What is New Zealand’s superhot geothermal resource potential?
This is not a simple question to answer, but it is important. Better understanding of the possible available resource will support work to investigate and realise energy production from New Zealand’s abundant superhot geothermal resources.
A recent report, published by members of the GNG team details a superhot / supercritical geothermal inventory assessment based on the United Nations Framework Classification for Resources and the United Nations Economic Commission for Europe (UNECE Supplementary Specifications).
The UNFC methodology categorises the New Zealand inventory of superhot geothermal projects at E3.2, F4.2, G4.1 (344), reflecting the current level of environmental-economic-social viability, technical feasibility, and level of confidence.
The team developed an assessment methodology to determine the resource potential. The inventory uses geophysical data and interpretations [visit Exploring for Geothermal Resources for more on how to “see” beneath the Earth’s surface], primarily magnetotellurics, available in the Taupō Volcanic Zone, in the Waikato and Bay of Plenty Regions, along with the Northland Region (Ngawha). It considers the depth range of 3.5 to 6km only; this depth targets the ‘deep roots’ of subcritical geothermal systems where the temperatures are >400°C.
Because of limited geophysical data coverage of the areas included, and constraining the lower depth limit at 6km, the inventory likely underestimates the nation’s potential.
The inventory identifies:
By way of comparison, New Zealand’s sub-critical geothermal capacity is currently ~1.1 GWe, generating ~8TWh / year. The total installed capacity in New Zealand is currently ~10 GWe generating 43TWh / year. Transpower estimates that between 14 and 17 GWe of capacity will be required by 2037 as the nation moves on its decarbonisation journey.