Geothermal energy is thermal energy generated and stored in the Earth, originating from the planet's formation and radioactive decay. Historically, hot springs have been used for bathing for thousands of years. Currently, geothermal energy is used to generate electricity and provide direct heating. Over 10,000 megawatts of geothermal power is online globally. While geothermal has the advantage of being immune to fuel costs, developing resources has high capital costs due to exploration and drilling risks. Effluents from geothermal plants can release pollutants if not mitigated by emission controls.