A Vast Untapped Green Energy Source Is Hiding Beneath Your Feet

Few people on Earth have reached closer to its center than Buzz Speyrer, a drilling engineer with a long career in oil and gas. It’s about 1,800 miles down to the core, smoldering from celestial impacts that date back billions of years and stoked to this day by friction and radioactivity. That heat percolating upwards turns the rock above into a viscous liquid and beyond that into a gelatinous state that geologists call plastic. It’s only within about 100 miles of the surface that rock becomes familiar and hard and drillable.

Right now, Speyrer’s equipment is about 8,500 feet below us, or about 2 percent of the way through that layer, where the heat is already so great that every extra foot, every extra inch, is a hard-won victory. Down there, any liquid you pumped in would become, as Speyrer puts it, hot enough to deep fry a turkey. “Imagine that splashing you,” he says. At that temperature, about 450 degrees Fahrenheit (228 degrees Celsius) his gear can start having problems. Electronics fail. Bearings warp. Hundreds of thousands dollars worth of equipment might go down a borehole, and if it breaks down there, make sure it doesn’t get stuck. In that case, best to just plug that hole, which probably cost millions to drill, tally up your losses, and move on.

Even when things are going well down there, it’s hard to know from up here on the Earth’s surface. “It’s frustrating as hell,” says Joseph Moore, a geologist at the University of Utah, as he watches the halting movements of a 160-foot-tall rig through a trailer window. It’s a cool day in 2022, in a remote western Utah county named Beaver, a breeze whipping off the Mineral Mountains toward hog farms and wind turbines on the valley floor below. The rig looks much like any oil and gas installation dotting the American West. But there are no hydrocarbons in the granite below us, only heat.

Since 2018, Moore has led a $220 million bet by the US Department of Energy (DOE), called FORGE, or the Frontier Observatory for Research in Geothermal Energy, that this heat can be harnessed to produce electricity in most parts of the world. Geothermal energy is today a rare resource, tapped only in places where the crust has cracked a little and heat mingles with groundwater, producing hot springs or geysers that can power electricity-generating turbines. But such watery hot spots are rare. Iceland, straddling two diverging tectonic plates, hits a geological jackpot and produces about a quarter of its electricity that way; in Kenya, volcanism in the Great Rift Valley helps push that figure to more than 40 percent. In the US, it’s just 0.4 percent, almost all of it coming from California and Nevada.

Yet there’s hot rock everywhere, if you drill deep enough. Moore’s project is trying to create an “enhanced” geothermal system, or EGS, by reaching hot, dense rock like granite, cracking it open to form a reservoir, and then pumping in water to soak up heat. The water is then drawn up through a second well, emerging a few hundred degrees hotter than it was before: an artificial hot spring that can drive steam turbines. That design can sound straightforward, plumbing water from point A to point B, but despite a half-century of work, the complexities of engineering and geology have meant no one has managed to make EGS work at practical scale—yet.

Moore is trying to demonstrate it can be done. And in the process, maybe he can get more entrepreneurs and investors as hyped about geothermal as he is. Renewable electricity generation, whether from sun or wind or hot ground, typically offers steady but unremarkable returns once the power starts flowing. That’s fine if your upfront costs are cheap—a requirement wind turbines and solar panels now generally meet. Geothermal happens to require a risky multimillion-dollar drilling project to get started. While clean, dependable power derived from the Earth’s core can complement the on-again, off-again juice from wind and solar, there are safer underground bets for those with the expertise and financing to drill: A geothermal well might take 15 years to pay for itself; a natural gas rig does it in two.

No surprise, then, that there are 2 million active oil and gas wells worldwide, but only 15,000 for geothermal, according to Norwegian energy consultancy Rystad Energy. Nearly all are hydrothermal, relying on those natural sources of hot water. Only a few are EGS. A trio of operating plants in eastern France produce only a trickle of power, having drilled into relatively cool rock. Then there are hotter experiments, like here in Utah and across the border in Nevada, where a Houston startup called Fervo is working to connect two wells of its own, a project that is meant to provide clean power to a Google data center.

Moore believes FORGE can make EGS more attractive by showing it’s possible to go hotter. Every extra degree should mean more energy zapped into the grid and more profit. But drilling hot and hard granite, rather than cooler and softer shale that gas frackers like Speyrer typically split apart, isn’t trivial. Nor is drilling the wide wells required to move large volumes of water for a geothermal plant. Thus, a chicken-and-egg problem: The geothermal industry needs tools and techniques adapted from oil and gas—and in some cases, entirely new ones—but because nobody knows whether EGS will work, they don’t exist yet. Which is where FORGE comes in, playing a role Moore describes as “de-risking” the tools and methods. “Nobody is going to spend that money unless I spend that money,” he says.

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