Associated Environmental Concerns
Depletion
of resources
The process of extracting geothermal resources (water, steam and gases) for power generation typically removes heat from natural reservoirs at over 10 times their rate of replenishment. This effect may be partially improved by injecting waste fluids back into the geothermal system.
Damage to natural geothermal features
Irreparable damage of natural features such as geysers and hot springs is associated with geothermal development. Long term changes to the famous Geyser Valley, Karapiti blowhole and Waiora Valley were caused by the Wairākei geothermal field when it began in 1958. The withdrawal of hot fluids from the underground reservoirs made the ground sink 3 metres in some areas and hot springs and geysers to decline as the steaming water supply was depleted.
In Geyser Valley, one of the first features to vanish was the great Wairākei geyser, which used to play to a height of 42 metres. Subsequently, the famous Champagne Pool, a blue-tinted boiling spring, dwindled away to a faint wisp of steam. Geyser Valley continued to deteriorate, and in 1973 it was shut down as a tourist spectacle. This story has been repeated many times where there has been geothermal development.
Subsidence
Sinking of the land in some areas may be caused by decreasing pressure in underground reservoirs by extracting geothermal fluids. The largest subsidence on record is at Wairākei, where the centre of the subsidence bowl is sinking at a rate of almost half a metre every year. The ground had sunk 14 metres in 2005 prior to the construction of the Wairākei power station.
Waterway pollution
Geothermal resources may contain certain amounts of arsenic, boron, mercury and lithium due to contact of hot fluids and rocks in underground reservoirs. If waste is released into rivers or lakes these pollutants can damage marine life and make the water unsafe for drinking or irrigation. Arsenic pollution is a serious environmental effect as a result from geothermal waste water being discharged. Hot springs and other natural features are contain amounts of arsenic but are often removed from the water as colourful mineral precipitates.
Air emissions
Dissolved gases are released into the atmosphere by geothermal fluids. These gases are potentially harmful to the workers of geothermal stations and can also be a problem for urban areas. The main toxic gases include carbon dioxide (CO2) and hydrogen sulphide (H2S). Both are denser than the air and may gather in tight and confined places. Hydrogen sulphate poisoning has been known to contribute to deaths in Rotorua. Carbon dioxide is a greenhouse gas and contributes greatly to global warming. However extracting geothermal energy releases far less toxic greenhouse gases per unit of electricity generated than burning fossil fuels.
The process of extracting geothermal resources (water, steam and gases) for power generation typically removes heat from natural reservoirs at over 10 times their rate of replenishment. This effect may be partially improved by injecting waste fluids back into the geothermal system.
Damage to natural geothermal features
Irreparable damage of natural features such as geysers and hot springs is associated with geothermal development. Long term changes to the famous Geyser Valley, Karapiti blowhole and Waiora Valley were caused by the Wairākei geothermal field when it began in 1958. The withdrawal of hot fluids from the underground reservoirs made the ground sink 3 metres in some areas and hot springs and geysers to decline as the steaming water supply was depleted.
In Geyser Valley, one of the first features to vanish was the great Wairākei geyser, which used to play to a height of 42 metres. Subsequently, the famous Champagne Pool, a blue-tinted boiling spring, dwindled away to a faint wisp of steam. Geyser Valley continued to deteriorate, and in 1973 it was shut down as a tourist spectacle. This story has been repeated many times where there has been geothermal development.
Subsidence
Sinking of the land in some areas may be caused by decreasing pressure in underground reservoirs by extracting geothermal fluids. The largest subsidence on record is at Wairākei, where the centre of the subsidence bowl is sinking at a rate of almost half a metre every year. The ground had sunk 14 metres in 2005 prior to the construction of the Wairākei power station.
Waterway pollution
Geothermal resources may contain certain amounts of arsenic, boron, mercury and lithium due to contact of hot fluids and rocks in underground reservoirs. If waste is released into rivers or lakes these pollutants can damage marine life and make the water unsafe for drinking or irrigation. Arsenic pollution is a serious environmental effect as a result from geothermal waste water being discharged. Hot springs and other natural features are contain amounts of arsenic but are often removed from the water as colourful mineral precipitates.
Air emissions
Dissolved gases are released into the atmosphere by geothermal fluids. These gases are potentially harmful to the workers of geothermal stations and can also be a problem for urban areas. The main toxic gases include carbon dioxide (CO2) and hydrogen sulphide (H2S). Both are denser than the air and may gather in tight and confined places. Hydrogen sulphate poisoning has been known to contribute to deaths in Rotorua. Carbon dioxide is a greenhouse gas and contributes greatly to global warming. However extracting geothermal energy releases far less toxic greenhouse gases per unit of electricity generated than burning fossil fuels.