15 August 2022
Full steam ahead as geothermal generators trial carbon reinjection technology • • •
Mercury, Contact Energy, Ngāwhā Generation and Eastland Generation commit to trials of geothermal carbon reinjection and sequestration technology. Carbon Reinjection returns naturally occurring carbon to the underground reservoirs from where it has been drawn, rather than being emitted during geothermal power generation. Mercury’s trial at Ngā Tamariki Power Station is the first use of the technology in the Southern Hemisphere.
Geothermal carbon reinjection may soon become a feature of Aotearoa New Zealand’s energy network as major generators commence trials of the technology to reduce emissions. If successful, carbon reinjection has the potential to reduce emissions from geothermal by 568,000 tonnes per year, equivalent to taking over 236,000 cars off the road (or 7% of the entire private vehicle fleet). Mercury, Contact Energy, Ngāwhā Generation and Eastland Generation, collectively representing 96% of total geothermal energy supply, have all committed to research and trials of carbon capture and reinjection. The first of the trials, at Mercury’s Ngā Tamariki Power Station near Taupō, commenced in October last year. Carbon dioxide released from deep geothermal reservoirs through the energy conversion process at one of the station’s four units is captured and reinjected back into the underground reservoirs. The process not only reduces emissions from the station but allows storage of carbon dioxide deep underground. Contact Energy’s trial at Te Huka Power station is set to commence in the coming months. Chief Executive of the New Zealand Geothermal Association Kennie Tsui said carbon reinjection had never been deployed in the Southern Hemisphere before and that the trials led by all major geothermal generators push the sector’s boundaries of science and technology for reducing emissions. “While emissions from geothermal make up a relatively small component of Aotearoa New Zealand’s emissions profile, this is a very important development for the energy sector’s decarbonisation. “It is an immensely challenging exercise to research, design and build these systems. A lot of work is involved to just get to a trial stage which is testament to the commitment of Mercury, Contact Energy, Ngāwhā Generation and Eastland Generation to make geothermal energy as close to zero emissions as possible. “As a renewable, non-weather dependant source of energy, geothermal is a vital contributor to our energy security. It’s therefore vital that we have the means to harness it with lowest possible impact on the environment and these trials offer enormous potential for the sector to reduce its emissions profile substantially.”