It uses water to power large turbines.
Geothermal power taps on the energy of natural steam from the earth's lithosphere.
Explanation:
The heat from deep in the the lithosphere heats up underground water into high-pressure steam trapped in within the rocks. Boreholes are sunk to tap on the potential energy of this high-pressure steam to turn large dynamo turbines that convert the steam energy into electricity.
The biggest advantage, moreover, is the fact that this method of electricity generation does not emit greenhouse emissions as compared to gas plants that burn hydrocarbons that release CO₂.