Scientists Are Drilling The Deepest Hole In History To Unlock Geothermal Energy

A groundbreaking effort is underway to tap into the Earth’s vast geothermal reserves using a technology borrowed from nuclear fusion research. Quaise, an MIT spin-off, is pioneering an ambitious drilling method that could reach unprecedented depths and unlock a nearly limitless, clean energy source.

The Earth’s core burns at a staggering 5,200°C (9,392°F), thanks to the lingering heat from planetary formation and ongoing radioactive decay. This immense heat represents a virtually endless energy source, and according to MIT fusion research engineer Paul Woskov, “tapping just 0.1% of it could supply the world’s energy needs for more than 20 million years.” However, accessing this energy has proven immensely difficult.

While geothermal energy is one of the most reliable renewable energy sources—unaffected by fluctuating sunlight or wind—it currently accounts for only about 0.3% of global consumption. This is because viable geothermal hotspots are rare and must be located near power grids to make energy transmission feasible. To make geothermal energy a mainstream power source, we need to drill deeper—far deeper than ever before.

Despite humanity’s best efforts, the deepest hole ever drilled—the Kola Superdeep Borehole in Russia—reached just 12,289 meters (40,318 feet) before being abandoned in 1989 due to extreme heat and technical difficulties. The drilling team had expected temperatures of around 100°C (212°F) but instead encountered 180°C (356°F), which, along with unexpectedly porous rock, rendered further drilling impossible.

Similarly, Germany’s KTB borehole project, which cost over a quarter-billion euros, had to be halted at 9,101 meters (29,859 feet) due to excessive temperatures and the infiltration of fluids and gases into the borehole. These issues have made traditional deep drilling techniques inadequate for reaching the ultra-hot rock layers necessary for high-efficiency geothermal power generation.

To overcome these obstacles, researchers have been experimenting with “direct energy drilling,” which uses powerful beams to vaporize rock without requiring physical drill bits. This method, known as spallation, was tested in military experiments during the 1990s, revealing that laser-assisted drilling could be 10 to 100 times faster than conventional methods.

However, lasers proved ineffective for deep drilling. As Kenneth Oglesby, President of Impact Technologies, explained in a 2014 MIT report, “The deepest rock penetration achieved to date with lasers has been only 30 cm (11.8 in).” He cited issues with energy inefficiency, scattering of the laser beams by rock dust, and excessive costs. This is where fusion research provided an alternative: the gyrotron.

Originally developed in Soviet Russia in the 1960s, gyrotrons generate high-power electromagnetic waves in the millimeter-wave spectrum, which fusion researchers later discovered were effective for heating plasma. Over the past 50 years, government funding for fusion research has led to significant advancements in gyrotron technology, making them a viable tool for deep drilling.

According to Oglesby, “The scientific basis, technical feasibility, and economic potential of directed energy millimeter wave rock drilling at frequencies of 30 to 300 GHz are strong.” Gyrotrons avoid the scattering issues that plagued laser drilling and can efficiently transfer energy to rock surfaces. Thermodynamic calculations suggest that with a 1-MW gyrotron, drilling rates of 70 meters per hour (230 feet per hour) are possible—far beyond the capabilities of traditional drilling.

Quaise, founded in 2018, has taken on the challenge of ultra-deep geothermal drilling by combining traditional rotary drilling with gyrotron-powered millimeter-wave technology. Their goal is to drill down to 20 km (12.4 miles), a depth never before reached by human drilling efforts.

Unlike past deep-drilling projects, Quaise expects its gyrotron-enhanced drilling method to take just 100 days to reach 20 km, compared to the nearly 20 years it took the Kola project to reach 12 km. These depths will allow access to supercritical water—heated beyond 500°C (932°F)—which offers dramatically improved energy conversion efficiency. As Quaise explains, “A power plant that uses supercritical water as the working fluid can extract up to 10 times more useful energy from each drop when compared to non-supercritical plants.”

To fund its ambitious plans, Quaise has raised $105 million so far and is aiming for an additional $200 million to launch its first commercial power plant. The company has also begun field tests, drilling its first outdoor boreholes at a granite quarry in Texas, with larger-scale trials planned for later in 2025.

Quaise’s ultimate goal is to repurpose existing fossil-fueled power plants by replacing their coal or gas-based heat sources with deep geothermal energy. These power plants already have the necessary infrastructure—steam turbines, electricity generation systems, and grid connections—making them ideal candidates for a transition to clean energy.

With over 8,500 coal-fired power plants worldwide producing more than 2,000 gigawatts of capacity, this transition could be a game-changer. Mark Cupta, Managing Director at Prelude Ventures, emphasized the significance of this shift: “Quaise Energy offers one of the most resource-efficient and nearly infinitely scalable solutions to power our planet. It is the perfect complement to our current renewable solutions, allowing us to reach baseload sustainable power in a not-so-distant future.”

If Quaise succeeds, this technology could fundamentally change the global energy landscape. Unlike solar and wind, which require vast land areas, ultra-deep geothermal would have a minimal surface footprint. Additionally, it could diminish geopolitical tensions over energy resources since every country could tap into its geothermal reserves.

Despite slower-than-expected progress, Quaise remains committed to its vision. The company aims to have its first fossil fuel plant repowered by 2028, with the long-term goal of scaling up geothermal energy worldwide. If the drilling process proves viable and cost-effective, gyrotron-powered geothermal energy might even surpass nuclear fusion in terms of practicality and economic feasibility.

The question remains: will the Earth’s crust yield to this new drilling technology, or will it present new challenges?

Only time will tell, but if successful, Quaise’s innovation could be one of the most significant breakthroughs in the transition to sustainable energy.