Short answers, pulled from the story.
Renewable energy, also called green energy, is energy made from renewable natural resources that are replenished on a human timescale. The most widely used types are solar energy, wind power, and hydropower, with bioenergy and geothermal power also significant in some countries.
Renewables grew from 20% of the global electricity supply in 2011 to 28% in 2021, and accounted for over 30% of global electricity generation in 2024. They are projected to reach over 45% by 2030.
The main motivation is to reduce greenhouse gas emissions, which cause climate change. Renewables also cause far less air pollution than fossil fuels, improving public health, and in some places solar or onshore wind is now the cheapest new-build electricity.
Solar and wind are intermittent because solar can only be captured during the day and wind varies day-to-day and month-to-month, giving them lower capacity factors. This is addressed with energy storage, sector coupling, grid improvements, and keeping dispatchable sources like gas-fired plants or hydropower on standby.
Renewable technologies depend on minerals including copper, lithium, nickel, cobalt, graphite, neodymium, and aluminum. Mining of each is 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, while China dominates processing of all of them.
The oldest known use of renewable energy is traditional biomass to fuel fires, dating back more than a million years. Harnessing wind to drive ships can be traced some 7000 years to the Persian Gulf and the Nile, and the earliest verified windmill designs date to Iran between 700 and 900 CE.