First posted March 7, 2023 For additional information, contact: Geology, Energy & Minerals Science CenterU.S. Geological SurveyMail Stop 95412201 Sunrise Valley DriveReston, VA 20192Email: AskEnergyProgram@usgs.gov As the United States transitions away from fossil fuels, its economy will rely on more renewable energy. Because current energy sources sometimes produce variable power supplies, it ...