Mijnwater starts drilling for new heat source on Terhoevenderweg in Heerlen New source expands Parkstad’s district heating and cooling network Mijnwater has started drilling work for a new heat source at Terhoevenderweg in Heerlen, marking another important step in the expansion of its sustainable heating and cooling network in Parkstad. After a period of preparation, work began this week and is expected to continue for three to four weeks. Because the operation must be completed safely and efficiently, the drilling is taking place 24 hours a day, seven days a week. The project is part of Mijnwater’s broader effort to strengthen a low-carbon energy system for the region. The new source will tap warm groundwater in a former mine passage deep underground and feed that energy into the company’s network. For Heerlen and the surrounding area, this means further development of a district energy system that draws value from the region’s mining past while supporting a more sustainable energy ...
Introduction: A Quiet Revolution Beneath the North Island
Regional Development and Resources Minister Shane Jones announced in early June 2026 that Cabinet had approved the release of the remaining $55 million for the project. That money, part of $60 million originally ring‑fenced in the Regional Infrastructure Fund (RIF), will finance pre‑drilling activities and the drilling of a deep exploratory well. The project is a collaborative effort, with the Ministry of Business, Innovation and Employment (MBIE) leading delivery alongside Mercury NZ and Tauhara North No.2 Trust. Todd Energy, a New Zealand firm, has been selected as the preferred drilling contractor.
The announcement marks a turning point. After years of feasibility studies, material tests, and international knowledge‑sharing, the GeoShot project is moving from design to execution. This article explores what supercritical geothermal actually is, why it matters for New Zealand’s energy security, the technical hurdles that remain, and how partnerships with countries like Iceland—and with Māori landowners—are shaping a uniquely Kiwi approach to deep energy.
What is Supercritical Geothermal? The Science of Immense Power
To understand why this project has generated such excitement, we need to step into the physics of supercritical fluids. Conventional geothermal wells in New Zealand typically reach depths of two to three kilometres, where temperatures range from 200°C to 300°C. The water remains liquid under pressure, and its energy is extracted via steam turbines. It is a mature, reliable technology that already supplies about a fifth of New Zealand’s electricity.
Supercritical geothermal targets conditions far more extreme. At depths of four to five kilometres—roughly twice as deep as conventional wells—temperatures can exceed 374°C, while pressures rise above 22 megapascals. Under these conditions, water enters a “supercritical” state: it is no longer simply liquid or gas but a dense, energetic fluid with properties of both. In this form, water can hold three to seven times the energy of conventional geothermal fluids.
The prize is immense. A single supercritical well could potentially generate five to ten times more power than a conventional one. That means fewer wells for the same output, less surface disturbance, and a much smaller land footprint for the same energy yield. In a country that has already exhausted much of its low‑hanging conventional geothermal resource, supercritical represents the next logical—and necessary—frontier.
But the science is not just about depth. It is about understanding how rock behaves under such extreme conditions. At supercritical temperatures, rock becomes ductile rather than brittle, and natural fractures can “heal” themselves—a phenomenon observed in experimental wells in Japan and Italy. That raises a fundamental question: even if you can drill to five kilometres, can you actually extract fluid? The GeoShot project is designed to answer exactly that question.
New Zealand’s Geothermal Heritage: From Wairakei to Rotokawa
New Zealand has long been a geothermal pioneer. In the 1950s, when most of the world was still burning coal without a second thought, the Wairakei power station became one of the first large‑scale geothermal plants on the planet. That project was considered high‑risk at the time; many engineers doubted that geothermal fluids could be reliably harnessed for commercial electricity. But New Zealand forged ahead, and Wairakei went on to operate for decades, proving that geothermal was not just a scientific curiosity but a workhorse renewable.
Today, geothermal energy supplies about 20 percent of New Zealand’s electricity, and the central North Island’s Taupō Volcanic Zone is one of the most intensely studied geothermal systems on Earth. The Rotokawa Geothermal Field, where GeoShot will drill, is already home to several conventional power stations, including the Nga Awa Purua plant, which once held the record for the world’s largest geothermal turbine.
What makes Rotokawa particularly attractive for supercritical exploration is its existing infrastructure, deep geological data, and the presence of a strong partnership with Tauhara North No.2 Trust—a Māori landowner collective. That partnership is not an afterthought. It reflects a growing recognition that New Zealand’s energy future must be co‑developed with iwi, who hold mana whenua over the geothermal resources and have lived alongside those steaming vents and hot springs for centuries.
Learning from Iceland: A Shared Journey to the Superhot
No discussion of supercritical geothermal would be complete without looking to Iceland. That small, volcanically active nation has been drilling deep for more than a decade through its Iceland Deep Drilling Project (IDDP). The IDDP‑1 well, drilled into a rhyolite magma body, encountered temperatures above 900°C—so hot that the well had to be abandoned when it was overwhelmed by superheated steam. But the lessons were invaluable.
The IDDP‑2 well, completed in 2017, was more successful. It reached a depth of 4.5 kilometres and encountered temperatures approaching 600°C at supercritical conditions. Flow tests showed that such a well could potentially produce three to five times the power of a conventional high‑temperature well. While technical challenges remain—particularly around corrosion and well casing integrity—Iceland proved that supercritical geothermal is not science fiction. It is a difficult, expensive, but achievable engineering problem.
New Zealand and Iceland have been sharing data, visiting each other’s drill sites, and collaborating through international geothermal networks. Minister Jones explicitly noted this relationship, stating that working with countries that are “operating at the edge of what is technologically possible” is critical. When GeoShot drills its first deep well, it will benefit directly from everything Iceland learned about high‑temperature cements, drill bit alloys, and pressure control systems. In turn, New Zealand’s results will feed back into the global knowledge pool, advancing the entire field.
The Three Technical Puzzles: Heat, Permeability, and Materials
Despite the progress, supercritical geothermal remains high‑risk. Minister Jones himself described it as a “high‑risk but high‑reward activity,” and the government’s $60 million investment is deliberately designed to de‑risk the technology so that private capital can eventually step in. The technical challenges can be grouped into three overlapping puzzles.
1. Material Integrity and Corrosion
At supercritical temperatures and pressures, ordinary steel loses its strength. Standard oil‑and‑gas well casings, designed for 200°C, would fail within days. The GeoShot team has spent the first $5 million of RIF funding on evaluating specialist alloys, ceramics, and composite materials capable of withstanding both extreme heat and the corrosive chemistry of deep geothermal fluids—which can contain chlorides, sulfates, and dissolved gases. This is not a problem with a ready‑made solution. It requires laboratory testing, computer modelling, and eventually real‑world validation in the well itself.
2. Permeability and Fluid Flow
Drilling to five kilometres is only half the battle. Once the well is in place, water must be able to flow through the rock and into the borehole. In some superhot environments, researchers have found that the rock becomes so hot and ductile that it “heals” natural fractures, effectively sealing itself shut. That would render the well useless. The GeoShot well at Rotokawa will include extensive flow testing and likely hydraulic stimulation—pumping fluids at high pressure to create or reopen fractures. Whether the rock responds favourably is one of the central scientific questions of the project.
3. Economics and Risk Allocation
Conventional geothermal wells cost roughly $5 million to $10 million each. A supercritical exploratory well, with its advanced materials, deeper drilling, and specialised monitoring, can cost several times that. Private investors are reluctant to underwrite such uncertainty without proof of concept. That is where the government’s Regional Infrastructure Fund becomes essential. By absorbing the upfront risk, the Crown enables a project that might otherwise never leave the drawing board. If the well succeeds, the knowledge and technology can be commercialised. If it fails, the lessons learned still advance the science.
Energy Security in a Changing Climate
Why is all of this urgency necessary? Because New Zealand faces a looming energy challenge. The country has committed to 100 percent renewable electricity by 2030, and while it already achieves around 80–85 percent in a good hydro year, the gaps are filled by fossil fuels—mostly natural gas, some coal. As the last thermal power stations are phased out, the grid will need firm, dispatchable renewable capacity to cover dry years when hydro lakes are low and wind is calm.
Solar and wind are becoming cheaper by the year, but they are variable. Batteries can smooth out hourly fluctuations, but they are expensive for seasonal storage. Geothermal, by contrast, provides 24/7 baseload power regardless of weather. Supercritical geothermal would amplify that advantage: a single well could supply firm power for decades with minimal surface disturbance.
Minister Jones has been blunt about the government’s role, stating that “the Crown must assume leadership for energy security.” That language is deliberate. It signals that energy is not just a commercial commodity but a strategic asset. In a world where global gas markets are volatile and supply chains uncertain, domestic, reliable, clean energy is a form of national resilience. The GeoShot project is a bet on that principle.
Regional Benefits and Māori Partnership
The benefits of supercritical geothermal would not be confined to the national grid. They would flow directly to the central North Island region—an area that has experienced economic ups and downs, particularly as the forestry and farming sectors face transition pressures.
The partnership with Tauhara North No.2 Trust is a model of what modern resource development can look like. Rather than extracting value and leaving, the project embeds Māori ownership and governance from the start. The Trust is a joint venture partner alongside Mercury NZ and MBIE, meaning it has a seat at the table for decisions about drilling, testing, and eventual commercialisation. That is not just good ethics; it is good engineering. Local knowledge of the geothermal field, combined with deep whakapapa connections to the land, improves project outcomes and reduces conflict.
Minister Jones emphasised that the project will deliver “long‑term regional benefits.” Those include high‑skill jobs for drillers, geologists, and engineers; contracts for local businesses; and the development of expertise that can be exported to other geothermal regions around the Pacific Rim, from Chile to Indonesia.
What Happens Next: The Drilling Timeline
With the remaining $55 million released, the GeoShot project now enters its active phase. The first order of business is securing long‑lead equipment. Specialised casings, high‑temperature downhole tools, and corrosion‑resistant wellheads are not off‑the‑shelf items. Some will need to be custom manufactured, with lead times of twelve months or more.
Once the equipment is secured, the drilling contractor—Todd Energy—will mobilise to the Rotokawa site. The first deep exploratory well is expected to take several months to drill, not only because of the depth but because progress will be slow and careful. Every few hundred metres, the team will stop to run logs, measure temperatures and pressures, and test rock properties. This is science as much as construction.
If the well encounters supercritical conditions and demonstrates viable flow rates, the project could then move to a second and third well, eventually leading to a small pilot power plant. That would be years away, but each milestone builds confidence. The ultimate goal is not a single well but a repeatable playbook for supercritical development across the Taupō Volcanic Zone and beyond.
The Bigger Picture: Unlimited, Clean, Affordable Energy
Minister Jones made a striking claim when he said that this project is “the groundwork for future unlimited, clean, and affordable energy.” “Unlimited” is a strong word, but in the context of geothermal, it has a kernel of truth. The heat beneath New Zealand’s feet is essentially inexhaustible on human timescales. The radioactive decay of elements in the Earth’s crust and the residual heat from planetary formation provide a continuous flow of energy that dwarfs current human consumption.
The limitation has never been the resource itself but our ability to access it economically and safely. Supercritical geothermal represents a step change in that access. If the GeoShot project succeeds, it could unlock thousands of megawatts of firm, clean power—enough to displace fossil fuels entirely from the electricity grid and even start powering industrial heat processes, such as milk powder drying or timber processing, which currently rely on coal and gas.
That vision is still several years away. The technical challenges are real, and there is no guarantee that the first well will hit commercial flow rates. But that is the nature of frontier exploration. New Zealand faced similar doubts in the 1950s with Wairakei, and again in the 1990s with the first deep wells at Ohaaki. Each time, the country proved that it could lead the world by combining government backing, private sector skill, and Māori partnership. GeoShot is the latest—and potentially the most transformative—chapter in that story.
Conclusion: Forging Ahead
As the drill rig prepares to sink a borehole five kilometres into the Earth, the significance of the moment should not be underestimated. New Zealand is not merely following a technology developed elsewhere. It is co‑creating that technology in real time, sharing knowledge with Iceland and other geothermal nations, and building a model for low‑carbon energy development that is both technically ambitious and socially inclusive.
The $60 million from the Regional Infrastructure Fund is a modest sum compared to the cost of a new gas plant or a large solar farm. But its leverage is enormous. Every dollar spent on understanding supercritical conditions, testing materials, and proving flow rates is a dollar that reduces the risk for the next ten or fifty wells. And in a climate‑constrained world where every fraction of a degree of warming matters, the ability to generate vast amounts of clean energy from beneath our feet is not just an engineering triumph—it is a gift to future generations.
The steam rising from the Rotokawa field has been there for millennia. Soon, for the first time, we may learn just how much power it truly holds.
Source: Beehive NZ, Grow Regions Govt NZ
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