How does geothermal energy generate electricity?

Geothermal power plants generate electricity by harnessing heat from underground reservoirs to drive turbines connected to electrical generators. While designs vary, they generally fall into three categories:12

• Dry Steam Plants: These collect naturally occurring steam directly from underground reservoirs and funnel it into a turbine to power a generator.1
• Flash Steam Plants: Pressurized, high-temperature water is drawn from the ground into flash tanks. The sudden drop in pressure causes the water to vaporize into steam, which then drives the turbine.1
• Binary Cycle Plants: Geothermally heated water passes through a heat exchanger, transferring its heat to a secondary working fluid (such as ammonia or hydrocarbons). This fluid vaporizes at a lower temperature and drives the turbine in a closed loop.1

Additionally, enhanced geothermal systems (EGS) can extract energy from hot dry rock by injecting fluid into fractured subsurface formations to absorb heat before returning it to the surface to power turbines.1