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Mokai geothermal system

The Mokai geothermal system is one of the seven systems classified for development in the Waikato region. The Tuaropaki Power Company, which is 75% owned by the Tuaropaki Trust owns two geothermal power stations at Mokai, and wishes to sustainably manage and use the Mokai system for as long as possible.

Photograph of Tuaropaki Power Station No 1, Mokai

The Mokai geothermal system lies 25 km north west of Taupo. See where it is on our Geothermal Fields - Map.

The natural features of the Mokai system include warm and hot springs, mud pools, a rare mud geyser, and fumaroles. It also has one of the largest populations of a rare geothermal plant, the fern Christella sp. 'thermal'.

The Tuaropaki Trust owns a large area of land overlying the Mokai geothermal system. The Mokai geothermal system is classified for development by Waikato Regional Council. At Mokai a single development body (the Tuaropaki Trust) has access to the majority of the resource. Mighty River Power now has a 25 per cent stake in the Tuaropaki Power Company.

Developing the system

In 1999 the Trust built a 55 megawatt geothermal power station on the site. In 2005 they completed another 40 megawatt station beside it, and in 2007 they increased their output to 110 megawatts. The Trust also has a twelve hectare, geothermally heated glasshouse producing tomatoes and capsicums for export. This venture employs more than 50 people from Mokai and Mangakino, most of them previously unemployed. This has had a significant positive effect on the socio-economic well-being of the two areas.

The Trust believes that developing the Mokai geothermal system is a unique opportunity for Maori to take the initiative and create a project that allows for self-determination.

The Trust is staging the development to minimise adverse environmental effects and accommodate the needs of existing users and potential needs of future generations. They recognise geothermal taonga (treasures) such as therapeutic and cooking pools. A key part of the development is re–injecting used geothermal fluid back into the deep geothermal aquifer to minimise the impact on existing geothermal features and natural ecosystems.

The Trust also has a major share in the Miraka milk powder plant, which uses geothermal steam to process the milk.  Waste from the milk plant and glasshouses is supplied to a worm farm, which grows native plants for riparian planting on Trust land.

Future work

The Trust plans to expand the glasshouse to 20, and then 50, hectares. Further expansion of the power station is also likely once the response to the existing takes has been quantified.