Renewable energy is energy collected from renewable resources that are naturally replenished on a human timescale. It includes sunlight, wind, rain, tides, waves, and geothermal heat. Unlike fossil fuels, which are finite and release harmful greenhouse gases, renewable energy sources are generally clean and sustainable. They are used for electricity generation, air and water heating/cooling, transportation, and rural energy services.
The use of renewable energy dates back to ancient times with biomass for fire, wind for sailing, and water for milling. The transition to fossil fuels in the 19th century sidelined renewables. However, the oil crises of the 1970s and growing environmental concerns spurred modern development. Solar photovoltaics and large-scale wind turbines became commercially viable in the late 20th century.
Renewable energy is the fastest-growing energy source globally. By 2023, it accounted for nearly 30% of global electricity generation. Countries like China, the US, and EU members are leading the transition. Costs have plummeted, with solar and wind often being cheaper than coal or gas. The sector is critical for achieving the goals of the Paris Agreement and mitigating climate change.