Salvation In Deep Hellfire

Geothermal energy has become the renewable that got left behind as solar and wind accelerate. Why then do its most determined advocates still insist it could be the key to the renewable energy transition?

A volcanic vent shaped the walls of Fort Rock in Oregon. Tapping that vast energy deep underground could be the key that unlocks humanity's energy crisis.

By Henry Wismayer January 23, 2025

Henry Wismayer is a writer based in London.

On a tawny hillside in central Tuscany, in a compound just 20 miles west of Siena’s medieval piazzas, Francesco Cannata was drilling for energy. Looming behind him was a red and white derrick, 80 feet tall, surrounded by trucks and heavy machinery. For three months, Cannata and his team had been at work sinking a diamond drill bit through the carbonates and dolomites of the Tuscan continental crust.

Once they reached a point around a mile deep, they planned to augment the borehole with lengths of metal casing. By February, they’d stopper its narrow surface aperture with a configuration of valves connected to an insulated pipe, the latest strand in a spaghetti of carbonized steel tubes that snaked for miles through forests and over hill passes toward a turbine hall at Valle Secolo.

To my eye, the whole operation looked like a drilling rig for oil or gas. Across the horizon, flanking the junction points where the pipes converged, I could see voluminous chimneys, structures that seemed emblematic of our toxic industrial age. Yet the gas spilling from their gaping mouths was a mostly harmless vapor. Cannata and his team weren’t drilling for hydrocarbons. They were drilling for steam. “You can use the same tools,” said Cannata, who’d started his career in the oil and gas industry in India and Peru before switching to geothermal at Enel, Italy’s largest energy company. “But the process, and the result, is totally different.”

Christened Lamarello-1, this new well had a long local ancestry. One hundred and twenty years ago, on a pediment in the town square of nearby Larderello, a local aristocrat and entrepreneur by the name of Prince Piero Ginori Conti had channeled steam from a fumarole into a reciprocating steam engine, producing just enough power to heat the filaments of five incandescent lightbulbs.

For centuries before, people in the Valle del Diavolo, or “Devil’s Valley,” had utilized the region’s bubbling waters and mineral deposits, surface manifestations of a vast reservoir of hot water deep underground. In bygone mythologies, the simmering pools and sulfurous belches became the fire and brimstone of lands of the dead. The ancient Etruscans used the warm water to heat thermal baths; a journey here in the early 14th century is thought to have inspired Dante Alighieri to write “Inferno.” Later, early industrialists harvested boron to make boric acid, a common ingredient in glass and ceramics. But Conti’s five lightbulbs represented something new. Nine years later, he oversaw the opening of the world’s first geothermal energy plant. A century on, geothermal operations here lattice an area of over 100 square miles. Once online, Lamarello-1 will become one of around 500 wells feeding steam to 34 power plants scattered about the valleys. Collectively, these cavernous turbine halls have an installed capacity of 916 megawatts and provide a third of Tuscany’s electricity.

But no less apparent, as I explored the time-honored Larderello complex, was how much the promise of Conti’s five lightbulbs had failed to fully materialize. For decades, this region of Italy was the only geothermal field in existence. Even today it is the only one of its scale in the European Union. 

While other clean energy sources like solar and wind have expanded rapidly over recent years, geothermal has become an appendix and an afterthought, the renewable that got left behind. So why, then, do its most determined advocates still insist that the furnace beneath our feet could yet power the world?

Steam ducts near the town of Larderello, Italy, the birthplace of geothermal energy (Image courtesy Enel).

For all the effort of generations of geologists, it’s remarkable how little we know about the planet’s internal dynamics. The familiar standard depiction of the inner Earth — the globe with a wedge or hemisphere cut out to reveal the four descending layers of crust, mantle, outer core and inner core — conceals a world of uncertainty.

Most of what we claim to understand about this mysterious realm is inferred from laboratory simulations and seismic reflection surveys — observations that measure the speed and amplitude of seismic waves traveling through the Earth’s interior to different points on the surface. The consensus holds that the mantle is a semisolid mass of silicate rock and that the inner core is a giant ball of iron and nickel some 1,500 miles in diameter. But this is ultimately supposition. Scientists have long dreamed of reaching the Mohorovičić Discontinuity, the theoretical boundary between the crust and the roiling mantle that could reveal much about our planet’s hidden workings, but no hole has been drilled deep enough to retrieve a sample. 

“Geothermal has become an appendix and an afterthought, the renewable that got left behind. So why do its most determined advocates still insist it could power the world?”

Despite, or perhaps because of, that ignorance, infiltrating the underground has long been synonymous with discovery and truth-seeking. The modern world was forged with the fossil fuels we greedily extracted from subterranean seams and reservoirs, even as their combustion on the surface now imperils our future. Down below, enlightenment and destruction are intertwined. Treasure, like death, is buried.

One characteristic of the Earth’s interior that we do know with near certainty is that the deeper you go, the hotter it gets. Some of this heat is primordial, a remnant of the Earth’s incendiary creation. But most of it is radiogenic. The inner Earth is a crucible where unstable isotopes fizz in a state of inexorable radioactive breakdown. 

Humanity’s excavations to date, shallow as they are, suggest that crustal heat increases by an average of approximately 100 degrees Fahrenheit for each vertical mile. Way deeper, in the hottest parts of the core, temperatures are believed to burn at nearly 11,000 degrees — as hot as the surface of the sun. We live, in other words, on the external casing of a giant, functionally inexhaustible battery. Geothermal experts have claimed that tapping just 0.1% of the heat stored within the Earth would satisfy global energy needs for the next two million years.

The overwhelming majority of geothermal plants in operation today are in areas of pronounced tectonic activity, where superheated water can get trapped close to the Earth’s surface, producing fumaroles, geysers and hot springs. Iceland, perched above the Mid-Atlantic Ridge, generates 30% of its electricity from these underground hydrothermal reservoirs. America’s first geothermal power complex, the Geysers in Sonoma County, has been generating electricity for Northern California since 1960 and remains the most productive plant of its kind in the world.

Globally, however, the total capacity of such installations is comparatively tiny. The current maximum output, generated by 198 geothermal fields in 32 countries, stands at 16.3 gigawatts, less than 0.2% of total electricity capacity and 1% of photovoltaic solar. 

Various governments and international organizations are eager to ramp up geothermal production, and it remains a component of many decarbonization roadmaps, not least owing to its potential as a baseload “gap-filler” for more fickle renewable energy sources. In 2017, at a summit organized by the Global Geothermal Alliance, representatives from 42 national governments signed the Florence Declaration, committing to increase geothermal power capacity by 500% by 2030. Last year, the U.S. Department of Energy declared its intention to “unlock” affordable geothermal energy for over 65 million American homes by 2035 as part of its Energy Earthshots program.

“We live on the external casing of a giant, functionally inexhaustible battery. Geothermal experts have claimed that tapping just 0.1% of the heat stored within the Earth would satisfy global energy needs for the next two million years.”

However, these political gestures have yet to translate into truly consequential capital investment and expansion. The overhaul of America’s energy policy contained within the government’s landmark infrastructure bill of 2021 earmarked $8.6 billion for carbon capture and storage, $3 billion for battery recycling. Geothermal research and extraction was allocated $84 million.

The inertia comes back to the geographical scarcity of extraction points at shallow depths and is exacerbated by issues of upfront cost and inefficiency that have dogged production from its earliest days. “It’s not uncommon for today’s plants to operate at between 7 and 10% efficiency,” said Terra Rogers, a geothermal energy expert at the Clean Air Task Force (CATF). “It’s pitiful.”

In order to really kickstart the geothermal revolution, the sector needs a bolder strategy, one that centers on solving a stubborn engineering puzzle: how to get deeper underground.

Back in the 1970s, geological surveys beneath the Valle del Diavolo identified an anomaly, a variation in the property of the rocks that impeded seismic waves. “Nobody knows what causes it,” Geoffrey Giudetti, Enel’s head of geothermal resource evaluation, told me. “We just knew it was a huge spot in the basement where the isotherms start to bunch.” Isotherms are contour lines for temperature; the fact that they bunched at the anomaly, which geophysicists labeled the “K-horizon,” most likely signaled a magmatic intrusion. Whatever the cause, what really mattered was that this part of the crust promised very high temperatures at potentially accessible depths. 

In 2017, Enel engineers working near the village of Lago began extending an existing well, dubbed Venelle-2, down toward the anomaly. The goal was to probe the exigencies and challenges of drilling into rock far deeper and hotter than those routinely tapped in the area. The operation stress-tested novel materials and technologies, including a “Full Stinger” polycrystalline diamond compact drill head specially designed to cope with extreme subterranean conditions. Within a year, the drill hit a depth of over 9,500 feet. The spiraling heat precluded further progress, but the researchers had already obtained what they were after. When they lowered a bespoke Kuster thermometer, the reading maxed out its temperature gauge: almost 850 degrees Fahrenheit. Further testing on crystal fragments, suspended within a capsule made of gold and lowered to the well bottom, yielded a final figure of 960 degrees, the highest subterranean temperature ever recorded in the European crust. The scientists at Larderello had taken a small stride toward a tantalizing new frontier in geothermal power production. Industry insiders call it “superdeep” or “superhot rock geothermal.” Giudetti captured its implications with a more expansive label. He called it “geothermal everywhere.”

This form of power could represent an altogether transformative advancement in geothermal — indeed, in the generation of electricity in general. It starts with supercritical water. “Supercriticality” describes the atmospheric threshold beyond which an element or molecular compound enters a fourth state beyond solid, liquid and gas. In the case of water, that threshold is at just over 700 degrees and 221 bars of pressure. Supercritical water has some extraordinary physiochemical properties, but the key factor for those working at the frontier of geothermal power is its volumetric enthalpy: its capacity to carry heat.

In practical terms, this means that sinking a geothermal well into temperatures like those at Venelle-2 could radically upscale geothermal energy output. It would no longer be necessary to depend on subsurface reservoirs of hot water. Instead, cold water could be injected into deep, dry rock where the ambient heat and pressure would bring it up to supercriticality. Then it could be extracted again to drive turbines. The consensus among geothermal experts is that such wells would offer 10 times as much enthalpy per cubic meter as current geothermal. A researcher at the National Autonomous University of Mexico concluded in a 2019 study that the differential could be double that.

Rogers, who spearheads the CATF’s superhot rock geothermal research and advocacy, told me that this untapped resource could provide energy in volumes “far beyond what we could conceivably consume at the surface.” Just as importantly, its efficiency relative to extant geothermal systems could overcome the geographical and economic constraints that have thus far stymied expansion and technological standardization. “At the very center of our bullseye is being able to extract energy from dry rock conditions, from formations that are adequately hot or energy dense to allow the lowest possible cost for the electron,” she said.

“Down below, enlightenment and destruction are intertwined. Treasure, like death, is buried.”

Getting there presents a formidable technical challenge. Venelle-2 is one of around two dozen test wells around the world that have drilled down to superhot rock conditions. Others in Japan, Iceland, New Zealand and Mexico are all at relatively shallow depths, usually two to five miles deep. Accessing the necessary temperatures more widely would sometimes require drilling much deeper, along with all manner of contingent innovations. Do that, Rogers told me, and “the potential is out of this world.”

As with existing geothermal production, the flow rate would be constant, with close to zero carbon emissions at the point of generation and without the intermittency of wind and solar. The surface footprint would be comparatively small: no open-cast mines, land-intensive energy storage or endless square miles of solar panels. It wouldn’t require the ecologically destructive terraforming of hydroelectric dam construction and would carry none of nuclear energy’s radioactive risk. Geographically agnostic, it could be made available almost anywhere on the globe, offering the prospect of universal energy security and negating the cost volatility that affects fossil-fuel markets. In theory, it is equitable, endlessly scalable, disaster-resilient. And it is the logical successor to oil and gas, leveraging the core competencies — subterranean prospecting, deep-drilling and extraction — of the very sector that greener alternatives urgently need to supplant.

In an age when energy policy is so often hostage to fierce partisanship, there is hope that geothermal can be politically agnostic, too — the one clean energy solution that could satisfy climate change campaigners and the “drill baby drill” lobby alike. “Environmentalists and drillers, dogs and cats, right and left: We all get what we want,” said the technologist and climate activist Jamie C. Beard in a TED talk in August 2021. “Clean energy where we need it, climate change solved, energy poverty solved, and drillers keep drilling. If we build the right collaborations here and unite behind a shared vision, we solve energy in the next 30 years.”

The prospective rewards are hard to overstate. A landmark report by the International Energy Agency (IEA), published last month, claimed that next-generation geothermal has “the technical potential to meet global electricity and heat demand many times over.” The analysis estimated that the national geothermal resource for America alone, based on an average well depth of just over 3 miles, is in the region of 7 terawatts, seven times the country’s current total energy capacity for all other electricity sources combined. CATF projects that a fully matured global superhot rock industry could produce electricity at around $25-30 per megawatt-hour, below the U.S. market average. In the context of the climate crisis, it seems on paper to be a panacea — hellfire recast as salvation. But the question remains: how to reach it?

Although industrial drilling remains something of a dark art, the principles are the same as with primitive rotary tools: A sharp-tipped instrument applied to a solid mass and rotated will create downward pressure, boring a hole.

On a mechanical deep-drilling rig, excavation is carried out by a heavy-duty bit: typically a “tricone” assembly, with three inward-canted rotating cones, each set with teeth forged from tungsten carbide. A motor at the surface keeps the whole apparatus spinning at around 50 rpm. As the drill’s weight and fluting guide it downward, a constant flow of drilling fluid, or “mud” in industry shorthand, is pumped through apertures to cool and lubricate the cutting face and to carry pulverized material, or “cuttings,” back to the surface for disposal. This technique has achieved some remarkable feats of engineering. Progress on a modern-day oil or gas well can approach 200 feet per hour. The world’s longest oil well, in the UAE’s Upper Zakum oilfield, runs 50,000 feet beneath an artificial island off the coast of Abu Dhabi.

The record for the deepest borehole — a “true vertical” hole drilled perpendicular to the Earth’s surface — belongs to Russia, though this one was excavated not in pursuit of hydrocarbons, but in the name of scientific idealism and Cold War competition. In 1970, a team of Soviet scientists and engineers broke ground on what would come to be known as the Kola Superdeep Borehole. Located a hundred miles west of Murmansk in a tract of bleak tundra close to the Norwegian border, the site was selected for its position atop the Baltic Shield, a great slab of Precambrian metamorphic rock, where engineers anticipated the stable geology would suppress subterranean temperatures.

At the center of a utilitarian compound of laboratories and barracks, they erected a nearly 250-foot-high derrick called the Uralmash-15000, a specially designed drilling platform weighing 15,000 tons. Around 700 personnel worked in shifts to keep the machine running day and night. Over the course of two decades, they extracted some 10,000 cylindrical cores. Analysis of these rock samples revealed the presence of mineralized water deeper than had ever been thought possible and fossilized plankton up to four miles down that carbon-dating identified as Paleoproterozoic — remnants of the earliest life on Earth. The Scottish geophysicist David Smythe, who visited in 1992 in the wake of perestroika, described the project as “the geological equivalent of going to the moon.”

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“In theory, advanced geothermal is equitable, endlessly scalable and disaster-resilient.”

But it was also a lesson in the difficulties of digging very deep holes. Three miles down the substrate began to behave in unexpected ways. The rock became more permeable and porous but also more malleable, as if the drill was moving through plastic. The drilling angle had to be adjusted several times in order to stay on a true vertical line. The resulting pattern of aborted shafts splayed like the root system of a tree. As the rig crunched through layers of plutonic bedrock, the heat rose in increments far greater than the project’s scientists had anticipated. Downhole equipment began to warp in temperatures nudging 400 degrees; drill bits splintered on progressively harder rock. Pressure toward the bottom reached 150 megapascals, greater than that found in the deepest oceanic trenches. 

In 1994, they halted drilling due to a lack of funds, never progressing past 40,230 feet. The facility was officially mothballed in 2007 and abandoned to the mercy of Siberian winters, reemerging now and again as a conduit for claustrophobic schlock-horror, like the recent film “The Superdeep” (2020), where a group of scientists catch an elevator down the hole into a catacomb and are set upon by an array of killer mutants. 

In reality, the hole has a diameter of just nine inches. The only outward sign of its existence today is a small iron cap, held with a dozen rusting bolts, surrounded by the disintegrated scrap of the derrick scaffold. The number “12,226,” the borehole’s depth in meters, is scrawled on its surface, though the shaft below has long since collapsed, inundated by the invisible shifting of the Earth.

For all its extraordinary depth, the Kola borehole crossed just 0.2% of the Earth’s total radius. The very heat that thwarted its progress is precisely the thing that those working at the cutting edge of geothermal innovation hope to exploit.

In a small hangar near Hobby Airport in Houston, Texas, sits a device that could redefine the future of deep drilling. In a cream-colored shipping container at one end of the hangar is a gyrotron, which looks to the untrained eye like a stack of aluminum and copper cylinders fed by a chaotic array of cables, gauges and color-coded pipes. At its base is a diamond window opening into a thin aluminum tube. Known as a “waveguide,” this tube exits the shipping container and enters a second, from which there emanates a loud monotone hum. 

On shelves and pallets around the edge of the room are the remnants of experiments that emerged from that second container: hundreds of square slabs of basalt and granite, each one perforated by a neat vitrified hole.

The underlying technology of the gyrotron has been around for several decades, a vestige of Soviet state-sponsored invention. It is a type of maser, a device that uses an electron gun and electromagnetic field to create an adjustable beam of energy. Unlike a laser, which uses visible light, the gyrotron’s beam utilizes lower-frequency microwave radiation, invisible to the human eye but still capable of generating extraordinary levels of heat. Its primary utility, then and now, is to turn hydrogen isotopes into plasma to assist with research into nuclear fusion. But the gyrotron humming in this Houston lab is being mobilized in pursuit of another elusive energy grail: opening the portal to superdeep geothermal.

The innovation pipeline that resulted in the experiments being conducted in this hangar began in 2008 when Paul Woskov started training a gyrotron beam onto chunks of basalt. A senior research engineer at MIT’s Plasma Science and Fusion Center, Woskov demonstrated that the gyrotron could make short work of the kind of igneous and metamorphic rock you would expect to find in deeper portions of the Earth’s crust.  

Calibrate the microwave beam frequency to the millimeter range, Woskov discovered, and the rocks yielded to it like a ream of paper held over a naked flame. By his calculation, the gyrotron could cut through Tholeiitic basalt, among the most common substances in the Earth’s crust, at a rate of over 65 feet per hour. Sustain that speed and the technology could conceivably blast past the Kola nadir in less than a month. In place of “mud,” the excavated material could be removed by the simultaneous injection of a “purge gas” composed of nitrogen or argon, which binds to the vaporized rock, bringing it back to the surface as a cloud of volcanic ash.

The company founded in 2018 to commercialize Woskov’s technology is Quaise Energy. It’s one of several enterprises working in the field of superdeep geothermal R&D, though its proposition is among the most audacious: to penetrate the Earth’s crust to over 12 miles. At such depths, Quaise contends that it should be possible to harvest superhot geothermal in more than 90% of terrestrial locations around the globe. “It’s crazy, but it’s not undoable,” Henry Phan, the company’s vice president of engineering, told me. “It’s not outside the realm of physics.”

“In an age when energy policy is so often hostage to fierce partisanship, there is hope that geothermal can be the one clean energy solution that could satisfy climate change campaigners and the ‘drill baby drill’ lobby alike.”

The next big task, according to Quaise co-founder and CEO Carlos Araque, is to test whether the efficacy Woskov confirmed over years of benchtop experiments holds true in the field. Armed with $95 million in funding from investors, including some gold-chip fossil fuel and drilling companies, Araque’s more long-term ambition is to “demonstrate that we can achieve power and economic parity with oil and gas.” But first he needs to make the numbers balance. “There’s two metrics that matter,” Araque told me. “One is the rate of penetration, the speed at which you’re destroying the rock. And the second metric is nonproductive time.”

The feasibility of expensive deep-drilling missions rests on a bald economic calculus, Araque explained. At shallow depths, a rotary drill is perfectly efficient. The crust’s uppermost layers comprise a veneer of softer sedimentary rock that has accumulated from the deposition of weathered minerals or organic matter that subsequently lithifies over eons. Drilling through rocks like limestone, gypsum, breccia or sandstone exerts less wear and tear on downhole equipment, which in turn means less downtime.

Lower down, the economic noose starts to tighten. Beneath the sedimentary rock lies the basement complex. This is the granite and basalt laid down in the depths of primordial time, crystalline in structure and very dense. Once you progress toward the basement rock, the rotary drill slows to a crawl. The massive abrasion at the cutting face means that even the toughest conventional drill rigs require incessant “trips” back to the surface so their worn-out or damaged bits can be replaced. This procedure becomes more time-consuming and costly the deeper you go; swapping out an exhausted bit from a multi-mile borehole might take seven days. Here, in the deeper strata, Quaise’s technology should come into its own. Not only does the non-contact method negate wear and tear, but it also sustains power output; lab-test data suggests that the gyrotron’s beam will lose only around 50% of its power at a depth of six miles. “To put that into perspective, the attenuation of a rotating drill string at 10 kilometers can be 98%,” Araque said. “You only get 2% of the mechanical power down to the pit.” It’s this cold arithmetic — penetration rate versus downtime, efficiency versus cost — that could make or break efforts to evolve geothermal into a terawatt-level power source.

For Quaise, proving the concept in the field will take place on a disused oil drilling pad in the northern exurbs of Houston. Next month, a gyrotron 100 times as powerful as the one in the laboratory will be pointed at the earth and switched on. By spring, Quaise will have erected another platform in a disused quarry near Marble Falls, a city on the Colorado River northwest of Austin. 

Araque migrated to geothermal after 15 years at the oilfield services giant Schlumberger and was keen to emphasize that he is “building a company out of oil and gas people, capital and infrastructure.” The company’s ultimate ambition is that its drills can be “dropped-in” to existing oil and gas wells, transforming the infrastructure responsible for the majority of anthropogenic carbon emissions into an apparatus for their mitigation. By 2026, Quaise should be positioned to launch its first commercial venture. Within that short timescale, an answer to the question of whether superdeep geothermal can be truly transformative should come into clearer focus.

Quaise Energy is part of a growing ecosystem of pioneering companies that together fall under the umbrella of Enhanced Geothermal Systems (EGS), all leveraging novel technologies that aim to revolutionize the sector. These systems have been a subject of conjecture and sporadic R&D for some time. (A seminal MIT report on their potential from 2006 runs to 372 pages.) But drilling a deep hole has only ever been half the battle. The other, arguably trickier challenge is to cultivate circulatory systems where injected water can absorb heat before being brought back up to the surface. In short, harvesting supercritical water from hot rock formations necessitates the creation of reservoirs, or “pore-space.” For years, engineering such complex lattices seemed to be beyond the scope of human ingenuity. But much of the pivotal innovation has emerged in the last decade or so as part of the “shale revolution” in oil and gas, and the development of pioneering techniques like hydraulic fracturing, hydroshearing and directional drilling. These methods, which can be used both to dilate natural fractures and to cultivate new ones, are directly transferable to geothermal extraction.

Such innovations precipitated a surge in the number of superdeep geothermal startups amid renewed optimism that they could succeed. In early 2023, another Houston-based outfit, Fervo, reported that it had successfully stimulated fractures stretching for over 3,000 feet between two 8,000-foot boreholes at its test site in Nevada. Though the temperatures in the reservoir were 375 degrees, far short of supercritical, the achievement was nonetheless widely hailed as a vital step; last October, the company received government permission to build a cutting-edge plant in Beaver County, Utah. Fervo claims that the plant will have an eventual capacity of 2 gigawatts, enough to power 2 million homes. Another startup, Eavor, based in Alberta, Canada, is developing the “Eavor-Loop,” a technology that will use magnetic sensors to drill lateral conduits between injection and extraction wells, a configuration that looks like a giant underground radiator. Its first commercial facility is currently under development in southern Germany.

Even as these novel techniques evolve and dovetail, significant obstacles remain. The success of future EGS systems depends not just on optimizing drilling and fracturing methods, but also on the simultaneous development of myriad supplementary technologies. Casing, cements, alloys, polymers, electronics: Every component of the deep-drilling toolkit needs to be armored, upgraded and re-engineered to cope with the extreme thermal stresses of supercritical conditions.

The industry also has to tackle questions of risk, both real and perceived. Hydraulic fracturing for superdeep geothermal wouldn’t involve the hazardous chemicals or scale of fractures that are involved in shale gas extraction. But the controversy surrounding fracking, born from a legitimate public anxiety that we can never be fully in control of subterranean forces, is not without foundation. In 2017, water injection at an EGS pilot project near Pohang, South Korea, triggered a magnitude 5.5 earthquake. The shock injured 90 people and caused an estimated $52 million worth of damage. One Korean seismologist described the incident as “a wake-up call.”

“In the context of the climate crisis, it seems on paper to be a panacea — hellfire recast as salvation.”

Subsequent investigations determined that the tremor was caused by the presence of a deep tectonic fault that earlier seismic profiling had failed to identify. In this context, the discovery made by the scientists at Kola — that, under certain conditions of temperature and pressure, subterranean rock becomes more ductile and less brittle — may transpire to be a blessing. Industry experts remain bullish that EGS projects tapping deep regions of the crust, accompanied by rigorous subsurface profiling, will be able to minimize the risk of “induced seismicity.” This science, like so much in the superhot geothermal space, requires further intensive research.

A common sentiment among geothermal experts is that marginal breakthroughs will eventually reach critical mass, luring more expertise — and, crucially, capital investment — away from oil and gas. But some advocates are equally keen to emphasize that the techno-utopian enthusiasm around superdeep geothermal risks obscuring more immediate gains. Beard, the activist whose impassioned TED talk on geothermal’s untapped potential has now been viewed over 2 million times, told me that there is a world of iteration between superhot rock and traditional geothermal production that is being overlooked.

Today, Beard heads up Project InnerSpace, a nonprofit geothermal research unit and think tank. Top of her agenda is persuading stakeholders of the need to start expanding geothermal production even while the more long-term supercritical engineering solutions are still gestating. This would involve going after the “low-hanging fruit”: the great quantities of dry-rock geothermal that could be harvested with current technology.

Beard remained a keen proponent of the superhot projects. But the tendency to get sidetracked by “super-sexy” concepts like vaporizing rock or drilling into magma gave energy policymakers an excuse to kick the can. “Government advisors say: ‘This is a moon shot that we can’t do anything with in the next 10 years. So thank you very much and come back later,’” Beard told me. “But the world needs projects in the ground. We don’t have time for later.”

Rather than wait for superhot rock projects to come online, there is a wealth of shale boom expertise and capital that could be leveraged right away. December’s long-awaited IEA report, which was published in partnership with InnerSpace, forecast that an expanded geothermal industry could meet “15% of global electricity demand growth to 2050.” However, Beard is convinced that this still undersells the potential dividends of an immediate transition. She pointed me to another InnerSpace study, this one written in conjunction with the University of Texas, which calculated what would happen if the whole oil and gas universe — every dime and drilling rig — switched from harvesting hydrocarbons to harvesting heat. The results saw geothermal providing 77% of global electricity demand within 20 years. In this dream-case scenario, Beard said: “The oil and gas industry becomes the geothermal industry, and we’re off to the races.”

“Rather than wait for superhot rock projects to come online, there is a wealth of shale boom expertise and capital that could be leveraged right away.”

The biggest barrier to such a wholesale conversion was less a technological challenge than “a people problem,” Beard said. All of the necessary expertise existed, just in two ecosystems — climate activism and Big Oil — that were mutually allergic. Beard took heart from the fact that some of the necessary crossover between deep-pocketed industries and geothermal startups has already begun. Devon Energy, an Oklahoman oil and gas exploration firm, has already plowed $100 million into Fervo. Some tech giants, keen to sate the burgeoning energy needs of A.I., have also thrown cash in the ring. In August, Meta struck a deal with Sage Geosystems, another Texan geothermal venture, to open a 150-megawatt dry-rock power plant to supply its data centers by 2027. Cranking up this kind of collaboration, Beard argued, offers the only plausible pathway to a geothermal future.

As for the environmental lobby, it would take some convincing. “When I walk into a group of climate donors and say the industry that you hate the most, and that you’ve spent your entire life villainizing and funding to sue, I think that we need to join forces with them and give them a redemption arc … there have been times where I felt like I was going to get booed out of the room,” Beard said.

From the Quaise office in Boston, Araque was clear-eyed about the stakes. “Our civilization uses 25 terawatts, and it doubles every 25 years,” he said. “By 2050 we need 50 terawatts. By 2100 we need 200 terawatts. When you look at those numbers, you realize that diffuse and intermittent renewables don’t have the scale. The externalities are too high.”

That left “only three options on the table”: nuclear fusion, nuclear fission and deep geothermal. Fusion doesn’t yet exist. “Even if it worked tomorrow, the industry would have to grow from scratch. So that’s going to take time,” Araque said. Fission, he argued, works in wealthy nations but is too complex and geopolitically sensitive for universal adoption. By a process of elimination, that left superdeep geothermal as the only resource with the scale, abundance and extant know-how to be universalized. “It’s a solution that lands in the world that actually takes off,” Araque told me. “But you have to break that technological barrier.”

Around midday on a slope above Larderello, I stood behind a red line painted onto the asphalt. A hundred feet away, inside a small chain-link cage on the verge, an oxidized cap marked the presence of a “spent” well, maintained, now, for demonstration purposes. From one of its vents coiled a restive wisp of steam.

An Enel technician donned a pair of yellow earmuffs, walked to a control panel on the other side of the service road, and turned a switch. Suddenly, the small puff of steam metastasized into a ferocious plume that billowed skyward before dissolving into the blue sky. The hiss as it exited the vent was so loud that I had to abandon my plan to take photos and instead thrust fingers in my ears. The volume, I learned afterward, was 140 decibels, like standing next to a long-bodied jet engine at take-off.

In that moment I understood at once the enduring menace and mythos of the underground. Within this burgeoning steam cloud was the merest glimpse of a vast power that simmers beneath us in volumes difficult to corral or comprehend. It was tempting to feel carried away with a wildcatter’s fever. Perhaps, through a combination of ingenuity and will, this resource could become the elixir that cures the energy crisis. If only we could acquire the recipe.

DeepFyre Comments

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