A vast untapped source of green energy lurks beneath your feet

Few people on The Earth has reached closer to its center than Buzz Speirer, a drilling engineer with a long career in the oil and gas industry. It’s about 1,800 miles to the core, smoldering from celestial collisions billions of years ago and fueled by friction and radioactivity to this day. This upward-seeking heat turns the rock into a viscous liquid, and further into a gelatinous state that geologists call plastic. Only within about 100 miles of the surface does the rock become familiar, hard, and drillable.

Speirer’s equipment is now about 8,500 feet below us, or about 2 percent of the way through this layer, where the heat is already so intense that every extra foot, every extra inch is a hard-won victory. Down there, whatever liquid you pumped in will become, Speirer says, hot enough to deep-fry a turkey. “Imagine it spraying you,” he says. At that temperature, around 450 degrees Fahrenheit (228 degrees Celsius), his gear could have problems. Electronics fail. Deformation of bearings. Hundreds of thousands of dollars worth of equipment can go down the well, and if it breaks down there, make sure it doesn’t get stuck. In that case, it’s better to just plug this hole, which will probably cost millions to drill, count your losses and move on.

Even if things are going well down there, it’s hard to tell from the Earth’s surface. “It’s pretty damn unpleasant,” says Joseph Moore, a geologist at the University of Utah, as he watches the 160-foot-tall rig grind to a halt through the trailer’s window. It’s a cool day in 2022 in remote Beaver County, western Utah, with the wind blowing from the Mineral Mountains toward the hog farms and wind turbines on the valley floor. The rig looks a lot like any of the oil and gas rigs that dot the American West. But there are no hydrocarbons in the granite below us, only heat.

Since 2018, Moore has bet the US Department of Energy’s (DOE) $220 million project, called FORGE, or Frontier Geothermal Energy Research Observatory, that this heat can be used to generate electricity in most parts of the world. Geothermal energy today is a rare resource, used only in places where the crust has cracked a bit and the heat mixes with underground water, creating hot springs or geysers that can power turbines that generate electricity. But such watery hot spots are rare. Situated on two diverging tectonic plates, Iceland hits the geological jackpot and produces about a quarter of its electricity this 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, and almost all of it comes from California and Nevada.

But there is hot rock everywhere if you drill deep enough. Moore’s project attempts to create an “enhanced” geothermal system, or EGS, by reaching for hot, dense rock like granite, cracking it to form a reservoir, and then pumping in water to absorb the heat. The water is then withdrawn through a second well, which becomes several hundred degrees hotter than before: this is an artificial hot spring that can drive steam turbines. Such a design might seem simple, getting water from point A to point B, but despite half a century of work, the complexities of engineering and geology mean that no one has been able to make EGS work on a practical scale—yet.

Moore tries to demonstrate that it is possible. And in the process, he may be able to attract more entrepreneurs and investors who are as passionate about geothermal energy as he is. Generating electricity from renewable sources, whether solar, wind or hot earth, usually provides steady but unspectacular returns once the electricity starts flowing. It’s okay if your upfront costs are low—wind turbines and solar panels usually meet that requirement now. Geothermal energy happens to require a risky multi-million dollar drilling project to get started. While clean, reliable energy from the Earth’s core can supplement current from wind and solar, there are safer underground bets for those with the experience and finances to drill: A geothermal well can take 15 years to pay for itself; a natural gas installation does it in two.

So it’s no surprise that there are 2 million active oil and gas wells worldwide, but only 15,000 geothermal wells, according to the Norwegian consulting firm Rystad Energy. Almost all of them are hydrothermal and rely on natural sources of hot water. Only some of them are EGS. A trio of operating plants in eastern France produce only a small amount of energy by drilling into relatively cool rock. There are even hotter experiments, like here in Utah and overseas in Nevada, where a Houston startup called Fervo is working to connect two of its own wells, a project that’s designed to power Google’s data center with clean energy.

Moore believes that FORGE can make EGS more attractive by showing that it’s possible to get hotter. Every additional degree should mean more energy fed into the grid and more profit. But drilling into hot, hard granite, rather than the cooler, softer shale that gas frackers like Speyrer typically break apart, is not trivial. Nor is it necessary to drill extensive wells to move large volumes of water for a geothermal plant. So the chicken-and-egg problem: the geothermal industry needs tools and techniques adapted to oil and gas, and in some cases completely new, but since no one knows if EGS will work, they don’t exist yet. That’s where FORGE comes in, playing the role of tools and techniques that Moore calls “risk mitigation.” “Nobody’s going to spend that money if I don’t spend that money,” he says.