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These 12-mile-deep holes could convert power plants from fossil fuel to geothermal

Using a new technology that employs energy waves to melt rock, the wells can do deeper than standard geothermal, potentially making the renewable energy work anywhere on earth.

These 12-mile-deep holes could convert power plants from fossil fuel to geothermal
[Source Image: urfinguss/iStock/Getty Images Plus]

Iceland was one of the first countries to move to 100% renewable electricity, in part because it was able to tap into geothermal energy from its unique volcano-filled geology. In many other places, that energy isn’t as readily available. But a new technology could make geothermal power accessible anywhere—and the company is aiming for one specific use case: putting the geothermal wells at power plants that currently run on fossil fuels.

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[Photo: courtesy Quaise]
Quaise Energy, a startup that just raised a $40 million Series A funding round led by Safar Partners, uses “millimeter wave” drilling systems to go as far as 12 miles underground—that’s 3 to 5 times deeper than typical oil and gas drilling—reaching a layer of rock which is more than 700 degrees Fahrenheit. The heat can be used as a constant power source essentially anywhere on the planet.

[Photo: courtesy Quaise]
“When we think about the scale of the energy transition, we measure that in terawatts—trillions of watts—that’s what it takes to cover the world,” says Carlos Araque, CEO and cofounder of Quaise Energy. “So when you look at that scale, it is very evident that we’re not going to be able to transition energy on wind and solar alone.”

[Photo: courtesy Quaise]
Both wind and solar are intermittent sources of energy, meaning that they aren’t always available (the sun obviously doesn’t always shine), and storing that renewable energy in batteries is still fairly expensive. Wind and solar also take up quite a bit of land. If geothermal power can be affordable anywhere, it could help fill an important gap in getting to 100% renewable electricity.

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[Photo: courtesy Quaise]
It’s technically possible to drill very deep underground using traditional equipment. But the farther you go, the more you have to stop drilling to change the drill bit, and it becomes too expensive to be feasible. “It’s not a question of whether we can do it or not, it is a question of economics,” Araque says. The startup, which spun out of MIT’s Plasma Science and Fusion Center, uses new technology developed at MIT. The tech uses millimeter wave energy—a much higher-frequency version of what happens in a microwave in which you cook food—on the tip of a drill. The waves melt and vaporize rock.

The company will do in-ground tests in a lab this year, and field tests in the following two years.  (There are still open questions about the earthquake risk of big geothermal projects; Araque says the company understands the risks and is taking steps to manage them.) Then it plans to begin deploying the technology at existing fossil fuel power plants. At most power plants, “you burn a fossil fuel to heat water up, make it into steam, and use the steam to make electricity with a turbine,” he says. “Geothermal replaces the burning of the fossil fuels—the steam comes from the ground.” By going to existing power plants and drilling holes there, the company can avoid rebuilding other infrastructure. “Imagine the savings in new infrastructure capital to be able to decarbonize the majority of the electric production assets in the world,” he says.

The company is targeting a cost of 1 to 3 cents per kilowatt hour, cheap enough to compete with fossil fuels and, ultimately, replace them for baseload power when other renewable electricity isn’t available.

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About the author

Adele Peters is a staff writer at Fast Company who focuses on solutions to some of the world's largest problems, from climate change to homelessness. Previously, she worked with GOOD, BioLite, and the Sustainable Products and Solutions program at UC Berkeley

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