Geothermal: the (almost) forgotten green renewable energy source

According to the World Economic Forum, geothermal energy accounts for only 0.5% of global renewable energy capacity (at 3.064GW). That compares with hydroelectric at 40%, solar at 28% and wind at 27%. ?Of the top ten geothermal producers the US is top with 3.7GW of capacity, Indonesia at 2.3GW, Philippines at 1.9GW, Turkey at 1.7GW, New Zealand and Mexico at 1.0GW each, Italy and Kenya at 0.9GW each, Iceland at 0.8GW and Japan at 0.6GW (2021 data). So why should we care much about geothermal?

But geothermal can be more of a contributor to our future energy ecosystem. It is renewable, zero-carbon and with the advent of enhanced geothermal systems (ESG), more accessible to more people that the industry provides today. Learning how to scavenge heat and steam from hot rock and even just warmer rock is leading to new opportunities. Current research in the US suggests learning lessons from oil and gas on drilling deeper wells plays a role as well.

This isn’t breaking news for the people of Iceland. Iceland, straddling two diverging tectonic plates, hits a geological jackpot and produces about a quarter of its electricity from geothermal; in Kenya, volcanism in the Great Rift Valley helps push that figure to more than 40 percent. However, in the US, geothermal role is just 0.4% of our energy production, almost all of it coming from California and Nevada.?

But how hard have we tried? There are two 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.

“Enhanced” geothermal system, or EGS, search for locations where they can drill wells 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.

FORGE and Fervo, Since 2018, the US Department of Energy has made a $220 million bet, called FORGE, or the Frontier Observatory for Research in Geothermal Energy, that the earth’s 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.? Yet there’s hot rock everywhere, if you drill deep enough. The FORGE project is trying to create an “enhanced” geothermal system, or EGS. 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.

While clean, dependable power derived from the Earth’s core can complement the on-again, off-again contributions 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. 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 FORGE 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.? The geothermal industry needs tools and techniques adapted from oil and gas—and in some cases, entirely new ones. Which is where FORGE comes in, playing a role in “de-risking” the tools and methods.

The challenges of natural hot springs have made creating artificial ones all the more appealing. In 2006, the DOE, along with researchers at MIT, issued a report describing a plan for making geothermal a major contributor to the US grid to help meet climate goals. The flexibility offered by EGS was at the heart of it. Although the depth at which rock gets hot enough varies—shallower out in the American West than on the East Coast, for example—the scientists reckoned it could be reasonable to drill for heat in most places, either to produce electricity or, at lower temperatures, hot water to warm buildings. In 2014, the DOE started looking for a place to serve as a testing ground for repurposing tools from oil and gas, and, four years later, picked Beaver County as the experiment’s home. Soon afterward, the agency calculated that geothermal could satisfy 8.5 percent of US electricity demand by 2050—a 26-fold increase from today. All that was missing was proof that EGS worked.

EGS proponents argue designs like FORGE strike the right balance, adding enough heat and flexibility over traditional geothermal, while being able to take advantage of oil and gas methods, The newest EGS experiments are enabled by advances in horizontal drilling and better fracking models. During the drilling of the first FORGE well, the team demonstrated it could halve the time using a new, diamond-tipped bit, cutting overall costs by 20 percent.

Fervo began drilling in Beaver County, Utah in 2023 and is now working on the third of what will become 100 geothermal wells drilled on public lands for the Utah power plant. If completed as planned, the Cape Station project could become the world’s largest geothermal facility to use next-generation technologies.

Fervo — which has raised $180 million from investors since 2017 — is among dozens of companies in the U.S. and globally that are striving to make it easier and cheaper to create geothermal energy virtually anywhere in the world. Vast amounts of heat sit far below our feet, promising to provide a nearly inexhaustible supply of hot water and steam for generating electricity and industrial heating, or for storing energy. The problem, however, is that most of the earth’s heat is too deep or technically complicated to reach cost-effectively using conventional methods.

Although it can produce carbon-free power, enhanced geothermal still carries certain environmental risks. Earlier projects using different types of drilling technologies were shut down after triggering earthquakes and rattling surrounding cities. But experts say it’s possible to minimize induced seismicity by siting plants appropriately and by following safety protocols, such as those developed by the DOE.

Developers face other challenges to scaling the technology, including convincing wary investors to back first-of-a-kind projects, navigating lengthy permitting processes and connecting to the backed-up U.S. electricity grid. If they can overcome such hurdles, the payoff could be significant for America’s energy mix. Enhanced geothermal projects could potentially provide 90 gigawatts of electricity by 2050, which would make it a key source of clean, around-the-clock power that can fill in gaps when the sun isn’t shining or the wind isn’t blowing. There are only a few enhanced-geothermal commercial power plants operating worldwide today, and they all have power-generating capacity in the single digits of megawatts.

At its Project Red site, the six-year-old startup has drilled two wells that reach some 7,700 feet deep, then connect with horizontal conduits stretching 3,250 feet long. The team pumps cold water down into the well, which returns hot brine to the surface. In July, Fervo said a 30-day test run showed the system can generate 3.5 megawatts of electricity — marking what it claims is a breakthrough that confirms the technology’s commercial viability.

The startup has an agreement with Google to provide 5 megawatts of 24/7 power from the Nevada site to help power the tech giant’s data center operations near Las Vegas. As of now, Fervo plans to begin delivering power to Nevada’s grid later this year, about a year behind its initial promised start date of 2022. For its Utah project, Fervo has so far signed power-purchase agreements with two California electricity providers to deliver a total of 53 megawatts from the proposed 400-megawatt facility.

As planned, Fervo’s Cape Station would generate 80 times more clean electricity than the Nevada project — a significant leap for any developer, particularly one that’s deploying new technology. Latimer said the challenge for Fervo isn’t to design a geothermal system that’s capable of generating greater amounts of power, but rather to replicate its Nevada model by drilling lots of individual wells.

It will only be in rare geologic circumstances where geothermal will be the primary energy source. But if you are a “all of the above” kind of energy portfolio investor, maybe you shouldn't ignore the heat below your feet and the power of innovation.