Renewable energy is energy that comes from resources which are continually replenished such as sunlight, wind, rain, tides, waves and geothermal heat. About 16% of global final energy consumption comes from renewable resources, with 10%discuss of all energy from traditional biomass, mainly used for heating, and 3.4% from hydroelectricity. New renewables (small hydro, modern biomass, wind, solar, geothermal, and biofuels) accounted for another 3% and are growing very rapidly.2 The share of renewables in electricity generation is around 19%, with 16% of electricity coming from hydroelectricity and 3% from new renewables.2
Wind power is growing at the rate of 30% annually, with a worldwide installed capacity of 282,482 megawatts (MW) at the end of 2012, and is widely used in Europe, Asia, and the United States. At the end of 2012 the photovoltaic (PV) capacity worldwide was 100,000 MW, and PV power stations are popular in Germany and Italy. Solar thermal power stations operate in the USA and Spain, and the largest of these is the 354 MW SEGS power plant in the Mojave Desert. The world's largest geothermal power installation is The Geysers in California, with a rated capacity of 750 MW. 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% of the country's automotive fuel. Ethanol fuel is also widely available in the USA.
There is an ongoing renewable energy debate, the debate on biofuels include the food vs fuel dilemma and the Indirect land use change impacts of biofuels. The debate on hydropower installations usually revolve around the footprint of dam floodplains, with for example the Three Gorges dam, the largest renewable electricity source in the world, having displaced 1.3 million people,34 and garnered environmental criticism.5 The debate on new renewables, such as wind and solar, is usually much less intense, and focuses on their intermittent supply of electricity, higher cost of electricity, and a small but growing community opposition to the industrialized footprint of large solar and wind farm installations.6 Renewable energy accidents with large losses of life include the Banqiao dam failure and the inhalation of particulate matter from the burning of biomass.7
While many renewable energy projects are large-scale, renewable technologies are also suited to rural and remote areas, where energy is often crucial in human development.8 As of 2011, small solar PV systems provide electricity to a few million households, and micro-hydro configured into mini-grids serves many more. Over 44 million households use biogas made in household-scale digesters for lighting and/or cooking, and more than 166 million households rely on a new generation of more-efficient biomass cookstoves.9 United Nations' Secretary-General Ban Ki-moon has said that renewable energy has the ability to lift the poorest nations to new levels of prosperity.10
Climate change and global warming concerns, coupled with high oil prices, peak oil, and increasing government support, are driving increasing renewable energy legislation, incentives and commercialization.11 New government spending, regulation and policies helped the industry weather the global financial crisis better than many other sectors.12 According to a 2011 projection by the International Energy Agency, solar power generators may produce most of the world’s electricity within 50 years, dramatically reducing the emissions of greenhouse gases that harm the environment.13
Renewable energy sources, that derive their energy from the sun, either directly or indirectly, such as Hydro and wind, are expected to be capable of supplying humanity energy for almost another 1 billion years, at which point the predicted increase in heat from the sun is expected to make the surface of the Earth too hot for liquid water to exist.1415
Renewable energy is derived from natural processes that are replenished constantly. In its various forms, it derives directly from the sun, or from heat generated deep within the earth. Included in the definition is electricity and heat generated from solar, wind, ocean, hydropower, biomass, geothermal resources, and biofuels and hydrogen derived from renewable resources.
Renewable energy resources and significant opportunities for energy efficiency exist over wide geographical areas, in contrast to other energy sources, which are concentrated in a limited number of countries. Rapid deployment of renewable energy and energy efficiency, and technological diversification of energy sources, would result in significant energy security and economic benefits.18
- Power generation. Renewable energy provides 19% of electricity generation worldwide. Renewable power generators are spread across many countries, and wind power alone already provides a significant share of electricity in some areas: for example, 14% in the U.S. state of Iowa, 40% in the northern German state of Schleswig-Holstein, and 49% in Denmark. Some countries get most of their power from renewables, including Iceland (100%), Norway (98%), Brazil (86%), Austria (62%), New Zealand (65%), and Sweden (54%).20
- Heating. Solar hot water makes an important contribution to renewable heat in many countries, most notably in China, which now has 70% of the global total (180 GWth). Most of these systems are installed on multi-family apartment buildings and meet a portion of the hot water needs of an estimated 50–60 million households in China. Worldwide, total installed solar water heating systems meet a portion of the water heating needs of over 70 million households. The use of biomass for heating continues to grow as well. In Sweden, national use of biomass energy has surpassed that of oil. Direct geothermal for heating is also growing rapidly.20
- Transport fuels. Renewable biofuels have contributed to a significant decline in oil consumption in the United States since 2006.20 The 93 billion liters of biofuels produced worldwide in 2009 displaced the equivalent of an estimated 68 billion liters of gasoline, equal to about 5% of world gasoline production.20
At the national level, at least 30 nations around the world already have renewable energy contributing more than 20% of energy supply. National renewable energy markets are projected to continue to grow strongly in the coming decade and beyond, and some 120 countries have various policy targets for longer-term shares of renewable energy, including a 20% target of all electricity generated for the European Union by 2020. Some countries have much higher long-term policy targets of up to 100% renewables. Outside Europe, a diverse group of 20 or more other countries target renewable energy shares in the 2020–2030 time frame that range from 10% to 50%.21
In international public opinion surveys there is strong support for promoting renewable sources such as solar power and wind power, requiring utilities to use more renewable energy (even if this increases the cost), and providing tax incentives to encourage the development and use of such technologies. There is substantial optimism that renewable energy investments will pay off economically in the long term.22
Prior to the development of coal in the mid 19th century, nearly all energy used was renewable. Almost without a doubt the oldest known use of renewable energy, in the form of traditional biomass to fuel fires, dates from 790,000 years ago. Use of biomass for fire did not become commonplace until many hundreds of thousands of years later, sometime between 200,000 and 400,000 years ago.23
Probably the second oldest usage of renewable energy is harnessing the wind in order to drive ships over water. This practice can be traced back some 7000 years, to ships on the Nile.24
Moving into the time of recorded history, the primary sources of traditional renewable energy were human labor, animal power, water power, wind, in grain crushing Windmills, and firewood, a traditional biomass. A graph of energy use in the United States up until 1900 shows oil and natural gas with about the same importance in 1900 as wind and solar played in 2010.
By 1873, concerns of running out of coal prompted experiments with using solar energy.25 Development of solar engines continued until the outbreak of World War I. The importance of solar energy was recognized in a 1911 Scientific American article: "in the far distant future, natural fuels having been exhausted [solar power] will remain as the only means of existence of the human race".26
In the 1970s environmentalists promoted the development of renewable energy both as a replacement for the eventual depletion of oil, as well as for an escape from dependence on oil, and the first electricity generating wind turbines appeared. Solar had long been used for heating and cooling, but solar panels were too costly to build solar farms until 1980.27 The theory of peak oil was published in 1956.28
According to the OECD Factbook 2011-2012, for all OECD countries taken as a whole, the contribution of renewables to total energy supply increased from 4.8% in 1971 to 7.6% in 2010. In general the contribution of renewables to the energy supply in non-OECD countries is higher than in developed OECD countries.29 With the world average(including OECD countries and non-OECD countries) percentage of total energy supplied from renewable energy at 13.1% in 2010.30
Mainstream renewable technologies
Airflows can be used to run wind turbines. Modern utility-scale wind turbines range from around 600 kW to 5 MW of rated power, although turbines with rated output of 1.5–3 MW have become the most common for commercial use; the power available from the wind is a function of the cube of the wind speed, so as wind speed increases, power output increases dramatically up to the maximum output for the particular turbine.31 Areas where winds are stronger and more constant, such as offshore and high altitude sites, are preferred locations for wind farms. Typical capacity factors are 20-40%, with values at the upper end of the range in particularly favourable sites.3233
Globally, the long-term technical potential of wind energy is believed to be five times total current global energy production, or 40 times current electricity demand, assuming all practical barriers needed were overcome. This would require wind turbines to be installed over large areas, particularly in areas of higher wind resources, such as offshore. As offshore wind speeds average ~90% greater than that of land, so offshore resources can contribute substantially more energy than land stationed turbines.34
Energy in water can be harnessed and used. Since water is about 800 times denser than air, even a slow flowing stream of water, or moderate sea swell, can yield considerable amounts of energy. There are many forms of water energy:
- Hydroelectric energy is a term usually reserved for large-scale hydroelectric dams. The largest of which is the Three Gorges dam in the Peoples Republic of China and a smaller example is the Akosombo Dam in Ghana.
- Micro hydro systems are hydroelectric power installations that typically produce up to 100 kW of power. They are often used in water rich areas as a remote-area power supply (RAPS).
- Run-of-the-river hydroelectricity systems derive kinetic energy from rivers and oceans without the creation of a large reservoir.
Solar energy applies energy from the sun in the form of solar radiation for heat or to generate electricity. Solar powered electricity generation uses either photovoltaics or heat engines (concentrated solar power). A partial list of other solar applications includes space heating and cooling through solar architecture, daylighting, solar hot water, solar cooking, and high temperature process heat for industrial purposes.
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. Solar energy capture is also being linked to research involving water splitting and carbon dioxide reduction for the development of artificial photosynthesis or solar fuels.35
Biomass (plant material) can be a renewable energy source, but importantly, only if the rate of extraction does not exceed the rate of production, as non-renewable biomass usage can easily occur, such as the historical Deforestation during the Roman period and the present Deforestation of the Amazon Rainforest.
Through the process of photosynthesis, plants capture the sun's energy. When the plants are burnt, they release the sun's energy they contain. In this way, biomass functions as a sort of natural battery for storing solar energy.36unreliable source?
In general there are two main approaches to using plants for energy production: growing plants specifically for energy use (known as first and third-generation biomass), and using the residues (known as second-generation biomass) from plants that are used for other things. See biobased economy. The best approaches vary from region to region according to climate, soils and geography.36
The proportion of truly renewable biomass in use is uncertain, as for example peat, one of the largest sources of biomass, is sometimes regarded as a renewable source of energy. However due to peats extraction rate in industrialized countries far exceeding its slow regrowth rate of 1mm per year,37 and due to it being reported that peat regrowth takes place only in 30-40% of peatlands,38 There is considerable controversy with this renewable classification.39 Organizations tasked with assessing climate change mitigation methods differ on the subject, the UNFCCC classify peat as a fossil fuel due to the thousand plus year length of time for peat to re-accumulate after harvesting,40 another organization affiliated with the United Nations also classified peat as a fossil fuel.41 However, the Intergovernmental Panel on Climate Change (IPCC) has begun to classify peat as a "slow-renewable" fuel,42 with this also being the classification used by many in the peat industry.43
Further controversy surrounding the classification of all biomass as "renewable" centers around the fact that depending on the plant source, it can take from 2 to 100 years for different sources of plant energy to regrow, such as the difference between fast growing switch grass and slow growing trees, therefore due to the high emission intensity of plant material, researchers have suggested that if the biomass source takes longer than 20 years to regrow, they argue the plant source should not be regarded as renewable from a climate change mitigation standpoint.44
As of early 2012, 85 of 107 biomass plants operating in the U.S. had been cited by federal or state regulators for violating clean air or water laws over the past five years.45 The Energy Information Administration projected that by 2017, biomass is expected to be about twice as expensive as natural gas, slightly more expensive than nuclear power, and much less expensive than solar panels.46
Biofuels include a wide range of fuels which are derived from biomass. The term covers solid biomass, liquid fuels and various biogases.47 Liquid biofuels include bioalcohols, such as bioethanol, and oils, such as biodiesel. Gaseous biofuels include biogas, landfill gas and synthetic gas.
Bioethanol is an alcohol made by fermenting the sugar components of plant materials and it is made mostly from sugar and starch crops. With advanced technology being developed, cellulosic biomass, such as trees and grasses, are also used as feedstocks for ethanol production. Ethanol can be used as a fuel for vehicles in its pure form, but it is usually used as a gasoline additive to increase octane and improve vehicle emissions. Bioethanol is widely used in the USA and in Brazil. However, according to the European Environment Agency, biofuels do not address global warming concerns.48
Biodiesel is made from vegetable oils, animal fats or recycled greases. Biodiesel can be used as a fuel for vehicles in its pure form, but it is usually used as a diesel additive to reduce levels of particulates, carbon monoxide, and hydrocarbons from diesel-powered vehicles. Biodiesel is produced from oils or fats using transesterification and is the most common biofuel in Europe.
Geothermal energy is from thermal energy generated and stored in the Earth. Thermal energy is the energy that determines the temperature of matter. Earth's geothermal energy originates from the original formation of the planet (20%) and from radioactive decay of minerals (80%).50 The geothermal gradient, which is the difference in temperature between the core of the planet and its surface, drives a continuous conduction of thermal energy in the form of heat from the core to the surface. The adjective geothermal originates from the Greek roots geo, meaning earth, and thermos, meaning heat.
The heat that is used for geothermal energy can be from deep within the Earth, all the way down to Earth’s core – 4,000 miles (6,400 km) down. At the core, temperatures may reach over 9,000 °F (5,000 °C). Heat conducts from the core to surrounding rock. Extremely high temperature and pressure cause some rock to melt, which is commonly known as magma. Magma convects upward since it is lighter than the solid rock. This magma then heats rock and water in the crust, sometimes up to 700 °F (371 °C).51
The Earth is a giant hydraulic pump without flow. Therefore, we can consider any of these, as analysis model.
No matter their inefficiency, when there is no flow of water: efficiency is zero, and all the energy in the shaft, is lost in heat or internal energy, and self-recirculation.52 When the flow rate increases, so does the efficiency until it reaches its maximum; being transferred more energy from the shaft, and lowering the energy loss. That is, one flow is primed, which implies, a percentage of the total shaft energy.
Also, there are estimates of the energy in the powerful, ocean currents, that I think, the most powerful are four; already such estimates of lost energy (370TW) is enough to justify our discovery. But the interesting thing is that, until the more inefficient, centrifugal pumps on our planet, if its impeller rotates, its efficiency is not less than 1%. Why think that the earth not have this efficiency, in the worst case? However, the discovery: Oceanogenic Power, and all its extraordinary implications, it is justified, although the efficiency be less than 0.000001%.
Heat 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 process).
Thermal 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 (i.e. by changing the temperature of a medium) or latent energy (i.e. 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 (e.g. collected via solar-thermal collectors, or dry cooling towers used to collect winter's cold), waste energy (e.g. from HVAC equipment, industrial processes or power plants), or surplus energy (e.g. as seasonally from hyropower projects or intermitently 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.5354 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 (PCMs).
Renewable energy commercialization
Growth of renewables
From the end of 2004, worldwide renewable energy capacity grew at rates of 10–60% annually for many technologies. For wind power and many other renewable technologies, growth accelerated in 2009 relative to the previous four years.19 More wind power capacity was added during 2009 than any other renewable technology. However, grid-connected PV increased the fastest of all renewables technologies, with a 60% annual average growth rate.19 In 2010, renewable power constituted about a third of the newly built power generation capacities.55 By 2014 the installed capacity of photovoltaics will likely exceed that of wind, but due to the lower capacity factor of solar, the energy generated from photovoltaics is not expected to exceed that of wind until 2015.
|Selected global indicators||2008||2009||2010||2011|
|Investment in new renewable capacity (annual) (109 USD)||130||160||211||257|
|Renewables power capacity (existing) (GWe)||1,140||1,230||1,320||1,360|
|Hydropower capacity (existing) (GWe)||885||915||945||970|
|Wind power capacity (existing) (GWe)||121||159||198||238|
|Solar PV capacity (grid-connected) (GWe)||16||23||40||70|
|Solar hot water capacity (existing) (GWth)||130||160||185||232|
|Ethanol production (annual) (109 litres)||67||76||86||86|
|Biodiesel production (annual) (109 litres)||12||17.8||18.5||21.4|
|Countries with policy targets
for renewable energy use
According to a 2011 projection by the International Energy Agency, solar power generators may produce most of the world’s electricity within 50 years, dramatically reducing the emissions of greenhouse gases that harm the environment. Cedric Philibert, senior analyst in the renewable energy division at the IEA said: “Photovoltaic and solar-thermal plants may meet most of the world’s demand for electricity by 2060 -- and half of all energy needs -- with wind, hydropower and biomass plants supplying much of the remaining generation”. “Photovoltaic and concentrated solar power together can become the major source of electricity,” Philibert said.13
Renewable energy technologies are getting cheaper, through technological change and through the benefits of mass production and market competition. A 2011 IEA report said: "A portfolio of renewable energy technologies is becoming cost-competitive in an increasingly broad range of circumstances, in some cases providing investment opportunities without the need for specific economic support," and added that "cost reductions in critical technologies, such as wind and solar, are set to continue."61
Hydro-electricity and geothermal electricity produced at favourable sites are now the cheapest way to generate electricity. Renewable energy costs continue to drop, and the levelised cost of electricity (LCOE) is declining for wind power, solar photovoltaic (PV), concentrated solar power (CSP) and some biomass technologies.62
Renewable energy is also the most economic solution for new grid-connected capacity in areas with good resources. As the cost of renewable power falls, the scope of economically viable applications increases. Renewable technologies are now often the most economic solution for new generating capacity. Where “oil-fired generation is the predominant power generation source (e.g. on islands, off-grid and in some countries) a lower-cost renewable solution almost always exists today”.62
The Three Gorges Dam in Hubei, China, has the world's largest instantaneous generating capacity (22,500 MW), with the Itaipu Dam in Brazil/Paraguay in second place (14,000 MW). The Three Gorges Dam is operated jointly with the much smaller Gezhouba Dam (3,115 MW). As of 2012[update], the total generating capacity of this two-dam complex is 25,615 MW. In 2008, this complex generated 97.9 TWh of electricity (80.8 TWh from the Three Gorges Dam and 17.1 TWh from the Gezhouba Dam), which is 3.4% more power in one year than the 94.7 TWh generated by Itaipu in 2008.
Wind power development
Wind power is growing at over 20% annually, with a worldwide installed capacity of 238,000 MW at the end of 2011,566465 and is widely used in Europe, Asia, and the United States.6667 Several countries have achieved relatively high levels of wind power penetration, such as 21% of stationary electricity production in Denmark,68 18% in Portugal,68 16% in Spain,68 14% in Ireland69 and 9% in Germany in 2010.4968 As of 2011, 83 countries around the world are using wind power on a commercial basis.49
|% world total|
|(rest of world)||39,853||14.1|
|World total||282,482 MW||100%|
As of 2012, the Alta Wind Energy Center (California, 1,020 MW) is the world's largest wind farm.71 As of February 2012, the Walney Wind Farm in the United Kingdom is the largest offshore wind farm in the world at 367 MW, followed by Thanet Offshore Wind Project (300 MW), also in the UK. The London Array (630 MW) is the largest project under construction. The United Kingdom is the world's leading generator of offshore wind power, followed by Denmark.72
There are many large wind farms under construction and these include Anholt Offshore Wind Farm (400 MW), BARD Offshore 1 (400 MW), Clyde Wind Farm (548 MW), Fântânele-Cogealac Wind Farm (600 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 the Sheringham Shoal (317 MW).
Large solar thermal power stations include the 354 MW Solar Energy Generating Systems power plant in the USA, Solnova Solar Power Station (Spain, 150 MW), Andasol Solar Power Station (Spain, 100 MW), Nevada Solar One (USA, 64 MW), PS20 solar power plant (Spain, 20 MW), and the PS10 Solar Power Plant (Spain, 11 MW).
The Ivanpah Solar Power Facility is a 392 MW solar power facility which is under construction in south-eastern California.73 The Solana Generating Station is a 280 MW solar power plant which is under construction near Gila Bend, Arizona, about 70 miles (110 km) southwest of Phoenix. The Crescent Dunes Solar Energy Project is a 110 MW solar thermal power project currently under construction near Tonopah, about 190 miles (310 km) northwest of Las Vegas.74
The solar thermal power industry is growing rapidly with 1.3 GW under construction in 2012 and more planned. Spain is the epicenter of solar thermal power development with 873 MW under construction, and a further 271 MW under development.75 In the United States, 5,600 MW of solar thermal power projects have been announced.76 In developing countries, three World Bank projects for integrated solar thermal/combined-cycle gas-turbine power plants in Egypt, Mexico, and Morocco have been approved.77
Photovoltaic power stations
|Year end capacities|
Solar photovoltaic cells (PV) convert sunlight into electricity and photovoltaic production has been increasing by an average of more than 20% each year since 2002, making it a fast-growing energy technology.7980 While wind is often cited as the fastest growing energy source, photovoltaics since 2007 has been increasing at twice the rate of wind - an average of 63.6%/year, due to the reduction in cost. At the end of 2011 the photovoltaic (PV) capacity world-wide was 67.4 GW, a 69.8% annual increase. Top capacity countries were, in GW: Germany 24.7, Italy 12.8, Japan 4.7, Spain 4.4, the USA 4.4, and China 3.1.7881
Many solar photovoltaic power stations have been built, mainly in Europe.82 As of May 2012, the largest photovoltaic (PV) power plants in the world are the Agua Caliente Solar Project (USA, 247 MW), Charanka Solar Park (India, 214 MW), Golmud Solar Park (China, 200 MW), Perovo Solar Park (Ukraine, 100 MW), Sarnia Photovoltaic Power Plant (Canada, 97 MW), Brandenburg-Briest Solarpark (Germany, 91 MW), Solarpark Finow Tower (Germany, 84.7 MW), Montalto di Castro Photovoltaic Power Station (Italy, 84.2 MW), and the Eggebek Solar Park (Germany, 83.6 MW).82
There are also many large plants under construction. The Desert Sunlight Solar Farm is a 550 MW solar power plant under construction in Riverside County, California, that will use thin-film solar photovoltaic modules made by First Solar.83 The Topaz Solar Farm is a 550 MW photovoltaic power plant, being built in San Luis Obispo County, California.84 The Blythe Solar Power Project is a 500 MW photovoltaic station under construction in Riverside County, California. The California Valley Solar Ranch (CVSR) is a 250 MW solar photovoltaic power plant, which is being built by SunPower in the Carrizo Plain, northeast of California Valley.85 The 230 MW Antelope Valley Solar Ranch is a First Solar photovoltaic project which is under construction in the Antelope Valley area of the Western Mojave Desert, and due to be completed in 2013.86
Many of these plants are integrated with agriculture and some use tracking systems that follow the sun's daily path across the sky to generate more electricity than fixed-mounted systems. There are no fuel costs or emissions during operation of the power stations.
However, when it comes to renewable energy systems and PV, it is not just large systems that matter. Building-integrated photovoltaics or "onsite" PV systems use existing land and structures and generate power close to where it is consumed.87
Biofuels provided 3% of the world's transport fuel in 2010.49 Mandates for blending biofuels exist in 31 countries at the national level and in 29 states/provinces.49 According to the International Energy Agency, biofuels have the potential to meet more than a quarter of world demand for transportation fuels by 2050.88
Since the 1970s, Brazil has had an ethanol fuel program which has allowed the country to become the world's second largest producer of ethanol (after the United States) and the world's largest exporter.89 Brazil’s ethanol fuel program uses modern equipment and cheap sugarcane as feedstock, and the residual cane-waste (bagasse) is used to produce heat and power.90 There are no longer light vehicles in Brazil running on pure gasoline. By the end of 2008 there were 35,000 filling stations throughout Brazil with at least one ethanol pump.91
Nearly all the gasoline sold in the United States today is mixed with 10% ethanol, a mix known as E10,92 and motor vehicle manufacturers already produce vehicles designed to run on much higher ethanol blends. Ford, Daimler AG, 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 6 million E85-compatible vehicles on U.S. roads.93 The challenge is to expand the market for biofuels beyond the farm states where they have been most popular to date. Flex-fuel vehicles are assisting in this transition because they allow drivers to choose different fuels based on price and availability. The Energy Policy Act of 2005, which calls for 7.5 billion US gallons (28,000,000 m3) of biofuels to be used annually by 2012, will also help to expand the market.93
Geothermal power is cost effective, reliable, sustainable, and environmentally friendly,94 but has historically been limited to areas near tectonic plate boundaries. Recent technological advances have dramatically expanded the range and size of viable resources, especially for applications such as home heating, opening a potential for widespread exploitation. Geothermal wells release greenhouse gases trapped deep within the earth, but these emissions are much lower per energy unit than those of fossil fuels. As a result, geothermal power has the potential to help mitigate global warming if widely deployed in place of fossil fuels.
The International Geothermal Association (IGA) has reported that 10,715 MW of geothermal power in 24 countries is online, which is expected to generate 67,246 GWh of electricity in 2010.95 This represents a 20% increase in geothermal power online capacity since 2005. IGA projects this will grow to 18,500 MW by 2015, due to the large number of projects presently under consideration, often in areas previously assumed to have little exploitable resource.95
In 2010, the United States led the world in geothermal electricity production with 3,086 MW of installed capacity from 77 power plants;96 the largest group of geothermal power plants in the world is located at The Geysers, a geothermal field in California.97 The Philippines follows the US as the second highest producer of geothermal power in the world, with 1,904 MW of capacity online; geothermal power makes up approximately 18% of the country's electricity generation.96
Renewable energy can be particularly suitable for developing countries. In rural and remote areas, transmission and distribution of energy generated from fossil fuels can be difficult and expensive. Producing renewable energy locally can offer a viable alternative.98
Technology advances are opening up a huge new market for solar power: the approximately 1.3 billion people around the world who don't have access to grid electricity. Even though they are typically very poor, these people have to pay far more for lighting than people in rich countries because they use inefficient kerosene lamps. Solar power costs half as much as lighting with kerosene.99 An estimated 3 million households get power from small solar PV systems.100 Kenya is the world leader in the number of solar power systems installed per capita. More than 30,000 very small solar panels, each producing 12 to 30 watts, are sold in Kenya annually. Some Small Island Developing States (SIDS) are also turning to solar power to reduce their costs and increase their sustainability.101
Micro-hydro configured into mini-grids also provide power. Over 44 million households use biogas made in household-scale digesters for lighting and/or cooking, and more than 166 million households rely on a new generation of more-efficient biomass cookstoves.9 Clean liquid fuel sourced from renewable feedstocks are used for cooking and lighting in energy-poor areas of the developing world. Alcohol fuels (ethanol and methanol) can be produced sustainably from non-food sugary, starchy, and cellulostic feedstocks. Project Gaia, Inc. and CleanStar Mozambique are implementing clean cooking programs with liquid ethanol stoves in Ethiopia, Kenya, Nigeria and Mozambique.102
Renewable energy projects in many developing countries have demonstrated that renewable energy can directly contribute to poverty alleviation by providing the energy needed for creating businesses and employment. Renewable energy technologies can also make indirect contributions to alleviating poverty by providing energy for cooking, space heating, and lighting. Renewable energy can also contribute to education, by providing electricity to schools.103
Industry and policy trends
U.S. President Barack Obama's American Recovery and Reinvestment Act of 2009 includes more than $70 billion in direct spending and tax credits for clean energy and associated transportation programs. Clean Edge suggests that the commercialization of clean energy will help countries around the world pull out of the current economic malaise.12 Leading renewable energy companies include First Solar, Gamesa, GE Energy, Q-Cells, Sharp Solar, Siemens, SunOpta, Suntech Power, and Vestas.105
The military has also focused on the use of renewable fuels for military vehicles. Unlike fossil fuels, renewable fuels can be produced in any country, creating a strategic advantage. The US military has already committed itself to have 50% of its energy consumption come from alternative sources.106
The International Renewable Energy Agency (IRENA) is an intergovernmental organization for promoting the adoption of renewable energy worldwide. It aims to provide concrete policy advice and facilitate capacity building and technology transfer. IRENA was formed on January 26, 2009, by 75 countries signing the charter of IRENA.107 As of March 2010, IRENA has 143 member states who all are considered as founding members, of which 14 have also ratified the statute.108
As of 2011, 119 countries have some form of national renewable energy policy target or renewable support policy. National targets now exist in at least 98 countries. There is also a wide range of policies at state/provincial and local levels.49
United Nations' Secretary-General Ban Ki-moon has said that renewable energy has the ability to lift the poorest nations to new levels of prosperity.10 In October 2011, he "announced the creation of a high-level group to drum up support for energy access, energy efficiency and greater use of renewable energy. The group is to be co-chaired by Kandeh Yumkella, the chair of UN Energy and director general of the UN Industrial Development Organisation, and Charles Holliday, chairman of Bank of America".109
100% renewable energy
Renewable energy use has grown much faster than anyone anticipated.110 Wind turbines generate nearly 30 percent of Danish electricity, and Denmark has many biogas digesters and waste-to-energy plants as well. Together, wind and biomass provide 44% of the electricity consumed by the country's six million inhabitants. In 2010, Portugal’s 10 million people produced more than half their electricity from indigenous renewable energy resources. Spain’s 40 million inhabitants meet one-third of their electrical needs from renewables.110
The incentive to use 100% renewable energy is created by global warming and ecological as well as economic concerns, post peak oil. The first country to propose 100% renewable energy was Iceland, in 1998.111 Proposals have been made for Japan in 2003,112 and for Australia in 2011.113 Norway and some other countries already obtain all of their electricity from renewable sources. Iceland proposed using hydrogen for transportation and its fishing fleet. Australia proposed biofuel for those elements of transportation not easily converted to electricity. The road map for the United States,114115 commitment by Denmark,116 and Vision 2050 for Europe set a 2050 timeline for converting to 100% renewable energy,117 later reduced to 2040 in 2011.118 Zero Carbon Britain 2030 proposes eliminating carbon emissions in Britain by 2030 by transitioning to renewable energy.119
It is estimated that the world will spend an extra $8 trillion over the next 25 years to prolong the use of non-renewable resources, a cost that would be eliminated by transitioning instead to 100% renewable energy.120 A 2009 study suggests that converting the entire world to 100% renewable energy by 2030 is both possible and affordable, but requires political support. It would require building many more wind turbines and solar power systems. Other changes involve use of electric cars and the development of enhanced transmission grids and storage.121122123124125
The Fourth Revolution: Energy is a German documentary film released in 2010. It shows the vision of a global society, which lives in a world where the energy is produced 100% with renewable energies, showing a complete reconstruction of the economy, to reach this goal. In 2011, Hermann Scheer wrote the book The Energy Imperative: 100 Percent Renewable Now, published by Routledge.
In 2011, the Intergovernmental Panel on Climate Change, the world's leading climate scientists convened by the United Nations, said "as infrastructure and energy systems develop, in spite of the complexities, there are few, if any, fundamental technological limits to integrating a portfolio of renewable energy technologies to meet a majority share of total energy demand in locations where suitable renewable resources exist or can be supplied".126 IPCC scenarios "generally indicate that growth in renewable energy will be widespread around the world".127 The IPCC said that if governments were supportive, and the full range of renewable technologies were deployed, renewable energy could account for almost 80% of the world's energy supply within four decades.128 Rajendra Pachauri, chairman of the IPCC, said the necessary investment in renewables would cost only about 1% of global GDP annually. This approach could keep greenhouse gas concentrations to less than 450 parts per million, the safe level beyond which climate change becomes catastrophic and irreversible.128
In 2011, the refereed journal Energy Policy published two articles by Mark Z. Jacobson, a professor of engineering at Stanford University, and Mark A. Delucchi, about changing our energy supply mix and "Providing all global energy with wind, water, and solar power". The articles analyze the feasibility of providing worldwide energy for electric power, transportation, and heating/cooling from wind, water, and sunlight (WWS), which are safe clean options. In Part I, Jacobson and Delucchi discuss WWS energy system characteristics, aspects of energy demand, WWS resource availability, WWS devices needed, and material requirements.129 They estimate that 3,800,000 5 MW wind turbines, 5350 100 MW geothermal power plants, and 270 new 1300 MW hydroelectric power plants will be required. In terms of solar power, an additional 49,000 300 MW concentrating solar plants, 40,000 300 MW solar photovoltaic power plants, and 1.7 billion 3 kW rooftop photovoltaic systems will also be needed. Such an extensive WWS infrastructure could decrease world power demand by 30%.129 In Part II, Jacobson and Delucchi address variability of supply, system economics, and energy policy initiatives associated with a WWS system. The authors advocate producing all new energy with WWS by 2030 and replacing existing energy supply arrangements by 2050. Barriers to implementing the renewable energy plan are seen to be "primarily social and political, not technological or economic". Energy costs with a WWS system should be similar to today's energy costs.130 NASA Climate scientist James Hansen and Environmentalists for nuclear energy in general, however do not agree, with Hansen describing the idea of a modern world run on renewable energy as equivalent to: "believing in the Easter Bunny and Tooth Fairy".131
In general, Jacobson has said wind, water and solar technologies can provide 100 per cent of the world's energy, eliminating all fossil fuels.132 He advocates a "smart mix" of renewable energy sources to reliably meet electricity demand:
Because the wind blows during stormy conditions when the sun does not shine and the sun often shines on calm days with little wind, combining wind and solar can go a long way toward meeting demand, especially when geothermal provides a steady base and hydroelectric can be called on to fill in the gaps.58
A 2012 study by the University of Delaware for a 72 GW system considered 28 billion combinations of renewable energy and storage and found the most cost effective, for the PJM Interconnection, would use 17 GW of solar, 68 GW of offshore wind, and 115 GW of onshore wind, although at times as much as three times the demand would be provided. 0.1% of the time would require generation from other sources.133
In March 2012, Denmark's parliament agreed on a comprehensive new set promotional programs for energy efficiency and renewable energy that will lead to the country getting 100 percent of electricity, heat and fuels from renewables by 2050.134
In 2013, scientist Vaclav Smil analyzed proposals to depend on wind and solar-generated electricity including the proposals of Mark Z. Jacobson and colleagues, and writing in an issue of Spectrum prepared by the Institute of Electrical and Electronics Engineers, he identified numerous points of concern, such as cost, intermittent power supply, growing NIMBYism and a lack of infrastructure as negative factors and said that "History and a consideration of the technical requirements show that the problem is much greater than these advocates have supposed."137138
Other renewable energy technologies are still under development, and include cellulosic ethanol, hot-dry-rock geothermal power, and ocean energy.139 These technologies are not yet widely demonstrated or have limited commercialization. Many are on the horizon and may have potential comparable to other renewable energy technologies, but still depend on attracting sufficient attention and research, development and demonstration (RD&D) funding.139
There are numerous organizations within the academic, federal, and commercial sectors conducting large scale advanced research in the field of renewable energy. This research spans several areas of focus across the renewable energy spectrum. Most of the research is targeted at improving efficiency and increasing overall energy yields.140 Multiple federally supported research organizations have focused on renewable 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.141 Sandia has a total budget of $2.4 billion142 while NREL has a budget of $375 million.143
Companies such as Iogen, POET, and Abengoa are building refineries that can process biomass and turn it into ethanol, while companies such as the Verenium Corporation, Novozymes, and Dyadic International are producing enzymes which could enable a cellulosic ethanol future. The shift from food crop feedstocks to waste residues and native grasses offers significant opportunities for a range of players, from farmers to biotechnology firms, and from project developers to investors.144
|Abengoa Bioenergy||Hugoton, KS||Wheat straw|
|BlueFire Renewables||Irvine, CA||Multiple sources|
|Gulf Coast Energy||Mossy Head, FL||Wood waste|
|POET||Emmetsburg, IA||Corn cobs|
|SunOpta||Little Falls, MN||Wood chips|
|Xethanol||Auburndale, FL||Citrus peels|
Systems to harvest utility-scale electrical power from ocean waves have recently been gaining momentum as a viable technology. The potential for this technology is considered promising, especially on west-facing coasts with latitudes between 40 and 60 degrees:147
In the United Kingdom, for example, the Carbon Trust recently estimated the extent of the economically viable offshore resource at 55 TWh per year, about 14% of current national demand. Across Europe, the technologically achievable resource has been estimated to be at least 280 TWh per year. In 2003, the U.S. Electric Power Research Institute (EPRI) estimated the viable resource in the United States at 255 TWh per year (6% of demand).147
Scotland is home to the European Marine Energy Centre the world's first testing facility for wave and tidal machines, located in the waters around the Orkney Islands. In 2012 at the wave test site, E.ON are testing a Pelamis Wave Energy Converter machine and Aquamarine Power are testing their near-shore Oyster device. Wave farm developments are planned in Scottish waters by E.ON, ScottishPower Renewables, SSE, Pelamis Wave Power, Aquamarine Power and Aegir Wave Power, a joint venture between Pelamis and Vattenfall.148
The world's first commercial tidal stream generator was installed in 2007 in the narrows of Strangford Lough in Ireland. The 1.2 MW underwater tidal electricity generator, part of Northern Ireland's Environment & Renewable Energy Fund scheme, takes advantage of the fast tidal flow (up to 4 metres per second) in the lough. Although the generator is powerful enough to power a thousand homes, the turbine has minimal environmental impact, as it is almost entirely submerged, and the rotors pose no danger to wildlife as they turn quite slowly.149
Ocean thermal energy
Ocean thermal energy conversion (OTEC) uses the temperature difference that exists between deep and shallow waters to run a heat engine.
Enhanced geothermal systems
Enhanced geothermal systems are a new type of geothermal power technologies that do not require natural convective hydrothermal resources. The vast majority of geothermal energy within drilling reach is in dry and non-porous rock.150 EGS technologies "enhance" and/or create geothermal resources in this "hot dry rock (HDR)" through hydraulic stimulation.
EGS / HDR technologies, like hydrothermal geothermal, are expected to be baseload resources which produce power 24 hours a day like a fossil plant. Distinct from hydrothermal, HDR / EGS may be feasible anywhere in the world, depending on the economic limits of drill depth. Good locations are over deep granite covered by a thick (3–5 km) layer of insulating sediments which slow heat loss.151
There are HDR and EGS systems currently being developed and tested in France, Australia, Japan, Germany, the U.S. and Switzerland. The largest EGS project in the world is a 25 megawatt demonstration plant currently being developed in the Cooper Basin, Australia. The Cooper Basin has the potential to generate 5,000–10,000 MW.
Experimental solar power
Concentrated photovoltaics (CPV) systems employ sunlight concentrated onto photovoltaic surfaces for the purpose of electricity generation. Thermoelectric, or "thermovoltaic" devices convert a temperature difference between dissimilar materials into an electric current.
Artificial photosynthesis uses techniques include nanotechnology to store solar electromagnetic energy in chemical bonds by splitting water to produce hydrogen and then using carbon dioxide to make methanol.152 Researchers in this field are striving to design molecular mimics of photosynthesis that utilize a wider region of the solar spectrum, employ catalytic systems made from abundant, inexpensive materials that are robust, readily repaired, non-toxic, stable in a variety of environmental conditions and perform more efficiently allowing a greater proportion of photon energy to end up in the storage compounds, i.e., carbohydrates (rather than building and sustaining living cells). Relevant approaches utilize coordination chemistry, material science and modified bio-engineered, synthetic biomimetic and bio-inspired techniques, as well as nanosciences, to construct photo-semiconductors and solid state catalysts for water oxidation, plus hydrogen evolution catalysts based on enzymes.153
Renewable energy debate
Renewable electricity production, from sources such as wind power and solar power, is sometimes criticized for being variable or intermittent. However, the International Energy Agency has stated that deployment of renewable technologies usually increases the diversity of electricity sources and, through local generation, contributes to the flexibility of the system and its resistance to central shocks.154
There have been "not in my back yard" (NIMBY) concerns relating to the visual and other impacts of some wind farms, with local residents sometimes fighting or blocking construction.155 In the USA, the Massachusetts Cape Wind project was delayed for years partly because of aesthetic concerns. However, residents in other areas have been more positive. According to a town councilor, the overwhelming majority of locals believe that the Ardrossan Wind Farm in Scotland has enhanced the area.156
A recent UK Government document states that “projects are generally more likely to succeed if they have broad public support and the consent of local communities. This means giving communities both a say and a stake”.157 In countries such as Germany and Denmark many renewable projects are owned by communities, particularly through cooperative structures, and contribute significantly to overall levels of renewable energy deployment.158159 In recent years, new online crowdfunding platforms have provided additional mechanisms for broader participation in, and support for, renewable energy by allowing anyone to invest even small amounts and benefit from the returns. Examples include Abundance Generation in the UK 160 and Solar Mosaic in the USA.
The market for renewable energy technologies has continued to grow. Climate change concerns, coupled with high oil prices, peak oil, and increasing government support, are driving increasing renewable energy legislation, incentives and commercialization.11 New government spending, regulation and policies helped the industry weather the 2009 economic crisis better than many other sectors.12
- Edwin Cartlidge (18 November 2011). "Saving for a rainy day". Science (Vol 334). pp. 922–924.
- REN21 (2011). "Renewables 2011: Global Status Report". pp. 17, 18.
- "重庆云阳长江右岸现360万方滑坡险情-地方-人民网". People's Daily. Retrieved 2009-08-01. See also: "探访三峡库区云阳故陵滑坡险情". News.xinhuanet.com. Retrieved 2009-08-01.
- Lin Yang (2007-10-12). "China's Three Gorges Dam Under Fire". Time. Retrieved 2009-03-28. "The giant Three Gorges Dam across China's Yangtze River has been mired in controversy ever since it was first proposed" See also: Laris, Michael (1998-08-17). "Untamed Waterways Kill Thousands Yearly". Washington Post. Retrieved 2009-03-28. "Officials now use the deadly history of the Yangtze, China's longest river, to justify the country's riskiest and most controversial infrastructure project – the enormous Three Gorges Dam." and Grant, Stan (2005-06-18). "Global Challenges: Ecological and Technological Advances Around the World". CNN. Retrieved 2009-03-28. "China's engineering marvel is unleashing a torrent of criticism. [...] When it comes to global challenges, few are greater or more controversial than the construction of the massive Three Gorges Dam in Central China." and Gerin, Roseanne (2008-12-11). "Rolling on a River". Beijing Review. Retrieved 2009-03-28. "..the 180-billion yuan ($26.3 billion) Three Gorges Dam project has been highly contentious."
- https://www.scientificamerican.com/article.cfm?id=chinas-three-gorges-dam-disaster China's Three Gorges Dam: An Environmental Catastrophe? Even the Chinese government suspects the massive dam may cause significant environmental damage
- http://spectrum.ieee.org/energy/renewables/a-skeptic-looks-at-alternative-energy/0Vaclav Smil 2013 Spectrum prepared by the Institute of Electrical and Electronics Engineers
- http://www.who.int/gho/phe/outdoor_air_pollution/en/ World Health Organization report on Outdoor air pollution. Of all...pollutants, fine particulate matter has the greatest effect on human health. Most fine particulate matter comes from fuel combustion...[amongst fossil fuel sources, fuels include] biomass burning. Fine particulate matter is associated with a broad spectrum of acute and chronic illness, such as lung cancer and cardiopulmonary disease. Worldwide, it is estimated to cause about 9% of lung cancer deaths, 5% of cardiopulmonary deaths and about 1% of respiratory infection deaths. Particulate matter pollution is an environmental health problem that affects people worldwide, but middle-income countries disproportionately experience this burden.
- World Energy Assessment (2001). Renewable energy technologies, p. 221.
- REN21 (2011). "Renewables 2011: Global Status Report". p. 14.
- Steve Leone (25 August 2011). "U.N. Secretary-General: Renewables Can End Energy Poverty". Renewable Energy World.
- United Nations Environment Programme Global Trends in Sustainable Energy Investment 2007: Analysis of Trends and Issues in the Financing of Renewable Energy and Energy Efficiency in OECD and Developing Countries (PDF), p. 3.
- Clean Edge (2009). Clean Energy Trends 2009 pp. 1-4.
- Ben Sills (Aug 29, 2011). "Solar May Produce Most of World’s Power by 2060, IEA Says". Bloomberg.
- Schröder, K.-P.; Smith, R.C. (2008). "Distant future of the Sun and Earth revisited". Monthly Notices of the Royal Astronomical Society 386 (1): 155. arXiv:0801.4031. Bibcode:2008MNRAS.386..155S. doi:10.1111/j.1365-2966.2008.13022.x. See also Palmer, J. (2008). "Hope dims that Earth will survive Sun's death". New Scientist. Retrieved 2008-03-24.
- Carrington, D. (2000-02-21). "Date set for desert Earth". BBC News. Retrieved 2007-03-31.
- "REN21, Renewables Global Status Report (2006 - 2012)". Ren21.net. Retrieved 2012-10-21.
- IEA Renewable Energy Working Party (2002). Renewable Energy... into the mainstream, p. 9.
- International Energy Agency (2012). "Energy Technology Perspectives 2012".
- REN21 (2010). Renewables 2010 Global Status Report p. 15.
- REN21 (2010). Renewables 2010 Global Status Report p. 53.
- REN21 (2013). "Renewables global futures report 2013".
- Council on Foreign Relations (January 18, 2012). "Public Opinion on Global Issues: Chapter 5b: World Opinion on Energy Security".
- K. Kris Hirst. "The Discovery of Fire". About.com. Retrieved 15 January 2013.
- "The Encyclopedia of Alternative Energy and Sustainable Living". Retrieved 15 January 2013.
- "The surprising history of sustainable energy". Sustainablehistory.wordpress.com. Retrieved 2012-11-01.
- “Power from Sunshine”: A Business History of Solar Energy May 25, 2012
- "History of PV Solar". Solarstartechnologies.com. Retrieved 2012-11-01.
- "Nuclear Energy and the Fossil Fuels" (PDF). Retrieved 2012-11-01.
- OECD Factbook 2011-2012: Economic, Environmental and Social Statistics - For the OECD as a whole, the contribution of renewables to energy supply increased from 4.8% in 1971 to 7.6% in 2010. The contribution of renewables varied greatly by country. On the high end, renewables represented 85% of energy supply in Iceland, 39% in New Zealand and 37% in Norway. On the low end, renewables contributed 3% or less of the energy supply for Japan, Korea, Luxembourg and the United Kingdom. In general, the contribution of renewables to the energy supply in non-OECD countries is higher than in OECD countries.
- http://www.oecd-ilibrary.org/deliver/fulltext/3011041ec051.pdf OECD Factbook 2011-2012: Economic, Environmental and Social Statistics. PDF indicator.
- EWEA Executive summary "Analysis of Wind Energy in the EU-25" (PDF). European Wind Energy Association. Retrieved 2007-03-11.
- How Does A Wind Turbine's Energy Production Differ from Its Power Production?
- Wind Power: Capacity Factor, Intermittency, and what happens when the wind doesn’t blow?. Retrieved 24 January 2008.
- "Offshore stations experience mean wind speeds at 80 m that are 90% greater than over land on average. Evaluation of global wind power
"Overall, the researchers calculated winds at 80 meters [300 feet] above sea level traveled over the ocean at approximately 8.6 meters per second and at nearly 4.5 meters per second over land [20 and 10 miles per hour, respectively]." Global Wind Map Shows Best Wind Farm Locations . Retrieved January 30, 2006.
- Faunce TA, Lubitz W, Rutherford AW, MacFarlane D, Moore GF, Yang P, Nocera DG, Moore TA, Gregory DH, Fukuzumi S, Yoon KB, Armstrong FA, Wasielewski MR Styring S. Energy and Environment “Policy Case for a Global Project on Artificial Photosynthesis.” Energy and Environmental Science 2013, 6 (3), 695 - 698 DOI:10.1039/C3EE00063J
- Union of Concerned Scientists. How Biomass Energy Worksdead link
- Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Chapter 7.
- http://www.un-documents.net/ocf-07.htm Today's primary sources of energy are mainly non-renewable: natural gas, oil, coal, peat, and conventional nuclear power. There are also renewable sources, including wood, plants, dung, falling water, geothermal sources, solar, tidal, wind, and wave energy, as well as human and animal muscle-power. Nuclear reactors that produce their own fuel ("breeders") and eventually fusion reactors are also in this category.
- Scheck, Justin; et al. (July 23, 2012). "Wood-Fired Plants Generate Violations". Wall Street Journal. Retrieved September 27, 2012.
- U.S. Energy Information Administration (April 2010). Annual Energy Outlook 2010 (report no. DOE/EIA-0383(2010)). Washington, DC. National Energy Information Center. http://www.eia.gov/oiaf/aeo/pdf/0383(2010).pdf. Retrieved September 27, 2012.
- Demirbas, A. . (2009). "Political, economic and environmental impacts of biofuels: A review". Applied Energy 86: S108–S117. doi:10.1016/j.apenergy.2009.04.036.
- "Opinion of the EEA Scientific Committee on Greenhouse Gas Accounting in Relation to Bioenergy". Retrieved 2012-11-01.
- REN21 (2011). "Renewables 2011: Global Status Report". pp. 13–14.
- Turcotte, D. L.; Schubert, G. (2002), "4", Geodynamics (2 ed.), Cambridge, England, UK: Cambridge University Press, pp. 136–137, ISBN 978-0-521-66624-4
- Nemzer, J. "Geothermal heating and cooling".
- Warren H. Fraser. "Flow recirculation in centrifugal pumps". Retrieved 2013-04-15.
- Wong, Bill (June 28, 2011), "Drake Landing Solar Community", IDEA/CDEA District Energy/CHP 2011 Conference, Toronto, pp. 1–30, retrieved 21 April 2013
- Wong B., Thornton J. (2013). Integrating Solar & Heat Pumps. Renewable Heat Workshop.
- UNEP, Bloomberg, Frankfurt School, Global Trends in Renewable Energy Investment 2011、Figure 24.
- REN21 (2011). "Renewables 2011: Global Status Report". p. 15.
- REN21 (2012). Renewables Global Status Report 2012 p. 17.
- Jacobson, Mark Z.; Delucchi, M.A. (November 2009). "A Path to Sustainable Energy by 2030" (PDF). Scientific American 301 (5): 58–65. doi:10.1038/scientificamerican1109-58. PMID 19873905.
- Mark Z. Jacobson and Mark A. Delucchi (30 December 2010). "Providing all global energy with wind, water, and solar power, Part I: Technologies, energy resources, quantities and areas of infrastructure, and materials". Energy Policy. Elsevier Ltd.
- E. Lantz, M. Hand, and R. Wiser (May 13–17, 2012) "The Past and Future Cost of Wind Energy," National Renewable Energy Laboratory conference paper no. 6A20-54526, page 4
- Henning Gloystein (Nov 23, 2011). "Renewable energy becoming cost competitive, IEA says". Reuters.
- International Renewable Energy Agency (2012). "Renewable Power Generation Costs in 2012: An Overview".
- "GWEC, Global Wind Report Annual Market Update". Gwec.net. Retrieved 2011-11-21.
- Alex Morales (February 7, 2012). "Wind Power Market Rose to 41 Gigawatts in 2011, Led by China". Bloomberg.
- Lars Kroldrup. Gains in Global Wind Capacity Reported Green Inc., February 15, 2010.
- Global wind energy markets continue to boom – 2006 another record year (PDF).
- David Beattie (18 March 2011). "Wind Power: China Picks Up Pace". Renewable Energy World.
- "World Wind Energy Report 2010" (PDF). Report. World Wind Energy Association. February 2011. Retrieved 30-April-2011.
- "Renewables". eirgrid.com. Retrieved 22 November 2010.
- "GWEC Global Wind Statistics 2012" (PDF). Global Wind Energy Commission. Retrieved 18 February 2013.
- Terra-Gen Closes on Financing for Phases VII and IX, Business Wire, April 17, 2012
- Patrick Barkham (2009-01-08). "Blown away". London: Guardian. Retrieved 2011-11-21.
- Steven Mufson. Solar power project in Mojave Desert gets $1.4 billion boost from stimulus funds Washington Post, February 23, 2010.
- "DOE Finalizes $737 Million Loan Guarantee to Tonopah Solar Energy for Nevada Project" (Press release). Loan Programs Office (LPO), Dept. of Energy (DOE). September 28, 2011. Retrieved 29 September 2011.
- "Global Concentrating Solar Power". International Renewable Energy Agency. June 2012. Retrieved 2012-09-08.
- "Solar Thermal Projects Under Review or Announced". Energy.ca.gov. Retrieved 2011-11-21.
- REN21 (2008). Renewables 2007 Global Status Report (PDF) p. 12.
- European Photovoltaic Industry Association (2012). "Market Report 2011".
- James Russell. Record Growth in Photovoltaic Capacity and Momentum Builds for Concentrating Solar Power Vital Signs, June 3, 2010.
- "Solar Expected to Maintain its Status as the World's Fastest-Growing Energy Technology". Socialfunds.com. 2009-03-03. Retrieved 2011-11-21.
- "Global Market Outlook 2016" (PDF). Retrieved 2012-11-01.
- Denis Lenardic. Large-scale photovoltaic power plants ranking 1 - 50 PVresources.com, 2010.
- "DOE Closes on Four Major Solar Projects". Renewable Energy World. 30 September 2011.
- Steve Leone (7 December 2011). "Billionaire Buffett Bets on Solar Energy". Renewable Energy World.
- "NRG Energy Completes Acquisition of 250-Megawatt California Valley Solar Ranch from SunPower". MarketWatch. 30 September 2011.
- "Exelon purchases 230 MW Antelope Valley Solar Ranch One from First Solar". Solar Server. 4 October 2011.
- Solar Integrated in New Jersey.
- "IEA says biofuels can displace 27% of transportation fuels by 2050 Washington". Platts. 20 April 2011.
- "Industry Statistics: Annual World Ethanol Production by Country". Renewable Fuels Association. Archived from the original on 2008-04-08. Retrieved 2008-05-02.
- Macedo Isaias, M. Lima Verde Leal and J. Azevedo Ramos da Silva (2004). "Assessment of greenhouse gas emissions in the production and use of fuel ethanol in Brazil" (PDF). Secretariat of the Environment, Government of the State of São Paulo. Archived from the original on 2008-05-28. Retrieved 2008-05-09.
- Daniel Budny and Paulo Sotero, editor (2007-04). "Brazil Institute Special Report: The Global Dynamics of Biofuels" (PDF). Brazil Institute of the Woodrow Wilson Center. Retrieved 2008-05-03.
- Erica Gies. As Ethanol Booms, Critics Warn of Environmental Effect The New York Times, June 24, 2010.
- "American Energy: The Renewable Path to Energy Security" (PDF). Worldwatch Institute. September 2006. Retrieved 2007-03-11.
- William E. Glassley. Geothermal Energy: Renewable Energy and the Environment CRC Press, 2010.
- Geothermal Energy Association. Geothermal Energy: International Market Update May 2010, p. 4-6.
- Geothermal Energy Association. Geothermal Energy: International Market Update May 2010, p. 7.
- Khan, M. Ali (2007). "The Geysers Geothermal Field, an Injection Success Story" (PDF). Annual Forum of the Groundwater Protection Council. Retrieved 2010-01-25
- Power for the People p. 3.
- Kevin Bullis (January 27, 2012). "In the Developing World, Solar Is Cheaper than Fossil Fuels". Technology Review.
- REN21 (2010). Renewables 2010 Global Status Report p. 12.
- Fry, Carolyn. 28 June 2012. Anguilla moves towards cleaner energy
- "Ethiopia". Projectgaia.com. Retrieved 2012-11-01.
- Energy for Development: The Potential Role of Renewable Energy in Meeting the Millennium Development Goals pp. 7-9.
- "Bloomberg New Energy Finance, UNEP SEFI, Frankfurt School, Global Trends in Renewable Energy Investment 2011". Unep.org. Retrieved 2011-11-21.
- REN21 (2008). Renewables 2007 Global Status Report (PDF) p. 18.
- Hooper, Craig (2011 [last update]). "Air Force cedes the Green lead–and the lede–to Navy". nextnavy.com. Retrieved December 27, 2011.
- Signatory Statesdead link
- Signatories of IRENA’s statutedead link
- Mark Tran (2 November 2011). "UN calls for universal access to renewable energy". The Guardian (London).
- Paul Gipe (4 April 2013). "100 Percent Renewable Vision Building". Renewable Energy World.
- "Implementation of Green Bookkeeping at Reykjavik Energy". Rio02.com. Retrieved 2012-11-01.
- "Energy Rich Japan". Energyrichjapan.info. Retrieved 2012-11-01.
- "Zero Carbon Australia Stationary Energy Plan" (PDF). Retrieved 2012-11-01.
- "A Roadmap for U.S. Energy Policy". Ieer.org. 2012-03-13. Retrieved 2012-11-01.
- "A Road Map for U.S. Energy Policy" (PDF). Retrieved 2012-11-01.
- Carrasco, Alicia (2012-04-09). "Denmark commits to 100% renewable energy". Emeter.com. Retrieved 2012-11-01.
- "Vision 2050". Inforse.org. 2010-12-02. Retrieved 2012-11-01.
- "EU Sustainable Energy Vision 2040". Inforse.org. 2010-12-02. Retrieved 2012-11-01.
- "Zero Carbon World". Zerocarbonbritain.org. 2011-11-09. Retrieved 2012-11-01.
- USA (2010-11-09). "Has the World Already Passed "Peak Oil"?". News.nationalgeographic.com. Retrieved 2012-11-01.
- Inman, Mason (2011-01-17). "Going "All The Way" With Renewable Energy?". News.nationalgeographic.com. Retrieved 2012-11-01.
- "Study claims 100 percent renewable energy possible by 2030". Phys.org. Retrieved 2012-11-01.
- "Providing all global energy with wind, water, and solar power, Part I Technologies, energy resources, quantities and areas of infrastructure, and materials" (PDF). Retrieved 2012-11-01.
- "Providing all global energy with wind, water, and solar power, Part II Reliability, system and transmission costs, and policies" (PDF). Retrieved 2012-11-01.
- Jacobson, Mark Z. (2010-06-15). "A Plan to Power 100 Percent of the Planet with Renewables". Scientificamerican.com. Retrieved 2012-11-01.
- IPCC (2011). "Special Report on Renewable Energy Sources and Climate Change Mitigation". Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. p. 17.
- IPCC (2011). "Special Report on Renewable Energy Sources and Climate Change Mitigation". Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. p. 22.
- Fiona Harvey (9 May 2011). "Renewable energy can power the world, says landmark IPCC study". The Guardian.
- Mark Z. Jacobson and Mark A. Delucchi (2011, Vol. 39). "Providing all global energy with wind, water, and solar power, Part I: Technologies, energy resources, quantities and areas of infrastructure, and materials". Energy Policy. Elsevier Ltd. pp. 1154–1169.
- Mark A. Delucchi and Mark Z. Jacobson (2011, Vol. 39). "Providing all global energy with wind, water, and solar power, Part II: Reliability, system and transmission costs, and policies". Energy Policy. Elsevier Ltd. pp. 1170–1190.
- Kate Galbraith. 100 Percent Renewables by 2030? Green Inc., December 1, 2009.
- Wind, solar power paired with storage could be cost-effective way to power grid
- Stephen Lacey (29 March 2012). "A True 'All of the Above' Energy Policy: Denmark Affirms Commitment to 100% Renewable Energy by 2050". Renewable Energy World.
- "International 100% Renewable Energy Conference". Irenec2012.com. 2012-06-26. Retrieved 2012-11-01.
- "IRENEC 2013". IRENEC 2013. Retrieved 2012-11-01.
- International Energy Agency (2007). Renewables in global energy supply: An IEA facts sheet (PDF), OECD, p. 3.
- S.C.E. Jupe, A. Michiorri, P.C. Taylor (2007). "Increasing the energy yield of generation from new and renewable energy sources". Renewable energy 14 (2): 37–62.
- "Defense-scale supercomputing comes to renewable energy research". Sandia National Laboratories. Retrieved 2012-04-016.
- "Sandia National Laboratories". Sandia National Laboratories. Retrieved 2012-04-016.
- *Chakrabarty, Gargi, April 16th, 2009. "Stimulus leaves NREL in cold" Denver Post”
- Pernick, Ron and Wilder, Clint (2007). The Clean Tech Revolution p. 96.
- Decker, Jeff. Going Against the Grain: Ethanol from Lignocellulosics, Renewable Energy World, January 22, 2009.
- "Building Cellulose" (PDF). Retrieved 2011-11-21.
- Jeff Scruggs and Paul Jacob. Harvesting Ocean Wave Energy, Science, Vol. 323, 27 February 2009, p. 1176.
- "The Crown Estates Map". Retrieved 2012-03-13.
- World tidal energy first for NI, BBC News BBC News, 7 June 2007.
- Duchane, Dave; Brown, Don (December 2002). "Hot Dry Rock (HDR) Geothermal Energy Research and Development at Fenton Hill, New Mexico". Geo-Heat Centre Quarterly Bulletin 23 (4) (Klamath Falls, Oregon: Oregon Institute of Technology). pp. 13–19. ISSN 0276-1084. Retrieved 2009-05-05
- 20 slide presentation inc geothermal maps of Australiadead link
- Collings AF and Critchley C (eds). Artificial Photosynthesis- From Basic Biology to Industrial Application (Wiley-VCH Weinheim 2005) p ix.
- Faunce TA, Lubitz W, Rutherford AW, MacFarlane D, Moore, GF, Yang P, Nocera DG, Moore TA, Gregory DH, Fukuzumi S, Yoon KB, Armstrong FA, Wasielewski MR, Styring S. ‘Energy and Environment Case for a Global Project on Artificial Photosynthesis.’ Energy and Environmental Science 2013, 6 (3), 695 - 698 DOI:10.1039/C3EE00063J http://pubs.rsc.org/en/content/articlelanding/2013/ee/c3ee00063j (accessed 13 March 2013)
- International Energy Agency (2007). Contribution of Renewables to Energy Security IEA Information Paper, p. 5.
- "Whatever Happened to Wind Energy?". LiveScience. 14 January 2008. Retrieved 17 January 2012.
- Simon Gourlay (2008-08-12). "Wind farms are not only beautiful, they're absolutely necessary". The Guardian (UK). Retrieved 17 January 2012.
- Department of Energy & Climate Change (2011). UK Renewable Energy Roadmap (PDF) p. 35.
- DTI, Co-operative Energy: Lessons from Denmark and Sweden, Report of a DTI Global Watch Mission, October 2004
- Morris C & Pehnt M, German Energy Transition: Arguments for a Renewable Energy Future, Heinrich Böll Foundation, November 2012
- Guardian (20 April 2012). "Invest in green energy for just £5".
- Aitken, Donald W. (2010). Transitioning to a Renewable Energy Future, International Solar Energy Society, January, 54 pages.
- HM Treasury (2006). Stern Review on the Economics of Climate Change, 575 pages.
- International Council for Science (c2006). Discussion Paper by the Scientific and Technological Community for the 14th session of the United Nations Commission on Sustainable Development, 17 pages.
- International Energy Agency (2006). World Energy Outlook 2006: Summary and Conclusions, OECD, 11 pages.
- International Energy Agency (2007). Renewables in global energy supply: An IEA facts sheet, OECD, 34 pages.
- International Energy Agency (2008). Deploying Renewables: Principles for Effective Policies, OECD, 8 pages.
- International Energy Agency (2011). Deploying Renewables 2011: Best and Future Policy Practice, OECD.
- International Energy Agency (2011). Solar Energy Perspectives, OECD.
- Lovins, Amory B. (2011). Reinventing Fire: Bold Business Solutions for the New Energy Era, Chelsea Green Publishing, 334 pages.
- Makower, Joel, and Ron Pernick and Clint Wilder (2009). Clean Energy Trends 2009, Clean Edge.
- National Renewable Energy Laboratory (2006). Non-technical Barriers to Solar Energy Use: Review of Recent Literature, Technical Report, NREL/TP-520-40116, September, 30 pages.
- REN21 (2008). Renewables 2007 Global Status Report, Paris: REN21 Secretariat, 51 pages.
- REN21 (2009). Renewables Global Status Report: 2009 Update, Paris: REN21 Secretariat.
- REN21 (2010). Renewables 2010 Global Status Report, Paris: REN21 Secretariat, 78 pages.
- REN21 (2011). Renewables 2011: Global Status Report, Paris: REN21 Secretariat.
- REN21 (2012). Renewables 2012: Global Status Report, Paris: REN21 Secretariat.
- United Nations Environment Programme and New Energy Finance Ltd. (2007). Global Trends in Sustainable Energy Investment 2007: Analysis of Trends and Issues in the Financing of Renewable Energy and Energy Efficiency in OECD and Developing Countries, 52 pages.
- Worldwatch Institute and Center for American Progress (2006). American energy: The renewable path to energy security, 40 pages.
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