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 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 renewables 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. For example, some
biomass sources are unsustainable at current rates of
exploitation. (Full article...)
A tide mill is a
water mill driven by
tidal rise and fall. A dam with a
sluice is created across a suitable tidal inlet, or a section of river
estuary is made into a
reservoir. As the tide comes in, it enters the mill pond through a one-way gate, and this gate closes automatically when the tide begins to fall. When the tide is low enough, the stored water can be released to turn a water wheel.
Tide mills are usually situated in river estuaries, away from the effects of waves but close enough to the sea to have a reasonable
tidal range. Cultures that built such mills have existed since the
Middle Ages, and some may date back to the Roman period.
"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.
Scheer believed that the continuation of current patterns of energy supply and use would be environmentally, socially, economically, and politically damaging, with
renewable energy being the only realistic alternative. Scheer had concluded that it is technically and environmentally feasible to harness enough solar radiation to achieve a total replacement of the foclear (fossil/nuclear) energy system by a global
renewable energy economy. The main obstacle to such a change is seen to be political, not technical or economic. In 1999 he was one of the initiators of the
German feed-in tariffs that were the major source of the rise of
renewable energies in Germany during the following years. (Full article...)
... 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.
Image 10Yearly hydro generation by continent (from Hydroelectricity)
Image 11The
Warwick Castle water-powered generator house, used for the generation of electricity for the castle from 1894 until 1940 (from Hydroelectricity)
Image 12Acceptance 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 13Wind 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 14Cost development of solar PV modules per watt (from Solar energy)
Image 15Seasonal 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 25Merowe 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 26Solar water heaters facing the
Sun to maximize gain (from Solar energy)
Image 27Share of electricity production from hydropower, 2022 (from Hydroelectricity)
Image 30Enhanced 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 32Concentrated 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 33Electricity generation at Wairakei, New Zealand (from Geothermal energy)
Image 37Global map of wind speed at 100 meters on land and around coasts. (from Wind power)
Image 38Greenhouses like these in the Westland municipality of the Netherlands grow vegetables, fruits and flowers. (from Solar energy)
Image 39Global map of wind power density potential (from Wind power)
Image 40Distribution 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 49A 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 59The
Hoover Dam in the United States is a large conventional dammed-hydro facility, with an installed capacity of 2,080
MW. (from Hydroelectricity)