What is renewable energy?
Renewable energy comes from natural sources that are constantly replenished, such as sunlight, wind, flowing water, heat from inside the Earth and plant material.
The main types are solar, wind, hydroelectric, geothermal and bioenergy. Unlike fossil fuels such as coal, oil and gas, these sources will not run out on human timescales. Most also produce little or no greenhouse gas emissions while generating electricity, making them important for slowing climate change.
Renewable energy has grown rapidly. Solar and wind power have become the cheapest sources of new electricity in many countries. In 2025, renewables generated more of the world's electricity than coal for the first time over a full half-year, according to energy think tank Ember. Hydropower is still the largest single renewable source.
Challenges
Solar and wind depend on the weather and time of day, so they need energy storage, such as large batteries, and stronger power grids. Building dams and wind farms can affect wildlife and landscapes. Still, many countries aim to get most of their electricity from renewables in the coming decades.
Did You Know?
Iceland generates almost all of its electricity from renewable sources, mainly hydropower and geothermal energy from its volcanic landscape.