Idemitsu Invests in Quaise Energy: How Millimeter-Wave Drilling Could Unlock the World’s Deepest, Cleanest Power
Idemitsu Invests in Quaise Energy: Unlocking Superhot Geothermal Power with Revolutionary Millimeter-Wave Drilling
By: Robert Buluma
In a significant move for the future of clean energy, Japanese energy giant Idemitsu Kosan Co., Ltd. has announced a strategic investment in Quaise Energy, a U.S.-based company pioneering next-generation geothermal technology. The investment, made through Idemitsu’s wholly owned subsidiary Idemitsu Americas Holdings Corporation (IAH) on June 25, 2026, involves the issuance of convertible preferred shares. This partnership aims to accelerate the development of ultra-deep, superhot geothermal systems capable of delivering stable, high-output renewable power—a crucial step as the world accelerates its transition away from fossil fuels.
Why Geothermal Matters More Than Ever
Geothermal energy stands apart from other renewables because it provides baseload power—consistent, reliable electricity generation unaffected by weather conditions, unlike solar or wind power. While solar panels falter on cloudy days and wind turbines pause when the air is still, geothermal plants generate electricity around the clock, 365 days a year.
Japan, with its abundant geothermal resources driven by volcanic activity, is particularly well-positioned to benefit from this technology. The country sits on the Pacific Ring of Fire, giving it access to some of the world's most significant geothermal potential. As global energy demand surges and the push for decarbonization intensifies, technologies that can tap deeper, hotter resources are becoming increasingly critical for both energy security and environmental sustainability.
Idemitsu’s investment comes at a time when next-generation geothermal is gaining substantial momentum. The United States is actively seeking new sources of electricity that can produce power without carbon emissions. Major funding rounds have been closing for geothermal startups, and the sector is attracting attention from investors worldwide. At "superhot" conditions around 350°C and above, wells can produce up to ten times more power than conventional geothermal systems.
Quaise’s Game-Changing Millimeter-Wave Technology
The Limits of Conventional Drilling
Traditional geothermal projects typically drill to depths of 1–2 kilometers, accessing temperatures around 100–200°C. These conventional systems rely on naturally occurring hot water or steam reservoirs, limiting their deployment to specific geographic locations with favorable geology. The deeper one goes, the hotter it gets—but conventional drill bits struggle with the extreme heat, pressure, and hardness of rock found at significant depths.
For decades, the geothermal industry has been constrained by the limitations of mechanical drilling. Drill bits wear out quickly in hard rocks like granite and basalt, and the cost and time required to reach meaningful depths have made deep geothermal economically challenging in most locations.
The Millimeter-Wave Breakthrough
Quaise Energy is developing a fundamentally different approach. The company’s millimeter-wave drilling system, developed after more than a decade of research at the Massachusetts Institute of Technology (MIT), harnesses a powerful device called a gyrotron to ablate—melt and vaporize—rock without any downhole hardware.
The gyrotron, a technology invented in the 1960s, generates high-frequency electromagnetic waves in the millimeter range. These waves travel down a waveguide and strike the target rock, which heats up and then cracks, melts, or vaporizes. Unlike conventional drill bits that grind through rock mechanically, millimeter-wave technology can penetrate the hardest rocks on Earth in record time.
The process creates a vitrified borehole lining—essentially a glass-like layer that stabilizes the wellbore—and uses purge gas via the waveguide to clear debris. No drill bit is required, and no drilling mud is needed. This represents what many are calling "the first drilling innovation in 100 years".
Reaching Unprecedented Depths
Quaise’s goal is to reach depths of up to 20 kilometers (approximately 12.4 miles), where rock temperatures reach 300–500°C (572–932°F). At these depths, geothermal heat is available almost everywhere on Earth—not just in volcanic regions or geologically active zones.
The company has already achieved significant milestones. In July 2025, Quaise successfully drilled to a depth of 100 meters using its millimeter-wave technology at a field site in Central Texas. Prior to 2025, millimeter-wave drilling had only been demonstrated in the laboratory, with MIT’s early system drilling a hole just a few centimeters deep. While 100 meters is only a fraction of the commercial depth needed, the granite drilled during the field test is the same type of hard rock that blankets the basement layer of the Earth's crust.
The company has since hosted public demonstrations of the technology, allowing observers to see the drilling process in action, including real-time drilling data and samples of ablated granite turned into grey ash. During these demonstrations, the drilling rate reached up to five meters per hour—described by the team as "extremely fast" compared to commercial operations that average just a tenth of a meter per hour through granite.
Quaise plans to build on this achievement with an upcoming gyrotron using ten times more power, with a target to complete a pilot power plant in the Western U.S. as early as 2028. The company aims to break its own drilling record by drilling ten times as deep—to one kilometer—within months of the 100-meter milestone.
Why Superhot Geothermal Changes Everything
Accessing superhot rock at extreme depths offers transformative advantages:
Significantly higher energy output – Superhot resources can increase the energy output of individual wells by a factor of 10 to 100 compared with traditional geothermal wells, dramatically improving power density while reducing the number of wells required for large-scale electricity generation.
Reduced land footprint – A superhot geothermal plant requires minimal land compared to traditional renewable resources. Quaise’s Project Obsidian in Oregon would occupy about 20 acres at the surface—a footprint far smaller than comparable wind or solar installations.
Less dependence on natural reservoirs – Enhanced Geothermal Systems (EGS) create artificial fractures in hot rock and circulate water to extract heat, eliminating the need for naturally occurring hot water or steam reservoirs.
Global deployment potential – By making geothermal viable almost anywhere—including near major population and industrial centers—Quaise’s approach could transform the global energy landscape.
Repurposing existing infrastructure – Quaise focuses on drilling at existing thermal generation plants and industrial centers to utilize existing infrastructure and workforce, enabling a faster energy transition.
Idemitsu’s Longstanding Geothermal Leadership
Idemitsu Kosan is no stranger to geothermal energy. The company began its geothermal business in 1996, conducting resource surveys and supplying steam to Kyushu Mirai Energy’s Takigami Power Station in Kokonoe, Oita Prefecture. In 2017, the company began independent operation of the 5 MW Takigami Binary Power Plant, a binary-cycle geothermal plant provided by Fuji Electric.
Today, Idemitsu is actively expanding its geothermal portfolio. The company is currently building a new geothermal power plant in the Oyasu region of Akita Prefecture. This project, known as the Katatsumuri Yama geothermal power plant, is being developed jointly with INPEX Corporation and Mitsui Oil Exploration Co., with a planned capacity of 15 MW. Oyasu Geothermal Co., Ltd., the joint venture overseeing construction, is owned 42.5% by INPEX and 42.5% by Idemitsu Kosan.
Geothermal is listed as a priority low-carbon business in Idemitsu’s Medium-term Management Plan (FY2026–FY2030). The company has formulated a new medium-term management plan covering the fiscal years 2026-2030, recalibrating its strategy amid rising uncertainty around global decarbonization timelines and energy security risks. With the goal of achieving carbon neutrality by 2050 and contributing to medium- to long-term energy security, Idemitsu is taking on low-carbon and decarbonized projects while carefully considering the timeframe.
The partnership with Quaise allows Idemitsu to gain expertise in next-generation technologies and potentially participate in future projects, extending its decades of experience in resource development and geothermal operations.
Executive Perspectives
Keitaro Sugihara, President and CEO of Idemitsu Americas Holdings Corporation, commented on the strategic significance of the investment:
"By combining Idemitsu’s resource development expertise with Quaise’s millimeter-wave technology, we will strengthen energy security worldwide. Our investment in Quaise will accelerate the development of next-generation geothermal technologies, an important step towards delivering stable energy supply."
Carlos Araque, CEO and President of Quaise Energy, welcomed Idemitsu as a strategic partner:
"We welcome Idemitsu as a strategic investor for developing more powerful, economic geothermal worldwide with our millimeter-wave technology. Idemitsu brings decades of experience in resource development and geothermal operations for a shared goal of delivering reliable, affordable, and sustainable energy on a global scale."
Araque has previously emphasized the significance of the company's technological progress: "Our progress this year has exceeded all expectations. We're drilling faster and deeper at this point than anyone believed possible, proving that millimeter wave technology is the only tool capable of reaching the superhot rock needed for next-generation geothermal power. We are opening up a path to a new energy frontier".
Project Obsidian: The Path to Commercialization
Quaise Energy is already moving beyond research and development toward commercial deployment. The company’s Project Obsidian in Oregon aims to become the world's first power plant built around superhot geothermal energy.
The first phase of the project is already under construction and could begin operations by 2030. An internal analysis presented at the 2026 Stanford Geothermal Workshop supports output of at least 50 MW from a small number of wells. Quaise has already signed a power-purchase agreement for the initial 50 MW with an undisclosed customer and is working to secure agreements for an additional 200 MW in future capacity.
The project site is a Tier I location where superhot temperatures can be reached at around five kilometers (approximately three miles) below ground. Early wells at the site will be drilled using conventional methods before millimeter-wave systems are introduced on hotter wells. The first phase will include two geothermal well systems targeting different temperature zones: one reaching rock averaging 315°C and the other targeting rock averaging 365°C.
A separate confirmation well is expected to begin operating in 2026, providing data on rock strength, underground conditions, fluid behavior, and how fractures should be created to allow water flow. According to the project's engineering team: "This analysis validates our long-held hypothesis that higher subsurface temperatures entail substantial improvements in power production. If these first wells work the way we think they will, they will be on par with exceptionally productive oil and gas wells in terms of equivalent power output".
Quaise is seeking $100 million in Series B financing to support the commercial plant, with plans to secure another $100 million in grants and debt. The company has already raised a total of $120 million from investors to accelerate testing and development, including from Mitsubishi Corporation and the oil-and-gas drilling contractor Nabors Industries. Other investors include Prelude Ventures, Safar Partners, Standard Investments, and Milano Investment Partners.
Later expansions at the same site could increase output to 250 MW, with longer-term plans targeting 1 GW. "Our goal is to build out to a gigawatt in the area," said Carlos Araque.
The Global Context: A Surge in Superhot Geothermal Interest
Idemitsu's investment in Quaise reflects a broader global trend. Interest in superhot and supercritical geothermal is accelerating worldwide:
· In New Zealand, the GeoShot NZ project aims to drill the country's first superhot geothermal well, targeting depths of around 4–5 km—about twice as deep as conventional wells and with approximately three times the energy.
· In the United States, Mazama Energy has created the world's hottest Enhanced Geothermal System with a bottomhole temperature of 331°C at its pilot site in Newberry, Oregon, with plans to reach 400°C and 15 MW of output.
· The SHiFT research consortium has received a €10 million grant from the EU to develop and test technologies to harness geothermal resources beyond 400°C.
· The IEA has featured superhot rock geothermal in a flagship report, marking a major milestone for this clean, firm power source.
Superhot geothermal systems have been identified as a key pathway to scaling clean, firm, cost-competitive electricity production worldwide.
Technical Challenges and Path Forward
While the potential of superhot geothermal is immense, significant technical challenges remain. Quaise still needs to determine what impurities may rise with produced water, whether the resource returns steam or liquid water, and what final plant design will be most suitable.
The company continues to conduct additional tests to optimize specific parts of the process. As a test group manager at Quaise explained: "We'll experiment with various parameters to, for example, control how straight the hole is and see if we can go even faster".
The company is also strengthening its supply chain through joint development and licensing agreements with manufacturers to ensure future equipment will meet design and capacity requirements as operations scale beyond first pilots.
What This Means for the Future
The Idemitsu-Quaise partnership highlights growing international interest in advanced geothermal solutions. For Japan, it could mean expanded domestic capacity and reduced reliance on imported fuels. Japan's abundant geothermal resources, combined with Quaise's technology and Idemitsu's operational expertise, could significantly accelerate the country's energy transition.
Globally, Quaise’s vision of accessing superhot rock near demand centers could make clean, firm power more accessible and cost-effective. Deep geothermal power plants, harnessed globally, have the potential to collectively generate terawatts of clean power, rivaling the output of fossil fuels but with zero carbon.
As the world transitions away from fossil fuels, investments like this signal growing confidence in geothermal’s potential to play a much larger role in the energy mix. The combination of Idemitsu's resource development expertise and Quaise's breakthrough drilling technology represents a powerful convergence of legacy energy experience and cutting-edge innovation.
Conclusion
Idemitsu Kosan's investment in Quaise Energy marks a significant milestone in the journey toward commercializing superhot geothermal power. By combining Idemitsu's decades of geothermal operational experience with Quaise's revolutionary millimeter-wave drilling technology, this partnership has the potential to unlock vast, previously inaccessible geothermal resources worldwide.
The technology—capable of reaching depths of 20 kilometers and temperatures of 500°C—could increase the energy output of individual wells by a factor of ten or more while dramatically reducing land requirements and eliminating dependence on naturally occurring geothermal reservoirs. With Project Obsidian targeting 50 MW by 2030 and ambitions scaling to 1 GW, Quaise is demonstrating that superhot geothermal is moving from laboratory concept toward commercial reality.
Source : Quaise Energy
See also Mazama vs Quaise: Superhot Geothermal Technology Comparison Guide
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