Portal:Renewable energy

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Introduction

Renewable energy (or green energy) is energy from renewable natural resources that are replenished on a human timescale. Using renewable energy technologies helps with climate change mitigation, energy security, and also has some economic benefits. Commonly used renewable energy types include solar energy, wind power, hydropower, bioenergy and geothermal power. Renewable energy installations can be large or small. They are suited for urban as well as 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 are rapidly becoming more efficient and cheaper. As a result, their share of global energy consumption is increasing. A large majority of worldwide newly installed electricity capacity is now renewable. In most countries, photovoltaic solar or onshore wind are the cheapest new-build electricity. Renewable energy can help reduce energy poverty in rural and remote areas of developing countries, where lack of energy access is often hindering economic development. Renewable energy resources exist all over the world. This is in contrast to fossil fuels resources which are concentrated in a limited number of countries.

There are also other renewable energy technologies that are still under development, for example enhanced geothermal systems, concentrated solar power, cellulosic ethanol, and marine energy.

From 2011 to 2021, renewable energy grew from 20% to 28% of global electricity supply. Use of fossil energy shrank from 68% to 62%, and nuclear from 12% to 10%. The share of hydropower decreased from 16% to 15% while power from sun and wind increased from 2% to 10%. Biomass and geothermal energy grew from 2% to 3%. In 2022, renewables accounted for 30% of global electricity generation, up from 21% in 1985.

Many countries around the world already have renewable energy contributing more than 20% of their total energy supply. Some countries generate over half their electricity from renewables. A few countries generate all their electricity from renewable energy. National renewable energy markets are projected to continue to grow strongly in the 2020s and beyond.

The deployment of renewable energy is being hindered by massive fossil fuel subsidies. In 2022 the International Energy Agency (IEA) requested all countries to reduce their policy, regulatory, permitting and financing obstacles for renewables. This would increase the chances of the world reaching net zero carbon emissions by 2050. According to the IEA, to achieve net zero emissions by 2050, 90% of global electricity generation will need to be produced from renewable sources.

Whether nuclear power is renewable energy or not is still controversial. There are also debates around geopolitics, the metal and mineral extraction needed for solar panels and batteries, possible installations in conservation areas and the need to recycle solar panels. Although most renewable energy sources are sustainable, some are not. For example, some biomass sources are unsustainable at current rates of exploitation. (Full article...)

Wave power is the capture of energy of wind waves to do useful work – for example, electricity generation, water desalination, or pumping water. A machine that exploits wave power is a wave energy converter (WEC).

Waves are generated primarily by wind passing over the sea's surface and also by tidal forces, temperature variations, and other factors. As long as the waves propagate slower than the wind speed just above, energy is transferred from the wind to the waves. Air pressure differences between the windward and leeward sides of a wave crest and surface friction from the wind cause shear stress and wave growth.

Wave power as a descriptive term is different from tidal power, which seeks to primarily capture the energy of the current caused by the gravitational pull of the Sun and Moon. However, wave power and tidal power are not fundamentally distinct and have significant cross-over in technology and implementation. Other forces can create currents, including breaking waves, wind, the Coriolis effect, cabbeling, and temperature and salinity differences. (Full article...)
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  • "The variability of sun, wind and so on, turns out to be a non-problem if you do several sensible things. One is to diversify your renewables by technology, so that weather conditions bad for one kind are good for another. Second, you diversify by site so they're not all subject to the same weather pattern at the same time because they're in the same place. Third, you use standard weather forecasting techniques to forecast wind, sun and rain, and of course hydro operators do this right now. Fourth, you integrate all your resources — supply side and demand side..." – Amory Lovins
  • "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". – Mark Z. Jacobson and Mark A. Delucchi. Scientific American, November 2009, p. 43.

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Renewable energy sources

General

Renewable energy commercialization · Smart grid · Timeline of sustainable energy research 2020–present

Renewable energy by country

List of countries by electricity production from renewable sources

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President Barack Obama addressed an audience of more than 450 people at the Nellis Solar Power Plant on May 27, 2009.

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Dan William Reicher is an American lawyer who was U.S. Assistant Secretary of Energy for Energy Efficiency and Renewable Energy at the U.S. Department of Energy (DOE) in the Clinton Administration. Reicher is currently executive director of the Steyer-Taylor Center for Energy Policy and Finance at Stanford University, a joint center of the Stanford Graduate School of Business and Stanford Law School, where he also holds faculty positions. Reicher joined Stanford in 2011 from Google, where he served since 2007 as Director of Climate Change and Energy Initiatives for the company's venture Google.org.

Reicher also served as an advisor to the 2008 Obama campaign and a member of the Obama Transition Team where he focused on the energy portions of the Obama stimulus package. (Full article...)

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... 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.

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