Production wellIt brings hot water up from the reservoir.
SteamIt rushes from the separator to spin the turbine.
TurbineSteam pushes its blades and makes the shaft spin.
GeneratorThe spinning shaft turns it to make electricity.
CondenserIt cools the used steam back into water.
Injection wellIt returns the used water to the reservoir.
The whole plant 5
Geothermal reservoirCracked rock deep underground that holds very hot water.
Hot rockThe heat source. It heats the water above it.
Separator (flash tank)A tank where some of the hot water flashes into steam.
TransformerIt raises the voltage before the electricity is sent out.
Power linesThey carry the electricity to homes and businesses.
Three kinds of plant 3
Dry steam plantSteam from the well goes straight to the turbine.
Flash steam plantHot water flashes into steam in a tank.
Binary cycle plantThe hot water boils a second liquid in a closed loop.
How this list was compiled: Every name and fact checked on 2026-10-03, a name kept only where two of these texts use it. (1) U.S. Energy Information Administration, Energy Explained: Geothermal power plants, and Electricity: Delivery to consumers: wells drilled to bring hot water or steam to the surface; a geothermal reservoir; a turbine that drives a generator; the three kinds of plant, dry steam, flash steam and binary cycle; steam that cools to water and is injected back into the ground; transformers and power lines. (2) U.S. Department of Energy, Geothermal Technologies Office, Electricity Generation, and the text of its animation How a Geothermal Power Plant Works (archived copy): a production well drilled into a geothermal reservoir and an injection well that returns the used fluid; fluid moving through hot rocks; a low-pressure tank where part of the fluid flashes to vapor; the turbine and the generator; a step-up transformer and power lines; a heat exchanger and a second fluid in a binary cycle plant. (3) U.S. Geological Survey, Circular 1249, Geothermal Energy: Clean Power From the Earth's Heat (2003): production wells; water heated by contact with hot rocks; steam separated from water in a separator; a turbine generator; a condenser; wastewater from the separator and the condenser injected back underground. (4) Wikipedia, text only, Geothermal power: lower-pressure tanks and flashed steam; steam separated from the water to power a turbine and generator; a condenser; water injected back into the reservoir; the three kinds of station; and Electric power transmission: the voltage stepped up by the power station transformer for transmission. (5) University of Calgary, Energy Education, Geothermal power plants: the production well and the Earth as the heat source. Licence: own work
The drawing: Drawn for this site on 2026-10-03 from plain geometry; a flow drawing of no real plant, not to scale; nothing traced or copied. Licence: own work
How it works
A geothermal power plant makes electricity from hot water deep underground. This easy diagram shows a flash steam plant from the hot rock to the power lines. Study it, then draw and label your own.
Read the full guide
From hot rock to power lines
Hot rock heats the water in the geothermal reservoir. The production well brings that water up to the separator, where part of it flashes into steam. The steam spins the turbine, the turbine turns the generator, and the electricity leaves through the transformer and the power lines. The condenser turns the used steam back into water, and the injection well returns it to the reservoir.
Three kinds of plant
A dry steam plant sends steam straight from the well to the turbine. A flash steam plant makes its steam from hot water. A binary cycle plant uses the hot water to boil a second liquid, and that vapor drives the turbine.
Questions and answers
How does a geothermal power plant work?
Wells bring hot water or steam up from a geothermal reservoir. The steam spins a turbine, the turbine drives a generator, and the generator makes electricity. The cooled water is injected back into the ground to be heated and used again.
What are the parts of a geothermal power plant?
A production well, a separator, a turbine, a generator, a condenser and an injection well, with a transformer and power lines to carry the electricity away. Underground are the hot rock and the geothermal reservoir.
What are the three types of geothermal power plants?
Dry steam, flash steam and binary cycle. Dry steam plants use steam straight from the ground, flash steam plants turn hot water into steam, and binary cycle plants pass the heat to a second liquid.
What is the difference between a production well and an injection well?
The production well brings hot water or steam up from the reservoir. The injection well sends the used, cooler water back down to be heated again.
Where was the first geothermal power plant?
In Italy, at Larderello in Tuscany, where steam from the ground first drove a generator in 1904. It was a dry steam plant, the oldest kind.