Digging Deeper: Quaise Energy’s Wave Drill Tech Aims for Earth’s Core

Quaise Energy, a startup born out of MIT's Plasma Science and Fusion Center, is making waves in the geothermal energy sector with its innovative drilling technology. On May 21, 2025, the company demonstrated its millimetre wave drilling technology at the Nabors facility in Houston, Texas, marking a significant step toward unlocking vast, untapped geothermal resources. The goal? To dig the world's deepest hole and tap into the Earth's “superhot” rock, making geothermal power accessible virtually anywhere.

The Promise of Deep Geothermal Energy

Geothermal energy, harnessing heat from within the Earth, offers a clean, constant, and reliable power source. Unlike solar and wind, geothermal energy operates 24/7, unaffected by weather conditions. However, traditional geothermal plants are limited to specific locations with naturally occurring hot reservoirs near the surface. Quaise Energy seeks to overcome this limitation by drilling deeper than ever before, accessing the Earth's abundant “superhot” rock, which exists everywhere.

According to Paul Woskov, a senior fusion research engineer at MIT, tapping into just 0.1% of the Earth's heat could supply the world's energy needs for over 20 million years. The challenge lies in reaching these extreme depths efficiently and economically.

How Quaise Energy's Technology Works

Quaise Energy's approach combines conventional drilling with millimetre wave technology, adapted from nuclear fusion research. Here's a breakdown of the process flow:

1. Conventional Drilling: Traditional rotary rigs bore through the first 2-3 kilometres (approximately 2 miles) of sediment and soft rock until they hit basement rock.
2. Millimetre Wave Drilling: Once basement rock is reached, Quaise swaps the mechanical drill bit for its millimetre-wave drilling system. This system utilises a gyrotron—a high-power vacuum tube device adapted from fusion energy research—that generates high-frequency millimetre waves (typically operating at 95 GHz) to vapourise the rock.
3. Vapourisation Process: The millimetre-wave beam, acting as an ultra-high-frequency, high-density energy source, heats the rock to temperatures exceeding 2,000°C. This melts and vapourises the silicate crystalline structures directly ahead of the drill path, creating a precise, round hole without mechanical contact.
4. Vitrification of Borehole Walls: The intense heat melts the outer edge of the borehole, forming a glassy, vitrified ceramic liner. This natural glass lining seals the borehole wall, preventing cave-ins and eliminating the need for expensive, heavy steel casing in the deepest segments.
5. Waste Removal: A high-pressure purging gas, typically dry nitrogen, is pumped down the central conduit to cool the waveguide and flush out the vapourised rock particles as a fine vitrified ash or dust to the surface.

Quaise's technology aims to reach depths exceeding 12 miles (20 kilometres), where ambient rock temperatures can exceed 1,000°F (500°C). At these extreme depths, any water introduced becomes supercritical—a thermodynamic state where water behaves with the density of a liquid but the viscosity and expansion characteristics of a gas. Supercritical water possesses up to ten times more energy transfer capacity than conventional subcritical water, allowing steam turbines at the surface to generate electricity far more efficiently.

Thermodynamics and Physics of Millimetre Wave Drilling

The core physics of Quaise's technology relies on directing high electromagnetic power density ($P_d$) down an engineered waveguide to exceed the specific ablation energy of hard rock. The specific energy of ablation ($E_s$) is the total thermal energy required to heat, melt, and vapourise a unit mass of silicate rock, represented by the following thermodynamic equation:

$$E_s=C_p(T_v-T_0)+\Delta H_m+\Delta H_v$$

Where:

• $E_s$ is the specific energy of ablation (J/kg)
• $C_p$ is the specific heat capacity of the rock (J/kg·K)
• $T_v$ is the vapourisation temperature of the silicate minerals (K)
• $T_0$ is the ambient temperature of the rock (K)
• $\Delta H_m$ is the latent heat of fusion (J/kg)
• $\Delta H_v$ is the latent heat of vapourisation (J/kg)

By delivering high-power electromagnetic waves at 95 GHz, the energy is selectively absorbed within a very thin skin depth of the rock face, minimising peripheral heat loss and thermal shock to surrounding formations, while maintaining an optimised energy transfer efficiency.

A Demonstration of Groundbreaking Tech

During the May 2025 demonstration, Quaise used a 100-kW gyrotron powered by 50,000 volts DC, connected to a Nabors F rig with a custom-engineered top drive. The drill, operating at roughly 48 kW of output power, successfully melted a deep hole into a dense granite and basalt rock mix at a rate of approximately 0.8 inches (2 cm) per minute. This demonstration showcased the technology's ability to precisely focus and project the millimetre-wave beam as the drilling assembly moves deeper, overcoming a significant engineering hurdle in beam transmission.

Overcoming Challenges and Future Plans

Quaise Energy's journey has involved overcoming several complex engineering challenges. Key among these was maintaining the millimetre wave's focus and power density as the drill descends kilometres into the Earth. The company's custom-engineered “articulated waveguide” has proven capable of achieving a consistent borehole shape and low propagation loss over extended transmission lengths.

Looking ahead, Quaise has ambitious plans:

• Near-Term Testing: Next month, Quaise will utilise a 1 MW gyrotron for further deep-drilling tests. They also operate a dedicated test site in Marble Falls, Texas, equipped with specialised rigs capable of digging nearly 500 feet (150 metres).
• First Commercial Plant: Quaise aims to have a 50-MW geothermal power plant operational near Bend, Oregon, within three years. This will start with a 20-MW system using conventional rotary drilling, followed by an additional 30 MW using their millimetre wave technology to access superhot rock.
• Repowering Fossil Fuel Plants: Quaise envisions retrofitting existing coal and natural-gas-fired power plants with their deep geothermal system. By swapping out the fossil-fuel boilers for clean, superhot geothermal steam loops, they can leverage existing turbine generators, electrical grids, and power infrastructure. They aim to repower their first fossil-fired power plant with clean geothermal steam by 2028.

The Kola Superdeep Borehole Inspiration

Quaise's ambition to drill the world's deepest hole draws inspiration from the Kola Superdeep Borehole, a scientific project undertaken by the Soviet Union in the 1970s. The Soviets aimed to drill 7.62 miles (12.26 km) into the Earth's crust, but they were eventually forced to abandon the project in 1992 due to unexpectedly high temperatures (180°C/356°F) which caused mechanical drill bits to deform, degrade, and melt in a matter of hours. The trip time required to withdraw kilometres of pipe just to replace a worn-out mechanical bit made further progress economically impossible.

Quaise plans to surpass this depth, reaching over 12 miles (20 km) and temperatures of nearly 1,000°F (500°C). Unlike the Kola project, which took nearly 20 years, Quaise estimates its non-contact, gyrotron-enhanced process will take just 100 days of drilling, assuming a continuous 1-MW gyrotron system.

Financial Backing and Partnerships

To date, Quaise Energy has raised $105 million in funding and seeks to raise an additional $200 million to develop its first commercial power plant. The company has secured multiple geothermal leases and is managing the power plant development process in-house.

Quaise is also collaborating with the existing drilling industry, adopting a “BYOG” (Bring Your Own Gyrotron) business model. This involves integrating their millimetre wave drilling technology with conventional drilling rigs, allowing them to leverage the existing global drilling infrastructure, rig crews, and supply chains.

Benefits of Quaise's Approach

Quaise Energy's technology offers several potential benefits:

• Access to Universal Geothermal Energy: By drilling deep enough to reach “superhot” rock (500°C), geothermal energy can become accessible virtually anywhere on Earth, liberating geothermal power from the tectonic boundaries where it is traditionally confined.
• Higher Power Density: Supercritical water at extreme depths enables higher power density, making geothermal energy competitive with fossil fuels on a megawatt-per-well basis.
• Repowering Existing Infrastructure: Retrofitting existing fossil-fueled power plants with geothermal systems accelerates the transition to clean energy while preserving jobs and avoiding stranded assets.
• Constant and Reliable Energy: Geothermal energy provides a constant, 24/7 baseload power supply, unlike intermittent sources like solar and wind.
• Small Land Footprint: Geothermal plants have a smaller land footprint compared to wind and solar farms for the same maximum output.
• No Fracking Required: Quaise's drilling method does not require hydraulic fracturing (fracking) to create reservoirs. The high-enthalpy systems tap into deep, naturally closed loops or high-pressure deep heat systems, eliminating the potential for induced seismicity associated with other geothermal systems.

Challenges and Considerations

Despite the potential benefits, Quaise Energy faces several challenges:

• Technological Hurdles: Scaling up the millimetre wave drilling technology to commercial levels requires further engineering advancements in waveguide durability and downhole telemetry.
• Vapour and Ash Management: Managing high-pressure vapour and ash blowout from the bottom of the wellbore requires sophisticated surface separation and filtration systems.
• Cost Competitiveness: The cost of drilling ultra-deep boreholes needs to be competitive with other clean energy sources, requiring high drilling velocities to remain economically viable.
• Regulatory Approvals: Securing permits and navigating regulatory hurdles for ultra-deep geothermal power plants can be a complex and time-consuming process.
• Material Science: Ensuring the durability and stability of materials used in ultra-deep boreholes under extreme temperatures, pressures, and corrosive supercritical fluids is crucial.

The Future of Geothermal Energy

Quaise Energy's innovative drilling technology holds immense potential to revolutionise the geothermal energy sector. By unlocking access to the Earth's vast reserves of “superhot” rock, geothermal energy can become a major player in the global transition to clean energy. While challenges remain, Quaise's progress and ambitious plans offer a promising glimpse into a future powered by the Earth's boundless heat.