Kyoto Fusioneering has received an order from Quaise Energy for the supply of a gyrotron system designed for millimeter-wave geothermal drilling. The agreement was signed on August 17, 2026, and represents the first commercial contract the Japanese company has signed with a customer outside the nuclear fusion sector.
The gyrotron is the core component of Quaise’s drilling technology. The system generates high-power millimeter waves directed at rock, progressively vaporizing it without the need for any mechanical drilling mechanism at the bottom of the borehole. Energy is transmitted entirely from the surface. This eliminates one of the primary bottlenecks of conventional deep drilling: the wear and replacement of cutting tools at great depth. Quaise aims to access geothermal resources at temperatures and depths that traditional mechanical drills cannot reach in an economically viable way. The technology is the result of more than a decade of research at the Massachusetts Institute of Technology.
The starting point for all of this is nuclear fusion. Gyrotrons are devices originally developed to heat plasma in experimental reactors: they emit extremely high-power microwave radiation in the millimeter-wave range and are essential for bringing plasma to the temperatures required for fusion. Kyoto Fusioneering designs and manufactures gyrotrons across a frequency range spanning from 28 GHz to 236 GHz. The company has already delivered systems to the UK Atomic Energy Authority for the MAST Upgrade facility and to the U.S. Department of Energy for the DIII-D reactor. Now it is bringing that same expertise to an entirely different sector.
There is a technical dimension to this agreement that also holds significance for the future of fusion itself. Gyrotrons currently used in experimental reactors operate in pulsed cycles. Future commercial fusion plants, however, will require devices capable of continuous operation. Building a gyrotron for continuous-wave operation in the context of geothermal drilling is, in practice, work that is directly applicable to fusion. Since September 2024, KF has been participating in the NEDO Deep-Tech Startups Support program under Japan’s green transition framework, with the specific goal of developing high-power, continuous-wave gyrotrons. The Quaise order is the first tangible commercial outcome of that effort.
The Japanese market adds a further strategic dimension. Japan holds one of the largest geothermal reserves in the world, yet its deep, high-temperature resources remain largely inaccessible because conventional drilling cannot reach them at an acceptable cost. The Ministry of Economy, Trade and Industry and NEDO are actively supporting supercritical geothermal development under the Green Innovation Fund. If millimeter-wave technology proves its reliability at operational scale, it could unlock access to a significant share of that potential. Quaise aims to convert existing fossil fuel power plants by supplying them with geothermal steam by 2028. The hardware making that goal possible was born from nuclear fusion — and today finds its first commercial application.
