Enhanced geothermal systems promise wider access to clean energy

Traditionally, entry to geothermal power has hinged on actual property’s famously three most vital components: location, location, and placement. As a result of standard geothermal energy vegetation require scorching, permeable rocks and loads of underground fluid, use of the know-how has been restricted principally to locations with latest volcanism, akin to Japan, New Zealand, the Philippines, Kenya, El Salvador, Iceland, and the western United States.

Over the previous 50 years, nevertheless, methods initially developed for oilfields and tailored for “enhanced geothermal systems” (EGS) have supplied the promise of tapping deep reserves of pure warmth throughout a broader swath of the planet.

“There’s numerous pleasure about enhanced geothermal energy,” mentioned Roland Horne, a professor of power science and engineering within the Stanford Doerr College of Sustainability, who convened greater than 450 engineers, scientists, and managers from 28 international locations earlier this month on the fiftieth Stanford Geothermal Workshop to trade concepts and report outcomes from initiatives all over the world.

So far, almost all EGS functions have been for analysis functions in one-off, small-scale vegetation, mentioned Horne, who was invited to collect a workforce of authors to write down a review paper for the February 2025 concern of Nature Opinions Clear Expertise about EGS and its potential to provide power at a bigger scale.

Millennia after historical Romans tapped subterranean warmth to heat their buildings, and greater than a century after Italy began up the world’s first geothermal energy plant, Horne and co-authors be aware that geothermal right this moment contributes as a lot as 45% of the electricity supply in some international locations, like Kenya. Nevertheless it nonetheless contributes lower than half of 1% globally. Photo voltaic and wind contribute greater than 25 instances as a lot. With EGS, the potential now exists for geothermal to comprise a far better share of humanity’s power wants.

Quicker drilling reduces prices

Lots of the drilling methods that enabled the shale gasoline growth of the early 2000s have been tailored to make geothermal work in additional areas at decrease price, mentioned Horne. These methods embrace horizontal drilling and hydraulic fracturingor fracking, which entails pumping fluids at excessive stress into wells drilled down into and throughout rock formations hundreds of toes underground. The stress forces open present fractures within the rock or creates new ones, easing the circulation of petroleum or different fluids to the floor. In enhanced geothermal techniques, the fluid is simply scorching water from the pure underground reservoirs.

Different tailored methods embrace drilling a number of wells from a single pad to extend effectivity and cut back prices. Artificial diamond drill bits, which may successfully chew by way of laborious rock, have additionally confirmed essential, making it doable to finish a brand new geothermal effectively inside a couple of weeks as an alternative of months.

“Drilling faster makes an enormous difference to the whole economics of EGS,” mentioned Horne, the Thomas Davies Barrow Professor at Stanford, who additionally serves on the scientific advisory board of an enhanced geothermal improvement firm co-founded by Stanford alumni Tim Latimer, MS-MBA ’17, and Jack Norbeck, Ph.D. ’16.

Primarily based partly on modeling led by Ph.D. pupil Mohammad Aljubran, Horne and his co-authors on the overview paper estimate the quicker drilling charges may make enhanced geothermal techniques aggressive with common electrical energy costs throughout a lot of the USA by 2027, at roughly $80 per megawatt-hour.

In California, which at the moment will get about 5% of its electricity from geothermal, the authors estimate geothermal capability may enhance tenfold with EGS to succeed in 40 gigawatts by 2045 and exchange fossil fuels for baseload energy. On this means, EGS would complement the intermittent renewables of wind and photo voltaic, including stability to a decarbonized energy grid.

“With EGS, we can meet the load,” mentioned Horne, whose co-authors on the Jan. 31 overview paper embrace Norbeck and former pupil Mark McClure, MS ’09, Ph.D. ’12, the co-founder and chief government of an organization that markets fracture modeling software program to grease, gasoline, and EGS corporations. Further co-authors embrace William Ellsworth, an emeritus analysis professor of geophysics within the Doerr College of Sustainability; Eva Schill, who leads Lawrence Berkeley Nationwide Laboratory’s geothermal techniques program; and Albert Genter, deputy director basic of geothermal at Electricité de Strasbourg, which is concerned with industrial improvement of EGS initiatives in France.

Mitigating earthquake dangers

As with fracking for oil and gasoline, fracturing deep rocks to entry geothermal reservoirs can set off earthquakes.

One apparent solution to mitigate danger once more hearkens again to location: Merely keep away from drilling in locations vulnerable to earthquakes. For instance, constructing a web site atop the San Andreas Fault that perilously wends by way of California can be ailing suggested, Horne mentioned.

A second method is monitoring seismicity with a system generally known as a traffic-light protocol. If a seismic event of a sure magnitude happens, operators decelerate their drilling. Larger seismic occasions are handled as crimson lights that halt all drilling and immediate a overview previous to potential restart.

A lately developed technique for limiting seismicity, Horne mentioned, entails creating many smaller fractures throughout drilling reasonably than only one or a couple of huge fractures. Most earthquakes related to EGS have occurred when large, human-stimulated fractures are pumped stuffed with fluid and activate faults, that are naturally present fractures in rock. “A drip-drip-drip instead of a fire hose approach can significantly reduce the risk and size of induced seismicity,” mentioned Horne.

He and his colleagues hope the brand new examine encourages additional analysis and improvement of EGS as a sustainable and dependable power supply. “EGS could be a game changer for green energy production not just in California but across the U.S. and worldwide,” mentioned Horne. “Safely harnessing Earth’s internal heat could substantially contribute to powering our future.”

Horne can be a senior fellow within the Precourt Institute for Power and serves on the scientific advisory boards of Utah FORGE and Fervo Power. Norbeck is the chief know-how officer at Fervo Power. McClure is the chief government at ResFrac, which markets software program to EGS improvement corporations together with Utah FORGE and Fervo.