Dr Isabelle Chambefort is the Science Energy Futures Leader at GNS Science, and the Programme Leader of the Geothermal: the Next Generation research programme. She spoke to MPs about how Aotearoa New Zealand can harness deeper and hotter geothermal resources to reach our goal to double renewable electricity by 2050. Today, geothermal energy makes up 18-19% of our electricity generation, but Dr Chambefort says that this could double.
Using geothermal energy means harnessing the power of the heat within the earth. Wells are drilled in the crust where heat is easily accessible and steam drives turbine generators on the surface. The generators provide electricity for our national grid and the leftover gases and water are pumped back underground.
In Aotearoa New Zealand, we have a massive, and almost infinite, heat engine beneath our feet. The subduction between the Australian and Pacific plates continuously drives huge amounts of heat energy to the surface, producing volcanoes, hot pools, and abundant geothermal resources.
Dr Chambefort argues that growing geothermal energy should be a key part of our energy security. Geothermal can provide a much needed boost to New Zealand’s baseload electricity generation to compliment the growth of intermittent supply from wind and solar generation. The advantage of geothermal is it is available 24/7/365, eases battery demand, and is not affected by weather. Geothermal also has a small surface footprint, low emissions, and with CO2 reinjection technology, can achieve completely carbon-neutral generation.
To identify the best locations to harness more geothermal energy, Dr Chambefort’s Geothermal: The Next Generation team studies the Earth’s crust and models the locations of the hot and superhot spots. Using only geothermal sites in the Taupō Volcanic Zone (and not including protected areas), they have calculated that by drilling deeper – around four to six km, rather than three km, – we can reach “superhot” spots of greater than 370˚C and high pressure.
Superhot geothermal is more efficient at energy generation, and in these sites, there is enough energy to provide 29,351 gigawatt hours of electricity per year (or about two thirds of what the entire country uses in a year).
But is this realistic? Castalia Limited independently evaluated the economic viability of superhot geothermal for New Zealand. The analysis verified that even at double the average cost of geothermal infrastructure development, it would be economically viable for superhot geothermal to produce a massive 2000MW as early as 2037, and conservatively by 2049.
This article was first published on the RSNZ webpage.