This article was first published on Knowable Magazine.
In the dry desert of Nevada, there is a unique power plant that uses heat from the Earth to generate energy, rather than relying on the sun or wind.
This plant, called Project Red, brings water deep underground, where the rocks are hot enough to heat it. Then, the heated water is brought back up to power generators. Since last November, this clean and Earth-powered energy has been added to the local grid in Nevada.
Geothermal energy, which is constantly emanating from the Earth's hot core, has been mainly used in specific volcanic areas like Iceland. However, energy enthusiasts have envisioned using Earth power in places without such geological conditions, like the Nevada site of Project Red, developed by energy startup Fervo Energy.
Advanced geothermal systems have been in development for many years, but they have been expensive and technologically challenging. They have also caused earthquakes. However, experts are optimistic that newer projects like Project Red could mark a turning point by using techniques from oil and gas extraction to improve reliability and cost-efficiency.
These advancements have raised hopes that with sufficient time and investment, geothermal energy, which currently only produces less than 1 percent of the world's electricity and 0.4 percent in the United States, could become a mainstream energy source. Some believe that geothermal could help transition the energy system away from fossil fuels by providing continuous backup to intermittent energy sources. Experts hope that with the transition to a carbon-free grid, geothermal energy becomes essential. Currently, it only accounts for less than 1 percent of the world's electricity and 0.4 percent in the United States., and Geothermal energy engineer Roland Horne from Stanford University is optimistic about its potential: “It’s been, to me, the most promising energy source for a long time. But now that we’re moving towards a carbon-free grid, geothermal is very important.”Geothermal energy works best where there is heat and permeable rock to carry water. In places where there is molten rock near the surface, water will move through porous volcanic rock, warm up, and rise as hot water or steam. solar and windThis energy source relies on water or steam that is at least around 300 degrees Fahrenheit to generate electricity. Kenya generates nearly 50 percent of its electricity through geothermal energy, while Iceland, New Zealand, and California also rely on it for a significant portion of their electricity needs. There are untapped geothermal resources in the western United States, according to geologist Ann Robertson-Tait, president of GeothermEx, a geothermal energy consulting division at the oilfield services company SLB. However, the natural, high-quality geothermal resources are running out, encouraging experts to explore ways of extracting geothermal energy from more difficult-to-reach areas. Getting that heat requires drilling deep and creating cracks in non-volcanic, dense rocks to let water flow through. Since 1970, engineers have been working on “enhanced geothermal systems” (EGS) to do just that.
engineers have been developing “enhanced geothermal systems” (EGS)
similar to the fracking used for extracting oil and gas, EGS apply high-pressure water to create cracks in deep rocks. These cracks and water form an underground radiator where water heats before rising to the surface through a second well. Many EGS installations have been built in the United States, Europe, Australia, and Japan, mostly as experimental and government-funded projects with varied success.
A well-known EGS plant in South Korea was suddenly closed in 2017 due to likely causing a 5.5 magnitude earthquake
; any type of fracking can add pressure to nearby tectonic faults. Other problems were technical—some plants didn’t create enough fractures for efficient heat exchange, or fractures traveled in the wrong direction and failed to connect the two wells. However, certain efforts became successful power plants, including several German and French systems built between 1987 and 2012 in the Rhine Valley where existing fractures in the rock were utilized.But overall, there hasn’t been enough interest to develop EGS into a more reliable and profitable technology, according to geophysicist Dimitra Teza of the energy research institute Fraunhofer IEG in Karlsruhe, Germany, who assisted in developing some of the Rhine Valley EGS systems.
Geothermal electricity has traditionally been limited to volcanic regions where underground heat is readily accessible. However, new types of power plants are making it possible to harness geothermal heat elsewhere in the world. Credit: Knowable Magazine New momentum
There are solutions for both safety and technological problems. Strong protocols exist for preventing earthquakes, such as by avoiding drilling near active faults. Long-term monitoring of operating EGS plants in France and Germany has only recorded minor tremors, increasing confidence in the safety of the technology. Moreover, drilling and fracking techniques have significantly improved due to the shale industry boom in oil and gas extraction since 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 an