Renewable energy (also called green energy) is energy made 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, as nuclear energy requires mining uranium, a nonrenewable resource. 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 2024, renewables accounted for over 30% of global electricity generation and are projected to reach over 45% by 2030. 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 use renewable energy instead of fossil fuels is to slow and eventually stop climate change, which is mostly caused by their greenhouse gas emissions. In general, renewable energy sources pollute much less than fossil fuels. The International Energy Agency estimates that to achieve net zero emissions by 2050, 90% of global electricity will need to be generated by renewables. 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...)
Grand Coulee Dam is a concrete gravity dam on the Columbia River in the U.S. state of Washington, built to produce hydroelectric power and provide irrigation water. Constructed between 1933 and 1942, Grand Coulee originally had two powerhouses. The third powerhouse ("Nat"), completed in 1974 to increase energy production, makes Grand Coulee the largest power station in the United States by nameplate capacity at 6,809 MW.
The proposal to build the dam was the focus of a bitter debate during the 1920s between two groups. One group wanted to irrigate the ancient Grand Coulee with a gravity canal while the other pursued a high dam and pumping scheme. The dam supporters won in 1933, but, although they fully intended otherwise, the initial proposal by the Bureau of Reclamation was for a "low dam" 290 feet (88 m) tall which would generate electricity without supporting irrigation. That year, the U.S. Bureau of Reclamation and a consortium of three companies called MWAK (Mason-Walsh-Atkinson Kier Company) began construction on a high dam, although they had received approval for a low dam. After visiting the construction site in August 1934, President Franklin Delano Roosevelt endorsed the "high dam" design, which at 550 ft (168 m) high would provide enough electricity to pump water into the Columbia basin for irrigation. Congress approved the high dam in 1935, and it was completed in 1942. The first waters overtopped Grand Coulee's spillway on June 1 of that year.
Power from the dam fueled the growing industries of the Northwest United States during World War II. Between 1967 and 1974, the third powerplant was constructed. The decision to construct the additional facility was influenced by growing energy demand, regulated river flows stipulated in the Columbia River Treaty with Canada, and competition with the Soviet Union. Through a series of upgrades and the installation of pump-generators, the dam now supplies four power stations with an installed capacity of 6,809 MW. As the centerpiece of the Columbia Basin Project, the dam's reservoir supplies water for the irrigation of 671,000 acres (2,700 km2). (Full article...)
"Wind projects boost local tax bases, helping to pay for schools, roads and hospitals. Wind projects also revitalize the economy of rural communities by providing steady income to farmers and other landowners. Each wind turbine contributes $3,000 to $5,000 or more per year in rental income, while farmers continue to grow crops or graze cattle up to the foot of the turbines." – American Wind Energy Association (2009). Annual Wind Industry Report, Year Ending 2008 pp. 9–10.
"A wind farm, when installed on agricultural land, has one of the lowest environmental impacts of all energy sources. It occupies less land area per kilowatt-hour (kWh) of electricity generated than any other energy conversion system, apart from rooftop solar energy, and is compatible with grazing and crops." – Mark Diesendorf, in Dissent, No. 13, Summer 2003/04, pp. 43–48.
Chu served as U.S. Secretary of Energy under the administration of President Barack Obama from 2009 to 2013. At the time of his appointment as Energy Secretary, Chu was a professor of physics and molecular and cellular biology at the University of California, Berkeley, and the director of the Lawrence Berkeley National Laboratory, where his research was concerned primarily with the study of biological systems at the single molecule level. Chu resigned as energy secretary on April 22, 2013. He returned to Stanford as Professor of Physics and Professor of Molecular & Cellular Physiology. (Full article...)
... that the first recorded instance of solar distillation was by 16th century Arab alchemists? A large-scale solar distillation project was first constructed in 1872 in Chile a mining town of Las Salinas. The plant, which had a solar collection area of 4,700 m², could produce up to 22,700 L per day and operated for 40 years. Individual still designs include single-slope, double-slope (or greenhouse type), vertical, conical, inverted absorber, multi-wick, and multiple effect. These stills can operate in passive, active, or hybrid modes. Double-slope stills are the most economical for decentralized domestic purposes, while active multiple effect units are more suitable for large-scale applications.
Image 10Acceptance 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 12Merowe 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 15Enhanced 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 16Share of electricity production from wind, 2024 (from Wind power)
Image 17Distribution 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 18Solar water heaters facing the Sun to maximize gain (from Solar energy)
Image 19Typical components of a wind turbine (gearbox, rotor shaft and brake assembly) being lifted into position (from Wind power)
Image 20Cost development of solar PV modules per watt (from Solar energy)
Image 21Krafla Geothermal Station in northeast Iceland (from Geothermal energy)
Image 33Seasonal 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 35Concentrated 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 38The Warwick Castle water-powered generator house, used for the generation of electricity for the castle from 1894 until 1940 (from Hydroelectricity)
Image 39Parabolic dish produces steam for cooking, in Auroville, India. (from Solar energy)
Image 40Collisions with wind turbines are a minor source of bird mortality compared to other human causes (from Wind power)
Image 41Yearly hydro generation by continent (from Hydroelectricity)
Image 45Wind 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 54The Hoover Dam in the United States is a large conventional dammed-hydro facility, with an installed capacity of 2,080 MW. (from Hydroelectricity)
Image 55World electricity production by source, 2000-2024 (from Wind power)
Image 57Energy 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 59A 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 60Share of electricity production from hydropower, 2024 (from Hydroelectricity)