Renewable energy
Renewable energy, green energy, or low-carbon energy is energy from renewable resources that are naturally replenished on a human timescale. Renewable resources include sunlight, wind, the movement of water, and geothermal heat.[1][2][3][4][5][6][7] Although most renewable energy sources are sustainable, some are not. For example, some biomass sources are considered unsustainable at current rates of exploitation.[8][9] Renewable energy is often used for electricity generation, heating and cooling. Renewable energy projects are typically large-scale, but they are also suited to rural and remote areas and developing countries, where energy is often crucial in human development.[10][11]
For the journal, see Renewable Energy (journal).
Renewable energy is often deployed together with further electrification, which has several benefits: electricity can move heat or objects efficiently, and is clean at the point of consumption.[12][13] 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%. There are 3,146 gigawatts installed in 135 countries, while 156 countries have laws regulating the renewable energy sector.[14][15] In 2021, China accounted for almost half of the global increase in renewable electricity.[16]
Renewable energy systems are rapidly becoming more efficient and cheaper and their share of total energy consumption is increasing,[17] with a large majority of worldwide newly installed electricity capacity being renewable.[18] In most countries, photovoltaic solar or onshore wind are the cheapest new-build electricity.[19]
Many nations around the world already have renewable energy contributing more than 20% of their total energy supply, with some generating over half their electricity from renewables.[20] A few countries generate all their electricity using renewable energy.[21] National renewable energy markets are projected to continue to grow strongly in the 2020s and beyond.[22] According to the IEA, to achieve net zero emissions by 2050, 90% of global electricity generation will need to be produced from renewable sources.[23] Some studies say that a global transition to 100% renewable energy across all sectors – power, heat, transport and industry – is feasible and economically viable.[24][25][26]
Renewable energy resources exist over wide geographical areas, in contrast to fossil fuels, which are concentrated in a limited number of countries. Deployment of renewable energy and energy efficiency technologies is resulting in significant energy security, climate change mitigation, and economic benefits.[27] However renewables are being hindered by hundreds of billions of dollars of fossil fuel subsidies.[28] In international public opinion surveys there is strong support for renewables such as solar power and wind power.[29][30] In 2022 the International Energy Agency asked countries to solve policy, regulatory, permitting and financing obstacles to adding more renewables, to have a better chance of reaching net zero carbon emissions by 2050.[31]
History[edit]
New government spending, regulation and policies helped the renewables industry weather the global financial crisis better than many other sectors.[43] In 2022, renewables accounted for 30% of global electricity generation, up from 21% in 1985.[44]
Consumption by sector[edit]
One of the efforts to decarbonize transportation is the increased use of electric vehicles (EVs).[162] Despite that and the use of biofuels, such as biojet, less than 4% of transport energy is from renewables.[163] Occasionally hydrogen fuel cells are used for heavy transport.[164] Meanwhile, in the future electrofuels may also play a greater role in decarbonizing hard-to-abate sectors like aviation and maritime shipping.[165]
Solar water heating makes an important contribution to renewable heat in many countries, most notably in China, which now has 70% of the global total (180 GWth). Most of these systems are installed on multi-family apartment buildings[166] and meet a portion of the hot water needs of an estimated 50–60 million households in China. Worldwide, total installed solar water heating systems meet a portion of the water heating needs of over 70 million households.
Heat pumps provide both heating and cooling, and also flatten the electric demand curve and are thus an increasing priority.[122] Renewable thermal energy is also growing rapidly.[167] About 10% of heating and cooling energy is from renewables.[168]