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NEWS RELEASE Gaining ground – new tech protects environment, delivers more power 19 November 2021 – In what’s believed to be a world first, a new approach developed in New Zealand is seeing two geothermal power stations generating more power, while protecting the environment they rely on. “The geothermal reservoir is our ‘Taonga tuku iho’, and as kaitiaki of this resource the sustainability of the reservoir was the most important kaupapa,” says Mana Newton, Group CEO of Tauhara North No.2 Trust (TN2T), who coown assets on the Rotokawa steamfield north of Taupō. “These improvements enable us to provide more benefits to our TN2T owners and descendants and contributes to our 100 year plan of a more sustainable and efficient relationship with Papatuanuku.” “Thanks to the innovative approach our team is taking, we're harnessing this technology to generate more renewable electricity, while protecting our environment at the same time. It's a win - win,” says Stewart Hamilton, General Manager Generation. “We believe it may be the first time in the world that this technology has been successfully applied.” Working with our joint venture partners Tauhara North No.2 Trust, the power stations on the Rotokawa geothermal field have been upgraded to help process more of the hot geothermal fluid, splitting it into flows of differing heat (either steam or brine), that is distributed to each power station. Geothermal fields are dynamic natural environments and change over time, often losing heat (enthalpy). While operators typically update their power stations to account for these changes, the approach on this field is pioneering. “Simply put, we’re now able to better use what nature provides in the geothermal field. It’s drawn up through wells around 2.8km deep, then split into steam or brine. Each power station on the field has been modified to be powered by either steam or brine, and that way we are able to get the most out of this field,” explains Hamilton. A significant investment of $30 million has increased the field’s output of renewable energy, with an additional 5MW on average each year. That’s enough to power around 19,000 electric vehicles* annually, and is now available to displace thermal-fuelled power in New Zealand’s power mix. “New Zealand’s electricity system is one of the best in the world and reliable, renewable geothermal generation will underpin our goal of net zero carbon by 2050,” says Hamilton. “We’re thinking hard about New Zealand’s transition to more renewable energy and the challenges we need to be leaning in to. One of these is the need to balance the new intermittent wind and solar generation coming to market, with reliable baseload such as geothermal.” While this is a good example of the market driving innovative approaches, the commercial rationale was only part of the picture. “The re-balancing process for TN2T was always about the longevity of the Rotokawa Reservoir,” says Newton. “We are able to get more production out of the resource we already extract, which ultimately means more efficiency for the reservoir and a better environmental outcome.” About the Rotokawa geothermal field The steamfield assets of the Rotokawa geothermal field are owned by a joint venture between Mercury and the Tauhara North No.2 Trust. This project results in an increase in megawatt output for both power stations on the Rotokawa field:
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Rotokawa (22 years old, wholly owned by Mercury, output 36.5 MW including gain through project of 2MW) Nga Awa Purua (10 years old, co-owned by Mercury (65%) and Tauhara North No.2 Trust (35%), output of 139MW including gain through project of 3MW).
* based on 95% availability of plant and Nissan Leaf using 2,175 kWh per annum
ENDS Howard Thomas General Counsel and Company Secretary Mercury NZ Limited For investor relations queries, please contact: Tim Thompson Head of Treasury and Investor Relations 0275 173 470
For media queries, please contact: Katy Scoullar Communications Manager 027 210 5337 media@mercury.co.nz
ABOUT MERCURY NZ LIMITED Mercury’s mission is energy freedom. Our purpose is to inspire New Zealanders to enjoy energy in more wonderful ways and our goal is to be New Zealand’s leading energy brand. We focus on our customers, our people, our partners and our country; maintain a long term view of sustainability; and promote wonderful choices. Mercury is energy made wonderful.
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