13-03-2025
The smell of toasted rock could spell victory for geothermal energy
One recent day in a warehouse south of downtown Houston, I got a peek at something that just might revolutionize the clean energy transition: a molten orange puddle of instantly liquefied rock.
Moments before, an attendant loaded a slug of basalt under a metal-frame structure that looked like something a supervillain might point at a tied-up James Bond, and I was ushered behind a protective barrier. An order went out, the contraption began to whir, and we turned our focus to a TV screen, where the solid rock erupted in a blast of white light that overwhelmed the livestream camera.
One mustn't believe everything that appears on a screen, but then Carlos Araque, CEO and co-founder of advanced geothermal startup Quaise Energy, led us back to the rig, and there was the freshly blasted rock. A minute ago, it hit as much as 2,000 degrees Celsius, but the molten goop had already solidified into a crown of shiny obsidian. Heat radiated from it, warming my hand as I hovered it a few inches away. The air smelled like toasted marshmallows, if the marshmallows were made of stone.
The flashy demonstration was just one example of how startups are looking to revolutionize geothermal energy production. The U.S. built its biggest geothermal power-plant complex in 1960, but construction has stagnated for decades. Geothermal serves a mere 0.4% of U.S. electricity generation; its nearly 4 gigawatts of capacity amounts to roughly the solar and battery capacity Texas installs in four months these days.
The way out of this decades-long malaise may simply be down. The more subterranean heat a geothermal plant can access, the more energy it can generate, and the Earth gets hotter closer to the core. But the intense conditions below a few miles deep rapidly wreck conventional drill bits.
Araque figured that if he could build a strong enough drill bit, it could harness this super-deep heat and deliver cheap, clean, and abundant geothermal power, pretty much anywhere.
So he left a career in oilfield drilling and formed Quaise in 2018 to do exactly that. Or, more precisely, the company adapted the gyrotron, a tool honed by the nuclear fusion industry that emits millimeter waves, which fall on the electromagnetic spectrum between microwaves and infrared waves. Fusion researchers use them to heat plasma to unfathomably high temperatures. But these waves exert a dramatic effect on rock, so Quaise leadership repurposed them to bore through depths that would demolish conventional drill bits, and perhaps unlock a new golden age of geothermal.
Araque likened the technology to the familiar microwave oven, which heats food by zapping it with a particular band of electromagnetic waves that excites water molecules.
'Translate that into rock,' he said. 'Well, rocks love millimeter waves. You put millimeter waves into rock, they soak it up, they light up instantly.'
He first pitched me on his super-powered drill bit six years ago. At the time, it all sounded like science fiction, something that Massachusetts Institute of Technology researchers might study and venture capitalists might take a flyer on but that wouldn't materialize as real technology.
In fact, Quaise did spin out of an MIT lab, and it did raise venture capital for the idea — more than $100 million to date from Prelude Ventures, Mitsubishi, and others. Seven years into the project, however, here I was, smelling the deep, toasty scent of freshly bruleed rock. Deep geothermal energy suddenly seemed a little less like sci-fi and a little more plausible.
Still, Quaise has plenty more work to do before it can deliver its transformative promise — and that starts with getting out of the lab and into the field.
By the time I visited in late January, Quaise had been melting rock outside of the lab but on its own property for weeks. I personally witnessed rock-melting in two places: in the hangar, with a drill rig pointing the millimeter-wave beam at a target rock, and in the yard, where a contraption mounted on tank treads blasted into a rock sample placed in a concrete receptacle on the ground.
'This is the first demonstration of capability, outside, at full scale,' Araque said of the installation.
These tests are necessary to calibrate the novel combination of millimeter-wave emitter and conventional oil-drilling rig. (The Quaise founders know their way around that world, having come from drilling powerhouse Schlumberger.) Quaise proved it can transmit the waves while moving the device, something that the nuclear fusion folks never needed to test. The company's 'articulated wave guide' also showed it can achieve a consistent round shape for its borehole, at least over short distances.
The tests so far amount to the karate demonstration where someone chops through a stack of two-by-fours: Most impressive but not a commercially viable way to chop wood. The next step is obvious — Quaise needs to get out and drill into the earth. That's coming soon.
Quaise obtained a test site in north Houston where it can drill up to 100 feet underground. The 100-kilowatt gyrotron system I saw firing up in the warehouse has already been moved to this field site, where Quaise is connecting it to a full-scale drilling rig owned by partner Nabors Industries; its mast will soar 140 feet tall. Drilling should begin in April, cutting into an existing well stuffed with rock samples — outdoors but still a controlled environment.
Soon after, Quaise will swap that out for a new 1-megawatt system, delivering 10 times the power to speed up subsurface boring and maintain an 8-inch-diameter hole, bigger than the initial test holes. That device will use a comparable amount of power as is used by conventional drilling rigs, Araque noted.
Drilling 100 feet down is a start but far from sufficient. The company also secured a quarry site near Austin that provides the opportunity to drill nearly 500 feet through pure granite. Once the technology graduates to drilling thousands of feet, Quaise plans to piggyback on the existing drilling industry with its 'BYOG' approach.
'Bring a gyrotron, bring the waveguide, bring the power supply, plug it into the drilling rig,' Araque said. 'There's thousands of drilling rigs in the world. You just go and plug and play into them.'
If and when the time comes to drill for actual power plants, Quaise aims to ride conventional drilling technologies as far as they'll go. The plan is to hire traditional rigs to burrow through the first 2 to 3 kilometers of subsurface (up to nearly 2 miles) until the drill hits what's known as basement rock.
After hitting basement rock, Quaise will swap drill bits for its millimeter-wave drill and blast to about 5 miles deep in favorable locations — even that far down, some places have easier access to heat than others. Operators will pump nitrogen gas into the hole to flush out the dust from vaporized rock as the drill moves ever deeper.
Quaise leaders did not disclose a timeline for the company's first commercial deep drilling. At that point, Quaise will need to build an actual power plant and navigate the myriad permitting and transmission-connection hurdles that face renewables developers broadly. The company is running this development process in-house and already has multiple geothermal leases secured, a spokesperson noted.
In the meantime, a handful of other startups are making headway on commercial-scale geothermal plants, albeit with different approaches.
Fervo Energy has applied fracking technologies to geothermal drilling to make the process more efficient; after a successful 3.5-megawatt trial project in Nevada, the company began drilling the 400-megawatt Cape Station plant in Utah.
Closer in principle to Quaise, a Canadian startup called Eavor is developing ways to drill deeper than was economically practical before. Instead of reinventing the drill itself, Eavor defends it with insulation and 'shock cooling' to avoid crumbling in deep, high-temperature rock.
'Most oil and gas directional drilling tools are rated for 180C temperatures, [but Eavor's] insulated drilling pipe has a cooling effect on the tools making them work at even higher temperatures just by insulating the pipe,' a company spokesperson said in an email.
Eavor notched a big win in 2023, when it drilled a test well in New Mexico to depths of 3.4 miles and through rock as hot as 250 degrees Celsius. Now it's drilling a closed-loop project in Germany to generate 8.2 megawatts of electricity and 64 megawatts of heating.
Taken together, geothermal innovators like Quaise, along with the somewhat less science-fictiony enhanced geothermal startups like Fervo and Eavor, could produce the 'clean firm' power that energy modelers say is necessary to balance out cheap wind and solar in the quest to decarbonize the electrical grid.
'Advanced geothermal technologies could unlock a terawatt-scale resource that can deliver clean energy on demand,' said Jesse Jenkins, an authority on net-zero modeling and assistant professor at Princeton University. 'That would be an enormously valuable tool to have in our toolbox.'
Quaise could in theory supply those other geothermal innovators with a better type of drill to extend their range. But Araque insisted Quaise wants to be in the power generation business, not the widget business.
The company also has to manage an evident chokepoint in its development: those highly specialized gyrotrons. Quaise owns four, Araque said; the global gyrotron supply chain currently can't handle an order for 10 more. That's not an issue while Quaise works its way up to deep subsurface drilling, but the growth trajectory of the gyrotron suppliers could limit how much power-plant drilling the company can perform simultaneously in the future.
The work to extend from boring a few inches of rock to miles of it should not be underestimated, but Quaise has already crossed the more daunting chasm from never melting rock with an energy beam to doing so daily.
