Renewable energy

Renewable energy, also called green energy, is energy made from natural resources that can be replenished quickly, like the sun, wind, and water. The most common types of renewable energy are solar energy, wind power, and hydropower. Other types include bioenergy and geothermal power. These energy sources can be used in both big cities and small towns, and they often work well with electricity, which can power homes, move heat, and run vehicles cleanly.

Over the past 30 years, renewable energy systems have become much better and cheaper. Today, most new electricity comes from renewable sources. Solar and wind power have become some of the cheapest ways to make electricity in many places. From 2011 to 2021, the share of electricity from renewable energy grew from 20% to 28%, with solar and wind power leading this growth. By 2024, renewables provided over 30% of the world's electricity, and experts think this could rise to over 45% by 2030.

The big reason to use renewable energy is to cut down on greenhouse gases that cause climate change. Unlike fossil fuels, renewables produce much less pollution and are quieter. However, there are still challenges, such as government support for fossil fuels and some people not wanting renewable energy projects built near them. While some argue that nuclear power a renewable power source, this is debated because it relies on uranium, which is not renewable.

Overview

See also: Lists of renewable energy topics

Renewable energy sources, especially solar photovoltaic and wind, are generating an increasing share of electricity. Coal, oil, and natural gas remain the primary global energy sources even as renewables have begun rapidly increasing.

Renewable energy is usually understood as energy harnessed from continuously occurring natural phenomena. The International Energy Agency defines it as "energy derived from natural processes that are replenished at a faster rate than they are consumed". Solar power, wind power, hydroelectricity, geothermal energy, and biomass are widely agreed to be the main types of renewable energy. Renewable energy often displaces conventional fuels in four areas: electricity generation, hot water/space heating, transportation, and rural (off-grid) energy services.

As part of the global effort to limit climate change, most countries have committed to net zero greenhouse gas emissions. In practice, this means phasing out fossil fuels and replacing them with low-emissions energy sources. At the 2023 United Nations Climate Change Conference, around three-quarters of the world's countries set a goal of tripling renewable energy capacity by 2030. The European Union aims to generate 40% of its electricity from renewables by the same year.

Renewable energy is more evenly distributed around the world than fossil fuels, which are concentrated in a limited number of countries. It also brings health benefits by reducing air pollution caused by the burning of fossil fuels.

The two most important forms of renewable energy, solar and wind, are intermittent energy sources: they are not available constantly. Solar energy can only be captured during the day, and ideally in cloudless conditions. Wind power generation can vary significantly. This poses a challenge when transitioning away from fossil fuels: energy demand will often be higher or lower than what renewables can provide. In the long-term, energy storage is an important way of dealing with intermittency. Using diversified renewable energy sources and smart grids can also help manage supply and demand.

Mainstream technologies

Main articles: Solar energy, Solar power, and Outline of solar energy

Solar power produced around 1.3 terrawatt-hours worldwide in 2022, representing 4.6% of the world's electricity. Solar energy can be harnessed anywhere that receives sunlight. There are two main ways to use solar energy: solar thermal, which turns sunlight into heat, and photovoltaics (PV), which turns it into electricity. PV is more common and is growing very fast.

Main articles: Wind power and Wind power by country

Wind power has been used for thousands of years, but today it mostly generates electricity using wind turbines. These turbines can be quite large and are often placed where the wind is strong and steady, like offshore or in high-altitude areas. Wind power provided nearly 4% of global electricity demand in 2015 and continues to grow.

Main articles: Hydroelectricity and Hydropower

Hydropower uses the energy of moving water to generate electricity. It is very efficient and can quickly adjust to supply power when needed. Large dams, small river systems, and run-of-the-river plants are all ways to harness hydropower. In 2021, hydropower made up a big part of the world's renewable energy capacity.

Main article: Bioenergy

Bioenergy comes from plants and organic materials. It can be used directly for heat or turned into biofuels like ethanol and biodiesel for transportation. While it can be a useful energy source, it must be managed carefully to avoid harming forests and ecosystems.

Main articles: Geothermal energy, Geothermal power, Renewable thermal energy, and Geothermal energy in the United States

Geothermal energy uses heat from deep within the Earth to provide warmth or generate electricity. It works best in areas with volcanic activity or tectonic plate edges. Countries like Iceland and the United States use geothermal energy to heat homes and power buildings.

Emerging technologies

There are other renewable energy technologies still being developed, including enhanced geothermal systems, concentrated solar power, cellulosic ethanol, piezoelectricity, and marine energy. These technologies are not yet widely used and need more research and development to become common.

Enhanced geothermal systems

Main article: Enhanced geothermal systems

Enhanced geothermal systems (EGS) are a new way to get geothermal power without needing natural hot water or steam. They use a process called hydraulic fracturing to break apart rocks deep underground, releasing heat that can be used to make electricity. This method could work almost anywhere, depending on how expensive it is to drill.

Sand battery

Sand batteries are big tanks filled with a special kind of stone that can store heat. They take extra energy from renewable sources and save it as heat, which can later be used to make hot water, steam, or warm air. Finland is using this technology with a large sand battery that can store a lot of energy.

Piezoelectricity

Piezoelectricity is a way to turn movement or vibration into electricity without using fuel. When certain materials are pressed or bent, they can create tiny electric charges. This can power small devices like sensors and medical tools.

Marine energy

Main article: Marine energy

Marine energy comes from the ocean, using waves, tides, and differences in salt levels to make electricity. Technologies include wave power, marine current power, and tidal power. Tidal energy is the most developed, but it is still not used very much. The largest tidal power station is in South Korea.

Earth infrared thermal radiation

The Earth gives off a lot of heat energy into space. Scientists are working on ways to capture this energy and turn it into electricity, which could be useful at night.

Others

Algae fuels

Main article: Algae fuels

Scientists are trying to make fuels from certain types of algae. These algae can grow in places like empty or desert lands.

Space-based solar power

Main article: Space-based solar power

Some people have suggested putting very large solar panels in space to collect solar power and send it back to Earth. A study in 2024 found that this idea is not currently practical with today’s technology.

Water vapor

Collecting static electricity from water droplets on metal surfaces is being tested as a way to generate power, especially in places with lots of humidity.

Nuclear energy

Breeder reactors could use almost all the energy in uranium or thorium, making nuclear energy more efficient. This could provide a lot of energy for a very long time.

Artificial photosynthesis

Main article: Artificial photosynthesis

Artificial photosynthesis tries to mimic how plants use sunlight. It uses tiny technologies to turn sunlight into fuels like hydrogen or methanol. This could help make clean fuels for things like airplanes and ships, but it still needs more research to work well.

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

Global energy consumption in 2019 was about 65,000 terawatt-hours each year. Different renewable energy sources have huge amounts of energy that could be used.

Solar power, wind power, and hydropower are some of the main types. Studies show that solar and wind energy alone could provide more than enough energy for the whole world many times over. Hydropower can also provide a lot of energy, about one-third of what the world needs each year. Geothermal energy, which comes from heat inside the Earth, also has great potential. Other ocean-based energies like wave and tidal power have smaller but still useful amounts of energy available.

Market and industry trends

Most new renewable energy comes from solar power, followed by wind, hydropower, and bioenergy. Investing in renewables, especially solar, creates more jobs than fossil fuels. As of 2020, about 12 million people worldwide work in renewable energy jobs, with solar jobs making up almost 4 million. However, there aren't enough trained workers to meet the growing demand for solar energy.

In 2021, China led the world in adding new renewable electricity, accounting for almost half of the global increase. By the end of 2025, renewables made up 49.4% of all electricity generation capacity worldwide, with solar power providing nearly three-quarters of the new capacity that year.

Renewable energy is becoming more common in many areas. Some studies show that it’s possible to power the whole world with 100% renewable energy. For example, many countries now use solar water heating systems, and heat pumps are becoming more popular because they can both heat and cool buildings efficiently. Electric vehicles are also growing in popularity as a way to reduce pollution from transportation.

Policy

Policies to support renewable energy have been important for its growth. Many countries now have energy policies to help use more renewable energy. The International Renewable Energy Agency (IRENA) is an organization that helps countries adopt renewable energy. It gives advice and supports training and technology sharing.

The 2015 Paris Agreement encouraged many countries to improve their renewable energy policies. In 2017, 121 countries had some form of renewable energy policy, and 176 countries set targets for renewable energy use. Some local governments also have policies to support renewable energy. Green banks are special financial institutions that help invest in clean energy projects.

Finance

Electrified transport and renewable energy are important areas for investment to help fight climate change through an energy transition. China has become a leader in patents for batteries and solar energy, while Europe leads in wind energy and smart grids. China also publishes many highly cited research papers.

The International Renewable Energy Agency reports that investment in renewable energy has grown steadily since 2018. In 2022, investments reached USD 499 billion, driven by the need to fight climate change and improve energy security. Policies like feed-in tariffs in China and Vietnam have helped increase renewable energy use. Costs for solar and wind energy have dropped a lot since 2013, making them more affordable.

In 2023, investments in solar and wind energy jumped by 75% to about USD 200 billion. The renewable energy sector adds 1% to 4% to the GDP in places like the United States, China, the European Union, and India. Overall, the energy sector gets about USD 3 trillion each year, with USD 1.9 trillion going to clean energy. To reach Net Zero Emissions goals by 2035, this needs to grow to USD 5.3 trillion yearly.

Debates

Further information: Climate change mitigation § Overviews, strategies and comparisons of measures

The growing use of renewable energy has big effects on the world. Countries that make a lot of money from oil, like Qatar, Russia, Saudi Arabia, and Norway, might lose influence as the world shifts to renewable energy. On the other hand, countries with lots of sunshine and wind, such as Australia, China, and many in Africa and the Middle East, could become important exporters of renewable energy.

Making renewable energy needs more metals and minerals, like copper, nickel, and lithium. Mining these can harm the environment and sometimes causes problems for local communities. For example, lithium mining uses a lot of water, which can affect nearby farms and animals. As we use more renewable energy, we will need to find ways to recycle these materials to help protect the planet.

Society and culture

Most people believe countries should support renewable energy to help fight climate change. Surveys show strong support for renewable energy in places like the European Union, China, and the United States.

Some people worry about how solar and wind power might affect the land or wildlife. For example, solar farms might use land that could grow food, and wind turbines can sometimes harm birds and bats. However, many communities support renewable energy when they have a chance to help decide and benefit from these projects.

History

Before coal became common in the mid-1800s, nearly all energy used came from renewable sources. The oldest known renewable energy is biomass used for fires, dating back over a million years. People also used wind to sail ships around 7000 years ago in the Persian Gulf and on the Nile. Geothermal energy from hot springs was used for bathing since ancient times.

Later, people used windmills for grinding grain and water mills for many tasks. In the 1900s, scientists began exploring solar energy, realizing its huge potential. By the 1970s, concerns about running out of oil led to more interest in wind and solar power. Today, renewable energy provides a growing part of the world's electricity.