How Does Geothermal Power Work?


Quick Answer

Geothermal power is generated by capturing and utilizing the steam and hot water produced by geothermal springs. As cold water seeps into the Earth’s crust, a layer of hot and molten rock heats it up and causes it to rise to the surface, where it’s used to power turbines.

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Full Answer

Geothermal power provides heat directly to homes and offices via pumping stations in areas where geothermal springs and reservoirs are close to the Earth’s surface. When used directly, a heat exchanger transfers the heat from the boiling water into the object’s heating system, and it returns the cold water back into the reservoir, where geothermal power heats it up again.

Geothermal power plants produce energy by tapping into the hydrothermal convection systems that occur naturally. When such systems aren’t available, power plants drill into the surface to capture the steam more easily. The simplest way to make use of geothermal power is to drive the captured steam directly to the turbines that produce electricity. In other cases, hot water is depressurized to produce steam, or it can be used to heat up another liquid, such as isobutane, which boils at a lower temperature relative to water.

As of 2014, the largest system that generates geothermal power in the United States is a steam-driven power plant in the Geysers, the world’s largest geothermal field, which is located 72 miles north of San Francisco, Calif. The amount of wastewater sent to the location to be heated reaches nearly 20 million gallons per day.

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