Geothermal power plants: Impact on the biosphere

Rotten-egg gas, sinking ground and the occasional earthquake

What this tab covers Effects on human, animal, plant, fungal and microbial life and on whole ecosystems: in the short term (construction and early years), medium term (operating life) and long term (decommissioning and legacy).

Geothermal plants have few deaths or air-pollution effects compared with fossil fuels, but they can release CO2 and hydrogen sulphide from the reservoir, cause ground subsidence and occasionally trigger earthquakes.

Operational CO2, global average about 121 g CO2/kWh reported (some Turkish plants 400-1,300)⁶ Life-cycle greenhouse gas emissions 38 g CO2e/kWh median (range 6-79)⁵ Maximum subsidence, Wairakei, New Zealand about 15 m after 50 years¹² H2S removed by abatement systems over 99.9%⁹

Effects over time

Life affected	Short term	Medium term	Long term
Humans⁹¹²	Drilling noise and construction traffic.	Hydrogen sulphide (rotten-egg gas) is toxic at high concentration; abatement removes over 99.9%. Subsidence damages buildings and pipes.	Low-level arsenic and boron in waste must be contained.
Animals⁹	Habitat disturbance at well pads.	Little evidence of effect beyond the site.	Little evidence of effect.
Plants⁹	Clearing for pads and pipelines.	Little evidence of effect beyond the site.	Little evidence of effect.
Fungi and soil life⁹	Little evidence of effect.	Little evidence of effect.	Little evidence of effect.
Ecosystems³¹²	Small footprint: well pads, pipelines and plant.	Reservoir pressure declines if extraction outpaces recharge, as at The Geysers; Wairakei subsided about 15 m over 50 years.	Reinjection can partly restore reservoirs; subsidence is permanent.

How the effects are reduced

Reinjecting spent fluid maintains pressure and limits subsidence; H2S abatement converts the gas to sulphur; binary plants that reinject all fluid emit almost nothing. Directional drilling from shared pads reduces land use, and air cooling avoids fresh-water use in dry regions.

Sources

The Geysers: Water (steam field recharge) Calpine (geysers.com), 2024
Climate Change 2014: Mitigation, Annex III Technology-specific cost and performance parameters, Table A.III.2 IPCC AR5 Working Group III, 2014
Understanding CO2 Emissions from Geothermal Power Generation in Turkey (Live Wire 2021/118) World Bank, 2021
A Guide to Geothermal Energy and the Environment Geothermal Energy Association, 2007
Update on subsidence at the Wairakei-Tauhara geothermal system, New Zealand (Allis, Bromley and Currie, Geothermics 38) Elsevier (USGS Publications Warehouse record), 2009