Energy and extraction

Primary energy – In 2018, New Zealand’s total primary energy supply was 890 petajoules (PJ). Twentyone percent (188 PJ) of New Zealand’s primary energy came from geothermal sources.

Primary energy comes directly from natural sources such as the sun, gas and oil, wood, coal and geothermal energy:

• Industries use it for process heat.
• Gas is used in vehicles and for cooking and heating.
• Households use it for heating (burning wood and coal, using geothermal heat and water).
• It is also turned into electricity.

Primary energy obtained from geothermal sources is forecast to increase to 30 per cent of the total by 2030. Estimates say we could extract between 30,000 and 57,000 PJ per year of geothermal energy using present technology. But this could lead to irreversible effects, such as the destruction of geysers and other surface features, and land subsidence.

Electrical energy - In 2018, New Zealand’s total electrical energy supply was 270 PJ per year. Geothermal energy from the power stations in the Waikato region provides about 16 per cent of our national electricity supply.

Waikato region - The Waikato region provides 90 per cent of the primary geothermal energy extracted in New Zealand. Of the geothermal energy extracted, only 15 per cent is converted to a useable form. The rest is re-injected or disposed of into the environment as heat. In the Waikato region there are about 60 separate industries, accommodation facilities and tourist facilities that take small amounts of heat for direct uses. 

New Zealand has sixteen geothermal power stations. Ten are in the Waikato region. There are plans to build others and expand existing stations, in the Waikato, Bay of Plenty, and Northland regions. The table below lists the stations in our region.

Geothermal power stations

As well as these large power stations, about 60 commercial operations use small or medium quantities of geothermal water and energy in the region. Most operations take the water from wells or springs, some obtain it from Contact Energy, and others take water from hot streams such as the Onekeneke at Taupō. This heated water is used mainly for public baths or motel pools, but some is used in primary and industrial processes.

Geothermal systems extend under large areas of land. To find, develop and extract these economic sources of geothermal energy and fluid resources (sometimes as deep as three kilometres below the Earth’s surface) requires large capital investment and complex infrastructures.

Although only a fraction of geothermal energy is currently used, the environmental effects have been dramatic.

Between the 1950s and 1990s, the number of geysers in the region fell because of heat and fluid extraction and the effects of overlying land uses. When water extraction prevents pressure from reaching the level necessary to fuel the geysers, they disappear. As a result, many sinter-depositing springs and geysers and their associated ecosystems were lost with the development of the Wairakei Geothermal Power Station.

Use our map to find out more about the state of geothermal features in the Waikato region.

The extraction of heat and fluid can cause land subsidence. For example, a marae near Ohaaki Geothermal Power Station is sinking and runs the risk of being inundated by the Waikato River, as the ground it sits on subsides.

Effects on other parts of the natural environment are summarised in the table below.

Environmental effects of geothermal contaminants

Find out more about the arsenic levels in the Waikato River.

In the past, once geothermal fluid extracted for electricity generation had been through the power station, any excess heat and fluid was discarded. Now increasingly, other industrial and domestic processes use the discarded heat and fluid before it is reinjected into the geothermal system. This means less of the energy extracted is wasted, and less heated water is produced as a by-product. For example:

• A prawn farm near Taupō heats its own freshwater by running it across pipes containing geothermal water used by its neighbour, the Wairakei Geothermal Power Station.
• At Ohaaki, geothermal heat is used to treat timber.

Developers must obtain resource consents prior to developing geothermal areas. The resource consent process requires consultation with iwi and considers potential effects on waahi tapu and other significant sites. Significant adverse environmental effects must be avoided, remedied, or mitigated.

Each power station needs a set of about 15 resource consents to cover such activities as taking geothermal fluid and fresh water, and discharging steam and other gases to air, reinjection of geothermal fluid to ground or its discharge to land or water, drilling geothermal wells, and building and maintaining roads.