Renewable energy (also called green energy) is energy from renewable natural resources that are replenished on a human timescale. The most widely used renewable energy types are solar energy, wind power, and hydropower. Bioenergy and geothermal power are also significant in some countries. Some also consider nuclear power a renewable power source, although this is controversial. Renewable energy installations can be large or small and are suited for both urban and rural areas. Renewable energy is often deployed together with further electrification. This has several benefits: electricity can move heat and vehicles efficiently and is clean at the point of consumption. Variable renewable energy sources are those that have a fluctuating nature, such as wind power and solar power. In contrast, controllable renewable energy sources include dammed hydroelectricity, bioenergy, or geothermal power.
Renewable energy systems have rapidly become more efficient and cheaper over the past 30 years. A large majority of worldwide newly installed electricity capacity is now renewable. Renewable energy sources, such as solar and wind power, have seen significant cost reductions over the past decade, making them more competitive with traditional fossil fuels. In most countries, photovoltaic solar or onshore wind are the cheapest new-build electricity. From 2011 to 2021, renewable energy grew from 20% to 28% of global electricity supply. Power from the sun and wind accounted for most of this increase, growing from a combined 2% to 10%. Use of fossil energy shrank from 68% to 62%. In 2022, renewables accounted for 30% of global electricity generation and are projected to reach over 42% by 2028. Many countries already have renewables contributing more than 20% of their total energy supply, with some generating over half or even all their electricity from renewable sources.
The main motivation to replace fossil fuels with renewable energy sources is to slow and eventually stop climate change, which is widely agreed to be caused mostly by greenhouse gas emissions. In general, renewable energy sources cause much lower emissions than fossil fuels. The International Energy Agency estimates that to achieve net zero emissions by 2050, 90% of global electricity generation will need to be produced from renewable sources. Renewables also cause much less air pollution than fossil fuels, improving public health, and are less noisy.
The deployment of renewable energy still faces obstacles, especially fossil fuel subsidies, lobbying by incumbent power providers, and local opposition to the use of land for renewable installations. Like all mining, the extraction of minerals required for many renewable energy technologies also results in environmental damage. In addition, although most renewable energy sources are sustainable, some are not. (Full article...)
Photovoltaics (PV) were initially solely used as a source of electricity for small and medium-sized applications, from the calculator powered by a single solar cell to remote homes powered by an off-grid rooftop PV system. Commercial concentrated solar power plants were first developed in the 1980s. Since then, as the cost of solar panels has fallen, grid-connected solar PV systems' capacity and production has doubled about every three years. Three-quarters of new generation capacity is solar, with both millions of rooftop installations and gigawatt-scale photovoltaic power stations continuing to be built.
In 2023, solar power generated 5.5% (1,631 TWh) of global electricity and over 1% of primary energy, adding twice as much new electricity as coal.
Along with onshore wind power, utility-scale solar is the source with the cheapest levelised cost of electricity for new installations in most countries.
As of 2023, 33 countries generated more than a tenth of their electricity from solar, with China making up more than half of solar growth.
Almost half the solar power installed in 2022 was mounted on rooftops. (Full article...)
"The sun provides more energy in one hour than all humanity uses, in all forms, in a single year. Sunlight can provide us with its own resolution to our energy problems. The only transformation required is for humanity to reduce, or end, consumption of stored solar (as fossil fuels) and, in its place, use freely available 'fresh' solar". – David S. Findley (2010). Solar power for your home, p.12.
Image 6Wind turbines such as these, in Cumbria, England, have been opposed for a number of reasons, including aesthetics, by some sectors of the population. (from Wind power)
Image 7Merowe Dam in Sudan. Hydroelectric power stations that use dams submerge large areas of land due to the requirement of a reservoir. These changes to land color or albedo, alongside certain projects that concurrently submerge rainforests, can in these specific cases result in the global warming impact, or equivalent life-cycle greenhouse gases of hydroelectricity projects, to potentially exceed that of coal power stations. (from Hydroelectricity)
Image 8Share of electricity production from hydropower, 2023 (from Hydroelectricity)
Image 9The Hoover Dam in the United States is a large conventional dammed-hydro facility, with an installed capacity of 2,080 MW. (from Hydroelectricity)
Image 13Seasonal cycle of capacity factors for wind and photovoltaics in Europe under idealized assumptions. The figure illustrates the balancing effects of wind and solar energy at the seasonal scale (Kaspar et al., 2019). (from Wind power)
Image 26Solar water heaters facing the Sun to maximize gain (from Solar energy)
Image 27Acceptance of wind and solar facilities in one's community is stronger among U.S. Democrats (blue), while acceptance of nuclear power plants is stronger among U.S. Republicans (red). (from Wind power)
Image 33Greenhouse gas emissions per energy source. Wind energy is one of the sources with the least greenhouse gas emissions. (from Wind power)
Image 34Hydro generation by country, 2021 (from Hydroelectricity)
Image 35Share of electricity production from wind, 2023 (from Wind power)
Image 36The Warwick Castle water-powered generator house, used for the generation of electricity for the castle from 1894 until 1940 (from Hydroelectricity)
Image 37Electricity generation at Ohaaki, New Zealand (from Geothermal energy)
Image 42Distribution of wind speed (red) and energy (blue) for all of 2002 at the Lee Ranch facility in Colorado. The histogram shows measured data, while the curve is the Rayleigh model distribution for the same average wind speed. (from Wind power)
Image 44Electricity generation at Poihipi, New Zealand (from Geothermal energy)
Image 45Installed geothermal energy capacity, 2022 (from Geothermal energy)
Image 46Global map of wind power density potential (from Wind power)
Image 47Yearly hydro generation by continent (from Hydroelectricity)
Image 48Concentrated solar panels are getting a power boost. Pacific Northwest National Laboratory (PNNL) will be testing a new concentrated solar power system – one that can help natural gas power plants reduce their fuel usage by up to 20 percent.[needs update] (from Solar energy)
Image 49Enhanced geothermal system 1:Reservoir 2:Pump house 3:Heat exchanger 4:Turbine hall 5:Production well 6:Injection well 7:Hot water to district heating 8:Porous sediments 9:Observation well 10:Crystalline bedrock (from Geothermal energy)
Image 50Museum Hydroelectric power plant "Under the Town" in Užice, Serbia, built in 1900 (from Hydroelectricity)
Image 54Energy from wind, sunlight or other renewable energy is converted to potential energy for storage in devices such as electric batteries or higher-elevation water reservoirs. The stored potential energy is later converted to electricity that is added to the power grid, even when the original energy source is not available. (from Wind power)
Image 57Electricity production by source (from Wind power)
Image 58A turbine blade convoy passing through Edenfield in the U.K. (2008). Even longer 2-piece blades are now manufactured, and then assembled on-site to reduce difficulties in transportation. (from Wind power)
Image 59Cost development of solar PV modules per watt (from Solar energy)
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![Image 48Concentrated solar panels are getting a power boost. Pacific Northwest National Laboratory (PNNL) will be testing a new concentrated solar power system – one that can help natural gas power plants reduce their fuel usage by up to 20 percent.[needs update] (from Solar energy)](view.php?q=Portal:Renewable_energy&sq=&lang=&file=File:Photo_of_the_Week-_Boosting_Solar_Technology_(8722948189).jpg)
