NZ Geothermal Institute receives funding for greenhouse gas capture project

The Geothermal Institute at the University of Auckland in New Zealand has received NZD 6.4 million (approx. USD 3.87 million) funding from the Ministry of Business, Innovation, and Employment for a project developing a process to capture greenhouse gas emissions (GHG) from the country’s geothermal facilities and reinject these back into the ground.

“Our research responds to the Government’s strategy to achieve a net-zero carbon economy by disposing of all the greenhouse gas emissions from New Zealand’s geothermal power plants.” said Associate Professor and Co-Director of the Geothermal Institute Sadiq Zarrouk.

“New Zealand is a world leader in geothermal energy technology and many countries implement our research,” says Research Fellow Dr. Eylem Kaya, a member of the team. “This could transform the industry, bringing it from low to no emissions.”

Although geothermal power plants produce much less GHG emissions than fossil fuel plants, there is still some emission of carbon dioxide (CO2), hydrogen sulfide (H2S) and other gases. These gases naturally exist in the subsurface and are carried to the surface along with the geothermal fluids. In New Zealand, geothermal power plants emit enough GHG that the carbon price can become significant. As the country moves toward net-zero goals by 2050, the carbon price is expected to increase to further incentivize emissions reduction.

Trapping gases as rock

To keep reinjected gases inside the formation, the dissolved gases need to turn into rock. This is a process that already happens naturally, albeit at the scale of several millennia. Geothermal scientists are seeking ways to make this much faster.

Carbon capture through reinjection is already being done in Iceland. The geological setting here is different, though, as the local basaltic rock readily traps CO2 as calcite. However, the geology of New Zealand is not as readily suitable as Iceland’s. The plan of the project team is to inject ions along with the reinjected gases that will cause them to petrify into common and non-toxic minerals – CO2 into calcite, and H2S into pyrite.

“Once the gas is mineralised, it’s stable, harmless and risk-free,” says Kaya. “Even if there is a seismic event, it remains as rock.”

The opportunities for GHG capture

If proven successful, the process can also be applied to other industries, including fossil fuel-based power plants. “We don’t claim we’ll be able to eliminate all global emissions but we’re going to help reduce them, starting with geothermal energy and going beyond.” added Zarrouk. After the technology is proven, the team plans to commercialize it either through licensing, consultancy, or by starting a company.

Geothermal power currently supplies 18.1 percent of New Zealand’s electricity. If every existing New Zealand geothermal plant adopted the technology, emissions would be reduced by 560 kilotonnes a year. If geothermal energy were made carbon neutral and scaled up, it would be a big step towards net zero and will help further realize the country’s geothermal potential.

The process can turn from carbon neutral to carbon negative by applying it internationally to fossil fuel plants. There will be a cost to bring in this technology, but this can be justified by savings in carbon pricing. “If this technology is taken up around the world, it will make a real dent in emissions,” says Zarrouk. “Others are also doing their bit, working on the electrification of cars, switching to hydrogen, etc. – this work is part of the big jigsaw to help solve the problem of climate change.”

Local and international partnerships

For this project, the team at the Geothermal Institute is working with a range of partners locally and internationally. Of particular importance are the Maori, who Zarrouk describes as the owners of the resources and land. “If this project is commercialised, mana whenua will be part of the business side as well.” says Zarrouk.

The team aims to develop community capacity by recruiting M?ori PhD students. The M?tauranga M?ori will also be integrated into decision making, reciprocity, and prioritization of geothermal resources for the benefit of the community.

“M?ori use geothermal resources in a very sustainable way,” says Kaya. “We have a lot to learn from them.”

Source: University of Auckland Uniservices