Energy Sources | Department of Energy Official websites use .gov .gov website belongs to an official government organization in the United States. Secure .gov websites use HTTPS lock ) or means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites. Energy Sources Energy sources are materials, processes, or systems that produce usable power to fuel human activities. Each source has unique characteristics regarding availability, efficiency, and economic viability. Geothermal There’s heat beneath your feet—a vast, largely untapped renewable energy resource. Geothermal energy has a unique role to play in providing clean energy across the entire United States. April 20, 2026 Nuclear Providing clean, reliable energy to meet the nation’s energy, environmental, and economic needs. April 8, 2026 Oil Oil The Energy Department works to ensure domestic and global oil supplies are environmentally sustainable and maintains emergency petroleum stockpiles. March 31, 2026