Source: MIL-OSI Submissions
Source: Mercury Energy
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.”
The trial at Mercury’s Ngā Tamariki Power Station involves re-sequestering up to a quarter of the station’s emissions, coming from one of four power units, and reinjecting the non-condensable gases into the northern injection wells.
The purpose of the trial is to determine the viability of reinjecting carbon dioxide back into the geothermal reservoir without affecting the operation of the power station or the environment. If successful, Mercury will evaluate if similar technology can be extended to Ngā Tamariki’s three other units, and to Mercury’s other geothermal power stations. The cumulative emissions reduced from all four units would be approximately 30,000 tonnes of carbon dioxide annually.
Vince Hawksworth, Mercury Chief Executive, said technological advances with carbon sequestration and reinjection technologies could be the missing piece in making Aotearoa New Zealand’s renewable electricity network close to zero carbon.
“Geothermal is a very important contributor to our energy portfolio. It is renewable and delivers through drought, low wind and cloud cover.
“We’re immensely proud of what we’ve achieved to date in bringing on new low carbon, renewable generation to power the transition to a low carbon economy. We know there’s much more work to be done to meet the demand for renewable electricity as the nation transitions towards a lower carbon emissions economy.
“Investing in technologies that further reduce comparatively low, naturally occurring emissions from geothermal energy is an important priority for us. The trials at Ngā Tamariki will inform how Mercury, and indeed the wider sector, could deploy carbon reinjection systems at other geothermal stations.
“The results to date are very encouraging and shows we can harness a natural energy source even more sustainably. After 6 months we learned we can deploy carbon reinjection processes with no disruption to power generation or detrimental effect to the underground reservoir environment. Importantly the performance of the geothermal wells is stable, and the pipeline and surface plant facilities are in good shape.
“The trial will continue until the end of the year. At that point we’ll review the data and explore how we could scale up to introduce the technology at further units later this year.
“We’ll be sharing the insights with other interested parties, including Ngāwhā Generation, Contact Energy and Eastland Generation and the wider sector and following with interest their own research and trials in this area. It’s a very exciting time for Mercury and indeed New Zealand’s decarbonisation journey.”
ABOUT GEOTHERMAL CARBON REINJECTION
• Geothermal stations power about 20% of New Zealand’s electricity. Unlike other forms of renewable energy, they don’t depend on rain or sun, making geothermal power a consistently reliable energy source.
The energy generation process brings up naturally occurring carbon dioxide, methane and hydrogen sulphide, collective known as ‘non-condensable gases’ to the surface with the high- pressure fluid that is used to move the turbines which create electricity.
Reinjection returns carbon to the underground reservoir with the water that is already drawn up and returned. The process diverts carbon dioxide from being released to the atmosphere as it is separated from steam in creating power, instead joining cooler water in the reinjection pipe.
ABOUT NZ GEOTHERMAL ASSOCIATION
NZ Geothermal Association (NZGA) is a non-political, non-governmental and not-for-profit organisation. Our focus is on providing leadership, connection and facilitation to sustain and grow sustainable geothermal opportunities in New Zealand. Our members are part of a diverse and skilled network of people working and living with our unique geothermal resources. We also connect with global geothermal communities and are well positioned to positively influence geothermal initiatives on the world stage.
Visit us at www.nzgeothermal.org.nz
ABOUT MERCURY NZ LIMITED
We generate electricity from 100% renewable sources – hydro, geothermal and wind. We also sell utility services to our customers through our retail brands – Mercury, Trustpower and GLOBUG. We’re listed on the New Zealand Stock Exchange and the Australian Stock Exchange with foreign exempt listed status. We’re listed on both exchanges with the ticker symbol ‘MCY’. The New Zealand Government (the Crown) holds a legislated 51% shareholding in the Company.
Visit us at: www.mercury.co.nz
