Deep Earth Geothermal: How Quaise Energy Plans to Drill with Light

The concept of geothermal energy is simple. The Earth is incredibly hot beneath the surface, but accessing that heat has historically been a challenge limited by geography and technology. You usually need to be near a volcano or tectonic fault line to get affordable geothermal power. However, a spinoff company from MIT called Quaise Energy is changing this dynamic. By using high-powered millimeter waves to vaporize rock, they plan to drill deeper than ever before to access “supercritical” heat that could power the globe.

The Limits of Mechanical Drilling

To understand why Quaise Energy’s approach is revolutionary, you first have to look at why we haven’t already tapped into the heat miles below our feet. The current record for the deepest hole ever drilled is the Kola Superdeep Borehole in Russia. It took nearly 20 years to reach a depth of about 7.6 miles (12 kilometers).

The problem was not the rock itself, but the heat. As drills go deeper, the rock becomes hot enough to melt or soften the mechanical drill bits. Additionally, the sheer weight of miles of drill pipe makes the process incredibly expensive and technically difficult. When the equipment breaks deep underground, replacing it takes days or weeks.

This mechanical limitation creates a hard floor for conventional geothermal energy. We can currently reach temperatures of around 300°F to 400°F fairly easily in specific locations. However, to make geothermal a viable replacement for fossil fuels globally, we need to reach temperatures closer to 932°F (500°C). That heat is located about 12 miles (20 kilometers) down, far beyond the reach of standard mechanical bits.

Vaporizing Rock with Gyrotrons

Quaise Energy is bypassing the mechanical problem entirely. Instead of using a spinning metal bit to crush rock, they are using a piece of technology called a gyrotron.

Gyrotrons are large vacuum tubes that generate high-power millimeter waves. This technology was originally developed for nuclear fusion research at the MIT Plasma Science and Fusion Center. In fusion experiments, gyrotrons are used to heat plasma to millions of degrees. Quaise realized that if you direct that same energy beam down a borehole, it doesn’t just heat the rock; it vaporizes it.

How the Process Works

1. Conventional Start: The drilling process begins with standard rotary drilling (the same kind used by the oil and gas industry) to get through the softer, sedimentary layers near the surface.
2. Switch to Waves: Once the drill hits hard, crystalline basement rock (granite or basalt), the system switches to millimeter waves.
3. Vaporization: The gyrotron fires a beam that superheats the rock. This turns the rock into dust and gas, which is pumped back up to the surface.
4. Vitrification: A distinct advantage of this method is that it vitrifies the borehole wall. As the beam melts the rock, the outer edges cool into a strong, glass-like liner. This seals the hole and prevents it from collapsing, reducing the need for expensive concrete casings.

The Target: Supercritical Water

The ultimate goal of this drilling method is to access “supercritical” geothermal resources. In physics, “supercritical” refers to a state of water that occurs at extreme pressures and temperatures (specifically above 374°C and 221 bar).

At this stage, water is neither a liquid nor a gas but holds the properties of both. Supercritical water is incredibly energy-dense. According to Quaise, a well producing supercritical water can generate up to 10 times more energy than a conventional geothermal well.

While a standard geothermal plant might need dozens of wells to produce a significant amount of electricity, a supercritical system might only need two or three. This density is what allows the technology to be competitive with coal, gas, and nuclear power.

Repowering Fossil Fuel Infrastructure

One of the most strategic aspects of Quaise Energy’s plan is how they intend to deploy the energy. Building new power plants is expensive and faces complex zoning and permitting hurdles. Instead, Quaise plans to “repower” existing fossil fuel plants.

Coal and gas power plants work by burning fuel to create steam, which spins a turbine to generate electricity. Quaise proposes drilling deep geothermal wells directly on the premises of retiring coal plants. They would simply replace the coal-burning boiler with a high-heat geothermal steam source.

This strategy offers three massive benefits:

• Grid Connection: The high-voltage transmission lines are already there.
• Workforce: The steam turbines and electrical equipment remain the same, allowing existing plant workers to transition to the new power source without total retraining.
• Speed: Retrofitting an existing site is significantly faster than building a greenfield power station.

Funding and Roadmap

This is not just theoretical science. Quaise Energy has raised over $63 million in funding to date. Their investors include major players like Safar Partners, Prelude Ventures, and TechEnergy Ventures.

The company is moving quickly through its development phases:

• Laboratory Proof: They have successfully demonstrated the drilling technique in the lab at MIT, boring holes in basalt with millimeter waves.
• Field Tests (2024-2025): The company is currently moving toward field demonstrations to prove the technology works in real-world geological conditions.
• Commercial Pilots (Late 2020s): The goal is to begin repowering pilot power plants by roughly 2026 to 2028.

If successful, this technology unlocks a practically infinite energy source. Unlike solar or wind, deep geothermal is “baseload” power, meaning it runs ²⁴⁄₇ regardless of the weather. By drilling deep enough, Quaise argues that we can access this heat anywhere on the planet, not just in volcanic regions like Iceland.

Frequently Asked Questions

Is deep geothermal drilling safe? Yes. Unlike fracking (hydraulic fracturing), which breaks apart rock layers to release gas and can cause induced seismicity (minor earthquakes), this method drills a clean, vertical hole. It does not involve shattering vast areas of rock underground.

How deep does Quaise plan to drill? The target depth is up to 20 kilometers (roughly 12.4 miles). At this depth, the temperature of the rock is expected to be around 500°C (932°F).

What happens to the vaporized rock? The rock is turned into ash and gas. This material is flushed out of the borehole using a purge gas (like nitrogen or argon) during the drilling process.

Why hasn’t this been done before? The gyrotron technology required to generate this level of power was expensive and scarce until recently. The research into nuclear fusion has matured the technology, making high-power millimeter-wave sources reliable enough for industrial applications.

Can this technology be used anywhere? Theoretically, yes. While the depth required to hit 500°C varies depending on where you are on Earth, the crust eventually gets hot everywhere if you go deep enough. Quaise’s drill is designed to reach those universal depths.