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Wind, solar, and hydroelectricity are three renewable sources of energy.

Renewable energy is energy that is collected from renewable resources, which are naturally replenished on a human timescale, such as sunlight, wind, rain, tides, waves, and geothermal heat. Renewable energy often provides energy in four important areas: electricity generation, air and water heating/cooling, transportation, and rural (off-grid) energy services.

Based on REN21's 2017 report, renewables contributed 19.3% to humans' global energy consumption and 24.5% to their generation of electricity in 2015 and 2016, respectively. This energy consumption is divided as 8.9% coming from traditional biomass, 4.2% as heat energy (modern biomass, geothermal and solar heat), 3.9% from hydroelectricity and the remaining 2.2% is electricity from wind, solar, geothermal, and other forms of biomass. Worldwide investments in renewable technologies amounted to more than US$286 billion in 2015. In 2017, worldwide investments in renewable energy amounted to US$279.8 billion, with China accounting for US$126.6 billion or 45% of the global investments, the United States for US$40.5 billion, and Europe for US$40.9 billion. Globally, there are an estimated 7.7 million jobs associated with the renewable energy industries, with solar photovoltaics being the largest renewable employer. Renewable energy systems are rapidly becoming more efficient and cheaper and their share of total energy consumption is increasing. worldwide, more than two-thirds of all new electricity capacity installed was renewable. Growth in consumption of coal and oil could end by 2020 due to increased uptake of renewables and natural gas.

At the national level, at least 30 nations around the world already have renewable energy contributing more than 20 percent of energy supply. National renewable energy markets are projected to continue to grow strongly in the coming decade and beyond. Some places and at least two countries, Iceland and Norway, generate all their electricity using renewable energy already, and many other countries have the set a goal to reach 100% renewable energy in the future. At least 47 nations around the world already have over 50 percent of electricity from renewable resources. Renewable energy resources exist over wide geographical areas, in contrast to fossil fuels, which are concentrated in a limited number of countries. Rapid deployment of renewable energy and energy efficiency technologies is resulting in significant energy security, climate change mitigation, and economic benefits. In international public opinion surveys there is strong support for promoting renewable sources such as solar power and wind power.

While many renewable energy projects are large-scale, renewable technologies are also suited to rural and remote areas and developing countries, where energy is often crucial in human development. As most of renewable energy technologies provide electricity, renewable energy deployment is often applied in conjunction with further electrification, which has several benefits: electricity can be converted to heat (where necessary generating higher temperatures than fossil fuels), can be converted into mechanical energy with high efficiency, and is clean at the point of consumption. In addition, electrification with renewable energy is more efficient and therefore leads to significant reductions in primary energy requirements.

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Krafla geothermal power plant in Iceland.
Krafla geothermal power station wiki.jpg

Geothermal power is power generated by geothermal energy. Technologies in use include dry steam power stations, flash steam power stations and binary cycle power stations. Geothermal electricity generation is currently used in 26 countries, while geothermal heating is in use in 70 countries.

As of 2015, worldwide geothermal power capacity amounts to 12.8 gigawatts (GW), of which 28 percent or 3,548 megawatts (MW) are installed in the United States. International markets grew at an average annual rate of 5 percent over the three years to 2015, and global geothermal power capacity is expected to reach 14.5–17.6 GW by 2020. Based on current geologic knowledge and technology the GEA publicly discloses, the Geothermal Energy Association (GEA) estimates that only 6.9 percent of total global potential has been tapped so far, while the IPCC reported geothermal power potential to be in the range of 35 GW to 2 TW. Countries generating more than 15 percent of their electricity from geothermal sources include El Salvador, Kenya, the Philippines, Iceland, New Zealand, and Costa Rica. Read more...

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View of the offshore wind farm at Middelgrunden, near Copenhagen
The Middelgrunden offshore wind farm in Øresund, delivers about 4% of the power for Copenhagen.

Selected biography

Jeremy Leggett 18Aug2007.JPG

Jeremy Leggett, a geologist by training, began his career as a consultant for the oil industry, while teaching at the Royal School of Mines. He later became an environmental campaigner for Greenpeace, before evolving into a social entrepreneur and author.

Jeremy Leggett is currently executive chairman of Solarcentury the UK’s largest independent solar electric company. He also serves as a founding director of the world's first private equity fund for renewable energy. From 2002 to 2006, Leggett was a member of the UK Government Renewables advisory board. He was the recipient of the President's Award of the Geological Society, and in 1987 the Geological Society's Lyell Fund.

In his 2009 book, The Solar Century, Leggett is critical of nuclear power, saying that investing in nuclear power would mean less money for other initiatives involving energy conservation, energy efficiency, and renewable energy. Leggett also states that carbon capture and storage has a "substantial timing problem" as it will take fifteen to twenty years to introduce the technology.


Did you know?

... that the International Renewable Energy Agency (IRENA) to promote widespread and increased adoption and sustainable use of all forms or renewable energy was founded in 2009 ? Acting as the global voice for renewable energies, IRENA will facilitate access to all relevant renewable energy information.

IRENA's founding reflects a growing consensus among governments around the world on the need to speed up the commercialization of renewable energy worldwide. IRENA provides advice and support to governments on renewable energy policy, capacity building, and technology transfer. IRENA will also co-ordinate with existing renewable energy organizations, such as REN21.




  • "To truly transform our economy, protect our security, and save our planet from the ravages of climate change, we need to ultimately make clean, renewable energy the profitable kind of energy." -Barack Obama, Address to Joint Session of Congress, Feb. 24, 2009

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