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Quaise, Inc is developing a millimeter-wave drilling system for converting existing power stations to use superdeep geothermal energy.^[1] The system would repurpose existing gyrotron technology to drill 20 kilometers beneath the surface, where temperatures exceed 400 °C. No fracking would be required, avoiding the potential for earthquakes that have occurred in other geothermal systems.^[2][3] Drilling using this technique is hoped to be fast, with boreholes aimed to be completed in 100 days^[4] using existing 1MW gyrotrons. To reduce costs and delays, the company planned to establish its wells on the sites of existing power plants.^[5]

By 2026, the company hopes to have achieved 100MW of geothermal power output.^[6] By 2028, Quaise aims to have converted an existing fossil-fueled power plant to run on geothermal steam.^{[citation needed]}

Quaise was founded in 2018. In October 2021, Quaise began initial testing of gyrotron boring at Oak Ridge National Laboratory^[7] and planned to have a full-scale drilling rig completed by 2024.^[8] It closed a $21 million in Series A1 financing in 2024. In 2025, it announced the completion of a test well that reached a depth of 100 metres (330 ft).^[5]

Existing geothermal power stations can only be deployed in rare locations where adequate heat is located within 3 km of the surface.^[9] These resources are of a comparatively low temperature, and require seismically risky stimulation techniques. Further, drilling at these depths is expensive and slow.^{[citation needed]}

Instead, Quaise plans to drill quickly using a gyrotron and waveguide, vaporizing the rock by heating it.^[10] Temperatures at 20 km depth are above the supercritical point of water, which allows ten times more energy to be transferred given the same volumetric flow.^[11] The supercritical water is then used in a supercritical steam generator which may previously have been powered with fossil fuels.^{[citation needed]}

The approach proposes advantages compared with other power sources:

• Constant 24-hour generation – Maximum output always available. Does not require storage. Wind and Solar are intermittent generators.^{[citation needed]}
• Small land footprint – Consumes less than 1% of the land area of wind or solar for the same maximum output.^[12]

• Plasma deep drilling technology
• Geothermal energy in the United States
• GA Drilling
• Eavor Technologies
• Fervo Energy
• AltaRock Energy