Geothermal power heats up

Glistening in the dry expanses of the Nevada desert is an unusual kind of power plant that harnesses energy not from the sun or wind, but from the Earth itself. Known as Project Red, it pumps water thousands of feet into the ground, down where rocks are hot enough to roast a turkey. Around the clock, the plant sucks the heated water back up to power generators. Since last November, this carbon-free, Earth-borne power has been flowing onto a local grid in Nevada. YOU MAY ALSO LIKE Food fracking of any kind can add pressure to nearby tectonic faults. Other issues were technological — some plants didn't create enough fractures for good heat exchange, or fractures traveled in the wrong direction and failed to connect the two wells. Some efforts, however, turned into viable power plants, including several German and French systems built between 1987 and 2012 in the Rhine Valley. There, engineers made use of existing fractures in the rock. But overall, there just hasn't been enough interest to develop EGS into a more reliable and lucrative technology, says geophysicist Dimitra Teza of the energy research institute Fraunhofer IEG in Karlsruhe, Germany, who helped develop some of the Rhine Valley EGS systems. "It has been quite tough for the industry. "Geothermal electricity has long been limited to volcanic regions where underground heat is easily accessible. But new kinds of power plants are making it possible to derive geothermal heat elsewhere in the world. New momentumSolutions exist for both safety and technological problems. There are, in fact, robust protocols for avoiding earthquakes, such as by not drilling near active faults. Long-term monitoring of the operating EGS plants in France and Germany has documented only minor tremors, building confidence in the safety of the technology. Importantly, drilling and fracking methodology has improved by leaps and bounds, thanks to the boom in oil and gas extraction from shale rocks that began in the 2010s. "Since then, we've seen a renewed interest in EGS as a concept, because the techniques that are central to EGS were perfected and brought down significantly in cost during that time, " says Wilson Ricks, an energy systems researcher at Princeton University. In 2015, for instance, the US Department of Energy launched a research site in Utah dedicated to advancing EGS technologies. Several new North American startups, including Sage Geosystems and E2E Energy Solutions, are developing new EGS systems in Texas and Canada, respectively. The most advanced is Fervo Energy, which has applied several techniques from the shale industry at its Nevada plant, which now supplies a local grid that includes energy-sucking data storage centers owned by Google. (Google partnered with Fervo to develop the plant. ) Engineers drilled almost 8, 000 feet downward into the Nevada rock, reaching temperatures of nearly 380 degrees Fahrenheit, and then, at the bottom, drilled another 3, 250-foot horizontal well to expand the area of hot rock that the system touches — a technique used in oil and gas extraction in order to maximize yield. The company also fractured the surrounding rock at several sites along the horizontal well to create a more extensive web of cracks for water to trickle through. Technologically speaking, compared to earlier EGS efforts, "they are, in fact, a big step forward, " says Horne, who is on Fervo's scientific advisory board. The geothermal power plant "Project Red" in Nevada, developed by startup Fervo Energy, has been working on methods that could make geothermal a more widespread electricity source. CREDIT: FERVO ENERGYIt remains to be seen how these new EGS systems perform in the long term. One advantage of systems like Fervo's is that they can be made more profitable by taking advantage of energy price fluctuations, according to recent research by Ricks, a Princeton colleague and several experts at Fervo Energy. Operators could plug the exit wells, causing water to accumulate inside the system, building up pressure and heat. Then the energy could be extracted during times when it is most valuable — such as during cloudy or windless periods when solar or wind aren't working. Still, such systems would have to be significantly scaled up to be commercially viable, Ricks says. Although Project Red claims a larger capacity than any other EGS plant — 3. 5 megawatts, enough to power more than 2, 500 homes — it's still relatively small; a nuclear or coal plant can easily have an output of 1, 000 megawatts, while large solar or traditional geothermal plants often produce several hundred megawatts. What the EGS field needs right now, Ricks says, is the funding to build and test more such systems to inspire investor confidence. "This all needs to be very well proven, out to the point where the perceived risk is low, " he says. Stay in the KnowSign up for the Knowable Magazine newsletter todayA turning point for geothermal? To that end, the US Department of Energy recently awarded 60 million in funding to three demonstration projects for EGS and related technologies as part of a broader initiative to speed up EGS development. One 2019 report from the agency estimated that, with advances in EGS, geothermal power could represent around 60 gigawatts (60, 000 megawatts) of installed capacity in the United States by 2050, generating 8. 5 percent of the country's electricity — a more-than-20-fold increase from today. Even an increase of a few percent could aid in a global energy transition that's aiming to get to net zero carbon emissions by 2050. "If in fifteen, twenty years, EGS is viable, I think it could play a huge part, " says Nils Angliviel de La Beaumelle, who recently coauthored an article on the global outlook for renewable energy in the Annual Review of Environment and Resources. Other geothermal technologies may also help. Some companies are exploring the feasibility of "super hot rock" geothermal — essentially, a young, extreme variant of EGS that involves drilling down even deeper into Earth's crust, to a depth where water reaches a "supercritical" vapor-like state that allows it to carry much more energy than either steam or liquid. In southern Germany, the energy company Eavor is building the world's first "closed-loop" geothermal system: Once pipes funnel water into the deep rock, the system fans out into a network of parallel boreholes, without water ever penetrating the rock. That's a more predictable — albeit less efficient — way of warming water, as it doesn't involve uncertainties around fracturing the rock in the right way, Teza says. "I'm really excited to see that there's investment into these technologies, " she says. "I think it can only help. "On the whole, it's an important moment for geothermal energy — and not just for providing carbon-free electricity, Robertson-Tait says. Geothermal brines hauled out of the Earth are rich in lithium and other critical minerals that can be used to build green technologies like solar panels and EV batteries. There's a growing push to use direct geothermal heat to warm buildings, either through shallow heat pumps for residential buildings or larger systems designed for entire districts — like Paris and Munich already have. Some oil and gas companies, recognizing that a change is coming, are increasingly interested in building geothermal systems of various kinds, says Robertson-Tait. "Our Earth is geothermal, " she says, "and so I think we owe it to ourselves to do everything we can to use it. "