sustainable energy is energy that is consumed at insignificant rates compared to its supply and with manageable collateral effects especially environmental effects another common definition of sustainable energy is an energy system that serves the needs of the present without compromising the ability of future generations to meet their needs the organizing principle for sustainability is sustainable development which includes the four interconnected domains ecology economics politics and culture sustainability science is the study of sustainable development and environmental sciencetechnologies that promote sustainable energy include renewable energy sources such as hydroelectricity solar energy wind energy wave power geothermal energy bioenergy tidal power and also technologies designed to improve energy efficiency costs have fallen dramatically in recent years and continue to fall most of these technologies are either economically competitive or close to being so increasingly effective government policies support investor confidence and these markets are expanding considerable progress is being made in the energy transition from fossil fuels to ecologically sustainable systems to the point where many studies support 100% renewable energydefinitionsenergy efficiency and renewable energy are said to be the twin pillars of sustainable energy some ways in which sustainable energy has been defined areeffectively the provision of energy such that it meets the needs of the present without compromising the ability of future generations to meet their own needs sustainable energy has two key components renewable energy and energy efficiency – renewable energy and efficiency partnership britishdynamic harmony between equitable availability of energy-intensive goods and services to all people and the preservation of the earth for future generations and the solution will lie in finding sustainable energy sources and more efficient means of converting and utilizing energy – sustainable energy by j w tester et al from mit pressany energy generation efficiency and conservation source where resources are available to enable massive scaling to become a significant portion of energy generation long term preferably 100 years – invest a green technology non-profit organizationenergy which is replenishable within a human lifetime and causes no long-term damage to the environment – jamaica sustainable development networkthis sets sustainable energy apart from other renewable energy terminology such as alternative energy by focusing on the ability of an energy source to continue providing energy sustainable energy can produce some pollution of the environment as long as it is not sufficient to prohibit heavy use of the source for an indefinite amount of time sustainable energy is also distinct from low-carbon energy which is sustainable only in the sense that it does not add to the co2 in the atmospheregreen energy is energy that can be extracted generated and/or consumed without any significant negative impact to the environment the planet has a natural capability to recover which means pollution that does not go beyond that capability can still be termed greengreen power is a subset of renewable energy and represents those renewable energy resources and technologies that provide the highest environmental benefit the us environmental protection agency defines green power as electricity produced from solar wind geothermal biogas biomass and low-impact small hydroelectric sources customers often buy green power for avoided environmental impacts and its greenhouse gas reduction benefitsrenewable energy technologiesrenewable energy technologies are essential contributors to sustainable energy as they generally contribute to world energy security reducing dependence on fossil fuel resources and providing opportunities for mitigating greenhouse gases the international energy agency states thatconceptually one can define three generations of renewables technologies reaching back more than 100 years first-generation technologies emerged from the industrial revolution at the end of the 19th century and include hydropower biomass combustion and geothermal power and heat some of these technologies are still in widespread usesecond-generation technologies include solar heating and cooling wind power modern forms of bioenergy and solar photovoltaics these are now entering markets as a result of research development and demonstration rd&d investments since the 1980s the initial investment was prompted by energy security concerns linked to the oil crises 1973 and 1979 of the 1970s but the continuing appeal of these renewables is due at least in part to environmental benefits many of the technologies reflect significant advancements in materialsfirst- and second-generation technologies have entered the markets and third-generation technologies heavily depend on long term research and development commitments where the public sector has a role to playregarding energy used by vehicles a comprehensive 2008 cost-benefit analysis review was conducted of sustainable energy sources and usage combinations in the context of global warming and other dominating issues it ranked wind power generation combined with battery electric vehicles bev and hydrogen fuel cell vehicles hfcvs as the most efficient wind was followed by concentrated solar power csp geothermal power tidal power photovoltaic wave power hydropower coal capture and storage ccs nuclear energy and biofuel energy sources it states in sum use of wind csp geothermal tidal pv wave and hydro to provide electricity for bevs and hfcvs and by extension electricity for the residential industrial and commercial sectors will result in the most benefit among the options considered the combination of these technologies should be advanced as a solution to global warming air pollution and energy security coal-ccs and nuclear offer less benefit thus represent an opportunity cost loss and the biofuel options provide no certain benefit and the greatest negative impactsfirst-generation technologiesfirst-generation technologies are most competitive in locations with abundant resources their future use depends on the exploration of the available resource potential particularly in developing countries and on overcoming challenges related to the environment and social acceptanceamong sources of renewable energy hydroelectric plants have the advantages of being long-lived—many existing plants have operated for more than 100 years also hydroelectric plants are clean and have few emissions criticisms directed at large-scale hydroelectric plants include dislocation of people living where the reservoirs are planned and release of significant amounts of carbon dioxide during construction and flooding of the reservoirhowever it has been found that high emissions are associated only with shallow reservoirs in warm tropical locales and recent innovations in hydropower turbine technology are enabling efficient development of low-impact run-of-the-river hydroelectricity projects generally speaking hydroelectric plants produce much lower life-cycle emissions than other types of generation hydroelectric power which underwent extensive development during growth of electrification in the 19th and 20th centuries is experiencing resurgence of development in the 21st century the areas of greatest hydroelectric growth are the booming economies of asia china is the development leader however other asian nations are installing hydropower at a rapid pace this growth is driven by much increased energy costs—especially for imported energy—and widespread desires for more domestically produced clean renewable and economical generationgeothermal power plants can operate 24 hours per day providing base-load capacity and the world potential capacity for geothermal power generation is estimated at 85 gw over the next 30 years however geothermal power is accessible only in limited areas of the world including the united states central america east africa iceland indonesia and the philippines the costs of geothermal energy have dropped substantially from the systems built in the 1970s geothermal heat generation can be competitive in many countries producing geothermal power or in other regions where the resource is of a lower temperature enhanced geothermal system egs technology does not require natural convective hydrothermal resources so it can be used in areas that were previously unsuitable for geothermal power if the resource is very large egs is currently under research at the us department of energybiomass briquettes are increasingly being used in the developing world as an alternative to charcoal the technique involves the conversion of almost any plant matter into compressed briquettes that typically have about 70% the calorific value of charcoal there are relatively few examples of large-scale briquette production one exception is in north kivu in eastern democratic republic of congo where forest clearance for charcoal production is considered to be the biggest threat to mountain gorilla habitat the staff of virunga national park have successfully trained and equipped over 3500 people to produce biomass briquettes thereby replacing charcoal produced illegally inside the national park and creating significant employment for people living in extreme poverty in conflict-affected areassecond-generation technologiesmarkets for second-generation technologies are strong and growing but only in a few countries the challenge is to broaden the market base for continued growth worldwide strategic deployment in one country not only reduces technology costs for users there but also for those in other countries contributing to overall cost reductions and performance improvementsolar heating systems are a well known second-generation technology and generally consist of solar thermal collectors a fluid system to move the heat from the collector to its point of usage and a reservoir or tank for heat storage and subsequent use the systems may be used to heat domestic hot water swimming pool water or for space heating the heat can also be used for industrial applications or as an energy input for other uses such as cooling equipment in many climates a solar heating system can provide a very high percentage 50 to 75% of domestic hot water energy energy received from the sun by the earth is that of electromagnetic radiation light ranges of visible infrared ultraviolet x-rays and radio waves received by the earth through solar energy the highest power of radiation comes from visible light solar power is complicated due to changes in seasons and from day to night cloud cover can also add to complications of solar energy and not all radiation from the sun reaches earth because it is absorbed and dispersed due to clouds and gases within the earths atmospheresin the 1980s and early 1990s most photovoltaic modules provided remote-area power supply but from around 1995 industry efforts have focused increasingly on developing building integrated photovoltaics and power plants for grid connected applications see photovoltaic power stations article for details currently the largest photovoltaic power plant in north america is the nellis solar power plant 15 mw there is a proposal to build a solar power station in victoria australia which would be the worlds largest pv power station at 154 mw other large photovoltaic power stations include the girassol solar power plant 62 mw and the waldpolenz solar park 40 mwsome of the second-generation renewables such as wind power have high potential and have already realised relatively low production costs at the end of 2008 worldwide wind farm capacity was 120,791 megawatts mw representing an increase of 28.8 percent during the year and wind power produced some 1.3% of global electricity consumption wind power accounts for approximately 20% of electricity use in denmark 9% in spain and 7% in germany however it may be difficult to site wind turbines in some areas for aesthetic or environmental reasons and it may be difficult to integrate wind power into electricity grids in some casessolar thermal power stations have been successfully operating in california commercially since the late 1980s including the largest solar power plant of any kind the 350 mw solar energy generating systems nevada solar one is another 64mw plant which has recently opened other parabolic trough power plants being proposed are two 50mw plants in spain and a 100mw plant in israelbrazil has one of the largest renewable energy programs in the world involving production of ethanol fuel from sugar cane and ethanol now provides 18 percent of the countrys automotive fuel as a result of this together with the exploitation of domestic deep water oil sources brazil which years ago had to import a large share of the petroleum needed for domestic consumption recently reached complete self-sufficiency in oilmost cars on the road today in the us can run on blends of up to 10% ethanol and motor vehicle manufacturers already produce vehicles designed to run on much higher ethanol blends ford daimlerchrysler and gm are among the automobile companies that sell flexible-fuel cars trucks and minivans that can use gasoline and ethanol blends ranging from pure gasoline up to 85% ethanol e85 by mid-2006 there were approximately six million e85-compatible vehicles on us roadsthird-generation technologiesthird-generation technologies are not yet widely demonstrated or commercialised they are on the horizon and may have potential comparable to other renewable energy technologies but still depend on attracting sufficient attention and rd&d funding these newest technologies include advanced biomass gasification biorefinery technologies solar thermal power stations hot dry rock geothermal energy and ocean energybio-fuels may be defined as renewable yet may not be sustainable due to soil degradation as of 2012 40% of american corn production goes toward ethanol ethanol takes up a large percentage of clean energy use when in fact it is still debatable whether ethanol should be considered as a clean energyaccording to the international energy agency new bioenergy biofuel technologies being developed today notably cellulosic ethanol biorefineries could allow biofuels to play a much bigger role in the future than previously thought cellulosic ethanol can be made from plant matter composed primarily of inedible cellulose fibers that form the stems and branches of most plants crop residues such as corn stalks wheat straw and rice straw wood waste and municipal solid waste are potential sources of cellulosic biomass dedicated energy crops such as switchgrass are also promising cellulose sources that can be sustainably produced in many regions of the united statesin terms of ocean energy another third-generation technology portugal has the worlds first commercial wave farm the aguçadora wave park under construction in 2007 the farm will initially use three pelamis p-750 machines generating 2.25 mw and costs are put at 8.5 million euro subject to successful operation a further 70 million euro is likely to be invested before 2009 on a further 28 machines to generate 525 mw funding for a wave farm in scotland was announced in february 2007 by the scottish executive at a cost of over 4 million pounds as part of a £13 million funding packages for ocean power in scotland the farm will be the worlds largest with a capacity of 3 mw generated by four pelamis machines see also wave farmin 2007 the worlds first turbine to create commercial amounts of energy using tidal power was installed in the narrows of strangford lough in ireland the 1.2 mw underwater tidal electricity generator takes advantage of the fast tidal flow in the lough which can be up to 4m/s although the generator is powerful enough to power up to a thousand homes the turbine has a minimal environmental impact as it is almost entirely submerged and the rotors turn slowly enough that they pose no danger to wildlifesolar power panels that use nanotechnology which can create circuits out of individual silicon molecules may cost half as much as traditional photovoltaic cells according to executives and investors involved in developing the products nanosolar has secured more than $100 million from investors to build a factory for nanotechnology thin-film solar panels the companys plant has a planned production capacity of 430 megawatts peak power of solar cells per year commercial production started and first panels have been shipped to customers in late 2007large national and regional research projects on artificial photosynthesis are designing nanotechnology-based systems that use solar energy to split water into hydrogen fuel and a proposal has been made for a global artificial photosynthesis project in 2011 researchers at the massachusetts institute of technology mit developed what they are calling an artificial leaf which is capable of splitting water into hydrogen and oxygen directly from solar power when dropped into a glass of water one side of the artificial leaf produces bubbles of hydrogen while the other side produces bubbles of oxygenmost current solar power plants are made from an array of similar units where each unit is continuously adjusted eg with some step motors so that the light converter stays in focus of the sun light the cost of focusing light on converters such as high-power solar panels stirling engine etc can be dramatically decreased with a simple and efficient rope mechanics in this technique many units are connected with a network of ropes so that pulling two or three ropes is sufficient to keep all light converters simultaneously in focus as the direction of the sun changesjapan and china have national programs aimed at commercial scale space-based solar power sbsp the china academy of space technology cast won the 2015 international sunsat design competition with this video of their multi-rotary joint design proponents of sbsp claim that space-based solar power would be clean constant and global and could scale to meet all planetary energy demand a recent multi-agency industry proposal echoing the 2008 pentagon recommendation won the secdef/secstate/usaid director d3 diplomacy development defense innovation challengeenabling technologies for renewable energyheat pumps and thermal energy storage are classes of technologies that can enable the utilization of renewable energy sources that would otherwise be inaccessible due to a temperature that is too low for utilization or a time lag between when the energy is available and when it is needed while enhancing the temperature of available renewable thermal energy heat pumps have the additional property of leveraging electrical power or in some cases mechanical or thermal power by using it to extract additional energy from a low quality source such as seawater lake water the ground the air or waste heat from a processthermal storage technologies allow heat or cold to be stored for periods of time ranging from hours or overnight to interseasonal and can involve storage of sensible energy ie by changing the temperature of a medium or latent energy ie through phase changes of a medium such between water and slush or ice short-term thermal storages can be used for peak-shaving in district heating or electrical distribution systems kinds of renewable or alternative energy sources that can be enabled include natural energy eg collected via solar-thermal collectors or dry cooling towers used to collect winters cold waste energy eg from hvac equipment industrial processes or power plants or surplus energy eg as seasonally from hydropower projects or intermittently from wind farms the drake landing solar community alberta canada is illustrative borehole thermal energy storage allows the community to get 97% of its year-round heat from solar collectors on the garage roofs which most of the heat collected in summer types of storages for sensible energy include insulated tanks borehole clusters in substrates ranging from gravel to bedrock deep aquifers or shallow lined pits that are insulated on top some types of storage are capable of storing heat or cold between opposing seasons particularly if very large and some storage applications require inclusion of a heat pump latent heat is typically stored in ice tanks or what are called phase-change materials pcmsenergy efficiencymoving towards energy sustainability will require changes not only in the way energy is supplied but in the way it is used and reducing the amount of energy required to deliver various goods or services is essential opportunities for improvement on the demand side of the energy equation are as rich and diverse as those on the supply side and often offer significant economic benefitsrenewable energy and energy efficiency are sometimes said to be the twin pillars of sustainable energy policy both resources must be developed in order to stabilize and reduce carbon dioxide emissions efficiency slows down energy demand growth so that rising clean energy supplies can make deep cuts in fossil fuel use if energy use grows too fast renewable energy development will chase a receding target a recent historical analysis has demonstrated that the rate of energy efficiency improvements has generally been outpaced by the rate of growth in energy demand which is due to continuing economic and population growth as a result despite energy efficiency gains total energy use and related carbon emissions have continued to increase thus given the thermodynamic and practical limits of energy efficiency improvements slowing the growth in energy demand is essential however unless clean energy supplies come online rapidly slowing demand growth will only begin to reduce total emissions reducing the carbon content of energy sources is also needed any serious vision of a sustainable energy economy thus requires commitments to both renewables and efficiencyrenewable energy and energy efficiency are no longer niche sectors that are promoted only by governments and environmentalists the increased levels of investment and the fact that much of the capital is coming from more conventional financial actors suggest that sustainable energy options are now becoming mainstream an example of this would be the alliance to save energys project with stahl consolidated manufacturing huntsville alabama usa stahlcon 7 a patented generator shaft designed to reduce emissions within existing power generating systems granted publishing rights to the alliance in 2007climate change concerns coupled with high oil prices and increasing government support are driving increasing rates of investment in the sustainable energy industries according to a trend analysis from the united nations environment programme according to unep global investment in sustainable energy in 2007 was higher than previous levels with $148 billion of new money raised in 2007 an increase of 60% over 2006 total financial transactions in sustainable energy including acquisition activity was $204 billioninvestment flows in 2007 broadened and diversified making the overall picture one of greater breadth and depth of sustainable energy use the mainstream capital markets are now fully receptive to sustainable energy companies supported by a surge in funds destined for clean energy investmentsmart-grid technologysmart grid refers to a class of technology people are using to bring utility electricity delivery systems into the 21st century using computer-based remote control and automation these systems are made possible by two-way communication technology and computer processing that has been used for decades in other industries they are beginning to be used on electricity networks from the power plants and wind farms all the way to the consumers of electricity in homes and businesses they offer many benefits to utilities and consumers—mostly seen in big improvements in energy efficiency on the electricity grid and in the energy users’ homes and officesgreen energy and green powergreen energy includes natural energetic processes that can be harnessed with little pollution green power is electricity generated from renewable energy sourcesanaerobic digestion geothermal power wind power small-scale hydropower solar energy biomass power tidal power wave power and some forms of nuclear power ones which are able to burn nuclear waste through a process known as nuclear transmutation such as an integral fast reactor and therefore belong in the green energy category some definitions may also include power derived from the incineration of wastesome people including greenpeace founder and first member patrick moore george monbiot bill gates and james lovelock have specifically classified nuclear power as green energy others including greenpeaces phil radford disagree claiming that the problems associated with radioactive waste and the risk of nuclear accidents such as the chernobyl disaster pose an unacceptable risk to the environment and to humanity however newer nuclear reactor designs are capable of utilizing what is now deemed nuclear waste until it is no longer or dramatically less dangerous and have design features that greatly minimize the possibility of a nuclear accident these designs have yet to be proven see integral fast reactorsome have argued that although green energy is a commendable effort in solving the worlds increasing energy consumption it must be accompanied by a cultural change that encourages the decrease of the worlds appetite for energyin several countries with common carrier arrangements electricity retailing arrangements make it possible for consumers to purchase green electricity renewable electricity from either their utility or a green power providerwhen energy is purchased from the electricity network the power reaching the consumer will not necessarily be generated from green energy sources the local utility company electric company or state power pool buys their electricity from electricity producers who may be generating from fossil fuel nuclear or renewable energy sources in many countries green energy currently provides a very small amount of electricity generally contributing less than 2 to 5% to the overall pool in some us states local governments have formed regional power purchasing pools using community choice aggregation and solar bonds to achieve a 51% renewable mix or higher such as in the city of san franciscoby participating in a green energy program a consumer may be having an effect on the energy sources used and ultimately might be helping to promote and expand the use of green energy they are also making a statement to policy makers that they are willing to pay a price premium to support renewable energy green energy consumers either obligate the utility companies to increase the amount of green energy that they purchase from the pool so decreasing the amount of non-green energy they purchase or directly fund the green energy through a green power provider if insufficient green energy sources are available the utility must develop new ones or contract with a third party energy supplier to provide green energy causing more to be built however there is no way the consumer can check whether or not the electricity bought is green or otherwisein some countries such as the netherlands electricity companies guarantee to buy an equal amount of green power as is being used by their green power customers the dutch government exempts green power from pollution taxes which means green power is hardly any more expensive than other powerin the united states one of the main problems with purchasing green energy through the electrical grid is the current centralized infrastructure that supplies the consumer’s electricity this infrastructure has led to increasingly frequent brown outs and black outs high co2 emissions higher energy costs and power quality issues an additional $450 billion will be invested to expand this fledgling system over the next 20 years to meet increasing demand in addition this centralized system is now being further overtaxed with the incorporation of renewable energies such as wind solar and geothermal energies renewable resources due to the amount of space they require are often located in remote areas where there is a lower energy demand the current infrastructure would make transporting this energy to high demand areas such as urban centers highly inefficient and in some cases impossible in addition despite the amount of renewable energy produced or the economic viability of such technologies only about 20 percent will be able to be incorporated into the grid to have a more sustainable energy profile the united states must move towards implementing changes to the electrical grid that will accommodate a mixed-fuel economyhowever several initiatives are being proposed to mitigate these distribution problems first and foremost the most effective way to reduce usa’s co2 emissions and slow global warming is through conservation efforts opponents of the current us electrical grid have also advocated for decentralizing the grid this system would increase efficiency by reducing the amount of energy lost in transmission it would also be economically viable as it would reduce the amount of power lines that will need to be constructed in the future to keep up with demand merging heat and power in this system would create added benefits and help to increase its efficiency by up to 80-90% this is a significant increase from the current fossil fuel plants which only have an efficiency of 34%a more recent concept for improving our electrical grid is to beam microwaves from earth-orbiting satellites or the moon to directly when and where there is demand the power would be generated from solar energy captured on the lunar surface in this system the receivers would be broad translucent tent-like structures that would receive microwaves and convert them to electricity nasa said in 2000 that the technology was worth pursuing but it is still too soon to say if the technology will be cost-effectivethe world wide fund for nature and several green electricity labelling organizations created the now defunct eugene green energy standard under which the national green electricity certification schemes could be accredited to ensure that the purchase of green energy leads to the provision of additional new green energy resourceslocal green energy systemsthose not satisfied with the third-party grid approach to green energy via the power grid can install their own locally based renewable energy system renewable energy electrical systems from solar to wind to even local hydro-power in some cases are some of the many types of renewable energy systems available locally additionally for those interested in heating and cooling their dwelling via renewable energy geothermal heat pump systems that tap the constant temperature of the earth which is around 7 to 15 degrees celsius a few feet underground and increases dramatically at greater depths are an option over conventional natural gas and petroleum-fueled heat approaches also in geographic locations where the earths crust is especially thin or near volcanoes as is the case in iceland there exists the potential to generate even more electricity than would be possible at other sites thanks to a more significant temperature gradient at these localesthe advantage of this approach in the united states is that many states offer incentives to offset the cost of installation of a renewable energy system in california massachusetts and several other us states a new approach to community energy supply called community choice aggregation has provided communities with the means to solicit a competitive electricity supplier and use municipal revenue bonds to finance development of local green energy resources individuals are usually assured that the electricity they are using is actually produced from a green energy source that they control once the system is paid for the owner of a renewable energy system will be producing their own renewable electricity for essentially no cost and can sell the excess to the local utility at a profitusing green energyrenewable energy after its generation needs to be stored in a medium for use with autonomous devices as well as vehicles also to provide household electricity in remote areas that is areas which are not connected to the mains electricity grid energy storage is required for use with renewable energy energy generation and consumption systems used in the latter case are usually stand-alone power systemssome examples areenergy carriers as hydrogen liquid nitrogen compressed air oxyhydrogen batteries to power vehiclesflywheel energy storage pumped-storage hydroelectricity is more usable in stationary applications eg to power homes and offices in household power systems conversion of energy can also be done to reduce smell for example organic matter such as cow dung and spoilable organic matter can be converted to biochar to eliminate emissions carbon capture and storage is then usedusually however renewable energy is derived from the mains electricity grid this means that energy storage is mostly not used as the mains electricity grid is organised to produce the exact amount of energy being consumed at that particular moment energy production on the mains electricity grid is always set up as a combination of large-scale renewable energy plants as well as other power plants as fossil-fuel power plants and nuclear power this combination however which is essential for this type of energy supply as eg wind turbines solar power plants etc can only produce when the wind blows and the sun shines this is also one of the main drawbacks of the system as fossil fuel powerplants are polluting and are a main cause of global warming nuclear power being an exception although fossil fuel power plants too can be made emissionless through carbon capture and storage as well as renewable if the plants are converted to eg biomass the best solution is still to phase out the latter power plants over time nuclear power plants too can be more or less eliminated from their problem of nuclear waste through the use of nuclear reprocessing and newer plants as fast breeder and nuclear fusion plantsrenewable energy power plants do provide a steady flow of energy for example hydropower plants ocean thermal plants osmotic power plants all provide power at a regulated pace and are thus available power sources at any given moment even at night windstill moments etc at present however the number of steady-flow renewable energy plants alone is still too small to meet energy demands at the times of the day when the irregular producing renewable energy plants cannot produce powerbesides the greening of fossil fuel and nuclear power plants another option is the distribution and immediate use of power from solely renewable sources in this set-up energy storage is again not necessary for example trec has proposed to distribute solar power from the sahara to europe europe can distribute wind and ocean power to the sahara and other countries in this way power is produced at any given time as at any point of the planet as the sun or the wind is up or ocean waves and currents are stirring this option however is probably not possible in the short-term as fossil fuel and nuclear power are still the main sources of energy on the mains electricity net and replacing them will not be possible overnightseveral large-scale energy storage suggestions for the grid have been done worldwide there is over 100 gw of pumped-storage hydroelectricity this improves efficiency and decreases energy losses but a conversion to an energy storing mains electricity grid is a very costly solution some costs could potentially be reduced by making use of energy storage equipment the consumer buys and not the state an example is batteries in electric cars that would double as an energy buffer for the electricity grid however besides the cost setting-up such a system would still be a very complicated and difficult procedure also energy storage apparatus as car batteries are also built with materials that pose a threat to the environment eg lithium the combined production of batteries for such a large part of the population would still have environmental concerns besides car batteries however other grid energy storage projects make use of less polluting energy carriers eg compressed air tanks and flywheel energy storagea carbon-neutral fuel is a synthetic fuel – such as methane gasoline diesel fuel or jet fuel – produced from renewable or nuclear energy used to hydrogenate waste carbon dioxide recycled from power plant flue-gas emissions recovered from automotive exhaust gas or derived from carbonic acid in seawater such fuels are carbon-neutral because they do not result in a net increase in atmospheric greenhouse gases to the extent that carbon-neutral fuels displace fossil fuels or if they are produced from waste carbon or seawater carbonic acid and their combustion is subject to carbon capture at the flue or exhaust pipe they result in negative carbon dioxide emission and net carbon dioxide removal from the atmosphere and thus constitute a form of greenhouse gas remediation such fuels are produced by the electrolysis of water to make hydrogen used in turn in the sabatier reaction to produce methane which may then be stored to be burned later in power plants as synthetic natural gas transported by pipeline truck or tanker ship or be used in gas to liquids processes such as the fischer–tropsch process to make traditional transportation or heating fuelsgreen energy and labeling by regiondirective 2004/8/ec of the european parliament and of the council of 11 february 2004 on the promotion of cogeneration based on a useful heat demand in the internal energy market includes the article 5 guarantee of origin of electricity from high-efficiency cogenerationeuropean environmental ngos have launched an ecolabel for green power the ecolabel is called ekoenergy it sets criteria for sustainability additionality consumer information and tracking only part of electricity produced by renewables fulfills the ekoenergy criteriaa green energy supply certification scheme was launched in the united kingdom in february 2010 this implements guidelines from the energy regulator ofgem and sets requirements on transparency the matching of sales by renewable energy supplies and additionalitythe united states department of energy doe the environmental protection agency epa and the center for resource solutions crs recognizes the voluntary purchase of electricity from renewable energy sources also called renewable electricity or green electricity as green powerthe most popular way to purchase renewable energy as revealed by nrel data is through purchasing renewable energy certificates recs according to a natural marketing institute nmi survey 55 percent of american consumers want companies to increase their use of renewable energydoe selected six companies for its 2007 green power supplier awards including constellation newenergy 3degrees sterling planet sunedison pacific power and rocky mountain power and silicon valley power the combined green power provided by those six winners equals more than 5 billion kilowatt-hours per year which is enough to power nearly 465,000 average us households in 2014 arcadia power made recs available to homes and businesses in all 50 states allowing consumers to use 100% green power as defined by the epas green power partnershipthe us environmental protection agency usepa green power partnership is a voluntary program that supports the organizational procurement of renewable electricity by offering expert advice technical support tools and resources this can help organizations lower the transaction costs of buying renewable power reduce carbon footprint and communicate its leadership to key stakeholdersthroughout the country more than half of all us electricity customers now have an option to purchase some type of green power product from a retail electricity provider roughly one-quarter of the nations utilities offer green power programs to customers and voluntary retail sales of renewable energy in the united states totaled more than 12 billion kilowatt-hours in 2006 a 40% increase over the previous yearsustainable energy researchthere are numerous organizations within the academic federal and commercial sectors conducting large scale advanced research in the field of sustainable energy this research spans several areas of focus across the sustainable energy spectrum most of the research is targeted at improving efficiency and increasing overall energy yields multiple federally supported research organizations have focused on sustainable energy in recent years two of the most prominent of these labs are sandia national laboratories and the national renewable energy laboratory nrel both of which are funded by the united states department of energy and supported by various corporate partners sandia has a total budget of $2.4 billion  while nrel has a budget of $375 millionscientific production towards sustainable energy systems is rising exponentially growing from about 500 english journal papers only about renewable energy in 1992 to almost 9,000 papers in 2011solarthe primary obstacle that is preventing the large scale implementation of solar powered energy generation is the inefficiency of current solar technology currently photovoltaic pv panels only have the ability to convert around 16% of the sunlight that hits them into electricity at this rate many experts believe that solar energy is not efficient enough to be economically sustainable given the cost to produce the panels themselves both sandia national laboratories and the national renewable energy laboratory nrel have heavily funded solar research programs the nrel solar program has a budget of around $75 million  and develops research projects in the areas of photovoltaic pv technology solar thermal energy and solar radiation the budget for sandia’s solar division is unknown however it accounts for a significant percentage of the laboratory’s $2.4 billion budget several academic programs have focused on solar research in recent years the solar energy research center serc at university of north carolina unc has the sole purpose of developing cost effective solar technology in 2008 researchers at massachusetts institute of technology mit developed a method to store solar energy by using it to produce hydrogen fuel from water such research is targeted at addressing the obstacle that solar development faces of storing energy for use during nighttime hours when the sun is not shining in february 2012 north carolina-based semprius inc a solar development company backed by german corporation siemens announced that they had developed the world’s most efficient solar panel the company claims that the prototype converts 33.9% of the sunlight that hits it to electricity more than double the previous high-end conversion rate major projects on artificial photosynthesis or solar fuels are also under way in many developed nationsspace-based solar power satellites seek to overcome the problems of storage and provide civilization-scale power that is clean constant and global japan and china have active national programs aimed at commercial scale space-based solar power sbsp and both nations hope to orbit demonstrations in the 2030s the china academy of space technology cast won the 2015 international sunsat design competition with this video of their multi-rotary joint design proponents of sbsp claim that space-based solar power would be clean constant and global and could scale to meet all planetary energy demand a recent multi-agency industry proposal echoing the 2008 pentagon recommendation won the secdef/secstate/usaid director d3 diplomacy development defense innovation challenge  with the following pitch and vision video northrop grumman is funding caltech with $17.5 million for an ultra lightweight design keith henson recently posted a video of a bootstrapping approachwindwind energy research dates back several decades to the 1970s when nasa developed an analytical model to predict wind turbine power generation during high winds today both sandia national laboratories and national renewable energy laboratory have programs dedicated to wind research sandia’s laboratory focuses on the advancement of materials aerodynamics and sensors the nrel wind projects are centered on improving wind plant power production reducing their capital costs and making wind energy more cost effective overall the field laboratory for optimized wind energy flowe at caltech was established to research renewable approaches to wind energy farming technology practices that have the potential to reduce the cost size and environmental impact of wind energy production the president of sky windpower corporation thinks that wind turbines will be able to produce electricity at a cent/kwh at an average which in comparison to coal-generated electricity is a fractional of the costa wind farm is a group of wind turbines in the same location used to produce electric power a large wind farm may consist of several hundred individual wind turbines and cover an extended area of hundreds of square miles but the land between the turbines may be used for agricultural or other purposes a wind farm may also be located offshoremany of the largest operational onshore wind farms are located in the usa and china the gansu wind farm in china has over 5,000 mw installed with a goal of 20,000 mw by 2020 china has several other wind power bases of similar size the alta wind energy center in california is the largest onshore wind farm outside of china with a capacity of 1020 mw of power europe leads in the use of wind power with almost 66 gw about 66 percent of the total globally with denmark in the lead according to the countries installed per-capita capacity as of february 2012 the walney wind farm in united kingdom is the largest offshore wind farm in the world at 367 mw followed by thanet wind farm 300 mw also in the ukthere are many large wind farms under construction and these include bard offshore 1 400 mw clyde wind farm 350 mw greater gabbard wind farm 500 mw lincs wind farm 270 mw london array 1000 mw lower snake river wind project 343 mw macarthur wind farm 420 mw shepherds flat wind farm 845 mw and sheringham shoal 317 mwwind power has expanded quickly its share of worldwide electricity usage at the end of 2014 was 3.1%carbon-neutral and negative fuelscarbon-neutral fuels are synthetic fuels including methane gasoline diesel fuel jet fuel or ammonia produced by hydrogenating waste carbon dioxide recycled from power plant flue-gas emissions recovered from automotive exhaust gas or derived from carbonic acid in seawater commercial fuel synthesis companies suggest they can produce synthetic fuels for less than petroleum fuels when oil costs more than $55 per barrel renewable methanol rm is a fuel produced from hydrogen and carbon dioxide by catalytic hydrogenation where the hydrogen has been obtained from water electrolysis it can be blended into transportation fuel or processed as a chemical feedstockthe george olah carbon dioxide recycling plant operated by carbon recycling international in grindavík iceland has been producing 2 million liters of methanol transportation fuel per year from flue exhaust of the svartsengi power station since 2011 it has the capacity to produce 5 million liters per year a 250 kilowatt methane synthesis plant was constructed by the center for solar energy and hydrogen research zsw at baden-württemberg and the fraunhofer society in germany and began operating in 2010 it is being upgraded to 10 megawatts scheduled for completion in autumn 2012 audi has constructed a carbon-neutral liquefied natural gas lng plant in werlte germany the plant is intended to produce transportation fuel to offset lng used in their a3 sportback g-tron automobiles and can keep 2,800 metric tons of co2 out of the environment per year at its initial capacity other commercial developments are taking place in columbia south carolina camarillo california and darlington englandsuch fuels are considered carbon-neutral because they do not result in a net increase in atmospheric greenhouse gases to the extent that synthetic fuels displace fossil fuels or if they are produced from waste carbon or seawater carbonic acid and their combustion is subject to carbon capture at the flue or exhaust pipe they result in negative carbon dioxide emission and net carbon dioxide removal from the atmosphere and thus constitute a form of greenhouse gas remediationsuch renewable fuels alleviate the costs and dependency issues of imported fossil fuels without requiring either electrification of the vehicle fleet or conversion to hydrogen or other fuels enabling continued compatible and affordable vehicles carbon-neutral fuels offer relatively low cost energy storage alleviating the problems of wind and solar intermittency and they enable distribution of wind water and solar power through existing natural gas pipelinesnighttime wind power is considered the most economical form of electrical power with which to synthesize fuel because the load curve for electricity peaks sharply during the warmest hours of the day but wind tends to blow slightly more at night than during the day so the price of nighttime wind power is often much less expensive than any alternative germany has built a 250 kilowatt synthetic methane plant which they are scaling up to 10 megawattsbiomassbiomass is biological material derived from living or recently living organisms it most often refers to plants or plant-derived materials which are specifically called lignocellulosic biomass as an energy source biomass can either be used directly via combustion to produce heat or indirectly after converting it to various forms of biofuel conversion of biomass to biofuel can be achieved by different methods which are broadly classified into thermal chemical and biochemical methods wood remains the largest biomass energy source today examples include forest residues – such as dead trees branches and tree stumps – yard clippings wood chips and even municipal solid waste in the second sense biomass includes plant or animal matter that can be converted into fibers or other industrial chemicals including biofuels industrial biomass can be grown from numerous types of plants including miscanthus switchgrass hemp corn poplar willow sorghum sugarcane bamboo and a variety of tree species ranging from eucalyptus to oil palm palm oilbiomass biogas and biofuels are burned to produce heat/power and in doing so harm the environment pollutants such as sulphurous oxides sox nitrous oxides nox and particulate matter pm are produced from this combustion the world health organisation estimates that 7 million premature deaths are caused each year by air pollution biomass combustion is a major contributorethanol biofuelsas the primary source of biofuel in north america many organizations are conducting research in the area of ethanol production on the federal level the usda conducts a large amount of research regarding ethanol production in the united states much of this research is targeted towards the effect of ethanol production on domestic food markets the national renewable energy laboratory has conducted various ethanol research projects mainly in the area of cellulosic ethanol cellulosic ethanol has many benefits over traditional corn based-ethanol it does not take away or directly conflict with the food supply because it is produced from wood grasses or non-edible parts of plants moreover some studies have shown cellulosic ethanol to be more cost effective and economically sustainable than corn-based ethanol even if we used all the corn crop that we have in the united states and converted it into ethanol it would only produce enough fuel to serve 13 percent of the united states total gasoline consumptionsandia national laboratories conducts in-house cellulosic ethanol research and is also a member of the joint bioenergy institute jbei a research institute founded by the united states department of energy with the goal of developing cellulosic biofuelsother biofuelsfrom 1978 to 1996 the national renewable energy laboratory experimented with producing algae fuel in the aquatic species program a self-published article by michael briggs at the university of new hampshire biofuels group offers estimates for the realistic replacement of all motor vehicle fuel with biofuels by utilizing algae that have a natural oil content greater than 50% which briggs suggests can be grown on algae ponds at wastewater treatment plants this oil-rich algae can then be extracted from the system and processed into biofuels with the dried remainder further reprocessed to create ethanol the production of algae to harvest oil for biofuels has not yet been undertaken on a commercial scale but feasibility studies have been conducted to arrive at the above yield estimate during the biofuel production process algae actually consumes the carbon dioxide in the air and turns it into oxygen through photosynthesis in addition to its projected high yield algaculture— unlike food crop-based biofuels — does not entail a decrease in food production since it requires neither farmland nor fresh water many companies are pursuing algae bio-reactors for various purposes including scaling up biofuels production to commercial levelsseveral groups in various sectors are conducting research on jatropha curcas a poisonous shrub-like tree that produces seeds considered by many to be a viable source of biofuels feedstock oil much of this research focuses on improving the overall per acre oil yield of jatropha through advancements in genetics soil science and horticultural practices sg biofuels a san diego-based jatropha developer has used molecular breeding and biotechnology to produce elite hybrid seeds of jatropha that show significant yield improvements over first generation varieties the center for sustainable energy farming cfsef is a los angeles-based non-profit research organization dedicated to jatropha research in the areas of plant science agronomy and horticulture successful exploration of these disciplines is projected to increase jatropha farm production yields by 200-300% in the next ten yearsgeothermalgeothermal energy is produced by tapping into the thermal energy created and stored within the earth it arises from the radioactive decay of an isotope of potassium and other elements found in the earths crust geothermal energy can be obtained by drilling into the ground very similar to oil exploration and then it is carried by a heat-transfer fluid eg water brine or steam geothermal systems that are mainly dominated by water have the potential to provide greater benefits to the system and will generate more power within these liquid-dominated systems there are possible concerns of subsidence and contamination of ground-water resources therefore protection of ground-water resources is necessary in these systems this means that careful reservoir production and engineering is necessary in liquid-dominated geothermal reservoir systems geothermal energy is considered sustainable because that thermal energy is constantly replenished however the science of geothermal energy generation is still young and developing economic viability several entities such as the national renewable energy laboratory and sandia national laboratories are conducting research toward the goal of establishing a proven science around geothermal energy the international centre for geothermal research igc a german geosciences research organization is largely focused on geothermal energy development researchhydrogenover $1 billion of federal money has been spent on the research and development of hydrogen and a medium for energy storage in the united states both the national renewable energy laboratory and sandia national laboratories have departments dedicated to hydrogen research hydrogen is useful for energy storage and for use in airplanes but is not practical for automobile use as it is not very efficient compared to using a battery — for the same cost a person can travel three times as far using a batterythoriumthere are potentially two sources of nuclear power fission is used in all current nuclear power plants fusion is the reaction that exists in stars including the sun and remains impractical for use on earth as fusion reactors are not yet available however nuclear power is controversial politically and scientifically due to concerns about radioactive waste disposal safety the risks of a severe accident and technical and economical problems in dismantling of old power plantsthorium is a fissionable material used in thorium-based nuclear power the thorium fuel cycle claims several potential advantages over a uranium fuel cycle including greater abundance superior physical and nuclear properties better resistance to nuclear weapons proliferation and reduced plutonium and actinide production therefore it is sometimes referred as sustainableclean energy investments2010 was a record year for green energy investments according to a report from bloomberg new energy finance nearly us $243 billion was invested in wind farms solar power electric cars and other alternative technologies worldwide representing a 30 percent increase from 2009 and nearly five times the money invested in 2004 china had $51.1 billion investment in clean energy projects in 2010 by far the largest figure for any countrywithin emerging economies brazil comes second to china in terms of clean energy investments supported by strong energy policies brazil has one of the world’s highest biomass and small-hydro power capacities and is poised for significant growth in wind energy investment the cumulative investment potential in brazil from 2010 to 2020 is projected as $67 billionindia is another rising clean energy leader while india ranked the 10th in private clean energy investments among g-20 members in 2009 over the next 10 years it is expected to rise to the third position with annual clean energy investment under current policies forecast to grow by 369 percent between 2010 and 2020it is clear that the center of growth has started to shift to the developing economies and they may lead the world in the new wave of clean energy investmentsaround the world many sub-national governments - regions states and provinces - have aggressively pursued sustainable energy investments in the united states californias leadership in renewable energy was recognised by the climate group when it awarded former governor arnold schwarzenegger its inaugural award for international climate leadership in copenhagen in 2009 in australia the state of south australia - under the leadership of former premier mike rann - has led the way with wind power comprising 26% of its electricity generation by the end of 2011 edging out coal fired generation for the first time south australia also has had the highest take-up per capita of household solar panels in australia following the rann governments introduction of solar feed-in laws and educative campaign involving the installation of solar photovoltaic installations on the roofs of prominent public buildings including the parliament museum airport and adelaide showgrounds pavilion and schools rann australias first climate change minister passed legislation in 2006 setting targets for renewable energy and emissions cuts the first legislation in australia to do soalso in the european union there is a clear trend of promoting policies encouraging investments and financing for sustainable energy in terms of energy efficiency innovation in energy exploitation and development of renewable resources with increased consideration of environmental aspects and sustainabilityrelated journalsamong scientific journals related to the interdisciplinary study of sustainable energy areenergy and environmental scienceenergy for sustainable developmentenergy policyjournal of renewable and sustainable energyrenewable and sustainable energy reviewssee alsorenewable energy portalenergy portalsustainable development portalecology portalashden awards for sustainable energyelectric vehicleenvironmental impact of the energy industryenergy globe awardenergy hierarchyenergy parkhydrogen economyinternational network for sustainable energy - inforseinternational renewable energy agencyleadership in energy and environmental design leedlist of energy storage projectsrenewable energy and energy efficiency partnership - reeepus department of energy solar decathlonsustainable energy for all initiativethe venus projectga mansoori n enayati lb agyarko 2016 energy sources utilization legislation sustainability illinois as model state world sci pub co isbn 978-981-4704-00-7energy economicssustainable energypages with reference errorscs1 maint multiple names authors listarticles with wayback machine linkspages with duplicate reference namespages containing cite templates with deprecated parameterscs1 german-language sources decs1 maint uses authors parameteruse dmy dates from august 2012