Sustainable energy
Renewable energy
Anaerobic digestion
Biofuels
Biomass
Geothermal power
Hydroelectricity
Solar energy
Topics by country
Tidal power
Wave power
Wind
Energy conservation
Cogeneration
Energy efficiency
Geothermal
Green building
Microgeneration
Passive solar
Organic Rankine cycle
Sustainable transport
Toolbox
Carbon neutral fuel
Electric vehicle
Green vehicle
Plug-in hybrid
Transportation demand management
Sustainability
Outline of sustainability
List of sustainability topics
Sustainable cities
Sustainable energy
Portals
Sustainable development portal
Renewable energy portal
Environment portal
Sustainable energy is the sustainable provision of energy that meets the needs of the present without compromising the ability of future generations to meet their needs.
Technologies that promote sustainable energy include renewable energy sources, such as hydroelectricity, solar energy, wind energy, wave power, geothermal energy, artificial photosynthesis, and tidal power, and also technologies designed to improve energy efficiency.
Contents
1 Definitions
2 Renewable energy technologies
2.1 First-generation technologies
2.2 Second-generation technologies
2.3 Third-generation technologies
2.4 Enabling technologies for renewable energy
3 Energy efficiency
3.1 Energy Star
3.2 Smart-grid technology
4 Green Energy
4.1 Local green energy systems
4.2 Using green energy
4.2.1 Carbon neutral and negative fuels
4.3 Green energy and labelling by region
4.3.1 European Union
4.3.2 United States
5 Sustainable energy research
5.1 Solar
5.2 Wind
5.3 Carbon-neutral and negative fuels
5.4 Ethanol biofuels
5.5 Other Biofuels
5.6 Geothermal
5.7 Hydrogen
6 Clean energy investments
7 Nuclear power
8 Related journals
9 See also
10 References
Definitions[edit]
Energy efficiency and renewable energy are said to be the twin pillars of sustainable energy.[1] Some ways in which sustainable energy has been defined are:
“Effectively, 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 (British)[2]
“Dynamic 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 Press.
“Any energy generation, efficiency & 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 organization.[3]
“Energy which is replenishable within a human lifetime and causes no long-term damage to the environment.” – Jamaica Sustainable Development Network[4]
This 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 atmosphere.
Green 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 green.
Green power is a subset of renewable energy and represents those renewable energy resources and technologies that provide the highest environmental benefit. The U.S. 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 benefits.[5]
Renewable energy technologies[edit]
Main articles: Renewable energy and Renewable energy commercialization
Renewable energy technologies are essential contributors to sustainable energy as they generally contribute to world energy security, reducing dependence on fossil fuel resources,[6] and providing opportunities for mitigating greenhouse gases.[6] The International Energy Agency states that:
Conceptually, 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 use.
Second-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 materials.
Third-generation technologies are still under development and include advanced biomass gasification, biorefinery technologies, concentrating solar thermal power, hot dry rock geothermal energy, and ocean energy. Advances in nanotechnology may also play a major role.
—International Energy Agency, RENEWABLES IN GLOBAL ENERGY SUPPLY, An IEA Fact Sheet[6]
First- 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 play.[6]
Regarding 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 lastly 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 impacts.”[7]
First-generation technologies[edit]
One of many power plants at The Geysers, a geothermal power field in northern California, with a total output of over 750 MW.
First-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 acceptance.
—International Energy Agency, RENEWABLES IN GLOBAL ENERGY SUPPLY, An IEA Fact Sheet[6]
Among 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 reservoir.[8]
Hydroelectric dams are one of the most widely deployed sources of sustainable energy.
However, 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.[9] 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 generation.
Hydroelectric dam in cross section
Geothermal 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.[6]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 U.S. Department of Energy.
Biomass 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 areas.[10]
Second-generation technologies[edit]
Wind power: worldwide installed capacity [11]
Markets 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 improvement.
—International Energy Agency, RENEWABLES IN GLOBAL ENERGY SUPPLY, An IEA Fact Sheet[6]
Solar 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.[12] The heat can also be used for industrial applications or as an energy input for other uses such as cooling equipment.[13] 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 earth’s atmospheres.[14]
11 MW solar power plant near Serpa, Portugal 38°1?51?N 7°37?22?W? / ?38.03083°N 7.62278°W? / 38.03083; -7.62278
In 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).[15][16] There is a proposal to build a Solar power station in Victoria, Australia, which would be the world’s largest PV power station, at 154 MW.[17][18] Other large photovoltaic power stations include the Girassol solar power plant (62 MW),[19] and the Waldpolenz Solar Park (40 MW).[20]
Sketch of a Parabolic Trough Collector
Some 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,[21] and wind power produced some 1.3% of global electricity consumption.[22] Wind power accounts for approximately 20% of electricity use in Denmark, 9% in Spain, and 7% in Germany.[23][24] 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 cases.[6]
Solar 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.[25] Other parabolic trough power plants being proposed are two 50MW plants in Spain, and a 100MW plant in Israel.[26]
Information on pump, California
Brazil 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 country’s 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 oil.[27][28][29]
Most cars on the road today in the U.S. 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 U.S. roads.[30]
Third-generation technologies[edit]
MIT’s Solar House#1 built in 1939 used seasonal thermal energy storage (STES) for year round heating.
Third-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 energy.
—International Energy Agency, RENEWABLES IN GLOBAL ENERGY SUPPLY, An IEA Fact Sheet[6]
Bio-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 Energy.”[31]
According 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.[32] 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 States.[33]
The world’s first commercial[34]tidal stream generator – SeaGen – in Strangford Lough. The strong wake shows the power in the tidal current.
In terms of ocean energy, another third-generation technology, Portugal has the world’s 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.[35][36] 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.[37] 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 world’s largest with a capacity of 3 MW generated by four Pelamis machines.[38] (see also Wave far