Story: Geothermal energy
Bubbling mud, erupting geysers and hot mineral pools are some of the surface features of New Zealand’s geothermal systems. Their energy has been tapped to feed geothermal power stations, producing electricity. The benefits are substantial, but they do not come without a cost to the environment.
Full story by Carol Stewart
Main image: Ōhākī power station
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What is geothermal energy?
The word ‘geothermal’ means ‘heat from the earth’. Geothermal energy comes from hot underground water, gas and steam and is used to produce power (electricity).
The Taupō Volcanic Zone, in the middle of the North Island, is rich in geothermal features, including hot pools, geysers and mud pools. They originate underground when heat from volcanic activity heats up water.
Turning steam into power
At a geothermal power station, steam is drawn from the ground and used to spin large turbines, which generate electricity. In 2002 New Zealand had seven geothermal power stations, which provided about 7% of the country’s electricity.
Geothermal heat is also used for heating houses in Rotorua and Taupō, the pulp and paper mill in Kawerau, and greenhouses which grow fruit, flowers and vegetables all year round.
When Māori used hot pools for cooking, heating and bathing, there were few bad effects on the environment. When Europeans arrived in the mid-1800s they used the resources on a large scale, building spa baths and drilling wells. In the 1950s the first power station was built at Wairākei. This extra use began to drain geothermal areas of their heat. As a result, some hot springs, geysers and blowholes have dwindled or become extinct.
Waste water from geothermal industry has polluted the Waikato River with arsenic and other elements.