Renewable energy, also called green energy, is energy made from natural resources that are replaced over time. The most common types of renewable energy are solar energy, wind power, and hydropower. Bioenergy and geothermal power are also important in some countries. Renewable energy systems can be large or small and work well in both cities and rural areas. Renewable energy is often used with electricity systems. This helps move heat and power vehicles efficiently and produces no pollution where it is used. Renewable energy sources that change a lot, like wind and solar power, are called variable. In contrast, renewable energy sources that can be controlled, such as dammed hydroelectricity, bioenergy, or geothermal power, are called controllable.

Renewable energy systems have become more efficient and less expensive over the past 30 years. Most new electricity systems added worldwide are now renewable. Solar and wind power have become much cheaper in the last 10 years, making them more competitive with traditional fossil fuels. In some places, solar or wind power is the cheapest way to create new electricity. From 2011 to 2021, renewable energy increased from 20% to 28% of the world’s electricity supply. Solar and wind power contributed most of this growth, rising from 2% to 10%. Use of fossil fuels dropped from 68% to 62%. In 2024, renewables provided over 30% of the world’s electricity, and they are expected to reach over 45% by 2030. Many countries already use renewables for more than 20% of their total energy, with some countries using over half or all of their electricity from renewable sources.

The main reason to use renewable energy instead of fossil fuels is to reduce greenhouse gas emissions, which cause climate change. Renewable energy sources create much less pollution than fossil fuels. They also cause less air pollution, which improves public health, and they are quieter. The International Energy Agency says that to reach net zero emissions by 2050, 90% of the world’s electricity must come from renewable sources. However, the current rate of renewable energy growth is not fast enough to meet this goal, even in wealthy countries like those in the G7 and the European Union.

Using renewable energy still has challenges, such as financial support for fossil fuels, efforts by traditional energy companies to resist change, and local resistance to using land for renewable projects. Mining for materials needed for renewable technologies, like solar panels and wind turbines, can also harm the environment.

Some people think nuclear power is a renewable energy source, but this is debated. Nuclear energy requires mining uranium, which is not a renewable resource.

Overview

Renewable energy comes from natural processes that happen all the time, like the sun, wind, and water. The International Energy Agency describes it as energy from natural events that are replaced faster than they are used. The main types of renewable energy include solar power, wind power, hydroelectricity, geothermal energy, and biomass. Renewable energy is often used instead of traditional fuels in four areas: making electricity, heating water and homes, transportation, and providing energy to places without a connection to the main power grid.

Although most renewable energy produces much less carbon than fossil fuels, it is not the same as low-carbon energy. Some non-renewable energy sources, like nuclear power, create almost no emissions, while some renewable sources, such as burning biomass without replanting new plants, can produce high levels of carbon. Renewable energy is also different from sustainable energy, which considers how energy sources affect future generations. For example, using biomass can sometimes lead to harmful deforestation if not managed carefully.

To help stop climate change, most countries have promised to reach net zero greenhouse gas emissions. This means reducing the use of fossil fuels and replacing them with energy sources that create fewer emissions. This process, called "low-carbon substitutions," needs to happen faster to reduce the effects of climate change. At the 2023 United Nations Climate Change Conference, about three-quarters of the world's countries set a goal to triple renewable energy capacity by 2030. The European Union plans to generate 40% of its electricity from renewable sources by that year.

Renewable energy is spread more evenly across the world than fossil fuels, which are found mainly in a few countries. It also helps improve health by reducing air pollution from burning fossil fuels. Experts estimate that using renewable energy could save trillions of dollars in healthcare costs each year.

The two most important renewable energy sources, solar and wind, are intermittent, meaning they are not always available. This makes their energy output less predictable compared to fossil fuel, nuclear, or hydropower plants, which can usually supply exactly the amount of energy needed. Solar energy is only captured during the day and works best in clear weather. Wind energy can change a lot, even from day to day or month to month. This creates a challenge when moving away from fossil fuels, as energy demand may not match what renewables can provide.

In the short to medium term, keeping some gas-fired power plants or other flexible power sources ready may be needed until better energy storage, improved grids, or reliable energy sources are available. In the long term, energy storage is a key solution to handle the unpredictability of renewable energy. Using a mix of renewable sources and smart grids can also help balance energy supply and demand.

Connecting the power generation sector with other sectors, like transportation and industry, can improve flexibility. For example, electric vehicles can be charged and used to send electricity back to the grid. Industry can use hydrogen made through electrolysis, and buildings can store heat for heating and cooling.

Building extra wind and solar power capacity can ensure enough electricity is available even during poor weather. However, during very good weather, it may be necessary to limit energy production if there is no way to use or store the extra electricity.

Electrical energy storage includes methods to save electricity when production, especially from sources like wind or solar, is higher than what is needed. This stored energy is used later when production is lower. Pumped-storage hydroelectricity is the most common way to store energy on the grid. Batteries are becoming more widely used for storage and to support the grid. Green hydrogen is a cost-effective option for long-term energy storage compared to other methods.

Solar and wind power are often used in systems where energy is generated close to where it is used. These systems have benefits but also risks, such as the concentration of supply chains in one country. Large-scale solar panels and wind farms can be vulnerable to cyberattacks if their remote control systems have security flaws. These attacks can disable power generation from millions of panels or wind turbines at once. The European NIS2 directive helps address these risks by including energy generation in cybersecurity rules.

In 2024, global solar power capacity reached 1 terawatt, providing about 6–7% of the world’s electricity. Renewable energy systems are also becoming more vulnerable to extreme weather linked to climate change, such as heatwaves, wildfires, and storms. Solar farms may produce less electricity during heat or smoke, and wind turbines may need to shut down during extreme wind or face damage from ice or waves. These challenges are causing governments and energy companies to strengthen infrastructure and create emergency plans to keep the power supply reliable.

Mainstream technologies

In 2022, solar power produced about 1.3 terrawatt-hours (TWh) of electricity worldwide. This amount made up 4.6% of the world's total electricity. Most of this increase happened after 2010. Solar energy can be used anywhere that gets sunlight. However, how much energy can be collected depends on weather, where the location is, and the time of day.

There are two main ways to use solar energy: solar thermal, which turns sunlight into heat, and photovoltaics (PV), which turns sunlight into electricity. PV is used more often, making up about two-thirds of the world’s solar energy capacity in 2022. It is also growing faster than solar thermal. In 2021, 170 gigawatts (GW) of new PV capacity was added, compared to 25 GW of solar thermal.

Passive solar uses building designs and materials to help control heat inside homes and buildings. Examples include using solar chimneys, orienting buildings to face the sun, using materials that store heat, and creating spaces that help air move naturally.

From 2020 to 2022, investments in solar technology nearly doubled, growing from USD 162 billion to USD 308 billion. This increase was due to better technology and lower costs, especially for PV systems, which made up 90% of all solar investments. China and the United States received most of these investments, together accounting for about half of all solar investments since 2013. Growth in China, the United States, and Vietnam helped offset declines in Japan and India. Between 2013 and 2021, the world added 714 GW of solar PV and concentrated solar power (CSP) capacity. In 2021, large solar heating projects increased, especially in China, Europe, Turkey, and Mexico. In 2023, global solar power capacity grew by nearly 30%, driven by lower prices for solar panels and more government support.

A photovoltaic (PV) system uses solar cells grouped into panels to change light into electricity through the photoelectric effect. PV systems can be small, like those on homes or businesses, or large, like power plants that supply electricity to many people. A household’s solar panels can provide power only for that home or, if connected to a power grid, can join with millions of other panels.

The first large solar power plant was built in 1982 in Hesperia, California, by ARCO. The plant was not profitable and was sold eight years later. However, over time, PV cells became more efficient and less expensive. Since 2010, the use of PV has grown rapidly. Global solar capacity increased from 230 GW at the end of 2015 to 890 GW in 2021. China added the most PV capacity between 2016 and 2021, adding 560 GW, more than all advanced countries combined. In 2025, four of the ten largest solar power plants were in China, including the largest, Talatan Solar Park.

Solar panels are recycled to reduce waste and reuse materials that would otherwise be mined. However, this process is still small, and efforts are ongoing to improve it.

Unlike PV systems, which turn sunlight directly into electricity, solar thermal systems use mirrors or lenses to focus sunlight onto a receiver, which heats water. The heated water can be used in homes. A benefit of solar thermal is that the heat can be stored until needed, avoiding the need for separate storage systems. Solar thermal energy can also be used to generate electricity by turning heated water into steam to power a turbine connected to a generator. However, this method is more expensive, and few such systems are used today.

Floating solar panels, or floatovoltaics, are solar panels that sit on water. Benefits include higher efficiency and lower costs for using water space instead of land. A drawback is that building floating panels may be more expensive.

Agrivoltaics combines energy production and farming on the same land. This approach can reduce land costs and create income from both energy and crops. However, crops grown under solar panels must be shade-tolerant, such as Polka Dot Plant, Pineapple Sage, and Begonia. Agrivoltaics can also help control temperatures under panels, possibly reducing water use and improving conditions for crops. Careful planning and crop choices are needed to ensure plants grow well in shaded areas.

Humans have used wind energy since at least 3500 BC. Before the 20th century, wind was used to power ships, windmills, and water pumps. Today, most wind energy is used to generate electricity through wind turbines. Modern large wind turbines can produce between 600 kilowatts (kW) and 9 megawatts (MW) of power. Wind speed affects how much electricity is produced, as power increases with the cube of wind speed. Areas with strong and steady winds, such as offshore and high-altitude regions, are ideal for wind farms.

In 2015, wind energy met nearly 4% of the world’s electricity needs. About 63 GW of new wind power was added that year. Wind energy was the main source of new power in Europe, the United States, and Canada, and the second-largest in China. In Denmark, wind energy met more than 40% of its electricity needs, while Ireland, Portugal, and Spain each met nearly 20%.

The long-term potential of wind energy is estimated to be five times the world’s current energy production or 40 times current electricity needs, assuming all challenges are overcome. This would require installing wind turbines over large areas, especially in places with strong winds, like offshore locations. Offshore wind speeds are about 90% higher than on land, making them a major source of energy.

In 2020, investments in wind technology reached USD 161 billion. Onshore wind made up 80% of investments from 2013 to 2022. Offshore wind investments nearly doubled to USD 41 billion between 2019 and 2020, driven by policies in China and growth in Europe. Global wind capacity increased by 557 GW between 2013 and 2021, with an average yearly increase of 19%.

Water is about 800 times denser than air, so even slow-moving water can produce significant energy. Water can generate electricity with about 90% efficiency, the highest among renewable energy sources. There are several types of

Emerging technologies

There are other renewable energy technologies that are still being developed, such as enhanced geothermal systems, concentrated solar power, cellulosic ethanol, piezoelectricity, and marine energy. These technologies are not yet widely used or have limited commercial applications. Some may have the same potential as other renewable energy sources, but they need more research, development, and engineering progress to become practical.

Enhanced geothermal systems (EGS) are a new type of geothermal power that does not require natural hot water or steam. Most underground heat is trapped in solid rocks, not in water. EGS uses hydraulic fracturing to break apart these rocks and release the heat. Water is then pumped into the ground to collect the heat. This process is sometimes called "hot dry rock." Unlike traditional geothermal energy, EGS may be possible anywhere in the world, depending on the cost of drilling. So far, EGS projects have mainly been tested in small demonstration plants because drilling is very expensive.

Sand batteries are large tanks filled with soapstone that store heat. Extra heat from renewable energy sources is sent into the tank, and later, the stored heat is released as hot water, steam, or heated air. Finland uses this technology in Pornainen, where a 1MW sand battery was built by Polar Night Energy. It can store up to 100 MWh of energy and became operational in 2025.

Piezoelectricity is the process of converting mechanical stress or vibration into electrical energy without using fuel. This technology allows piezoelectric materials to interact with semiconductors to control energy flow. Since the invention of nanogenerators, the efficiency of capturing tiny amounts of energy has improved. Nanogenerators often use piezoelectric nanowires. When these wires bend or compress, the movement causes ions in the material to shift, creating an electrical charge. This charge produces usable alternating current (AC) electricity, which can power small sensors. Piezoelectric systems are also used in medical devices, such as artificial organs, pacemakers, and drug delivery tools. Components like piezoelectric resonators and quartz crystal oscillators help control electrical circuits.

Marine energy, also called ocean energy, comes from waves, tides, salinity differences, and ocean temperature changes. Technologies to capture this energy include wave power, marine current power, and tidal power. Reverse electrodialysis (RED) is a method that generates electricity by mixing fresh water and saltwater in large cells. Most marine energy technologies are still in early stages and not widely used. Tidal energy is the most developed, but it is not yet widely deployed. The largest tidal power station is on Sihwa Lake in South Korea, which produces about 550 gigawatt-hours of electricity each year.

Earth emits about 10 watts of infrared thermal radiation into space. Solar energy reaches Earth and warms the surface and atmosphere. Theoretical devices, such as emissive energy harvesters or thermoradiative diodes, could convert this energy flow into electricity. This technology could work even at night.

Producing liquid fuels from oil-rich algae is an area of ongoing research. Scientists are testing different types of microalgae in open or closed systems, including those that can be placed on unused land or deserts.

Space-based solar power involves placing large satellites with solar panels in space. These satellites would use microwaves to send energy back to Earth. A 2024 NASA study found that this idea is not economically viable with current or near-future technology.

Collecting static electricity from water droplets on metal surfaces is an experimental technology that could help in areas with high humidity, such as low-income countries.

Breeder reactors could extract nearly all the energy from uranium or thorium, reducing fuel needs by 100 times compared to traditional reactors, which use less than 1% of the energy in mined materials. This high efficiency could reduce concerns about fuel supply, mining energy use, and radioactive waste storage. If seawater uranium extraction becomes economical, breeder reactors could provide energy for billions of years, making nuclear energy a renewable resource. Uranium and thorium are also found in granite rocks, which could supply energy for the rest of the sun's lifespan.

Artificial photosynthesis uses nanotechnology to store solar energy in chemical bonds by splitting water to make hydrogen and using carbon dioxide to create methanol. Researchers aim to design systems that use more of the solar spectrum and are made from affordable, non-toxic materials. However, challenges remain. A company called Sun Catalytix stopped developing its prototype in 2012 because it did not offer significant advantages over other hydrogen production methods.

Recent studies suggest that artificial photosynthesis could help create dense, carbon-based fuels for transportation, such as aviation and shipping. These fuels, made from sunlight, water, and carbon dioxide, could reduce reliance on fossil fuels. However, major technical challenges remain, including developing efficient catalysts for water splitting and carbon dioxide conversion, as well as addressing land use and public concerns.

Comparison of the theoretical and practical potentials of different renewable energy technologies

In 2019, the total energy used worldwide was about 65 petawatt-hours (PWh) per year, or 65,000 terawatt-hours (TWh) annually.

A detailed study published in 2023 found that the maximum energy that can be produced by large-scale solar photovoltaic systems, concentrated solar power, onshore wind, and offshore wind is more than 100 PWh per year for each. This means each of these energy sources could, in theory, meet the world’s total energy needs.

For solar photovoltaic systems alone, the technical potential is over 5,800 PWh per year using current technology. This is about 89 times the world’s current energy demand. In principle, using just 2% of this solar energy could solve the world’s energy needs.

For onshore and offshore wind combined, the technical potential is nearly 900 PWh per year, or 900 trillion kWh per year. This is about 14 times the world’s current energy demand. However, wind energy is not always available when needed, and it is not practical to use wind power from all areas of the Earth.

Using current technology, solar and wind energy together could capture at least 6,700 PWh per year, which is more than 100 times the world’s current energy demand.

The gross theoretical potential for energy from all sources is about 52 PWh per year, spread across 11.8 million possible locations worldwide. This equals about 33% of the energy needed each year.

Conventional geothermal energy has a technical potential of more than 10 PWh per year. Enhanced geothermal systems (EGS) could provide about 4,000 PWh per year by using heat from underground resources up to 8 kilometers deep. This potential is enough to meet the world’s electricity needs 140 times over and is the second-largest renewable energy source after solar photovoltaic systems.

Rooftop solar photovoltaic systems, wave energy, tidal energy, and ocean thermal energy conversion each have technical potentials of more than 1 PWh per year. Salinity gradient energy has a technical potential of more than 0.1 PWh per year.

When considering all renewable energy sources, the total technical potential ranges from 164 to 27,200 PWh per year. This is 6.6 to 1,101 times the world’s electricity use in 2021, which was 24.7 PWh per year.

Studies on the economic potential of renewable energy show that this potential is greater than current and near-future electricity needs. Specifically, about 60% of the world’s solar energy and 15% of its wind energy are already cost-effective compared to energy from local fossil fuels.

Market and industry trends

Most new renewable energy sources are solar power, followed by wind power, then hydroelectric power, and finally bioenergy. Investing in renewable energy, especially solar power, often creates more jobs than investing in coal, gas, or oil. In 2020, renewable energy employed about 12 million people worldwide, with solar photovoltaics being the technology that employed the most, nearly 4 million people. However, as of February 2024, the number of workers available for solar energy jobs is much lower than the number of jobs needed because universities worldwide still train more people for fossil fuel industries than for renewable energy jobs.

In 2021, China contributed nearly half of the global increase in renewable electricity. A total of 3,146 gigawatts of renewable energy were installed in 135 countries, and 156 countries have laws that regulate the renewable energy sector.

The International Renewable Energy Agency reported that in 2025, renewables accounted for 85.6% of new electricity generation capacity globally, with solar photovoltaics providing nearly three-quarters of the increase. By the end of 2025, renewables made up 49.4% of the world’s installed electricity-generating capacity.

In 2020, over 10 million jobs were associated with renewable energy industries worldwide, with solar photovoltaics being the largest employer among renewables. Between 2019 and 2022, the clean energy sectors added about 4.7 million jobs globally, totaling 35 million jobs by 2022.

Some studies suggest that a global shift to 100% renewable energy across all sectors—power, heat, transport, and industry—is possible and cost-effective.

One effort to reduce carbon emissions in transportation is the increased use of electric vehicles (EVs). Despite this and the use of biofuels, such as biojet fuel, less than 4% of transport energy comes from renewables. Occasionally, hydrogen fuel cells are used for heavy transport. In the future, electrofuels may also help reduce emissions in hard-to-decarbonize sectors like aviation and maritime shipping.

Solar water heating contributes significantly to renewable heat in many countries, especially in China, which now has 70% of the global total (180 gigawatts thermal). Most of these systems are installed on multi-family apartment buildings and meet hot water needs for an estimated 50–60 million households in China. Worldwide, solar water heating systems meet hot water needs for over 70 million households.

Heat pumps provide both heating and cooling, and they help balance electricity demand, making them an increasing priority. Renewable thermal energy is also growing rapidly, with about 10% of heating and cooling energy coming from renewables.

The International Renewable Energy Agency (IRENA) stated that about 86% (187 gigawatts) of renewable energy capacity added in 2022 had lower costs than electricity from fossil fuels. IRENA also noted that renewable energy capacity added since 2000 reduced electricity bills in 2022 by at least $520 billion. In non-OECD countries, the lifetime savings from 2022 renewable energy additions will reduce costs by up to $580 billion.

In 2018, a review of research concluded that as greenhouse gas (GHG) emitters are held responsible for damages caused by climate change, strong incentives for renewable energy deployment may arise.

From 2010 to 2019, worldwide investment in renewable energy capacity (excluding large hydropower) reached $2.7 trillion. China contributed $818 billion, the United States $392.3 billion, Japan $210.9 billion, Germany $183.4 billion, and the United Kingdom $126.5 billion. This was more than three times the investment in the previous decade (2000–2009).

By 2022, an estimated 28% of the world’s electricity was generated by renewables, up from 19% in 1990. By the end of 2024, global renewable power capacity reached 4,300 gigawatts (GW), with solar photovoltaics accounting for over 60% of annual additions.

A December 2022 report by the International Energy Agency (IEA) forecasts that renewables will grow by almost 2,400 gigawatts between 2022 and 2027, equal to China’s total power capacity in 2021. This growth rate is 85% faster than the previous five years and 30% higher than the IEA’s 2021 forecast, the largest upward revision in its history. Renewables are expected to account for over 90% of global electricity capacity expansion during this period. To achieve net zero emissions by 2050, the IEA believes that 90% of global electricity must come from renewable sources.

In June 2022, IEA Executive Director Fatih Birol said countries should invest more in renewables to reduce the impact of high fossil fuel prices on consumers, improve energy security, and meet climate goals.

The EU’s REPowerEU plan, aimed at reducing dependence on Russian fossil fuels, is expected to increase demand for green hydrogen.

After a transition period, renewable energy is expected to supply most of the world’s energy. In 2018, DNV GL, a risk management firm, predicted that by 2050, the world’s primary energy mix will be split equally between fossil fuels and non-fossil sources.

Middle Eastern nations are also planning to reduce reliance on fossil fuels. Many green energy projects in the region are expected to provide 26% of energy supply by 2050, reducing emissions by 1.1 gigatons of CO₂ per year.

Major renewable energy projects in the Middle East include:
– Mohammed bin Rashid Al Maktoum Solar Park in Dubai, UAE
– Shuaibah Two Solar Facility in Mecca Province, Saudi Arabia
– NEOM Green Hydrogen Project in NEOM, Saudi Arabia
– Gulf of Suez Wind Power Project in Suez, Egypt
– Al-Ajban Solar Park in Abu Dhabi, UAE

In July 2

Policy

Policies that support renewable energy have helped increase its use. In the early 2000s, Europe led the way in creating energy policies. Today, most countries around the world have some type of energy policy.

The International Renewable Energy Agency (IRENA) is an organization formed by many countries to help promote renewable energy globally. IRENA provides advice on policies, helps countries build skills, and supports sharing of technology. IRENA was created in 2009, with 75 countries joining at first. By April 2019, 160 countries were members. The former United Nations Secretary-General Ban Ki-moon stated that renewable energy can help the poorest countries become more prosperous.

The 2015 Paris Agreement on climate change encouraged many countries to create or improve their renewable energy policies. In 2017, 121 countries had some type of renewable energy policy. At that time, 176 countries had national goals for renewable energy. Policies also exist at state/provincial and local levels. Some public utilities assist with planning or installing energy improvements in homes.

Many governments have created green banks. A green bank is a financial institution that uses public money to encourage private investment in clean energy technologies. These banks use different financial tools to help overcome challenges that stop clean energy from being widely used.

Renewable energy policies can be grouped by sectors such as agriculture, transportation, buildings, and industry. The European Green Deal aims for climate neutrality, meaning no net greenhouse gas emissions, by 2050. To reach this goal, the European Union plans to reduce emissions from its energy system to achieve "net-zero greenhouse gas emissions by 2050."

Finance

The International Renewable Energy Agency (IRENA) 2023 report shows that investments in renewable energy have grown steadily since 2018. In 2020, investments reached USD 348 billion, which was a 5.6% increase from 2019. In 2021, investments rose to USD 430 billion, a 24% increase from 2020. In 2022, investments reached USD 499 billion, which was 16% higher than 2021. This growth is due to greater awareness of how renewable energy helps reduce climate change and improve energy security. Investors are also showing more interest in renewable energy instead of fossil fuels. Policies like feed-in tariffs in China and Vietnam have helped increase the use of renewable energy. Between 2013 and 2022, the cost to install solar photovoltaic (PV), onshore wind, and offshore wind energy dropped by 69%, 33%, and 45%, respectively. These cost reductions have made renewable energy more affordable.

From 2013 to 2022, investment priorities in the renewable energy sector changed. Investments in solar and wind energy increased significantly. However, investments in other renewable technologies, such as hydropower (including pumped storage hydropower), biomass, biofuels, geothermal, and marine energy, decreased. Between 2017 and 2022, investments in these technologies dropped by 45%, from USD 35 billion to USD 17 billion.

In 2023, investments in renewable energy rose sharply, especially in solar and wind technologies, reaching about USD 200 billion. This was a 75% increase from 2022. These investments added between 1% and 4% to the GDP in important regions like the United States, China, the European Union, and India.

Each year, the energy sector receives about USD 3 trillion in investments. Of this, USD 1.9 trillion goes to clean energy technologies and infrastructure. To meet the goals of the Net Zero Emissions (NZE) Scenario by 2035, investments in clean energy must increase to USD 5.3 trillion per year.

Debates

Whether nuclear power should be considered a form of renewable energy is a topic that people often discuss. Legal definitions of renewable energy usually do not include nuclear energy, except in the U.S. state of Utah. Definitions from dictionaries often leave out nuclear energy, except for the natural heat from radioactive elements inside Earth.

The most common fuel used in nuclear power plants is uranium-235, which is called "non-renewable" by the U.S. Energy Information Administration. However, the organization does not mention recycled fuel made from nuclear waste. The National Renewable Energy Laboratory does not include nuclear power in its basic definition of renewable energy.

In 1987, the Brundtland Commission (WCED) classified certain nuclear reactors that create more fuel than they use, like breeder reactors and future fusion power, as renewable energy sources, similar to solar or hydropower. Managing and storing radioactive waste is also needed for some renewable energy sources, such as geothermal energy.

The use of renewable energy affects global politics. Countries with large oil reserves, like Qatar, Russia, Saudi Arabia, and Norway, often use their oil wealth to influence other nations. These countries may lose power as the world shifts to renewable energy, though some, like Norway, also produce renewable energy. Fossil fuel resources and the systems to extract them may become less valuable over time. Some countries that rely on oil income may sell their remaining fossil fuels quickly in the future.

At the same time, countries with strong renewable resources or minerals needed for renewable technology, like China, may gain more influence. China is now the world’s largest maker of solar panels, wind turbines, and lithium-ion batteries. Countries with lots of sunlight or wind may become major exporters of renewable energy. Electricity is expected to be the main energy source by 2050, making up nearly half of all energy use. Countries with large empty areas, like Australia, China, and parts of Africa and the Middle East, have the potential to build large renewable energy projects. Producing renewable energy requires rare minerals, which will need new supply chains.

Some countries in Africa with weak governments and heavy reliance on oil income may face more political problems as oil becomes less valuable. Countries like Nigeria, Angola, Chad, Gabon, and Sudan, which have had past political instability, are at risk of more problems if their oil income drops.

A study found that switching from fossil fuels to renewable energy systems can reduce risks linked to mining, trade, and political dependence. Renewable energy systems do not need fuel, only materials and parts for construction.

In October 2021, European Commissioner Frans Timmermans said reducing reliance on fossil fuels is the best way to address the global energy crisis. He said critics of the European Green Deal may be doing so for personal or economic reasons. Some people blamed the European Union’s emissions trading system and the closing of nuclear plants for the energy crisis. European Commission President Ursula von der Leyen said Europe is too dependent on natural gas and needs to diversify suppliers and speed up the shift to clean energy.

Moving to renewable energy can improve a country’s energy security and independence, reducing reliance on fossil fuel markets and pressure from oil-producing countries. As the world uses more electricity, renewable technology will become important in many countries, weakening the influence of nations that rely on oil exports.

The shift to renewable energy requires more mining for certain metals and minerals. This can harm the environment and cause conflicts. For example, lithium mining in the Salar de Atacama desert uses much of the region’s water, forcing people to leave their homes and harming the environment. In some African countries, the push for renewable energy has led to more mining, causing deforestation and threatening endangered species. Wind power needs large amounts of copper and zinc, as well as smaller amounts of neodymium. Solar power requires aluminum, and expanding electrical grids needs copper and aluminum. Batteries for storing renewable energy use copper, nickel, aluminum, and graphite. Demand for lithium is expected to grow 42 times by 2040, and demand for nickel, cobalt, and graphite is expected to grow 20–25 times. Most of these minerals are dominated by a single country: copper in Chile, nickel in Indonesia, rare earths in China, cobalt in the Democratic Republic of the Congo, and lithium in Australia. China controls the processing of all these materials.

Recycling metals from used devices is important to create a sustainable renewable energy system. By 2040, recycling copper, lithium, cobalt, and nickel from old batteries could reduce the need for new mining by about 10%.

Deep sea mining, which involves collecting minerals from the ocean floor, is a controversial method. It could harm underwater life, but supporters argue that ocean mining areas have less wildlife than land mining areas, which often harm forests and other sensitive ecosystems.

Rare-earth mining can produce low-level radioactive waste because rare-earth elements often occur with radioactive materials like thorium, uranium, and radium.

Renewable energy projects, such as wind, solar, and hydropower, can threaten important natural areas. These projects often need large spaces, up to 10 times more than fossil fuel plants, to produce the same amount of energy. More than 2,000 renewable energy projects are built or planned in areas that are important for nature or conservation. Scientists emphasize that renewable energy is essential for reducing carbon emissions, but projects must avoid harming wildlife and ecosystems.

In 2020, scientists created a world map showing where renewable energy materials are found and how they overlap with areas important for protecting wildlife and preserving untouched land.

Society and culture

Solar power plants can sometimes take space that is used for growing food, while on-shore wind farms are sometimes opposed because of concerns about how they look and the noise they make. People who oppose these projects near their homes are often called NIMBYs, which stands for "not in my back yard." Some environmentalists worry that wind turbines can cause harm to birds and bats by hitting them. Although some people protest against new wind farms in certain areas, surveys in many regions and countries show that most people support solar and wind energy.

Community-owned wind energy projects are sometimes suggested to help gain support from local people. A 2011 UK government report said that projects are more likely to succeed if local communities support them and have a say in decisions. This includes allowing communities to be involved and to benefit from the projects. In the 2000s and early 2010s, many renewable energy projects in Germany, Sweden, and Denmark were owned by local communities, often through groups working together. In recent years, more wind energy projects in Germany have been run by large companies, but community ownership is still common in Denmark.

History

Before the use of coal in the mid-1800s, most energy came from renewable sources. The earliest known use of renewable energy was burning traditional biomass, like wood and plants, to make fire. This practice began over a million years ago, but it became common much later, after hundreds of thousands of years. The second oldest use of renewable energy was using wind to move ships on water. This method dates back about 7,000 years, with evidence found in the Persian Gulf and along the Nile River. People used geothermal energy, such as hot springs, for bathing as far back as the Paleolithic era and for heating buildings during ancient Roman times. In recorded history, the main sources of traditional renewable energy included human labor, animal power, water power, windmills for grinding grain, and firewood, which is a type of traditional biomass.

In 1885, Werner Siemens wrote about the discovery that sunlight could produce electricity in solid materials. In 1905, Max Weber discussed the future end of fossil fuels in his book The Protestant Ethic and the Spirit of Capitalism. The development of solar engines continued until World War I began. A 1911 article in Scientific American stated that solar power might be the only energy source left for humans if natural fuels eventually ran out.

The idea of peak oil, meaning the point when oil production would stop increasing, was introduced in 1956. In the 1970s, environmentalists encouraged the use of renewable energy to replace oil as it ran out and to reduce dependence on it. The first electricity-generating wind turbines were built during this time. Solar energy had been used for heating and cooling for a long time, but solar panels were too expensive to build large solar farms until 1980.

Government spending, rules, and policies helped the renewable energy industry survive the 2008 financial crisis and the Great Recession better than many other industries. In 2022, renewable energy provided 30% of the world’s electricity, compared to 21% in 1985.

Some of the most important historical uses of renewable energy include:

• Windmills in Europe and Asia, such as those in the Netherlands and Nashtifan, Iran. Verified windmill designs from Iran date back to 700–900 CE.
• Water mills in Ancient China and Ancient Persia.
• Archimedes’ burning lens, used to focus sunlight.
• Traditional cooling and ventilation systems using windcatchers and solar updraft towers.
• Ancient buildings designed to use natural heat transfer and energy processes.
• Gravity-based fountains.
• Using animal biomass, like plant and animal waste, to make fuel bricks.
• Solar ovens and furnaces in Ancient China, India, Egypt, and Persia.
• Solar energy used for drying crops, curing pottery and ceramics, and natural disinfection through sunlight.
• Long-distance water transport using ancient qanat systems.
• Transportation of goods and people using sails on rivers, seas, and oceans.
• Transportation using knowledge of water currents in rivers, seas, and oceans.
• Using renewable plant materials, like desert shrubs and pruned branches, to produce light and heat.
• Using renewable oils, such as vegetable or animal-based oils, to make light and heat.
• Designing buildings to use natural sunlight during the day and moonlight at night for lighting, decoration, timekeeping, and other purposes.