| Title | Geothermal the next generation: Five years of findings to propose a new exploration phase for New Zealand |
|---|---|
| Authors | I. Chambefort, C.A. Miller, O. Bachmann, J. Barreto, S. Bannister, E.A. Bertrand, T. Driesner, W. Heise, S. Jylhänkangas, A.L. Kirkby, W.M. Kissling, C. Massiot, S.D. Milicich, N. Mortimer, S.M. Rooyakkers, L. Seelig, T. Solms, C.J.N. Wilson |
| Year | 2024 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | Geothermal the Next Generation, supercritical, exploration, magnetic, heat flow, magnetotelluric, fracture and modelling |
| Abstract | After 5 years of research, the Geothermal: the Next Generation team delivered on exploration, understanding, integration of the science, and communication of the challenges facing discovery and exploitation of supercritical geothermal resources. We summarise the findings and new models of the programme that increased and challenged our understanding of the supercritical geothermal possibility for New Zealand. Here, we particularly focus on the exploration part of the programme and propose a new potential phase of geothermal exploration for New Zealand geothermal. New seismic, magnetic, heat flow and gravity models were produced with a specific focus on the southern part of the central Taupō Volcanic Zone / Te Ahi Tupua. From seismic tomography, we identified a deep large area of partial melt that is the heat source for the Wairakei – Tauhara and Rotokawa geothermal fields. For the first time, we compile geology and geophysics models of these fields. We refined the buried geology underneath the area by proposing a new geological model that better fits observed gravity and magnetic data to constrain the deep stratigraphy likely to be intercepted by deeper drilling. We characterised fracture patterns and orientation and proposed a new understanding of the distribution of basement terranes that are likely to be the reservoir rocks below the current drilled depths. We modelled the hydrothermal fluid circulation around large, deep-seated silicic magma reservoirs and around shallower magmatic heat sources to understand the fluid properties at those conditions. Furthermore, we simulated the magmatic degassing of shallow silicic intrusions to elucidate how hydrothermal convection is affected by magmatic degassing. We ultimately identified where the prime targets are for exploration drilling to develop supercritical resources. With the government's goal to double renewable electricity generation and achieve this through increased production from renewable, low-carbon energy sources that promote equity and improved socio-economic outcomes for Aotearoa New Zealand, along with wind and solar, geothermal is key to deliver on this vision. With the existing but limited additional conventional geothermal resources, supercritical geothermal and superhot deep enhanced geothermal systems may just be the solution needed. |