By Christopher Mims

America has an effectively limitless supply of energy waiting to be tapped, right beneath the feet of hundreds of millions of its citizens.

The equipment required to get at it is almost 100% domestic or comes from nearby allies. And politicians on both sides of the aisle love it, unlike other low-carbon, renewable energy sources.

The only problem? For over a century, Mother Earth herself has thwarted every attempt to get at all but the most readily available sources of it.

Projects attempting to tap the heat deep inside the earth have, again and again, failed or fallen short. Cost overruns have stymied efforts. The biggest issue of all: Older types of geothermal plants worked only if they could tap in to existing, naturally occurring reservoirs of hot water.

But now, boosters of geothermal energy say that thanks to a combination of new technologies and generous tax incentives, it is finally ready to compete with all comers on cost and reliability. Geothermal energy is the only low-carbon, renewable energy source whose generous subsidies in Joe Biden's big infrastructure bill of 2022 were preserved in President Trump's "Big Beautiful Bill."

Decades of investment in fundamental research by the U.S. Energy Department has finally culminated in the commercialization of a new type of geothermal power that gets around the problems of previous generations of the tech. This kind doesn't require water to be naturally present beneath the surface, and instead uses local supplies of nonpotable surface water, pumped deep underground, to extract earth's heat and bring it back to the surface, where it can be used to generate power.

The biggest and best known of the startups pursuing this technology in the U.S., Fervo Energy, recently nabbed north of $100 million from Bill Gates, for a total of nearly $700 million in funding since its founding in 2017.

This is enabling Fervo and a handful of other companies to demonstrate that it is possible to dig deeper into solid granite than ever before.

To do that, they blast open the rock with the same fracking technology that has led to a natural-gas boom in the U.S., and pump cold water more than a mile underground. The companies then recover that same water from another well nearby, where it comes up hotter than an oven and ready to produce megawatts -- and, someday, gigawatts -- of power.

After more than a century of false starts, the dark horse of the renewable-energy industry seems finally poised to make a significant dent in America's insatiable appetite for new sources of power.

An all-in calculation of the total cost per unit of energy for geothermal versus natural-gas power shows that this technology could someday soon be far cheaper than natural gas by that measure -- and eventually, cheaper even to set up in the first place.

Drilling deeper

About 200 miles south of Salt Lake City, the Utah Forge geothermal research lab harvests energy from underground, using water hot enough to drive a steam turbine in a conventional power plant.

Joseph Moore, principal managing investigator at Utah Forge, says that his site has continued to receive funding from the DOE for two reasons. The first is that the hot rocks under it are typical of the kind of ultrahot granite that underlies much of the Western U.S. That makes the Forge site, which has netted nearly $300 million in federal research funds, ideal for the development of techniques intended to be reproduced elsewhere.

Moore's site has also conquered the unprecedented challenge of digging into rocks that can be as hot as 466degF (241degC).

That hot, hard rock devours conventional drill bits and makes a hash of the concrete usually poured deep underground around the steel pipes required to line such a well and keep it from collapsing.

The solution to these challenges has been a mix of creative applications of technologies first developed in the oil patch and totally new ones specific to drilling for geothermal power, says Fervo Chief Executive Tim Latimer. These include ultrahard drill bits encased in artificial diamond.

Drilling generally eats up about half the cost of a typical new geothermal project, says Moore. Drilling rigs cost upward of $80,000 a day to run, so minimizing delays is critical. Every time a drill bit wears out and has to be brought back to the surface -- at the end of what can be more than a mile of drilling pipe -- projects can lose an entire day.

This summer Fervo managed to drill a well 15,000 feet deep in just 16 days. The company reached a maximum drilling speed of 95 feet an hour and a maximum distance of more than 3,000 feet on a single drill bit.

Once an initial well is drilled to a mile or so down, drill bits can turn at an angle, or even a full 90 degrees, to chew through rock in preparation for fracking. Then small explosions are set off, and water is pumped into the well to further fracture the surrounding rock.

This creates what is effectively a radiator deep inside the earth's hot, granite basement.

The economics

All this cool new tech has resulted in some concrete results for researchers and Fervo. Research at the Utah Forge site over the past decade demonstrated that these new kinds of wells could be drilled, fracked and yield water hot enough to run a power plant. Fervo plans to start sending power to the grid from its initial complex of Utah wells, which are adjacent to Forge's, in 2026.

The challenge that has defeated all previous attempts at developing new geothermal resources still looms over these projects, however. Researchers must show that they can be economically competitive with other sources of energy.

Latimer says Fervo's current tech can yield a power plant with all-in drilling and building costs at around $6,000 per kilowatt of energy-generating capacity. For comparison, natural-gas power plants typically cost around $800 to $1,000 per kilowatt of capacity to build -- but they also come with considerable costs to run, mostly in the form of all the natural gas they burn.

Once you tally up the costs of building both types of plants and throw in natural-gas costs, which fluctuate considerably, the critical question is whether geothermal energy can compete on the basis of each unit of electricity generated.

In the topsy-turvy world of a power grid besieged by exploding demands from artificial-intelligence data centers, the economics are tilting toward geothermal.

That is because so many new AI data centers are relying on natural gas to power themselves that waiting lists for the turbines they require are stretching out to years. The cost of natural-gas power plants has climbed from less than $1,000 per kilowatt to $3,000 per kilowatt.

Still, drilling into the earth also comes with risks. Experimental drilling for a South Korea geothermal project caused a magnitude 5.5 earthquake in 2017, injuring 90 people and causing tens of millions in damage. Engineers have since instituted intensive monitoring and a multistage risk-assessment and response protocol to prevent such a disaster from happening again, Moore says.

Soviet-era microwave tech

Critics think that the economics of Fervo's power plants might never be competitive with the natural-gas and oil resources with which they must compete for drilling rigs. Some rivals are pursuing even more radical -- and far-off -- technology to tap even deeper, hotter reservoirs of earth's heat.

At a granite quarry near Austin, Texas, Quaise Energy, a Cambridge, Mass.-based spinout from the Massachusetts Institute of Technology, is using tech invented by the Soviets in the 1960s to explore the possibility of drilling the deepest, hottest wells in history.

The goal, Quaise CEO Carlos Araque says, is to tap rocks that are so hot that when water contacts them, it becomes a fourth state of matter. This strange stuff is as dense as water but flows like steam, and can in theory produce 10 times as much energy as conventional hot water from beneath earth's surface.

To get at rocks hot enough to turn water into that state, Quaise is using something called a gyrotron to create microwaves -- yes, the same kind that cook your food -- at the bottom of a well. These microwaves are powerful enough to melt rock.

Critics of Quaise's drilling tech, including Utah Forge's Moore, are concerned that rock at the temperatures Quaise is seeking can't be made into permanent, usable sources of heat.

But Araque and many other pioneers of next-generation geothermal tech are undeterred. If humanity can someday economically drill wells more than 6 miles deep, he says, we can tap energy that amounts to more than double all the electricity used on earth today. Others, like researchers at the National Renewable Energy Laboratory, have calculated that in the U.S. alone, thousands of times as much energy as Americans use in a year is already available at much shallower depths.

Biden-era tax incentives for producers of geothermal power have been extended to 2036 by legislation signed by Trump. Between that and new technology for drilling and tapping into Earth's heat, builders of geothermal power plants are practically giddy about their prospects.

They have even adopted a phrase popularized by the president, says Latimer, although he used it to describe a very different kind of energy: "Drill baby, drill."

Write to Christopher Mims at christopher.mims@wsj.com

(END) Dow Jones Newswires

October 23, 2025 05:30 ET (09:30 GMT)

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