in 1958 on the shores of the Dead Sea near Jerusalem.[66] The pond consisted of layers of water that successively increased from a weak salt solution at the top to a high salt solution at the bottom. This solar pond was capable of producing temperatures of 90 °C in its bottom layer and had an estimated solar-to-electric efficiency of two percent.
Thermoelectric, or "thermovoltaic" devices convert a temperature difference between dissimilar materials into an electric current. First proposed as a method to store solar energy by solar pioneer Mouchout in the 1800s,[67] thermoelectrics reemerged in the Soviet Union during the 1930s. Under the direction of Soviet scientist Abram Ioffe a concentrating system was used to thermoelectrically generate power for a 1 hp engine.[68] Thermogenerators were later used in the US space program as an energy conversion technology for powering deep space missions such as Cassini, Galileo and Viking. Research in this area is focused on raising the efficiency of these devices from 7–8% to 15–20%.[69]
Solar chemical
Main article: Solar chemical
Solar chemical processes use solar energy to drive chemical reactions. These processes offset energy that would otherwise come from an alternate source and can convert solar energy into storable and transportable fuels. Solar induced chemical reactions can be divided into thermochemical or photochemical.[70]
Hydrogen production technologies been a significant area of solar chemical research since the 1970s. Aside from electrolysis driven by photovoltaic or photochemical cells, several thermochemical processes have also been explored. One such route uses concentrators to split water into oxygen and hydrogen at high temperatures (2300-2600 °C).[71] Another approach uses the heat from solar concentrators to drive the steam reformation of natural gas thereby increasing the overall hydrogen yield compared to conventional reforming methods.[72] Thermochemical cycles characterized by the decomposition and regeneration of reactants present another avenue for hydrogen production. The Solzinc process under development at the Weizmann Institute uses a 1 MW solar furnace to decompose zinc oxide (ZnO) at temperatures above 1200 °C. This initial reaction produces pure zinc, which can subsequently be reacted with water to produce hydrogen.[73]
Sandia's Sunshine to Petrol (S2P) technology uses the high temperatures generated by concentrating sunlight along with a zirconia/ferrite catalyst to break down atmospheric carbon dioxide into oxygen and carbon monoxide (CO). The carbon monoxide can then be used to synthesize conventional fuels such as methanol, gasoline and jet fuel.[74]
A photogalvanic device is a type of battery in which the cell solution (or equivalent) forms energy-rich chemical intermediates when illuminated. These energy-rich intermediates can potentially be stored and subsequently reacted at the electrodes to produce an electric potential. The ferric-thionine chemical cell is an example of this technology.[75]
Photoelectrochemical cells or PECs consist of a semiconductor, typically titanium dioxide or related titanates, immersed in an electrolyte. When the semiconductor is illuminated an electrical potential develops. There are two types of photoelectrochemical cells: photoelectric cells that convert light into electricity and photochemical cells that use light to drive chemical reactions such as electrolysis.[76]
A combination thermal/photochemical cell has also been proposed. The Stanford PETE process uses solar thermal energy to raise the temperature of a thermionic metal to about 800C to increase the rate of production of electricity to electrolyse atmospheric CO2 down to carbon or carbon monoxide which can then be used for fuel production, and the waste heat can be used as well.[77]
Solar vehicles
Main articles: Solar vehicle, Solar-charged vehicle, Electric boat, and Solar balloon
Australia hosts the World Solar Challenge where solar cars like the Nuna3 race through a 3,021 km (1,877 mi) course from Darwin to Adelaide.
Development of a solar powered car has been an engineering goal since the 1980s. The World Solar Challenge is a biannual solar-powered car race, where teams from universities and enterprises compete over 3,021 kilometres (1,877 mi) across central Australia from Darwin to Adelaide. In 1987, when it was founded, the winner's average speed was 67 kilometres per hour (42 mph) and by 2007 the winner's average speed had improved to 90.87 kilometres per hour (56.46 mph).[78] The North American Solar Challenge and the planned South African Solar Challenge are comparable competitions that reflect an international interest in the engineering and development of solar powered vehicles.[79][80]
Some vehicles use solar panels for auxiliary power, such as for air conditioning, to keep the interior cool, thus reducing fuel consumption.[81][82]
In 1975, the first practical solar boat was constructed in England.[83] By 1995, passenger boats incorporating PV panels began appearing and are now used extensively.[84] In 1996, Kenichi Horie made the first solar powered crossing of the Pacific Ocean, and the sun21 catamaran made the first solar powered crossing of the Atlantic Ocean in the winter of 2006–2007.[85] There are plans to circumnavigate the globe in 2010.[86]
Helios UAV in solar powered flight.
In 1974, the unmanned AstroFlight Sunrise plane made the first solar flight. On 29 April 1979, the Solar Riser made the first flight in a solar powered, fully controlled, man carrying flying machine, reaching an altitude of 40 feet (12 m). In 1980, the Gossamer Penguin made the first piloted flights powered solely by photovoltaics. This was quickly followed by the Solar Challenger which crossed the English Channel in July 1981. In 1990 Eric Raymond in 21 hops flew from California to North Carolina using solar power.[87] Developments then turned back to unmanned aerial vehicles (UAV) with the Pathfinder (1997) and subsequent designs, culminating in the Helios which set the altitude record for a non-rocket-propelled aircraft at 29,524 metres (96,864 ft) in 2001.[88] The Zephyr, developed by BAE Systems, is the latest in a line of record-breaking solar aircraft, making a 54-hour flight in 2007, and month-long flights are envisioned by 2010.[89]
A solar balloon is a black balloon that is filled with ordinary air. As sunlight shines on the balloon, the air inside is heated and expands causing an upward buoyancy force, much like an artificially heated hot air balloon. Some solar balloons are large enough for human flight, but usage is generally limited to the toy market as the surface-area to payload-weight ratio is relatively high.[90]
Solar sails are a proposed form of spacecraft propulsion using large membrane mirrors to exploit radiation pressure from the Sun. Unlike rockets, solar sails require no fuel. Although the thrust is small compared to rockets, it continues as long as the Sun shines onto the deployed sail and in the vacuum of space significant speeds can eventually be achieved.[91]
The High-altitude airship (HAA) is an unmanned, long-duration, lighter-than-air vehicle using helium gas for lift, and thin film solar cells for power. The United States Department of Defense Missile Defense Agency has contracted Lockheed Martin to construct it to enhance the Ballistic Missile Defense System (BMDS).[92] Airships have some advantages for solar-powered flight: they do not require power to remain aloft, and an airship's envelope presents a large area to the Sun.
Energy storage methods
Main articles: Thermal mass, Thermal energy storage, Phase change material, Grid energy storage, and V2G
Solar Two's thermal storage system generated electricity during cloudy weather and at night.
Solar energy is not available at night, and energy storage is an important issue because modern energy systems usually assume continuous availability of energy.[93]
Thermal mass systems can store solar energy in the form of heat at domestically useful temperatures for daily or seasonal durations. Thermal storage systems generally use readily available materials with high specific heat capacities such as water, earth and stone. Well-designed systems can lower peak demand, shift time-of-use to off-peak hours and reduce overall heating and cooling requirements.[94][95]
Phase change materials such as paraffin wax and Glauber's salt are another thermal storage media. These materials are inexpensive, readily available, and can deliver domestically useful temperatures (approximately 64 °C). The "Dover House" (in Dover, Massachusetts) was the first to use a Glauber's salt heating system, in 1948.[96]
Solar energy can be stored at high temperatures using molten salts. Salts are an effective storage medium because they are low-cost, have a high specific heat capacity and can deliver heat at temperatures compatible with conventional power systems. The Solar Two used this method of energy storage, allowing it to store 1.44 TJ in its 68 m³ storage tank with an annual storage efficiency of about 99%.[97]
Off-grid PV systems have traditionally used rechargeable batteries to store excess electricity. With grid-tied systems, excess electricity can be sent to the transmission grid. Net metering programs give these systems a credit for the electricity they deliver to the grid. This credit offsets electricity provided from the grid when the system cannot meet demand, effectively using the grid as a storage mechanism.[98]
Pumped-storage hydroelectricity stores energy in the form of water pumped when energy is available from a lower elevation reservoir to a higher elevation one. The energy is recovered when demand is high by releasing the water to run through a hydroelectric power generator.[99]
Development, deployment and economics
Main article: Deployment of solar power to energy grids
A parabolic dish and stirling engine system, which concentrates sunlight to produce useful solar power.
Beginning with the surge in coal use which accompanied the Industrial Revolution, energy consumption has steadily transitioned from wood and biomass to fossil fuels. The early development of solar technologies starting in the 1860s was driven by an expectation that coal would soon become scarce. However development of solar technologies stagnated in the early 20th century in the face of the increasing availability, economy, and utility of coal and petroleum.[100]
The 1973 oil embargo and 1979 energy crisis caused a reorganization of energy policies around the world and brought renewed attention to developing solar technologies.[101][102] Deployment strategies focused on incentive programs such as the Federal Photovoltaic Utilization Program in the US and the Sunshine Program in Japan. Other efforts included the formation of research facilities in the US (SERI, now NREL), Japan (NEDO), and Germany (Fraunhofer Institute for Solar Energy Systems ISE).[103]
Commercial solar water heaters began appearing in the United States in the 1890s.[104] These systems saw increasing use until the 1920s but were gradually replaced by cheaper and more reliable heating fuels.[105] As with photovoltaics, solar water heating attracted renewed attention as a result of the oil crises in the 1970s but interest subsided in the 1980s due to falling petroleum prices. Development in the solar water heating sector progressed steadily throughout the 1990s and growth rates have averaged 20% per year since 1999.[39] Although generally underestimated, solar water heating and cooling is by far the most widely deployed solar technology with an estimated capacity of 154 GW as of 2007.[39]
ISO Standards
The International Organization for Standardization has established a number of standards relating to solar energy equipment. For example, ISO 9050 relates to glass in building while ISO 10217 relates to the materials used in solar water heaters.
Tuesday, January 18, 2011
Efficient energy use
Efficient energy use, sometimes simply called energy efficiency, is the goal of efforts to reduce the amount of energy required to provide products and services. For example, insulating a home allows a building to use less heating and cooling energy to achieve and maintain a comfortable temperature. Installing fluorescent lights or natural skylights reduces the amount of energy required to attain the same level of illumination compared to using traditional incandescent light bulbs. Compact fluorescent lights use two-thirds less energy and may last 6 to 10 times longer than incandescent lights. Improvements in energy efficiency are most often achieved by adopting a more efficient technology or production process.[2]
There are various motivations to improve energy efficiency. Reducing energy use reduces energy costs and may result in a financial cost saving to consumers if the energy savings offset any additional costs of implementing an energy efficient technology. Reducing energy use is also seen as a key solution to the problem of reducing greenhouse gas emissions. According to the International Energy Agency, improved energy efficiency in buildings, industrial processes and transportation could reduce the world's energy needs in 2050 by one third, and help control global emissions of greenhouse gases.[3]
Energy efficiency and renewable energy are said to be the twin pillars of sustainable energy policy.[4] In many countries energy efficiency is also seen to have a national security benefit because it can be used to reduce the level of energy imports from foreign countries and may slow down the rate at which domestic energy resources are depleted.
Overview
Making homes, vehicles, and businesses more energy efficient is seen as a largely untapped solution to addressing the problems of pollution, global warming, energy security, and fossil fuel depletion. Many of these ideas have been discussed for years, since the 1973 oil crisis brought energy issues to the forefront. In the late 1970s, physicist Amory Lovins popularized the notion of a "soft energy path", with a strong focus on energy efficiency. Among other things, Lovins popularized the notion of negawatts—the idea of meeting energy needs by increasing efficiency instead of increasing energy production.
Energy efficiency has proved to be a cost-effective strategy for building economies without necessarily growing energy consumption. For example, the state of California began implementing energy-efficiency measures in the mid-1970s, including building code and appliance standards with strict efficiency requirements. During the following years, California's energy consumption has remained approximately flat on a per capita basis while national U.S. consumption doubled. As part of its strategy, California implemented a "loading order" for new energy resources that puts energy efficiency first, renewable electricity supplies second, and new fossil-fired power plants last.[5]
Lovins' Rocky Mountain Institute points out that in industrial settings, "there are abundant opportunities to save 70% to 90% of the energy and cost for lighting, fan, and pump systems; 50% for electric motors; and 60% in areas such as heating, cooling, office equipment, and appliances." In general, up to 75% of the electricity used in the U.S. today could be saved with efficiency measures that cost less than the electricity itself. The same holds true for home-owners, leaky ducts have remained an invisible energy culprit for years. In fact, researchers at the US Department of Energy and their consortium, Residential Energy Efficient Distribution Systems (REEDS) have found that duct efficiency may be as low as 50-70%. The US Department of Energy has stated that there is potential for energy saving in the magnitude of 90 Billion kWh by increasing home energy efficiency.[6]
Other studies have emphasized this. A report published in 2006 by the McKinsey Global Institute, asserted that "there are sufficient economically viable opportunities for energy-productivity improvements that could keep global energy-demand growth at less than 1 percent per annum"—less than half of the 2.2 percent average growth anticipated through 2020 in a business-as-usual scenario. Energy productivity, which measures the output and quality of goods and services per unit of energy input, can come from either reducing the amount of energy required to produce something, or from increasing the quantity or quality of goods and services from the same amount of energy.
The Vienna Climate Change Talks 2007 Report, under the auspices of the United Nations Framework Convention on Climate Change (UNFCCC), clearly shows "that energy efficiency can achieve real emission reductions at low cost."[7]
[edit] Appliances
EU energy label.png
See also: green computing, solar lamp, energy saving lamp, and power usage effectiveness
Modern energy-efficient appliances, such as refrigerators, freezers, ovens, stoves, dishwashers, and clothes washers and dryers, use significantly less energy than older appliances. Current energy efficient refrigerators, for example, use 40 percent less energy than conventional models did in 2001. Following this, if all households in Europe changed their more than ten year old appliances into new ones, 20 billion kWh of electricity would be saved annually, hence reducing CO2 emissions by almost 18 billion kg.[8] In the US, the corresponding figures would be 17 billion kWh of electricity and 27,000,000,000 lb (1.2×1010 kg) CO2.[9] According to a 2009 study from McKinsey & Company the replacement of old appliances is one of the most efficient global measures to reduce emissions of greenhouse gases.[10] Modern power management systems also reduce energy usage by idle appliances by turning them off or putting them into a low-energy mode after a certain time. Many countries identify energy-efficient appliances using energy input labeling.[11]
The impact of energy efficiency on peak demand depends on when the appliance is used.[12] For example, an air conditioner uses more energy during the afternoon when it is hot. Therefore, an energy efficient air conditioner will have a larger impact on peak demand than off-peak demand. An energy efficient dishwasher, on the other hand, uses more energy during the late evening when people do their dishes. This appliance may have little to no impact on peak demand.
[edit] Building design
See also: building performance, energy efficiency in British housing, energy-efficient landscaping, window insulation film, and phase-out of incandescent light bulbs
A building’s location and surroundings play a key role in regulating its temperature and illumination. For example, trees, landscaping, and hills can provide shade and block wind. In cooler climates, designing buildings with a south facing windows increases the amount of sun (ultimately heat energy) entering the building, minimizing energy use, by maximizing passive solar heating. Tight building design, including energy-efficient windows, well-sealed doors, and additional thermal insulation of walls, basement slabs, and foundations can reduce heat loss by 25 to 50 percent.[11]
Dark roofs may become up to 39 C° (70 F°) hotter than the most reflective white surfaces, and they transmit some of this additional heat inside the building. US Studies have shown that lightly colored roofs use 40 percent less energy for cooling than buildings with darker roofs. White roof systems save more energy in sunnier climates. Advanced electronic heating and cooling systems can moderate energy consumption and improve the comfort of people in the building.[11]
Proper placement of windows and skylights and use of architectural features that reflect light into a building, can reduce the need for artificial lighting. Increased use of natural and task lighting have been shown by one study to increase productivity in schools and offices.[11] Compact fluorescent lights use two-thirds less energy and may last 6 to 10 times longer than incandescent light bulbs. Newer fluorescent lights produce a natural light, and in most applications they are cost effective, despite their higher initial cost, with payback periods as low as a few months.[13]
Effective energy-efficient building design can include the use of low cost Passive Infra Reds (PIRs) to switch-off lighting when areas are unnoccupied such as toilets, corridors or even office areas out-of-hours. In addition, lux levels can be monitored using daylight sensors linked to the building's lighting scheme to switch on/off or dim the lighting to pre-defined levels to take into account the natural light and thus reduce consumption. Building Management Systems (BMS) link all of this together in one centralised computer to control the whole building's lighting and power requirements.[14]
The choice of which space heating or cooling technology to use in buildings can have a significant impact on energy use and efficiency. For example, replacing an older 50% efficient natural gas furnace with a new 95% one will dramatically reduce energy use, carbon emissions, and winter natural gas bills. Ground source heat pumps can be even more energy efficient and cost effective. These systems use pumps and compressors to move refrigerant fluid around a thermodynamic cycle in order to "pump" heat against its natural flow from hot to cold, for the purpose of transferring heat into a building from the large thermal reservoir contained within the nearby ground. The end result is that heat pumps typically use four times less electrical energy to deliver an equivalent amount of heat than a direct electrical heater does. Another advantage of a ground source heat pump is that it can be reversed in summertime and operate to cool the air by transferring heat from the building to the ground. The disadvantage of ground source heat pumps is their high initial capital cost, but this is typically recouped within 5 to 10 years as a result of lower energy use.
Smart meters are slowly being adopted by the commerial sector to highlight to staff and for internal monitoring purposes the building's energy usage in a dynamic presentable format. The use of Power Quality Analysers can be introduced into an existing building to assess usage, harmonic distortion, peaks, swells and interruptions amongst others to ultimately make the building more energy-efficient. Often such meters communicate by using wireless sensor networks.[15]
A term relevant for efficient energy use is energy use intensity, which is defined as energy consumption per floor area.[16]
[edit] Industry
Industry uses a large amount of energy to power a diverse range of manufacturing and resource extraction processes. Many industrial processes require large amounts of heat and mechanical power, most of which is delivered as natural gas, petroleum fuels and as electricity. In addition some industries generate fuel from waste products that can be used to provide additional energy.
Because industrial processes are so diverse it is impossible to describe the multitude of possible opportunities for energy efficiency in industry. Many depend on the specific technologies and processes in use at each industrial facility. However there are a number of processes and energy services that are widely used in many industries.
Various industries generate steam and electricity for subsequent use within their facilities. When electricity is generated, the heat that is produced as a by-product can be captured and used for process steam, heating or other industrial purposes. Conventional electricity generation is about 30 percent efficient, whereas combined heat and power (also called co-generation) converts up to 90 percent of the fuel into usable energy.[17]
Advanced boilers and furnaces can operate at higher temperatures while burning less fuel. These technologies are more efficient and produce fewer pollutants.[17]
Over 45 percent of the fuel used by US manufacturers is burnt to make steam. The typical industrial facility can reduce this energy usage 20 percent (according to the US Department of Energy) by insulating steam and condensate return lines, stopping steam leakage, and maintaining steam traps.[17]
Electric motors usually run at a constant speed, but a variable speed drive allows the motor’s energy output to match the required load. This achieves energy savings ranging from 3 to 60 percent, depending on how the motor is used. Motor coils made of superconducting materials can also reduce energy losses.[17] Motors may also benefit from voltage optimisation.
Industry uses a large number of pumps and compressors of all shapes and sizes and in a wide variety of applications. The efficiency of pumps and compressors depends on many factors but often improvements can be made by implementing better process control and better maintenance practices. Compressors are commonly used to provide compressed air which is used for sand blasting, painting, and other power tools. According to the US Department of Energy, optimizing compressed air systems by installing variable speed drives, along with preventive maintenance to detect and fix air leaks, can improve energy efficiency 20 to 50 percent.[17]
[edit] Vehicles
See also: Alternative fuel vehicle and Plug-in hybrid vehicle
The estimated energy efficiency for an automobile is 280 Passenger-Mile/106 Btu.[18] There are several ways to enhance a vehicle's energy efficiency. Using improved aerodynamics to minimize drag can increase vehicle fuel efficiency. Reducing vehicle weight can also improve fuel economy, which is why composite materials are widely used in car bodies.
More advanced tires, with decreased tire to road friction and rolling resistance, can save gasoline. Fuel economy can be improved by up to 3.3% by keeping tires inflated to the correct pressure.[19] Replacing a clogged air filter can improve a cars fuel consumption by as much as 10 percent on older vehicles.[20] On newer vehicles (1980's and up) with fuel-injected, computer-controlled engines, a clogged air filter has no effect on mpg but replacing it may improve acceleration by 6-11 percent.[21]
Energy-efficient vehicles may reach twice the fuel efficiency of the average automobile. Cutting-edge designs, such as the diesel Mercedes-Benz Bionic concept vehicle have achieved a fuel efficiency as high as 84 miles per US gallon (2.8 L/100 km; 101 mpg-imp), four times the current conventional automotive average.[20]
The mainstream trend in automotive efficiency is the rise of electric vehicles (all@electric or hybrid electric). Hybrids, like the Toyota Prius, use regenerative braking to recapture energy that would dissipate in normal cars; the effect is especially pronounced in city driving. plug-in hybrids also have increased battery capacity, which makes it possible to drive for limited distances without burning any gasoline; in this case, energy efficiency is dictated by whatever process (such as coal-burning, hydroelectric, or renewable source) created the power. Plug-ins can typically drive for around 40 miles (64 km) purely on electricity without recharging; if the battery runs low, a gas engine kicks in allowing for extended range. Finally, all-electric cars are also growing in popularity; the Tesla Roadster sports car is the only high-performance all-electric car currently on the market, and others are in preproduction.[22]
[edit] Energy conservation
Main article: Energy conservation
Energy conservation is broader than energy efficiency in including active efforts to decrease energy consumption, for example through behavioural change, in addition to using energy more efficiently. Examples of conservation without efficiency improvements are heating a room less in winter, using the car less, or enabling energy saving modes on a computer. As with other definitions, the boundary between efficient energy use and energy conservation can be fuzzy, but both are important in environmental and economic terms.[23] This is especially the case when actions are directed at the saving of fossil fuels.[24] Energy conservation is a challenge requiring policy programmes, technological development and behavioral change to go hand in hand. Many energy intermediary organisations, for example governmental or non-governmental organisations on local, regional, or national level, are working on often publicly funded programmes or projects to meet this challenge.[25]
[edit] Sustainable energy
Main article: Sustainable energy
Energy efficiency and renewable energy are said to be the “twin pillars” of a sustainable energy policy. Both strategies must be developed concurrently in order to stabilize and reduce carbon dioxide emissions. Efficient energy use is essential to slowing the energy demand growth so that rising clean energy supplies can make deep cuts in fossil fuel use. If energy use grows too rapidly, renewable energy development will chase a receding target. Likewise, unless clean energy supplies come online rapidly, slowing demand growth will only begin to reduce total carbon emissions; a reduction in the carbon content of energy sources is also needed. A sustainable energy economy thus requires major commitments to both efficiency and renewables.[26]
[edit] Rebound effect
Further information: Rebound effect (conservation) and Jevons' paradox
If the demand for energy services remains constant, improving energy efficiency will reduce energy consumption and carbon emissions. However, many efficiency improvements do not reduce energy consumption by the amount predicted by simple engineering models. This is because they make energy services cheaper, and so consumption of those services increases. For example, since fuel efficient vehicles make travel cheaper, consumers may choose to drive farther and/or faster, thereby offsetting some of the potential energy savings. This is an example of the direct rebound effect.[27]
Estimates of the size of the rebound effect range from roughly 5% to 40%.[28][29][30] The rebound effect is likely to be less than 30% at the household level and may be closer to 10% for transport.[27] A rebound effect of 30% implies that improvements in energy efficiency should achieve 70% of the reduction in energy consumption projected using engineering models.
Since more efficient (and hence cheaper) energy will also lead to faster economic growth, there are suspicions that improvements in energy efficiency may eventually lead to even faster resource use. This was postulated by economists in the 1980s and remains a controversial hypothesis. Ecological economists have suggested that any cost savings from efficiency gains be taxed away by the government in order to avoid this outcome.[31]
[edit] Organizations and programs for promoting energy efficiency
International
* 80 PLUS
* 2000-watt society
* IEA Solar Heating & Cooling Implementing Agreement Task 13
* International Institute for Energy Conservation
* International Energy Agency (e.g. One watt initiative)
* International Electrotechnical Commission
* International Partnership for Energy Efficiency Cooperation
* World Sustainable Energy Days
Australia
* Department of Climate Change and Energy Efficiency
* Department of the Environment, Water, Heritage and the Arts
* Sustainable House Day
European Union
* Building energy rating
* Eco-Design of Energy-Using Products Directive
* Energy efficiency in Europe
* Orgalime, the European engineering industries association
Iceland
* Marorka
India
* 88888 Lights Out
Japan
* Cool Biz campaign
Lebanon
* The Lebanese Center for Energy Conservation
United Kingdom
* The Carbon Trust
* Energy Saving Trust
* National Energy Action
* National Energy Foundation
United States
* Alliance to Save Energy
* American Council for an Energy-Efficient Economy (ACEEE)
* Building Codes Assistance Project
* Building Energy Codes Program
* Energy Star, from United States Environmental Protection Agency
* Industrial Assessment Center
* National Electrical Manufacturers Association
* Rocky Mountain Institute
[edit] See also
Crystal energy.svg Energy portal
* Cogeneration
* Data center infrastructure efficiency
* Electrical energy efficiency on United States farms
* Electric vehicle#Efficiency
* Energy audit
* Energy policy
* Energy recovery
* Energy resilience
* Performance per watt
* Green energy
* Home performance
* Negawatt power
* One watt initiative
* Passenger miles per gallon
* Renewable heat
* Standby power
* U.S. Department of Energy Solar Decathlon
* World Energy Engineering Congress
[edit] References
1. ^ "Philips Tornado Asian Compact Fluorescent". Philips. http://www.lamptech.co.uk/Spec%20Sheets/Philips%20CFL%20Tornado.htm. Retrieved 2007-12-24.
2. ^ Diesendorf, Mark (2007). Greenhouse Solutions with Sustainable Energy, UNSW Press, p. 86.
3. ^ Sophie Hebden (2006-06-22). "Invest in clean technology says IEA report". Scidev.net. http://www.scidev.net/News/index.cfm?fuseaction=readNews&itemid=2929&language=1. Retrieved 2010-07-16.
4. ^ "The Twin Pillars of Sustainable Energy: Synergies between Energy Efficiency and Renewable Energy Technology and Policy". Aceee.org. Archived from the original on 2008-05-05. http://web.archive.org/web/20080505041521/http://aceee.org/store/proddetail.cfm?CFID=2957330&CFTOKEN=50269931&ItemID=432&CategoryID=7. Retrieved 2010-07-16.
5. ^ "Loading Order White Paper" (PDF). http://www.energy.ca.gov/2005publications/CEC-400-2005-043/CEC-400-2005-043.PDF. Retrieved 2010-07-16.
6. ^ "Weatherization in Austin, Texas". Green Collar Operations. http://www.greencollaroperations.com/weatherization-austin-tx.html. Retrieved 2010-07-16.
7. ^ "Microsoft Word - 20070831_vienna_closing_press_release.doc" (PDF). http://unfccc.int/files/press/news_room/press_releases_and_advisories/application/pdf/20070831_vienna_closing_press_release.pdf. Retrieved 2010-07-16.
8. ^ "Ecosavings". Electrolux.com. http://www.electrolux.com/ecosavings. Retrieved 2010-07-16.
9. ^ "Ecosavings (Tm) Calculator". Electrolux.com. http://www.electrolux.com/ecosavings_us. Retrieved 2010-07-16.
10. ^ McKinsey & Company (2009). Pathway to a Low-Carbon Economy : Version 3 of the Global Greenhouse Gas Abatement Cost Curve, p. 7.
11. ^ a b c d Environmental and Energy Study Institute. "Energy-Efficient Buildings: Using whole building design to reduce energy consumption in homes and offices". Eesi.org. http://www.eesi.org/publications/Fact%20Sheets/EC_Fact_Sheets/EE_Buildings.pdf. Retrieved 2010-07-16.
12. ^ "The impact of energy efficiency on peak demand". Energydsm.com. http://www.energydsm.com/energy-efficiency. Retrieved 2010-07-16.
13. ^ CFL savings calculator, Green Energy Efficient Homes
14. ^ Creating Energy Efficient Offices - Electrical Contractor Fit-out Article
15. ^ "Wireless smart meter by ecowizard". Ecowizard.net. http://www.ecowizard.net/. Retrieved 2010-07-16.
16. ^ www.ashrae.org/members/doc/shapiro_8090903.pdf
17. ^ a b c d e Environmental and Energy Study Institute. "Industrial Energy Efficiency: Using new technologies to reduce energy use in industry and manufacturing". Eesi.org. http://www.eesi.org/publications/Fact%20Sheets/EC_Fact_Sheets/EE_Industry.pdf. Retrieved 2010-07-16.
18. ^ Richard C. Dorf, The Energy Factbook, McGraw-Hill, 1981
19. ^ "Tips to improve your Gas Mileage". Fueleconomy.gov. http://www.fueleconomy.gov/feg/maintain.shtml. Retrieved 2010-07-16.
20. ^ a b Automotive Efficiency: Using technology to reduce energy use in passenger vehicles and light trucks[dead link]
21. ^ http://www.fueleconomy.gov/feg/pdfs/Air_Filter_Effects_02_26_2009.pdf
22. ^ "2008 Tesla Roadster - Car News". Car and Driver. http://www.caranddriver.com/reviews/hot_lists/car_shopping/green_machines/2008_tesla_roadster_car_news. Retrieved 2010-07-16.
23. ^ Dietz, T. et al. (2009).Household actions can provide a behavioral wedge to rapidly reduce U.S. carbon emissions. PNAS. 106(44).
24. ^ Diesendorf, Mark (2007). Greenhouse Solutions with Sustainable Energy, UNSW Press, p. 87.
25. ^ Breukers, Heiskanen, et al. (2009). Interaction schemes for successful demand-side management. Deliverable 5 of the CHANGING BEHAVIOUR project. Funded by the EC (#213217).
26. ^ The Twin Pillars of Sustainable Energy: Synergies between Energy Efficiency and Renewable Energy Technology and Policy (American Council for an Energy-Efficient Economy)
27. ^ a b The Rebound Effect: an assessment of the evidence for economy-wide energy savings from improved energy efficiency pp. v-vi.
28. ^ Greening, L; David L. Greene, Carmen Difiglio (2000). "Energy efficiency and consumption—the rebound effect—a survey.". Energy Policy 28: 389–401. doi:10.1016/S0301-4215(00)00021-5
29. ^ Kenneth A. Small and Kurt Van Dender (September 21, 2005). "The Effect of Improved Fuel Economy on Vehicle Miles Traveled: Estimating the Rebound Effect Using U.S. State Data, 1966-2001". University of California Energy Institute: Policy & Economics. http://repositories.cdlib.org/ucei/policy/EPE-014. Retrieved 2007-11-23.
30. ^ "Energy Efficiency and the Rebound Effect: Does Increasing Efficiency Decrease Demand?". http://www.ncseonline.org/nle/crsreports/energy/eng-80.cfm?&CFID=11262148&CFTOKEN=7028302. Retrieved 2007-11-21.
31. ^ Wackernagel, Mathis and William Rees, 1997, "Perpetual and structural barriers to investing in natural capital: economics from an ecological footprint perspective." Ecological Economics, Vol.20 No.3 p3-24.
Retrieved from "http://en.wikipedia.org/wiki/Efficient_energy_use"
Categories: Energy conservation | Energy policy | Climate change | Industrial ecology | Sustainable energy
Hidden categories: All articles with dead external links | Articles with dead external links from July 2010 | Articles with inconsistent citation formats
Personal tools
* Log in / create account
Namespaces
* Article
* Discussion
Variants
Views
* Read
* Edit
* View history
Actions
Search
Search
Navigation
* Main page
* Contents
* Featured content
* Current events
* Random article
* Donate to Wikipedia
Interaction
* Help
* About Wikipedia
* Community portal
* Recent changes
* Contact Wikipedia
Toolbox
* What links here
* Related changes
* Upload file
* Special pages
* Permanent link
* Cite this page
Print/export
* Create a book
* Download as PDF
* Printable version
Languages
* العربية
* Français
* Magyar
* Polski
* Русский
* This page was last modified on 22 December 2010 at 19:07.
* Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. See Terms of Use for details.
Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
* Contact us
* Privacy policy
* About Wikipedia
* Disclaimer
There are various motivations to improve energy efficiency. Reducing energy use reduces energy costs and may result in a financial cost saving to consumers if the energy savings offset any additional costs of implementing an energy efficient technology. Reducing energy use is also seen as a key solution to the problem of reducing greenhouse gas emissions. According to the International Energy Agency, improved energy efficiency in buildings, industrial processes and transportation could reduce the world's energy needs in 2050 by one third, and help control global emissions of greenhouse gases.[3]
Energy efficiency and renewable energy are said to be the twin pillars of sustainable energy policy.[4] In many countries energy efficiency is also seen to have a national security benefit because it can be used to reduce the level of energy imports from foreign countries and may slow down the rate at which domestic energy resources are depleted.
Overview
Making homes, vehicles, and businesses more energy efficient is seen as a largely untapped solution to addressing the problems of pollution, global warming, energy security, and fossil fuel depletion. Many of these ideas have been discussed for years, since the 1973 oil crisis brought energy issues to the forefront. In the late 1970s, physicist Amory Lovins popularized the notion of a "soft energy path", with a strong focus on energy efficiency. Among other things, Lovins popularized the notion of negawatts—the idea of meeting energy needs by increasing efficiency instead of increasing energy production.
Energy efficiency has proved to be a cost-effective strategy for building economies without necessarily growing energy consumption. For example, the state of California began implementing energy-efficiency measures in the mid-1970s, including building code and appliance standards with strict efficiency requirements. During the following years, California's energy consumption has remained approximately flat on a per capita basis while national U.S. consumption doubled. As part of its strategy, California implemented a "loading order" for new energy resources that puts energy efficiency first, renewable electricity supplies second, and new fossil-fired power plants last.[5]
Lovins' Rocky Mountain Institute points out that in industrial settings, "there are abundant opportunities to save 70% to 90% of the energy and cost for lighting, fan, and pump systems; 50% for electric motors; and 60% in areas such as heating, cooling, office equipment, and appliances." In general, up to 75% of the electricity used in the U.S. today could be saved with efficiency measures that cost less than the electricity itself. The same holds true for home-owners, leaky ducts have remained an invisible energy culprit for years. In fact, researchers at the US Department of Energy and their consortium, Residential Energy Efficient Distribution Systems (REEDS) have found that duct efficiency may be as low as 50-70%. The US Department of Energy has stated that there is potential for energy saving in the magnitude of 90 Billion kWh by increasing home energy efficiency.[6]
Other studies have emphasized this. A report published in 2006 by the McKinsey Global Institute, asserted that "there are sufficient economically viable opportunities for energy-productivity improvements that could keep global energy-demand growth at less than 1 percent per annum"—less than half of the 2.2 percent average growth anticipated through 2020 in a business-as-usual scenario. Energy productivity, which measures the output and quality of goods and services per unit of energy input, can come from either reducing the amount of energy required to produce something, or from increasing the quantity or quality of goods and services from the same amount of energy.
The Vienna Climate Change Talks 2007 Report, under the auspices of the United Nations Framework Convention on Climate Change (UNFCCC), clearly shows "that energy efficiency can achieve real emission reductions at low cost."[7]
[edit] Appliances
EU energy label.png
See also: green computing, solar lamp, energy saving lamp, and power usage effectiveness
Modern energy-efficient appliances, such as refrigerators, freezers, ovens, stoves, dishwashers, and clothes washers and dryers, use significantly less energy than older appliances. Current energy efficient refrigerators, for example, use 40 percent less energy than conventional models did in 2001. Following this, if all households in Europe changed their more than ten year old appliances into new ones, 20 billion kWh of electricity would be saved annually, hence reducing CO2 emissions by almost 18 billion kg.[8] In the US, the corresponding figures would be 17 billion kWh of electricity and 27,000,000,000 lb (1.2×1010 kg) CO2.[9] According to a 2009 study from McKinsey & Company the replacement of old appliances is one of the most efficient global measures to reduce emissions of greenhouse gases.[10] Modern power management systems also reduce energy usage by idle appliances by turning them off or putting them into a low-energy mode after a certain time. Many countries identify energy-efficient appliances using energy input labeling.[11]
The impact of energy efficiency on peak demand depends on when the appliance is used.[12] For example, an air conditioner uses more energy during the afternoon when it is hot. Therefore, an energy efficient air conditioner will have a larger impact on peak demand than off-peak demand. An energy efficient dishwasher, on the other hand, uses more energy during the late evening when people do their dishes. This appliance may have little to no impact on peak demand.
[edit] Building design
See also: building performance, energy efficiency in British housing, energy-efficient landscaping, window insulation film, and phase-out of incandescent light bulbs
A building’s location and surroundings play a key role in regulating its temperature and illumination. For example, trees, landscaping, and hills can provide shade and block wind. In cooler climates, designing buildings with a south facing windows increases the amount of sun (ultimately heat energy) entering the building, minimizing energy use, by maximizing passive solar heating. Tight building design, including energy-efficient windows, well-sealed doors, and additional thermal insulation of walls, basement slabs, and foundations can reduce heat loss by 25 to 50 percent.[11]
Dark roofs may become up to 39 C° (70 F°) hotter than the most reflective white surfaces, and they transmit some of this additional heat inside the building. US Studies have shown that lightly colored roofs use 40 percent less energy for cooling than buildings with darker roofs. White roof systems save more energy in sunnier climates. Advanced electronic heating and cooling systems can moderate energy consumption and improve the comfort of people in the building.[11]
Proper placement of windows and skylights and use of architectural features that reflect light into a building, can reduce the need for artificial lighting. Increased use of natural and task lighting have been shown by one study to increase productivity in schools and offices.[11] Compact fluorescent lights use two-thirds less energy and may last 6 to 10 times longer than incandescent light bulbs. Newer fluorescent lights produce a natural light, and in most applications they are cost effective, despite their higher initial cost, with payback periods as low as a few months.[13]
Effective energy-efficient building design can include the use of low cost Passive Infra Reds (PIRs) to switch-off lighting when areas are unnoccupied such as toilets, corridors or even office areas out-of-hours. In addition, lux levels can be monitored using daylight sensors linked to the building's lighting scheme to switch on/off or dim the lighting to pre-defined levels to take into account the natural light and thus reduce consumption. Building Management Systems (BMS) link all of this together in one centralised computer to control the whole building's lighting and power requirements.[14]
The choice of which space heating or cooling technology to use in buildings can have a significant impact on energy use and efficiency. For example, replacing an older 50% efficient natural gas furnace with a new 95% one will dramatically reduce energy use, carbon emissions, and winter natural gas bills. Ground source heat pumps can be even more energy efficient and cost effective. These systems use pumps and compressors to move refrigerant fluid around a thermodynamic cycle in order to "pump" heat against its natural flow from hot to cold, for the purpose of transferring heat into a building from the large thermal reservoir contained within the nearby ground. The end result is that heat pumps typically use four times less electrical energy to deliver an equivalent amount of heat than a direct electrical heater does. Another advantage of a ground source heat pump is that it can be reversed in summertime and operate to cool the air by transferring heat from the building to the ground. The disadvantage of ground source heat pumps is their high initial capital cost, but this is typically recouped within 5 to 10 years as a result of lower energy use.
Smart meters are slowly being adopted by the commerial sector to highlight to staff and for internal monitoring purposes the building's energy usage in a dynamic presentable format. The use of Power Quality Analysers can be introduced into an existing building to assess usage, harmonic distortion, peaks, swells and interruptions amongst others to ultimately make the building more energy-efficient. Often such meters communicate by using wireless sensor networks.[15]
A term relevant for efficient energy use is energy use intensity, which is defined as energy consumption per floor area.[16]
[edit] Industry
Industry uses a large amount of energy to power a diverse range of manufacturing and resource extraction processes. Many industrial processes require large amounts of heat and mechanical power, most of which is delivered as natural gas, petroleum fuels and as electricity. In addition some industries generate fuel from waste products that can be used to provide additional energy.
Because industrial processes are so diverse it is impossible to describe the multitude of possible opportunities for energy efficiency in industry. Many depend on the specific technologies and processes in use at each industrial facility. However there are a number of processes and energy services that are widely used in many industries.
Various industries generate steam and electricity for subsequent use within their facilities. When electricity is generated, the heat that is produced as a by-product can be captured and used for process steam, heating or other industrial purposes. Conventional electricity generation is about 30 percent efficient, whereas combined heat and power (also called co-generation) converts up to 90 percent of the fuel into usable energy.[17]
Advanced boilers and furnaces can operate at higher temperatures while burning less fuel. These technologies are more efficient and produce fewer pollutants.[17]
Over 45 percent of the fuel used by US manufacturers is burnt to make steam. The typical industrial facility can reduce this energy usage 20 percent (according to the US Department of Energy) by insulating steam and condensate return lines, stopping steam leakage, and maintaining steam traps.[17]
Electric motors usually run at a constant speed, but a variable speed drive allows the motor’s energy output to match the required load. This achieves energy savings ranging from 3 to 60 percent, depending on how the motor is used. Motor coils made of superconducting materials can also reduce energy losses.[17] Motors may also benefit from voltage optimisation.
Industry uses a large number of pumps and compressors of all shapes and sizes and in a wide variety of applications. The efficiency of pumps and compressors depends on many factors but often improvements can be made by implementing better process control and better maintenance practices. Compressors are commonly used to provide compressed air which is used for sand blasting, painting, and other power tools. According to the US Department of Energy, optimizing compressed air systems by installing variable speed drives, along with preventive maintenance to detect and fix air leaks, can improve energy efficiency 20 to 50 percent.[17]
[edit] Vehicles
See also: Alternative fuel vehicle and Plug-in hybrid vehicle
The estimated energy efficiency for an automobile is 280 Passenger-Mile/106 Btu.[18] There are several ways to enhance a vehicle's energy efficiency. Using improved aerodynamics to minimize drag can increase vehicle fuel efficiency. Reducing vehicle weight can also improve fuel economy, which is why composite materials are widely used in car bodies.
More advanced tires, with decreased tire to road friction and rolling resistance, can save gasoline. Fuel economy can be improved by up to 3.3% by keeping tires inflated to the correct pressure.[19] Replacing a clogged air filter can improve a cars fuel consumption by as much as 10 percent on older vehicles.[20] On newer vehicles (1980's and up) with fuel-injected, computer-controlled engines, a clogged air filter has no effect on mpg but replacing it may improve acceleration by 6-11 percent.[21]
Energy-efficient vehicles may reach twice the fuel efficiency of the average automobile. Cutting-edge designs, such as the diesel Mercedes-Benz Bionic concept vehicle have achieved a fuel efficiency as high as 84 miles per US gallon (2.8 L/100 km; 101 mpg-imp), four times the current conventional automotive average.[20]
The mainstream trend in automotive efficiency is the rise of electric vehicles (all@electric or hybrid electric). Hybrids, like the Toyota Prius, use regenerative braking to recapture energy that would dissipate in normal cars; the effect is especially pronounced in city driving. plug-in hybrids also have increased battery capacity, which makes it possible to drive for limited distances without burning any gasoline; in this case, energy efficiency is dictated by whatever process (such as coal-burning, hydroelectric, or renewable source) created the power. Plug-ins can typically drive for around 40 miles (64 km) purely on electricity without recharging; if the battery runs low, a gas engine kicks in allowing for extended range. Finally, all-electric cars are also growing in popularity; the Tesla Roadster sports car is the only high-performance all-electric car currently on the market, and others are in preproduction.[22]
[edit] Energy conservation
Main article: Energy conservation
Energy conservation is broader than energy efficiency in including active efforts to decrease energy consumption, for example through behavioural change, in addition to using energy more efficiently. Examples of conservation without efficiency improvements are heating a room less in winter, using the car less, or enabling energy saving modes on a computer. As with other definitions, the boundary between efficient energy use and energy conservation can be fuzzy, but both are important in environmental and economic terms.[23] This is especially the case when actions are directed at the saving of fossil fuels.[24] Energy conservation is a challenge requiring policy programmes, technological development and behavioral change to go hand in hand. Many energy intermediary organisations, for example governmental or non-governmental organisations on local, regional, or national level, are working on often publicly funded programmes or projects to meet this challenge.[25]
[edit] Sustainable energy
Main article: Sustainable energy
Energy efficiency and renewable energy are said to be the “twin pillars” of a sustainable energy policy. Both strategies must be developed concurrently in order to stabilize and reduce carbon dioxide emissions. Efficient energy use is essential to slowing the energy demand growth so that rising clean energy supplies can make deep cuts in fossil fuel use. If energy use grows too rapidly, renewable energy development will chase a receding target. Likewise, unless clean energy supplies come online rapidly, slowing demand growth will only begin to reduce total carbon emissions; a reduction in the carbon content of energy sources is also needed. A sustainable energy economy thus requires major commitments to both efficiency and renewables.[26]
[edit] Rebound effect
Further information: Rebound effect (conservation) and Jevons' paradox
If the demand for energy services remains constant, improving energy efficiency will reduce energy consumption and carbon emissions. However, many efficiency improvements do not reduce energy consumption by the amount predicted by simple engineering models. This is because they make energy services cheaper, and so consumption of those services increases. For example, since fuel efficient vehicles make travel cheaper, consumers may choose to drive farther and/or faster, thereby offsetting some of the potential energy savings. This is an example of the direct rebound effect.[27]
Estimates of the size of the rebound effect range from roughly 5% to 40%.[28][29][30] The rebound effect is likely to be less than 30% at the household level and may be closer to 10% for transport.[27] A rebound effect of 30% implies that improvements in energy efficiency should achieve 70% of the reduction in energy consumption projected using engineering models.
Since more efficient (and hence cheaper) energy will also lead to faster economic growth, there are suspicions that improvements in energy efficiency may eventually lead to even faster resource use. This was postulated by economists in the 1980s and remains a controversial hypothesis. Ecological economists have suggested that any cost savings from efficiency gains be taxed away by the government in order to avoid this outcome.[31]
[edit] Organizations and programs for promoting energy efficiency
International
* 80 PLUS
* 2000-watt society
* IEA Solar Heating & Cooling Implementing Agreement Task 13
* International Institute for Energy Conservation
* International Energy Agency (e.g. One watt initiative)
* International Electrotechnical Commission
* International Partnership for Energy Efficiency Cooperation
* World Sustainable Energy Days
Australia
* Department of Climate Change and Energy Efficiency
* Department of the Environment, Water, Heritage and the Arts
* Sustainable House Day
European Union
* Building energy rating
* Eco-Design of Energy-Using Products Directive
* Energy efficiency in Europe
* Orgalime, the European engineering industries association
Iceland
* Marorka
India
* 88888 Lights Out
Japan
* Cool Biz campaign
Lebanon
* The Lebanese Center for Energy Conservation
United Kingdom
* The Carbon Trust
* Energy Saving Trust
* National Energy Action
* National Energy Foundation
United States
* Alliance to Save Energy
* American Council for an Energy-Efficient Economy (ACEEE)
* Building Codes Assistance Project
* Building Energy Codes Program
* Energy Star, from United States Environmental Protection Agency
* Industrial Assessment Center
* National Electrical Manufacturers Association
* Rocky Mountain Institute
[edit] See also
Crystal energy.svg Energy portal
* Cogeneration
* Data center infrastructure efficiency
* Electrical energy efficiency on United States farms
* Electric vehicle#Efficiency
* Energy audit
* Energy policy
* Energy recovery
* Energy resilience
* Performance per watt
* Green energy
* Home performance
* Negawatt power
* One watt initiative
* Passenger miles per gallon
* Renewable heat
* Standby power
* U.S. Department of Energy Solar Decathlon
* World Energy Engineering Congress
[edit] References
1. ^ "Philips Tornado Asian Compact Fluorescent". Philips. http://www.lamptech.co.uk/Spec%20Sheets/Philips%20CFL%20Tornado.htm. Retrieved 2007-12-24.
2. ^ Diesendorf, Mark (2007). Greenhouse Solutions with Sustainable Energy, UNSW Press, p. 86.
3. ^ Sophie Hebden (2006-06-22). "Invest in clean technology says IEA report". Scidev.net. http://www.scidev.net/News/index.cfm?fuseaction=readNews&itemid=2929&language=1. Retrieved 2010-07-16.
4. ^ "The Twin Pillars of Sustainable Energy: Synergies between Energy Efficiency and Renewable Energy Technology and Policy". Aceee.org. Archived from the original on 2008-05-05. http://web.archive.org/web/20080505041521/http://aceee.org/store/proddetail.cfm?CFID=2957330&CFTOKEN=50269931&ItemID=432&CategoryID=7. Retrieved 2010-07-16.
5. ^ "Loading Order White Paper" (PDF). http://www.energy.ca.gov/2005publications/CEC-400-2005-043/CEC-400-2005-043.PDF. Retrieved 2010-07-16.
6. ^ "Weatherization in Austin, Texas". Green Collar Operations. http://www.greencollaroperations.com/weatherization-austin-tx.html. Retrieved 2010-07-16.
7. ^ "Microsoft Word - 20070831_vienna_closing_press_release.doc" (PDF). http://unfccc.int/files/press/news_room/press_releases_and_advisories/application/pdf/20070831_vienna_closing_press_release.pdf. Retrieved 2010-07-16.
8. ^ "Ecosavings". Electrolux.com. http://www.electrolux.com/ecosavings. Retrieved 2010-07-16.
9. ^ "Ecosavings (Tm) Calculator". Electrolux.com. http://www.electrolux.com/ecosavings_us. Retrieved 2010-07-16.
10. ^ McKinsey & Company (2009). Pathway to a Low-Carbon Economy : Version 3 of the Global Greenhouse Gas Abatement Cost Curve, p. 7.
11. ^ a b c d Environmental and Energy Study Institute. "Energy-Efficient Buildings: Using whole building design to reduce energy consumption in homes and offices". Eesi.org. http://www.eesi.org/publications/Fact%20Sheets/EC_Fact_Sheets/EE_Buildings.pdf. Retrieved 2010-07-16.
12. ^ "The impact of energy efficiency on peak demand". Energydsm.com. http://www.energydsm.com/energy-efficiency. Retrieved 2010-07-16.
13. ^ CFL savings calculator, Green Energy Efficient Homes
14. ^ Creating Energy Efficient Offices - Electrical Contractor Fit-out Article
15. ^ "Wireless smart meter by ecowizard". Ecowizard.net. http://www.ecowizard.net/. Retrieved 2010-07-16.
16. ^ www.ashrae.org/members/doc/shapiro_8090903.pdf
17. ^ a b c d e Environmental and Energy Study Institute. "Industrial Energy Efficiency: Using new technologies to reduce energy use in industry and manufacturing". Eesi.org. http://www.eesi.org/publications/Fact%20Sheets/EC_Fact_Sheets/EE_Industry.pdf. Retrieved 2010-07-16.
18. ^ Richard C. Dorf, The Energy Factbook, McGraw-Hill, 1981
19. ^ "Tips to improve your Gas Mileage". Fueleconomy.gov. http://www.fueleconomy.gov/feg/maintain.shtml. Retrieved 2010-07-16.
20. ^ a b Automotive Efficiency: Using technology to reduce energy use in passenger vehicles and light trucks[dead link]
21. ^ http://www.fueleconomy.gov/feg/pdfs/Air_Filter_Effects_02_26_2009.pdf
22. ^ "2008 Tesla Roadster - Car News". Car and Driver. http://www.caranddriver.com/reviews/hot_lists/car_shopping/green_machines/2008_tesla_roadster_car_news. Retrieved 2010-07-16.
23. ^ Dietz, T. et al. (2009).Household actions can provide a behavioral wedge to rapidly reduce U.S. carbon emissions. PNAS. 106(44).
24. ^ Diesendorf, Mark (2007). Greenhouse Solutions with Sustainable Energy, UNSW Press, p. 87.
25. ^ Breukers, Heiskanen, et al. (2009). Interaction schemes for successful demand-side management. Deliverable 5 of the CHANGING BEHAVIOUR project. Funded by the EC (#213217).
26. ^ The Twin Pillars of Sustainable Energy: Synergies between Energy Efficiency and Renewable Energy Technology and Policy (American Council for an Energy-Efficient Economy)
27. ^ a b The Rebound Effect: an assessment of the evidence for economy-wide energy savings from improved energy efficiency pp. v-vi.
28. ^ Greening, L; David L. Greene, Carmen Difiglio (2000). "Energy efficiency and consumption—the rebound effect—a survey.". Energy Policy 28: 389–401. doi:10.1016/S0301-4215(00)00021-5
29. ^ Kenneth A. Small and Kurt Van Dender (September 21, 2005). "The Effect of Improved Fuel Economy on Vehicle Miles Traveled: Estimating the Rebound Effect Using U.S. State Data, 1966-2001". University of California Energy Institute: Policy & Economics. http://repositories.cdlib.org/ucei/policy/EPE-014. Retrieved 2007-11-23.
30. ^ "Energy Efficiency and the Rebound Effect: Does Increasing Efficiency Decrease Demand?". http://www.ncseonline.org/nle/crsreports/energy/eng-80.cfm?&CFID=11262148&CFTOKEN=7028302. Retrieved 2007-11-21.
31. ^ Wackernagel, Mathis and William Rees, 1997, "Perpetual and structural barriers to investing in natural capital: economics from an ecological footprint perspective." Ecological Economics, Vol.20 No.3 p3-24.
Retrieved from "http://en.wikipedia.org/wiki/Efficient_energy_use"
Categories: Energy conservation | Energy policy | Climate change | Industrial ecology | Sustainable energy
Hidden categories: All articles with dead external links | Articles with dead external links from July 2010 | Articles with inconsistent citation formats
Personal tools
* Log in / create account
Namespaces
* Article
* Discussion
Variants
Views
* Read
* Edit
* View history
Actions
Search
Search
Navigation
* Main page
* Contents
* Featured content
* Current events
* Random article
* Donate to Wikipedia
Interaction
* Help
* About Wikipedia
* Community portal
* Recent changes
* Contact Wikipedia
Toolbox
* What links here
* Related changes
* Upload file
* Special pages
* Permanent link
* Cite this page
Print/export
* Create a book
* Download as PDF
* Printable version
Languages
* العربية
* Français
* Magyar
* Polski
* Русский
* This page was last modified on 22 December 2010 at 19:07.
* Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. See Terms of Use for details.
Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
* Contact us
* Privacy policy
* About Wikipedia
* Disclaimer
20 THINGS YOU CAN DO TO CONSERVE ENERGY
Whenever you save energy, you not only save money, you also reduce the demand for such fossil fuels as coal, oil, and natural gas. Less burning of fossil fuels also means lower emissions of carbon dioxide (CO2), the primary contributor to global warming, and other pollutants.
You do not have to do without to achieve these savings. There is now an energy efficient alternative for almost every kind of appliance or light fixture. That means that consumers have a real choice and the power to change their energy use on a revolutionary scale.
The average American produces about 40,000 pounds of CO2 emissions per year. Together, we use nearly a million dollars worth of energy every minute, night and day, every day of the year. By exercising even a few of the following steps, you can cut your annual emissions by thousands of pounds and your energy bills by a significant amount!
Home appliances
1. Turn your refrigerator down. Refrigerators account for about 20% of Household electricity use. Use a thermometer to set your refrigerator temperature as close to 37 degrees and your freezer as close to 3 degrees as possible. Make sure that its energy saver switch is turned on. Also, check the gaskets around your refrigerator/freezer doors to make sure they are clean and sealed tightly.
2. Set your clothes washer to the warm or cold water setting, not hot. Switching from hot to warm for two loads per week can save nearly 500 pounds of CO2 per year if you have an electric water heater, or 150 pounds for a gas heater.
3. Make sure your dishwasher is full when you run it and use the energy saving setting, if available, to allow the dishes to air dry. You can also turn off the drying cycle manually. Not using heat in the drying cycle can save 20 percent of your dishwasher's total electricity use.
4. Turn down your water heater thermostat. Thermostats are often set to 140 degrees F when 120 is usually fine. Each 10 degree reduction saves 600 pounds of CO2 per year for an electric water heater, or 440 pounds for a gas heater. If every household turned its water heater thermostat down 20 degrees, we could prevent more than 45 million tons of annual CO2 emissions - the same amount emitted by the entire nations of Kuwait or Libya.
5. Select the most energy-efficient models when you replace your old appliances. Look for the Energy Star Label - your assurance that the product saves energy and prevents pollution. Buy the product that is sized to your typical needs - not the biggest one available. Front loading washing machines will usually cut hot water use by 60 to 70% compared to typical machines. Replacing a typical 1973 refrigerator with a new energy-efficient model, saves 1.4 tons of CO2 per year. Investing in a solar water heater can save 4.9 tons of CO2 annually.
Home Heating and Cooling
6. Be careful not to overheat or overcool rooms. In the winter, set your thermostat at 68 degrees in daytime, and 55 degrees at night. In the summer, keep it at 78. Lowering your thermostat just two degrees during winter saves 6 percent of heating-related CO2 emissions. That's a reduction of 420 pounds of CO2 per year for a typical home.
7. Clean or replace air filters as recommended. Energy is lost when air conditioners and hot-air furnaces have to work harder to draw air through dirty filters. Cleaning a dirty air conditioner filter can save 5 percent of the energy used. That could save 175 pounds of CO2 per year.
Small investments that pay off
8. Buy energy-efficient compact fluorescent bulbs for your most-used lights. Although they cost more initially, they save money in the long run by using only 1/4 the energy of an ordinary incandescent bulb and lasting 8-12 times longer. They provide an equivalent amount of bright, attractive light. Only 10% of the energy consumed by a normal light bulb generates light. The rest just makes the bulb hot. If every American household replaced one of its standard light bulbs with an energy efficient compact fluorescent bulb, we would save the same amount of energy as a large nuclear power plant produces in one year. In a typical home, one compact fluorescent bulb can save 260 pounds of CO2 per year.
9. Wrap your water heater in an insulating jacket, which costs just $10 to $20. It can save 1100 lbs. of CO2 per year for an electric water heater, or 220 pounds for a gas heater.
10. Use less hot water by installing low-flow shower heads. They cost just $10 to $20 each, deliver an invigorating shower, and save 300 pounds of CO2 per year for electrically heated water, or 80 pounds for gas-heated water.
11. Weatherize your home or apartment, using caulk and weather stripping to plug air leaks around doors and windows. Caulking costs less than $1 per window, and weather stripping is under $10 per door. These steps can save up to 1100 pounds of CO2 per year for a typical home. Ask your utility company for a home energy audit to find out where your home is poorly insulated or energy inefficient. This service may be provided free or at low cost. Make sure it includes a check of your furnace and air conditioning.
Getting around
12. Whenever possible, walk, bike, car pool, or use mass transit. Every gallon of gasoline you save avoids 22 pounds of CO2 emissions. If your car gets 25 miles per gallon, for example, and you reduce your annual driving from 12,000 to 10,000 miles, you'll save 1800 pounds of CO2.
13. When you next buy a car, choose one that gets good mileage. If your new car gets 40 miles per gallon instead of 25, and you drive 10,000 miles per year, you'll reduce your annual CO2 emissions by 3,300 pounds.
Reduce, reuse, recycle
14. Reduce the amount of waste you produce by buying minimally packaged goods, choosing reusable products over disposable ones, and recycling. For every pound of waste you eliminate or recycle, you save energy and reduce emissions of CO2 by at least 1 pound. Cutting down your garbage by half of one large trash bag per week saves at least 1100 pounds of CO2 per year. Making products with recycled materials, instead of from scratch with raw materials, uses 30 to 55% less for paper products, 33% less for glass, and a whopping 90% less for aluminum.
15. If your car has an air conditioner, make sure its coolant is recovered and recycled whenever you have it serviced. In the United States, leakage from auto air conditioners is the largest single source of emissions of chlorofluorocarbons (CFCs), which damage the ozone layer as well as add to global warming. The CFCs from one auto air conditioner can add the equivalent of 4800 pounds of CO2 emissions per year.
Home Improvements.
When you plan major home improvements, consider some of these energy saving investments. They save money in the long run, and their CO2 savings can often be measured in tons per year.
16. Insulate your walls and ceilings. This can save 20 to 30 percent of home heating bills and reduce CO2 emissions by 140 to 2100 pounds per year. If you live in a colder climate, consider superinsulating. That can save 5.5 tons of CO2 per year for gas-heated homes, 8.8 tons per year for oil heat, or 23 tons per year for electric heat. (If you have electric heat, you might also consider switching to more efficient gas or oil.)
17. Modernize your windows. Replacing all your ordinary windows with argon filled, double-glazed windows saves 2.4 tons of CO2 per year for homes with gas heat, 3.9 tons of oil heat, and 9.8 tons for electric heat.
18. Plant shade trees and paint your house a light color if you live in a warm climate, or a dark color if you live in a cold climate. Reductions in energy use resulting from shade trees and appropriate painting can save up to 2.4 tons of CO2 emissions per year. (Each tree also directly absorbs about 25 pounds of CO2 from the air annually.)
Business and community
19. Work with your employer to implement these and other energy-efficiency and waste-reduction measures in your office or workplace. Form or join local citizens' groups and work with local government officials to see that these measures are taken in schools and public buildings.
20. Keep track of the environmental voting records of candidates for office. Stay abreast of environmental issues on both local and national levels, and write or call your elected officials to express your concerns about energy efficiency and global warming.
Click below to e-mail this article to a friend
or to post a link on your favorite sites.
Thank you! Bookmark and Share
Written by: Power Scorecard
You do not have to do without to achieve these savings. There is now an energy efficient alternative for almost every kind of appliance or light fixture. That means that consumers have a real choice and the power to change their energy use on a revolutionary scale.
The average American produces about 40,000 pounds of CO2 emissions per year. Together, we use nearly a million dollars worth of energy every minute, night and day, every day of the year. By exercising even a few of the following steps, you can cut your annual emissions by thousands of pounds and your energy bills by a significant amount!
Home appliances
1. Turn your refrigerator down. Refrigerators account for about 20% of Household electricity use. Use a thermometer to set your refrigerator temperature as close to 37 degrees and your freezer as close to 3 degrees as possible. Make sure that its energy saver switch is turned on. Also, check the gaskets around your refrigerator/freezer doors to make sure they are clean and sealed tightly.
2. Set your clothes washer to the warm or cold water setting, not hot. Switching from hot to warm for two loads per week can save nearly 500 pounds of CO2 per year if you have an electric water heater, or 150 pounds for a gas heater.
3. Make sure your dishwasher is full when you run it and use the energy saving setting, if available, to allow the dishes to air dry. You can also turn off the drying cycle manually. Not using heat in the drying cycle can save 20 percent of your dishwasher's total electricity use.
4. Turn down your water heater thermostat. Thermostats are often set to 140 degrees F when 120 is usually fine. Each 10 degree reduction saves 600 pounds of CO2 per year for an electric water heater, or 440 pounds for a gas heater. If every household turned its water heater thermostat down 20 degrees, we could prevent more than 45 million tons of annual CO2 emissions - the same amount emitted by the entire nations of Kuwait or Libya.
5. Select the most energy-efficient models when you replace your old appliances. Look for the Energy Star Label - your assurance that the product saves energy and prevents pollution. Buy the product that is sized to your typical needs - not the biggest one available. Front loading washing machines will usually cut hot water use by 60 to 70% compared to typical machines. Replacing a typical 1973 refrigerator with a new energy-efficient model, saves 1.4 tons of CO2 per year. Investing in a solar water heater can save 4.9 tons of CO2 annually.
Home Heating and Cooling
6. Be careful not to overheat or overcool rooms. In the winter, set your thermostat at 68 degrees in daytime, and 55 degrees at night. In the summer, keep it at 78. Lowering your thermostat just two degrees during winter saves 6 percent of heating-related CO2 emissions. That's a reduction of 420 pounds of CO2 per year for a typical home.
7. Clean or replace air filters as recommended. Energy is lost when air conditioners and hot-air furnaces have to work harder to draw air through dirty filters. Cleaning a dirty air conditioner filter can save 5 percent of the energy used. That could save 175 pounds of CO2 per year.
Small investments that pay off
8. Buy energy-efficient compact fluorescent bulbs for your most-used lights. Although they cost more initially, they save money in the long run by using only 1/4 the energy of an ordinary incandescent bulb and lasting 8-12 times longer. They provide an equivalent amount of bright, attractive light. Only 10% of the energy consumed by a normal light bulb generates light. The rest just makes the bulb hot. If every American household replaced one of its standard light bulbs with an energy efficient compact fluorescent bulb, we would save the same amount of energy as a large nuclear power plant produces in one year. In a typical home, one compact fluorescent bulb can save 260 pounds of CO2 per year.
9. Wrap your water heater in an insulating jacket, which costs just $10 to $20. It can save 1100 lbs. of CO2 per year for an electric water heater, or 220 pounds for a gas heater.
10. Use less hot water by installing low-flow shower heads. They cost just $10 to $20 each, deliver an invigorating shower, and save 300 pounds of CO2 per year for electrically heated water, or 80 pounds for gas-heated water.
11. Weatherize your home or apartment, using caulk and weather stripping to plug air leaks around doors and windows. Caulking costs less than $1 per window, and weather stripping is under $10 per door. These steps can save up to 1100 pounds of CO2 per year for a typical home. Ask your utility company for a home energy audit to find out where your home is poorly insulated or energy inefficient. This service may be provided free or at low cost. Make sure it includes a check of your furnace and air conditioning.
Getting around
12. Whenever possible, walk, bike, car pool, or use mass transit. Every gallon of gasoline you save avoids 22 pounds of CO2 emissions. If your car gets 25 miles per gallon, for example, and you reduce your annual driving from 12,000 to 10,000 miles, you'll save 1800 pounds of CO2.
13. When you next buy a car, choose one that gets good mileage. If your new car gets 40 miles per gallon instead of 25, and you drive 10,000 miles per year, you'll reduce your annual CO2 emissions by 3,300 pounds.
Reduce, reuse, recycle
14. Reduce the amount of waste you produce by buying minimally packaged goods, choosing reusable products over disposable ones, and recycling. For every pound of waste you eliminate or recycle, you save energy and reduce emissions of CO2 by at least 1 pound. Cutting down your garbage by half of one large trash bag per week saves at least 1100 pounds of CO2 per year. Making products with recycled materials, instead of from scratch with raw materials, uses 30 to 55% less for paper products, 33% less for glass, and a whopping 90% less for aluminum.
15. If your car has an air conditioner, make sure its coolant is recovered and recycled whenever you have it serviced. In the United States, leakage from auto air conditioners is the largest single source of emissions of chlorofluorocarbons (CFCs), which damage the ozone layer as well as add to global warming. The CFCs from one auto air conditioner can add the equivalent of 4800 pounds of CO2 emissions per year.
Home Improvements.
When you plan major home improvements, consider some of these energy saving investments. They save money in the long run, and their CO2 savings can often be measured in tons per year.
16. Insulate your walls and ceilings. This can save 20 to 30 percent of home heating bills and reduce CO2 emissions by 140 to 2100 pounds per year. If you live in a colder climate, consider superinsulating. That can save 5.5 tons of CO2 per year for gas-heated homes, 8.8 tons per year for oil heat, or 23 tons per year for electric heat. (If you have electric heat, you might also consider switching to more efficient gas or oil.)
17. Modernize your windows. Replacing all your ordinary windows with argon filled, double-glazed windows saves 2.4 tons of CO2 per year for homes with gas heat, 3.9 tons of oil heat, and 9.8 tons for electric heat.
18. Plant shade trees and paint your house a light color if you live in a warm climate, or a dark color if you live in a cold climate. Reductions in energy use resulting from shade trees and appropriate painting can save up to 2.4 tons of CO2 emissions per year. (Each tree also directly absorbs about 25 pounds of CO2 from the air annually.)
Business and community
19. Work with your employer to implement these and other energy-efficiency and waste-reduction measures in your office or workplace. Form or join local citizens' groups and work with local government officials to see that these measures are taken in schools and public buildings.
20. Keep track of the environmental voting records of candidates for office. Stay abreast of environmental issues on both local and national levels, and write or call your elected officials to express your concerns about energy efficiency and global warming.
Click below to e-mail this article to a friend
or to post a link on your favorite sites.
Thank you! Bookmark and Share
Written by: Power Scorecard
Energy conservation
Electrical energy conservation is an important element of energy policy. Energy conservation reduces the energy consumption and energy demand per capita and thus offsets some of the growth in energy supply needed to keep up with population growth. This reduces the rise in energy costs, and can reduce the need for new power plants, and energy imports. The reduced energy demand can provide more flexibility in choosing the most preferred methods of energy production.
[edit] Climate change
By reducing emissions, energy conservation is an important part of lessening climate change. Energy conservation facilitates the replacement of non-renewable resources with renewable energy. Energy conservation is often the most economical solution to energy shortages, and is a more environmentally being alternative to increased energy production.
[edit] Energy conservation by country
[edit] The Republic of India
Petroleum Conservation Research Association (PCRA) www.pcra.org is an Indian government body created in 1976 and engaged in promoting energy efficiency and conservation in every walk of life. In the recent past PCRA has done mass media campaigns in television, radio & print media. An impact assessment survey by a third party revealed that due to these mega campaigns by PCRA, overall awareness level have gone up leading to saving of fossil fuels worth crores of rupees besides reducing pollution.
Bureau of Energy Efficiency is an Indian governmental organization created in 2002 responsible for promoting energy efficiency and conservation.
[edit] Japan
Advertising with high energy in Shinjuku, Japan.
Since the 1973 oil crisis, energy conservation has been an issue in Japan. All oil based fuel is imported, so indigenous sustainable energy is being developed.
The Energy Conservation Center promotes energy efficiency in every aspect of Japan. Private entities are implementing the efficient use of energy for industries.
[edit] Lebanon
In Lebanon and since 2002 The Lebanese Center for Energy Conservation (LCEC) has been promoting the development of efficient and rational uses of energy and the use of renewable energy at the consumer level. It was created as a project financed by the Global Environment Facility (GEF) and the Ministry of Energy Water (MEW) under the management of the United Nations Development Programme (UNDP) and gradually established itself as an independent technical national center although it continues to be supported by the United Nations Development Programme (UNDP) as indicated in the Memorandum of Understanding (MoU) signed between MEW and UNDP on June 18, 2007.
[edit] New Zealand
In New Zealand the Energy Efficiency and Conservation Authority is responsible for promoting energy efficiency and conservation.
[edit] European Union
See also: Energy policy of the European Union
At the end of 2006, the European Union-EU pledged to cut its annual consumption of primary energy by 20% by 2020.[1] The 'European Union Energy Efficiency Action Plan' is long awaited. As part of the EU's SAVE Programme,[2] aimed at promoting energy efficiency and encouraging energy-saving behaviour, the Boiler Efficiency Directive[3] specifies minimum levels of efficiency for boilers fired with liquid or gaseous fuels. The European Commission is funding large-scale research projects to learn about success factors for effective energy conservation programmes.[4]
[edit] United Kingdom
Main article: Energy use and conservation in the United Kingdom
Energy conservation in the United Kingdom has been receiving increased attention over recent years. Key factors behind this are the Government's commitment to reducing carbon emissions, the projected 'energy gap' in UK electricity generation, and the increasing reliance on imports to meet national energy needs. Domestic housing and road transport are currently the two biggest problem areas.
Responsibility for energy conservation fall between three Government departments although is led by the Department for Energy and Climate Change (DECC). The Department for Communities and Local Government (CLG) is still responsible for energy standards in buildings, and the Department for Environment, Food and Rural Affairs (Defra) retains a residual interest in energy insofar as it leads to emissions of CO2, the main greenhouse gas. The Department for Transport retains many responsibilities for energy conservation in transport. At an operational level, there are two main non-departmental governmental bodies ("quangoes") - the Energy Saving Trust, working mainly in the domestic sector with some interest in transport, and the Carbon Trust, working with industry and innovative energy technologies. In addition there are many independent NGOs working in the sector such as the Centre for Sustainable Energy in Bristol or the National Energy Foundation in Milton Keynes, and directly helping consumers make informed choices on energy efficiency sust-it
[edit] United States
Main article: Energy conservation in the United States
The United States is currently the largest single consumer of energy. The U.S. Department of Energy categorizes national energy use in four broad sectors: transportation, residential, commercial, and industrial.[5]
Energy usage in transportation and residential sectors, about half of U.S. energy consumption, is largely controlled by individual consumers. Commercial and industrial energy expenditures are determined by businesses entities and other facility managers. National energy policy has a significant effect on energy usage across all four sectors, and its strengthening is part of the 2010 Presidential-Congressional legislative debate.
[edit] Issues with energy conservation
Advocates and critics of various forms and policies of energy conservation debate some issues, such as:
* Standard economic theory suggests that technological improvements which increase energy efficiency, tends to increase, rather than reduce, energy use. This is called the Jevons Paradox and occurs through two channels. Firstly, increased energy efficiency makes the use of energy relatively cheaper, thus encouraging increased use. Secondly, increased energy efficiency leads to increased economic growth, which pulls up energy use in the whole economy. This does not imply that increased fuel efficiency is worthless, increased fuel efficiency enables greater production and a higher quality of life. However, in order to reduce energy consumption, efficiency gains must be paired with a government intervention that reduces demand (a green tax, cap and trade).[6][7]
* Some retailers argue that bright lighting stimulates purchasing. However, health studies have demonstrated that headache, stress, blood pressure, fatigue and worker error all generally increase with the common over-illumination present in many workplace and retail settings.[8][9] It has been shown that natural daylighting increases productivity levels of workers, while reducing energy consumption.[10]
* The use of telecommuting by major corporations is a significant opportunity to conserve energy, as many Americans now work in service jobs that enable them to work from home instead of commuting to work each day.[11]
* Electric motors consume more than 60% of all electrical energy generated and are responsible for the loss of 10 to 20% of all electricity converted into mechanical energy.[12]
* Consumers are often poorly informed of the savings of energy efficient products. The research one must put into conserving energy often is too time consuming and costly when there are cheaper products and technology available using today's fossil fuels.[13] Some governments and NGOs are attempting to reduce this complexity with ecolabels that make differences in energy efficiency easy to research while shopping.
* Technology needs to be able to change behavioral patterns, it can do this by allowing energy users, business and residential, to see graphically the impact their energy use can have in their workplace or homes. Advanced real-time energy metering is able to help people save energy by their actions. Rather than become wasteful automatic energy saving technologies, real-time energy monitors and meters such as the Energy Detective, Enigin Plc's Eniscope, Ecowizard, or solutions like EDSA'a Paladin Live are examples of such solutions [14]
* It is frequently argued that effective energy conservation requires more than informing consumers about energy consumption, for example through smart meters at home or ecolabels while shopping. People need practical and tailored advice how to reduce energy consumption in order to make change easy and lasting.[15] This applies to both efficiency investments, such as investment in building renovation, or behavioral change, for example turning down the heating. To provide the kind of information and support people need to invest money, time and effort in energy conservation, it is imprtant to understand and link to people's topical concerns.[16]
* In deregulated states commercial utility customers have the ability to compare energy rates among available electricity and natural gas providers.
[edit] See also
* Annual fuel utilization efficiency (AFUE)
* Biofuel
* Brushless wound-rotor doubly-fed electric machine
* Daylighting
* Ecolabel
* Energy saving
* Energy crisis
* Energy monitoring and targeting
* Energy recovery
* Fuel efficiency
* Green building
* Green computing
* Heat Pump
* High temperature insulation wool
* Lighting
* List of low-energy building techniques
* Low Carbon Communities
* Low energy building
* Low-energy vehicle
Sustainable development portal
Energy portal
* Marine fuel management
* Minimum Efficiency Performance Standards
* MIT Design Advisor
* Oil price increases since 2003
* One Watt Initiative
* Over-consumption
* Passive house
* Plug-in hybrid
* Renewable heat
* Smart grid
* Solar energy
* Superinsulation
* Sustainability
* Renewable heat
* Thermal efficiency
* Timeline of environmental events
* Zero energy building
[edit] References
* Gary Steffy, Architectural Lighting Design, John Wiley and Sons (2001) ISBN 0-471-38638-3
* Lumina Technologies, Analysis of energy consumption in a San Francisco Bay Area research office complex, for (confidential) owner, Santa Rosa, Ca. May 17, 1996
* GSA paves way for IT-based buildings [17]
* The official homepage for the European Intelligent Metering project. [3]
[edit] Notes
1. ^ "Energy: What do we want to achieve ? - European commission". Ec.europa.eu. http://ec.europa.eu/energy/efficiency/index_en.htm. Retrieved 2010-07-29.
2. ^ For an Energy-Efficient Millennium: SAVE 2000, Directorate-General for Energy
3. ^ Council Directive 92/42/EEC of 21 May 1992 on efficiency requirements for new hot-water boilers fired with liquid or gaseous fuels
4. ^ see for example CHANGING BEHAVIOUR
5. ^ US Dept. of Energy, "Annual Energy Report" (July 2006), Energy Flow diagram
6. ^ Wackernagel, Mathis and William Rees, 1997, "Perpetual and structural barriers to investing in natural capital: economics from an ecological footprint perspective." Ecological Economics, Vol.20 No.3 p3-24.
7. ^ Carl Marziali (2008). "Does Sustainability Clash with the American Dream?" Excerpted from USC Trojan Family Magazine feature "Watt Now?" in Winter 2008 issue.
8. ^ Scott Davis, Dana K. Mirick, Richard G. Stevens (2001). "Night Shift Work, Light at Night, and Risk of Breast Cancer". Journal of the National Cancer Institute 93 (20): 1557–1562. doi:10.1093/jnci/93.20.1557. PMID 11604479. http://jncicancerspectrum.oupjournals.org/cgi/content/full/jnci;93/20/1557?ijkey=e1472aefe9398c2c26bf8515391f5940acc05495.
9. ^ Bain, A (1997). "The Hindenburg Disaster: A Compelling Theory of Probable Cause and Effect". Procs. NatL Hydr. Assn. 8th Ann. Hydrogen Meeting, Alexandria, Va., March 11–13,: 125–128.
10. ^ Lumina Technologies Inc., Santa Rosa, Ca., Survey of 156 California commercial buildings energy use, August, 1996
11. ^ Best Buy Optimas Award Winner for 2007
12. ^ European Commission of the Institute for Environment and Sustainability, "Electricity Consumption and Efficiency Trends in the Enlarged European Union [1]", 2006
13. ^ The Difficulties of Energy Efficiency. "The Elusive Negawatt [2]", 2008
14. ^ July 2009 European Commission's Directorate-General for Energy and Transport initiative, "Energy Savings from Intelligent Metering and Behavioural Change (INTELLIGENT METERING) http://www.managenergy.net/products/R1951.htm", 2009
15. ^ Breukers, Heiskanen, et al. (2009). Interaction schemes for successful demand-side management. Deliverable 5 of the CHANGING BEHAVIOUR project. Funded by the EC (#213217)
16. ^ Toolkit for managers of energy conservation projects: How to learn about people's topical concerns
17. ^ Robb, Drew (2007-06-02). "GSA paves way for IT-based buildings - Government Computer News". Gcn.com. http://www.gcn.com/print/26_13/44402-1.html. Retrieved 2010-07-29.
[edit] External links
Wikibooks has a book on the topic of
How to reduce home energy usage
* David Suzuki Foundation: Energy Conservation and Efficiency
* Energy saving advice and grants for UK consumers
* Energy efficiency and renewable energy at the U.S. Department of Energy
* EnergyStar - for commercial buildings and plants
[show]v · d · eTopics related to environmental technology
Environmental impact assessment · Environmental design · Sustainable development
Pollution
Industrial ecology · Solid waste treatment · Waste management · Air pollution (control · dispersion modeling) · Water (Wastewater treatment · Agricultural wastewater treatment · Industrial wastewater treatment · Water purification)
Renewable energy
Alternative energy · Energy development · Energy recovery · Energy efficiency · Renewable energy (development) · Sustainable energy · Fuel (Alternative fuel · Biofuel · Hydrogen technologies) · Transportation (Electric vehicle · Hybrid vehicle)
Conservation
Birth control · Permaculture · Conservation ethic · Recycling · Ecoforestry · Conservation biology · Environmental preservation · Remediation · Green computing · Building (Green · Natural · Sustainable architecture)
[show]v · d · eSustainability
Philosophy and
definition
Environmentalism · Environmental ethics · Rio Declaration on Environment and Development · Ecological modernization · Sustainable development
Population
Birth control · Family planning · Overpopulation · Population control · Zero population growth
Consumption
Anthropization · Anti-consumerism · Ecological footprint · Ethical consumerism · Overconsumption · Tragedy of the commons
Technology
Environmental technology · Appropriate technology
[show] Resource use and conservation
Food
Food security · Local food · Permaculture · Sustainable agriculture · Sustainable fisheries · Urban horticulture
Water
Footprint · Crisis · Efficiency · Conservation
Energy
Carbon footprint · Climate change mitigation · Efficient energy use · Emissions trading · Energy conservation · Energy descent · Peak oil · Renewable energy
Materials
Industrial ecology · Recycling · Waste · Zero waste
Biodiversity
Biosecurity · Biosphere · Conservation biology · Endangered species · Holocene extinction · Invasive species
[show] Sustainability disciplines and activities
Disciplines
Science · Measurement (reporting · Planetary boundaries · Yield)
Sustainable
activities
Sustainable advertising / architecture / art / business / city (infrastructure / drainage) / community / design / education / fashion / gardening / landscape architecture / living / industries / packaging / procurement / tourism / transport
Management
Planetary management · Environmental · Fisheries · Forest
Environmental
Environmental biotechnology / chemistry / design / economics / engineering / ethics / history / law / psychology / science / sociology
[show] International reports and agreements
UN Conference on the Human Environment (Stockholm 1972) · Brundtlandt Commission Report, 1983 (Our Common Future, 1987) · Earth Summit (1992) · Agenda 21 (1992) · Convention on Biological Diversity (1992) · ICPD Programme of Action (1994) · Earth Charter · Lisbon Principles · Millennium Declaration (2000) · Millennium Ecosystem Assessment (2005)
[show] Lists and glossaries
Lists
Climate change topics · Conservation issues / topics · Environmental agreements / health hazards / issues / organisations / topics (studies topics) · Global sustainability statistics
Glossaries
Climate change · Environmental science
Category · Portal · Outline
Retrieved from "http://en.wikipedia.org/wiki/Energy_conservation"
Categories: Energy conservation | Energy policy | Environmental issues with energy | Building engineering | Sustainable building
Personal tools
* Log in / create account
Namespaces
* Article
* Discussion
Variants
Views
* Read
* Edit
* View history
Actions
Search
Search
Navigation
* Main page
* Contents
* Featured content
* Current events
* Random article
* Donate to Wikipedia
Interaction
* Help
* About Wikipedia
* Community portal
* Recent changes
* Contact Wikipedia
Toolbox
* What links here
* Related changes
* Upload file
* Special pages
* Permanent link
* Cite this page
Print/export
* Create a book
* Download as PDF
* Printable version
Languages
* العربية
* Català
* Deutsch
* Eesti
* Español
* Euskara
* فارسی
* Français
* Galego
* ગુજરાતી
* 한국어
* हिन्दी
* Bahasa Indonesia
* Íslenska
* Italiano
* Lietuvių
* Nederlands
* 日本語
* Português
* Русский
* Simple English
* Suomi
* Svenska
* Українська
* 中文
* This page was last modified on 17 January 2011 at 15:27.
* Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. See Terms of Use for details.
Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
* Contact us
[edit] Climate change
By reducing emissions, energy conservation is an important part of lessening climate change. Energy conservation facilitates the replacement of non-renewable resources with renewable energy. Energy conservation is often the most economical solution to energy shortages, and is a more environmentally being alternative to increased energy production.
[edit] Energy conservation by country
[edit] The Republic of India
Petroleum Conservation Research Association (PCRA) www.pcra.org is an Indian government body created in 1976 and engaged in promoting energy efficiency and conservation in every walk of life. In the recent past PCRA has done mass media campaigns in television, radio & print media. An impact assessment survey by a third party revealed that due to these mega campaigns by PCRA, overall awareness level have gone up leading to saving of fossil fuels worth crores of rupees besides reducing pollution.
Bureau of Energy Efficiency is an Indian governmental organization created in 2002 responsible for promoting energy efficiency and conservation.
[edit] Japan
Advertising with high energy in Shinjuku, Japan.
Since the 1973 oil crisis, energy conservation has been an issue in Japan. All oil based fuel is imported, so indigenous sustainable energy is being developed.
The Energy Conservation Center promotes energy efficiency in every aspect of Japan. Private entities are implementing the efficient use of energy for industries.
[edit] Lebanon
In Lebanon and since 2002 The Lebanese Center for Energy Conservation (LCEC) has been promoting the development of efficient and rational uses of energy and the use of renewable energy at the consumer level. It was created as a project financed by the Global Environment Facility (GEF) and the Ministry of Energy Water (MEW) under the management of the United Nations Development Programme (UNDP) and gradually established itself as an independent technical national center although it continues to be supported by the United Nations Development Programme (UNDP) as indicated in the Memorandum of Understanding (MoU) signed between MEW and UNDP on June 18, 2007.
[edit] New Zealand
In New Zealand the Energy Efficiency and Conservation Authority is responsible for promoting energy efficiency and conservation.
[edit] European Union
See also: Energy policy of the European Union
At the end of 2006, the European Union-EU pledged to cut its annual consumption of primary energy by 20% by 2020.[1] The 'European Union Energy Efficiency Action Plan' is long awaited. As part of the EU's SAVE Programme,[2] aimed at promoting energy efficiency and encouraging energy-saving behaviour, the Boiler Efficiency Directive[3] specifies minimum levels of efficiency for boilers fired with liquid or gaseous fuels. The European Commission is funding large-scale research projects to learn about success factors for effective energy conservation programmes.[4]
[edit] United Kingdom
Main article: Energy use and conservation in the United Kingdom
Energy conservation in the United Kingdom has been receiving increased attention over recent years. Key factors behind this are the Government's commitment to reducing carbon emissions, the projected 'energy gap' in UK electricity generation, and the increasing reliance on imports to meet national energy needs. Domestic housing and road transport are currently the two biggest problem areas.
Responsibility for energy conservation fall between three Government departments although is led by the Department for Energy and Climate Change (DECC). The Department for Communities and Local Government (CLG) is still responsible for energy standards in buildings, and the Department for Environment, Food and Rural Affairs (Defra) retains a residual interest in energy insofar as it leads to emissions of CO2, the main greenhouse gas. The Department for Transport retains many responsibilities for energy conservation in transport. At an operational level, there are two main non-departmental governmental bodies ("quangoes") - the Energy Saving Trust, working mainly in the domestic sector with some interest in transport, and the Carbon Trust, working with industry and innovative energy technologies. In addition there are many independent NGOs working in the sector such as the Centre for Sustainable Energy in Bristol or the National Energy Foundation in Milton Keynes, and directly helping consumers make informed choices on energy efficiency sust-it
[edit] United States
Main article: Energy conservation in the United States
The United States is currently the largest single consumer of energy. The U.S. Department of Energy categorizes national energy use in four broad sectors: transportation, residential, commercial, and industrial.[5]
Energy usage in transportation and residential sectors, about half of U.S. energy consumption, is largely controlled by individual consumers. Commercial and industrial energy expenditures are determined by businesses entities and other facility managers. National energy policy has a significant effect on energy usage across all four sectors, and its strengthening is part of the 2010 Presidential-Congressional legislative debate.
[edit] Issues with energy conservation
Advocates and critics of various forms and policies of energy conservation debate some issues, such as:
* Standard economic theory suggests that technological improvements which increase energy efficiency, tends to increase, rather than reduce, energy use. This is called the Jevons Paradox and occurs through two channels. Firstly, increased energy efficiency makes the use of energy relatively cheaper, thus encouraging increased use. Secondly, increased energy efficiency leads to increased economic growth, which pulls up energy use in the whole economy. This does not imply that increased fuel efficiency is worthless, increased fuel efficiency enables greater production and a higher quality of life. However, in order to reduce energy consumption, efficiency gains must be paired with a government intervention that reduces demand (a green tax, cap and trade).[6][7]
* Some retailers argue that bright lighting stimulates purchasing. However, health studies have demonstrated that headache, stress, blood pressure, fatigue and worker error all generally increase with the common over-illumination present in many workplace and retail settings.[8][9] It has been shown that natural daylighting increases productivity levels of workers, while reducing energy consumption.[10]
* The use of telecommuting by major corporations is a significant opportunity to conserve energy, as many Americans now work in service jobs that enable them to work from home instead of commuting to work each day.[11]
* Electric motors consume more than 60% of all electrical energy generated and are responsible for the loss of 10 to 20% of all electricity converted into mechanical energy.[12]
* Consumers are often poorly informed of the savings of energy efficient products. The research one must put into conserving energy often is too time consuming and costly when there are cheaper products and technology available using today's fossil fuels.[13] Some governments and NGOs are attempting to reduce this complexity with ecolabels that make differences in energy efficiency easy to research while shopping.
* Technology needs to be able to change behavioral patterns, it can do this by allowing energy users, business and residential, to see graphically the impact their energy use can have in their workplace or homes. Advanced real-time energy metering is able to help people save energy by their actions. Rather than become wasteful automatic energy saving technologies, real-time energy monitors and meters such as the Energy Detective, Enigin Plc's Eniscope, Ecowizard, or solutions like EDSA'a Paladin Live are examples of such solutions [14]
* It is frequently argued that effective energy conservation requires more than informing consumers about energy consumption, for example through smart meters at home or ecolabels while shopping. People need practical and tailored advice how to reduce energy consumption in order to make change easy and lasting.[15] This applies to both efficiency investments, such as investment in building renovation, or behavioral change, for example turning down the heating. To provide the kind of information and support people need to invest money, time and effort in energy conservation, it is imprtant to understand and link to people's topical concerns.[16]
* In deregulated states commercial utility customers have the ability to compare energy rates among available electricity and natural gas providers.
[edit] See also
* Annual fuel utilization efficiency (AFUE)
* Biofuel
* Brushless wound-rotor doubly-fed electric machine
* Daylighting
* Ecolabel
* Energy saving
* Energy crisis
* Energy monitoring and targeting
* Energy recovery
* Fuel efficiency
* Green building
* Green computing
* Heat Pump
* High temperature insulation wool
* Lighting
* List of low-energy building techniques
* Low Carbon Communities
* Low energy building
* Low-energy vehicle
Sustainable development portal
Energy portal
* Marine fuel management
* Minimum Efficiency Performance Standards
* MIT Design Advisor
* Oil price increases since 2003
* One Watt Initiative
* Over-consumption
* Passive house
* Plug-in hybrid
* Renewable heat
* Smart grid
* Solar energy
* Superinsulation
* Sustainability
* Renewable heat
* Thermal efficiency
* Timeline of environmental events
* Zero energy building
[edit] References
* Gary Steffy, Architectural Lighting Design, John Wiley and Sons (2001) ISBN 0-471-38638-3
* Lumina Technologies, Analysis of energy consumption in a San Francisco Bay Area research office complex, for (confidential) owner, Santa Rosa, Ca. May 17, 1996
* GSA paves way for IT-based buildings [17]
* The official homepage for the European Intelligent Metering project. [3]
[edit] Notes
1. ^ "Energy: What do we want to achieve ? - European commission". Ec.europa.eu. http://ec.europa.eu/energy/efficiency/index_en.htm. Retrieved 2010-07-29.
2. ^ For an Energy-Efficient Millennium: SAVE 2000, Directorate-General for Energy
3. ^ Council Directive 92/42/EEC of 21 May 1992 on efficiency requirements for new hot-water boilers fired with liquid or gaseous fuels
4. ^ see for example CHANGING BEHAVIOUR
5. ^ US Dept. of Energy, "Annual Energy Report" (July 2006), Energy Flow diagram
6. ^ Wackernagel, Mathis and William Rees, 1997, "Perpetual and structural barriers to investing in natural capital: economics from an ecological footprint perspective." Ecological Economics, Vol.20 No.3 p3-24.
7. ^ Carl Marziali (2008). "Does Sustainability Clash with the American Dream?" Excerpted from USC Trojan Family Magazine feature "Watt Now?" in Winter 2008 issue.
8. ^ Scott Davis, Dana K. Mirick, Richard G. Stevens (2001). "Night Shift Work, Light at Night, and Risk of Breast Cancer". Journal of the National Cancer Institute 93 (20): 1557–1562. doi:10.1093/jnci/93.20.1557. PMID 11604479. http://jncicancerspectrum.oupjournals.org/cgi/content/full/jnci;93/20/1557?ijkey=e1472aefe9398c2c26bf8515391f5940acc05495.
9. ^ Bain, A (1997). "The Hindenburg Disaster: A Compelling Theory of Probable Cause and Effect". Procs. NatL Hydr. Assn. 8th Ann. Hydrogen Meeting, Alexandria, Va., March 11–13,: 125–128.
10. ^ Lumina Technologies Inc., Santa Rosa, Ca., Survey of 156 California commercial buildings energy use, August, 1996
11. ^ Best Buy Optimas Award Winner for 2007
12. ^ European Commission of the Institute for Environment and Sustainability, "Electricity Consumption and Efficiency Trends in the Enlarged European Union [1]", 2006
13. ^ The Difficulties of Energy Efficiency. "The Elusive Negawatt [2]", 2008
14. ^ July 2009 European Commission's Directorate-General for Energy and Transport initiative, "Energy Savings from Intelligent Metering and Behavioural Change (INTELLIGENT METERING) http://www.managenergy.net/products/R1951.htm", 2009
15. ^ Breukers, Heiskanen, et al. (2009). Interaction schemes for successful demand-side management. Deliverable 5 of the CHANGING BEHAVIOUR project. Funded by the EC (#213217)
16. ^ Toolkit for managers of energy conservation projects: How to learn about people's topical concerns
17. ^ Robb, Drew (2007-06-02). "GSA paves way for IT-based buildings - Government Computer News". Gcn.com. http://www.gcn.com/print/26_13/44402-1.html. Retrieved 2010-07-29.
[edit] External links
Wikibooks has a book on the topic of
How to reduce home energy usage
* David Suzuki Foundation: Energy Conservation and Efficiency
* Energy saving advice and grants for UK consumers
* Energy efficiency and renewable energy at the U.S. Department of Energy
* EnergyStar - for commercial buildings and plants
[show]v · d · eTopics related to environmental technology
Environmental impact assessment · Environmental design · Sustainable development
Pollution
Industrial ecology · Solid waste treatment · Waste management · Air pollution (control · dispersion modeling) · Water (Wastewater treatment · Agricultural wastewater treatment · Industrial wastewater treatment · Water purification)
Renewable energy
Alternative energy · Energy development · Energy recovery · Energy efficiency · Renewable energy (development) · Sustainable energy · Fuel (Alternative fuel · Biofuel · Hydrogen technologies) · Transportation (Electric vehicle · Hybrid vehicle)
Conservation
Birth control · Permaculture · Conservation ethic · Recycling · Ecoforestry · Conservation biology · Environmental preservation · Remediation · Green computing · Building (Green · Natural · Sustainable architecture)
[show]v · d · eSustainability
Philosophy and
definition
Environmentalism · Environmental ethics · Rio Declaration on Environment and Development · Ecological modernization · Sustainable development
Population
Birth control · Family planning · Overpopulation · Population control · Zero population growth
Consumption
Anthropization · Anti-consumerism · Ecological footprint · Ethical consumerism · Overconsumption · Tragedy of the commons
Technology
Environmental technology · Appropriate technology
[show] Resource use and conservation
Food
Food security · Local food · Permaculture · Sustainable agriculture · Sustainable fisheries · Urban horticulture
Water
Footprint · Crisis · Efficiency · Conservation
Energy
Carbon footprint · Climate change mitigation · Efficient energy use · Emissions trading · Energy conservation · Energy descent · Peak oil · Renewable energy
Materials
Industrial ecology · Recycling · Waste · Zero waste
Biodiversity
Biosecurity · Biosphere · Conservation biology · Endangered species · Holocene extinction · Invasive species
[show] Sustainability disciplines and activities
Disciplines
Science · Measurement (reporting · Planetary boundaries · Yield)
Sustainable
activities
Sustainable advertising / architecture / art / business / city (infrastructure / drainage) / community / design / education / fashion / gardening / landscape architecture / living / industries / packaging / procurement / tourism / transport
Management
Planetary management · Environmental · Fisheries · Forest
Environmental
Environmental biotechnology / chemistry / design / economics / engineering / ethics / history / law / psychology / science / sociology
[show] International reports and agreements
UN Conference on the Human Environment (Stockholm 1972) · Brundtlandt Commission Report, 1983 (Our Common Future, 1987) · Earth Summit (1992) · Agenda 21 (1992) · Convention on Biological Diversity (1992) · ICPD Programme of Action (1994) · Earth Charter · Lisbon Principles · Millennium Declaration (2000) · Millennium Ecosystem Assessment (2005)
[show] Lists and glossaries
Lists
Climate change topics · Conservation issues / topics · Environmental agreements / health hazards / issues / organisations / topics (studies topics) · Global sustainability statistics
Glossaries
Climate change · Environmental science
Category · Portal · Outline
Retrieved from "http://en.wikipedia.org/wiki/Energy_conservation"
Categories: Energy conservation | Energy policy | Environmental issues with energy | Building engineering | Sustainable building
Personal tools
* Log in / create account
Namespaces
* Article
* Discussion
Variants
Views
* Read
* Edit
* View history
Actions
Search
Search
Navigation
* Main page
* Contents
* Featured content
* Current events
* Random article
* Donate to Wikipedia
Interaction
* Help
* About Wikipedia
* Community portal
* Recent changes
* Contact Wikipedia
Toolbox
* What links here
* Related changes
* Upload file
* Special pages
* Permanent link
* Cite this page
Print/export
* Create a book
* Download as PDF
* Printable version
Languages
* العربية
* Català
* Deutsch
* Eesti
* Español
* Euskara
* فارسی
* Français
* Galego
* ગુજરાતી
* 한국어
* हिन्दी
* Bahasa Indonesia
* Íslenska
* Italiano
* Lietuvių
* Nederlands
* 日本語
* Português
* Русский
* Simple English
* Suomi
* Svenska
* Українська
* 中文
* This page was last modified on 17 January 2011 at 15:27.
* Text is available under the Creative Commons Attribution-ShareAlike License; additional terms may apply. See Terms of Use for details.
Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a non-profit organization.
* Contact us
Subscribe to:
Posts (Atom)