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How a geothermal power plant operates

Short answer

Production wells bring hot pressurized water or steam to the surface; a separator flashes water into steam, which drives a turbine and generator. Exhaust steam condenses, and condensate and brine are reinjected into the reservoir. Plants run continuously as base load with about 90% capacity factor.

How does a geothermal power plant operate? Describe briefly.

A geothermal power plant produces electricity from the heat of hot water or steam taken from underground reservoirs through wells. It works on a steam (Rankine) cycle like a thermal plant, but the boiler is replaced by the earth.

Operation (flash steam plant, most common)

 Prod. well -> Separator -> Steam -> Turbine -> Gen
                  |                    |
                Brine              Condenser <- Cooling
                  |                    |        tower
                  +-> Injection well <-+
  1. Production well brings hot, pressurised water (about 180–300 °C) to the surface.
  2. In the separator/flash tank the pressure drops, part of the water flashes into steam.
  3. The steam drives the turbine, which turns the generator.
  4. Exhaust steam is condensed in a condenser, cooled by a cooling tower.
  5. Condensate and separated brine are reinjected into the reservoir to maintain pressure and avoid pollution.

Other types

  • Dry steam: steam directly from the well to the turbine (e.g. The Geysers, USA).
  • Binary cycle: moderate-temperature water heats an organic fluid (isobutane) in a heat exchanger; its vapour drives the turbine.

Geothermal plants run continuously as base-load plants with high capacity factor (about 90%).

✓ Answer checked by Claude Opus 5.5 (high effort)

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