# Geothermal power plants

Steam or hot water from underground reservoirs drives turbines.

Source page: https://www.materialinsights.org/energy/e_geo_power/

Capture · Geothermal · No. 34

- Capture
- Output: Electricity
 Capture · Geothermal · Foundation · Energy

Geothermal plants turn only about 12% of their underground heat into power, yet run about 85% of the time.

Chart: Illustration: Geothermal power plants

##### Where it comes from

Chart: Map of where it comes from

Heat from deep inside the Earth warms water held in porous rock. Wells bring it up as steam or hot brine; dry steam fields such as Darajat in Indonesia convert up to 21%.

##### Three things to know

1. The ground at Wairakei in New Zealand has sunk about 15 m in 50 years as fluid was drawn from beneath it.
2. Some Turkish plants release 400-1,300 g CO2/kWh from reservoir gas, while binary plants that reinject everything emit almost nothing.
3. A 50 MW flash plant needs about 21 wells: 15 to bring hot fluid up and 6 to send it back down.

##### The journey

1. 1 **Deep heat**Hot rock warms water underground
2. 2 **Wells**Bring up steam or hot brine
3. 3 **Power plant**Dry steam, flash or binary turbine
4. 4 **Reinjection**Spent fluid pumped back to hold pressure
5. 5 **Grid**Steady power around the clock
 Covered in [Earth's energy flows: sun, wind, water, heat and lifeEnergy](https://www.materialinsights.org/learn/energy/earths-energy-flows/)

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## Other sections

- [Overview](https://www.materialinsights.org/energy/e_geo_power/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_geo_power/correlation/index.md)
- [Efficiency](https://www.materialinsights.org/energy/e_geo_power/efficiency/index.md)
- [Techniques](https://www.materialinsights.org/energy/e_geo_power/techniques/index.md)
- [Resources and labour](https://www.materialinsights.org/energy/e_geo_power/resources/index.md)
- [Impact on the biosphere](https://www.materialinsights.org/energy/e_geo_power/biosphere/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_geo_power/links/index.md)