Quaise Takes Geothermal Tech Deeper, Hotter in Texas Hill Country

Amid the humming of a drilling rig and the chatter of existing and potential investors, prospective offtakers and others, Quaise Energy employees demonstrated how its technology called millimeter wave drilling could revolutionize geothermal energy production.

The company, an advanced startup aiming to become a geothermal energy producer, uses millimeter waves generated by a gyrotron to vaporize rock to access hot geothermal resources for energy. On this sunny day, watchers gathered at the Nabors Technology Center in Houston to see a 100-kilowatt (kW) gyrotron in action on a full-scale drilling rig. The gyrotron melts basalt lowered into the hole for testing.

“We want to show depth. Here, because it’s in a controlled environment, this rig can only go like 100 feet, so we can only put about 80 feet of rock in there,” Henry Phan, vice president of engineering at Quaise, told Hart Energy.

Plans are to go deeper in July when the technology is tested in the field at a granite quarry in Marble Falls, Texas, northwest of Austin. “In Marble Falls, the granite quarry has 2,000 meters of this pure granite,” Phan said.

Quaise intends to drill 150 m deep (about 492 ft), proof to investors that the technology is capable of drilling into extremely hard rock. Up to five holes could be drilled with multiple shots. Each hole is expected to take about one month to drill, Phan said, noting the work might last until the end of the year.

The testing is expected to help move Quaise’s technology closer to a commercial test as it aims to lower geothermal drilling costs by eliminating the drill bit. By beaming microwaves downhole via a gyrotron, instead of using conventional techniques and technology, Quaise is able to melt and vaporize rock to create deep holes to harness heat from underground.

When it comes to temperature and depth, conventional geothermal relies on what is available in oil and gas, according to Phan.

“In oil and gas right now, they’re using conventional drill bits and conventional electronics and conventional seals that basically limits them from going beyond 200 C,” Phan said. “This technology can go much deeper. By going much deeper, 300 C versus 200 C, the amount of electricity you can produce is 10 times more. So, this is where the economics work in our favor.”

Going deeper and hotter allows the technology to be cost competitive with electricity produced with fossil fuels, he said.

Millimeter wave drilling enables deeper drilling into hotter temperatures without the use of drill bits that break and have to be changed, according to Quaise Energy CEO Carlos Araque.

“Bear in mind that humans have drilled 12-km deep holes. This is eight miles … but it took 20 years to do that,” Araque said. “Humans have also drilled 50 or more wells at more than 500 C. That’s 1,000 Fahrenheit. … But that’s not economic and that’s not scalable. So, millimeter wave drilling is our answer to drilling without the drill bit. I think it’s the first time in human history that you can actually do that, get through rock—basalts and granites—without actually crushing or grinding the rock.”

Targeting tiers

The company said it will initially target what it calls Tier 1 sites, which has temperatures of 300 C to 500 C closer to the surface. Quaise’s tiered approach is based on geothermal gradient, the rate at which temperature increases with depth.

“For every kilometer drilled, the temperature rises by at least 60 degrees Celsius, making it easier to reach superhot conditions,” the company explained in a video. “While superhot geothermal temperatures at Tier 1 sites are accessible with conventional drilling, millimeter wave drilling improves the economics of accessing these higher temperatures.”

Scaling to access Tier 2 and higher sites requires millimeter wave drilling, it said. Tier 2 sites have geothermal gradients of at least 40 C per kilometer, with Tier 3 sites having at least 20 C per kilometer.

People would love Quaise to drill 20-km deep, Araque said, but “we’re not going to do that anytime soon because that’s not a good way to start our business. We’re going to start with three to five kilometers to get to the target temperatures. We’re going to develop hundreds of megawatts” before going deeper in pursuit of a gigawatt.

“Temperature gets us economics and power densities that matter. We’re talking about LCOEs [levelized cost of electricity] in the $50 to $100 per megawatt hour no matter where you are in the world.”

Quaise has already proven it can transmit millimeter waves while moving and that its wave guide can achieve a round shape for its borehole. Its test at Nabors, one of Quaise’s investors, has proven its 100-kW gyrotron system can cut into rock samples.

The Marble Falls testing is expected to help pave the way toward a commercial test of the millimeter wave drilling system in 2026, using a 1-megawatt (MW) gyrotron in Newberry, Oregon. The Newberry Volcano region of Oregon is one of the largest heat reservoirs in the U.S. Quaise expects to receive the 1-MW gyrotron at its Houston lab in July or August. The device will drill 8 1/2-inch holes, compared to the 100-kW gyrotron’s 4-inch holes.

“We’ll likely go back to Marble Falls to prove out that this larger size [gyrotron] will make an 8 ½-inch hole at a rate that we believe is viably competitive,” Phan said. “And then from there we will then transition the equipment to Newberry to do a commercial job.”