Renewable energy
Renewable energy (or green energy) is energy 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. 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.[1][2] 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.
For the journal, see Renewable Energy (journal).
Renewable energy systems have rapidly become more efficient and cheaper over the past 30 years.[3] A large majority of worldwide newly installed electricity capacity is now renewable.[4] 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.[5] In most countries, photovoltaic solar or onshore wind are the cheapest new-build electricity.[6] 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%.[7] In 2022, renewables accounted for 30% of global electricity generation, and are projected to reach over 42% by 2028.[8][9] 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.[10][11]
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.[12] 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.[13] Renewables also cause much less air pollution than fossil fuels, improving public health, and are less noisy.[12]
The deployment of renewable energy still faces obstacles, especially fossil fuel subsidies,[14] lobbying by incumbent power providers,[15] and local opposition to the use of land for renewables installations.[16][17] Like all mining, the extraction of minerals required for many renewable energy technologies also results in environmental damage.[18] In addition, although most renewable energy sources are sustainable, some are not. For example, some biomass sources are unsustainable at current rates of exploitation.[19]
Consumption by sector[edit]
One of the efforts to decarbonize transportation is the increased use of electric vehicles (EVs).[146] Despite that and the use of biofuels, such as biojet, less than 4% of transport energy is from renewables.[147] Occasionally hydrogen fuel cells are used for heavy transport.[148] Meanwhile, in the future electrofuels may also play a greater role in decarbonizing hard-to-abate sectors like aviation and maritime shipping.[149]
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[150] 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.[151] Renewable thermal energy is also growing rapidly.[152] About 10% of heating and cooling energy is from renewables.[153]
Some studies say that a global transition to 100% renewable energy across all sectors – power, heat, transport and industry – is feasible and economically viable.[154][155][156]
Policies to support renewable energy have been vital in their expansion. Where Europe dominated in establishing energy policy in the early 2000s, most countries around the world now have some form of energy policy.[200]
The International Renewable Energy Agency (IRENA) is an intergovernmental organization for promoting the adoption of renewable energy worldwide. It aims to provide concrete policy advice and facilitate capacity building and technology transfer. IRENA was formed in 2009, with 75 countries signing the charter of IRENA.[201] As of April 2019, IRENA has 160 member states.[202] The then United Nations Secretary-General Ban Ki-moon has said that renewable energy can lift the poorest nations to new levels of prosperity,[203] and in September 2011 he launched the UN Sustainable Energy for All initiative to improve energy access, efficiency and the deployment of renewable energy.[204]
The 2015 Paris Agreement on climate change motivated many countries to develop or improve renewable energy policies.[205] In 2017, a total of 121 countries adopted some form of renewable energy policy.[200] National targets that year existed in 176 countries.[205] In addition, there is also a wide range of policies at the state/provincial, and local levels.[104] Some public utilities help plan or install residential energy upgrades.
Many national, state and local governments have created green banks. A green bank is a quasi-public financial institution that uses public capital to leverage private investment in clean energy technologies.[206] Green banks use a variety of financial tools to bridge market gaps that hinder the deployment of clean energy.
Global and national policies related to renewable energy can be divided based on sectors :
Agricultural
By the end of 2023, 43 national and sub-national jurisdictions had renewable energy policies for to this sector.[207]
Fiscal and financial policies :
Grants of up to 60% for farmers to install solar PV systems in Greece.[208]
EU allocated EUR 1.7 billion (USD 1.84 billion) to support agrivoltaics in Italy.[209]
In order to use energy efficiency and precision farming to enhance resource management EU adopted the 2023-2027 Common Agricultural Policy.[210]
Transport
The total number of countries with renewable energy policies for transport is 65.[211]
Electric vehicle policies
In aviation
ReFuelEU initiative set a mandate for 2% sustainable aviation fuel in all planes at EU airports by 2025, with a gradual increase to 70% by 2070. [214]
Building
Industry
Climate neutrality by the year 2050 is the main goal of the European Green Deal.[218] For the European Union to reach their target of climate neutrality, one goal is to decarbonise its energy system by aiming to achieve "net-zero greenhouse gas emissions by 2050."[219]
Finance[edit]
The International Renewable Energy Agency's (IRENA) 2023 report on renewable energy finance highlights steady investment growth since 2018: USD 348 billion in 2020 (a 5.6% increase from 2019), USD 430 billion in 2021 (24% up from 2020), and USD 499 billion in 2022 (16% higher). This trend is driven by increasing recognition of renewable energy's role in mitigating climate change and enhancing energy security, along with investor interest in alternatives to fossil fuels. Policies such as feed-in tariffs in China and Vietnam have significantly increased renewable adoption. Furthermore, from 2013 to 2022, installation costs for solar photovoltaic (PV), onshore wind, and offshore wind fell by 69%, 33%, and 45%, respectively, making renewables more cost-effective.[220][57]
Between 2013 and 2022, the renewable energy sector underwent a significant realignment of investment priorities. Investment in solar and wind energy technologies markedly increased. In contrast, other renewable technologies such as hydropower (including pumped storage hydropower), biomass, biofuels, geothermal, and marine energy experienced a substantial decrease in financial investment. Notably, from 2017 to 2022, investment in these alternative renewable technologies declined by 45%, falling from USD 35 billion to USD 17 billion.[57]
In 2023, the renewable energy sector experienced a significant surge in investments, particularly in solar and wind technologies, totaling approximately USD 200 billion—a 75% increase from the previous year. The increased investments in 2023 contributed between 1% and 4% to the GDP in key regions including the United States, China, the European Union, and India.[221]
The energy sector receives investments of approximately USD 3 trillion each year, with USD 1.9 trillion directed towards clean energy technologies and infrastructure. To meet the targets set in the Net Zero Emissions (NZE) Scenario by 2035, this investment must increase to USD 5.3 trillion per year.[222]: 15