Geothermal energy has long been underexploited as it was seen to be too difficult to access without the necessary advanced technologies to do so. Now, with greater investment in clean technologies and general advances in technological innovation, geothermal energy is growing increasingly accessible. Further, innovative new technologies could even lead to enhanced geothermal projects and alternative approaches to accessing underground heat power.
Geothermal Energy Explained
Geothermal energy is heat found within the Earth, stored in rocks and fluids. The water and rock within the Earth’s crust can reach temperatures of 370°C. Some countries have been accessing shallow geothermal reservoirs for thousands of years, to use for cooking and heating. A geothermal heat pump installed just 10 feet underground can help access abundant renewable energy in areas with shallow geothermal waters. However, accessing deeper geothermal resources is more complex.
To access deeper geothermal deposits, it is necessary to dig wells of one of more miles deep. From around a mile under the Earth’s crust, steam and hot water can be found to power turbines connected to electricity generators. There are three types of geothermal energy operations: dry steam, flash and binary. The use of new technologies could provide greater access to geothermal resources, providing abundant, clean power that is available at all hours of the day, unlike solar and wind power.
Enhanced Geothermal Energy
In the U.S., in January, a geothermal well called Project Red was opened around 200 miles from Reno above the Nevada desert. Houston-based startup Fervo Energy carried out a successful 30-day test, generating 3.5MW of renewable energy, a quantity higher than any other enhanced geothermal project globally. The project is very small compared to other renewable energy operations in the U.S., but it could provide the blueprint for other geothermal energy companies to follow. The U.S. Department of Energy’s Enhanced Geothermal Shot Analysis suggests that enhanced geothermal could achieve 90GW of installed geothermal capacity by 2050, which would be enough to provide 65 million U.S. households with power.
Enhanced geothermal energy technology allows for producers to drill horizontally to create several wells in geothermal reservoirs from just one location, to access reservoirs that were previously inaccessible. This reduces the drilling footprint and associated risks. Hydraulic fracking techniques can be used to widen cracks within hot rock underground to inject water and create new geothermal reservoirs that can be used again and again.
Project Red, which is backed by Google, began to send green electricity to the Nevada grid in November, following a successful pilot period. The energy is being sent to NV Energy, a Las Vegas-based utility. The project is currently producing enough energy to power around 2,600 houses, but the success of the pilot phase could encourage greater investment in enhanced geothermal energy to drive a widespread rollout of the technology.
Michael Terrell, Google’s senior director of energy and climate, explained in a recent blog post, “When we began our partnership with Fervo, we knew that a first-of-a-kind project like this would require a wide range of technical and operational innovations.” Terrell went on to say, “The result is a geothermal plant that can produce round-the-clock [carbon-free energy] using less land than other clean energy sources.” He added that Google “worked closely with Fervo to overcome obstacles and prove that this technology can work.”
Transforming Fracking Technologies
Fervo is also developing its geothermal technologies in Utah, looking to transform decades-old fracking equipment into technology capable of accessing geothermal resources. Few locations have the necessary conditions to access geothermal energy using conventional techniques, which has driven companies like Fervo to explore alternative options. Two major new geothermal projects are being developed in Utah, the Utah FORGE, a $220 million research effort funded by the DoE, and another by Fervo.
The two projects use similar techniques, which require the drilling of two L-shaped wells that extend thousands of feet below the Earth’s surface into hot granite before curving and extending thousands of feet horizontally. The DoE and Fervo both use fracking techniques, utilizing controlled explosives and high-pressure fluids, to produce a series of cracks between the two wells where water can be injected.
Following success in Nevada, Fervo is now drilling wells to develop a 400MW commercial power plant in Utah, next to the DoE’s FORGE site. This development has happened more quickly than the company expected, showing great promise for a wider rollout of the technology in the U.S. This acceleration has been largely thanks to the use of existing fracking equipment, which meant that Fervo did not have to develop specialist drilling equipment from scratch, saving both time and money. While energy companies have been discussing the possibilities of enhanced geothermal projects since the 1970s, the technology required to carry out this process was not available until recently, which could signal a huge transformation in the geothermal industry.