Why geothermal energy is heating up
Posted: May 16, 2025
Humans have made use of the energy potential of the literal ground they walk on for a very long time.
Civilizations including the Romans used thermal waters for cooking or heating, and there is now even evidence suggesting that our ancestors could have cooked food in hot springs some 1.7 million years ago. The first geothermal district heating system was connected as early as 1332 in France.
But it took until the mid-1800s for Italian engineers to start drilling farther down into the earth to extract more steam from the subsoil. By 1913, they opened their first geothermal power plant in Tuscany, which still runs today.
While it has spread since then, geothermal power still only makes up a tiny share of renewable electricity and currently meets less than 1% of global energy demand.
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That’s partly because easily accessible geothermal resources are concentrated in just a few countries, including Iceland and the US. Now, thanks to growing political support and a suite of drilling techniques adapted from the oil and gas industry, it could be on the cusp of a boom.
Government funding for geothermal has helped boost a growing crop of US-based companies developing innovative technologies that promise to make geothermal more competitive. “We’re seeing a real skyrocket of startups,” Robert Mellors, a program director at the Department of Energy’s Advanced Research Projects Agency, said at an industry conference in March.
How companies are pushing the boundaries of geothermal energy
One of those innovative approaches is horizontal drilling. Traditionally, geothermal power plants consist of a vertical well to pump cold water underground, boil it in natural heat reservoirs and then bring it back up to drive a power turbine.
That approach requires very specific conditions, however—chiefly, high temperatures and high rock permeability that allows water to percolate continually.
“Historically, we've only really had the drilling technology to make that work if you're sitting on top of really special geologic hotspots,” Tim Latimer, CEO of Texas-based geothermal developer Fervo Energy, recently explained to Volts.
So, to make geothermal viable in areas that were previously thought unsuitable, Fervo has started to branch out horizontally. The company is scheduled to start producing power from a large-scale project in Utah by next year.
Fervo’s approach falls under the wider umbrella of enhanced geothermal systems[1], which have actually been in development since as far back as the 1970s. Back then, researchers at Los Alamos National Laboratory started using hydraulic fracturing techniques to create or widen cracks within more solid, very hot rock.
Over the past decade, the US has finally ramped up funding for further research and development, most notably at Utah FORGE—a dedicated underground field lab in the desert south of Salt Lake City, which is sponsored by the Department of Energy.
Another company pushing the boundaries of geothermal is Sage Geosystems, which uses fracking techniques to crack open rocks and create artificial reservoirs. It has several projects in development, including a 150-megawatt power plant to supply Meta’s data centers.
Sage also wants to use its wells to store energy, providing a crucial secondary function to balance the grid. It works like a pumped-storage hydro plant, turned upside down: the company would buy cheap wind or solar power to pump water underground and release it during high-demand periods. Fervo has similarly tested flexible geothermal plants that could ramp output up or down as needed and store energy for up to days at a time.
Then there’s Eavor Technologies, a Canadian company building a proprietary closed-loop system that relies on conduction from hot rocks, rather than convection. Its first commercial plant, located in southern Germany, consists of twin boreholes that reach down 4.5km, where they fan out horizontally into 12 parallel branches about 3km long, arrayed like a radiator. When fluid is pumped through this network of pipes, it functions like a giant subsurface heat exchanger.
Its biggest benefit over other enhanced geothermal techniques, the company says, is scalability—in theory, closed-loop systems can be located anywhere, not just where the rock is permeable enough. The company is already replicating its system in several other German cities.
“We thought ‘What if we didn’t frack’?” Eavor CEO John Redfern told The Engineer. “What if we didn’t have a reservoir, artificial or otherwise? What if we just built this big radiator? That’s what’s happening in Germany right now.”
Some think we need to simply dig deeper. AltaRock, another US company, wants to drill to depths of more than 7km and up to 20km, reaching temperatures above 400°C. It has studied doing so by replacing mechanical drilling methods with millimeter wave radiation to melt and vaporize rocks instead.
The future potential of geothermal energy
Whatever the method, the potential for enhanced geothermal energy is huge.
According to the International Energy Agency, “If geothermal can follow in the footsteps of innovation success stories such as solar PV, wind, [electric vehicles] and batteries, it can become a cornerstone of tomorrow’s electricity and heat systems as a dispatchable and clean source of energy.”
Specifically, the IEA estimates that geothermal could meet up to 15% of additional global electricity demand out to 2050. (The technical potential of geothermal, it says, would be more than enough to meet all electricity and heat demand in Africa, China, Europe, Southeast Asia and the U.S.)[2]
Others are similarly bullish on the technology. A recent study by the Rhodium Group estimates that geothermal power could economically meet 55% to 64% of electricity demand growth from hyperscale US data centers by the early 2030s, for example. That would mean building at least 15 gigawatts of new enhanced geothermal capacity, compared with around 4 GW of existing plants in the country today.[3]
Of course, meeting any of these forecasts heavily depends on more improvements in technology and lower project costs, as well as political support. But the IEA points out that up to 80% of the investment required in a geothermal project involves skills, data, technologies and supply chains that are already common in the oil and gas industry.
As Sage CEO Cindy Taff told The Atlantic, referencing a drive through southern Texas: “The same drilling rig that drilled our well in September was on a lease right off the highway drilling an oil-and-gas well. It’s just the same.”
