What will be needed to unleash the potential of geothermal energy

“Geothermal is really ready for prime time,” said Tim Latimer, founder and CEO of Fervo EGS.

The attractiveness of Geothermal is related to consistency: while the production of electricity from wind and solar power plants varies depending on the time and time of day, geothermal energy is always on, providing a stable source of electricity.

“It’s really the only renewable base load,” said Jody Robbins, a geothermal engineer at the National Renewable Energy Laboratory. Nuclear energy (which does not contain carbon but is not renewable) can play a similar role, although costs, waste problems and public perceptions have limited its deployment.

Modern geothermal power plants have been operating in the United States since the 1970s. These plants usually pump hot water or steam from underground to the surface to move the turbine and generate electricity. The water is then pumped back to maintain the ground pressure so that the process can continue.

The main geothermal sites share certain characteristics: heat, rock with cracks in it and water, all close to each other and within a few miles of the surface. But so far the most accessible geothermal resources – in the US, they are largely concentrated in the west – have been used. Although researchers believe that there are still many potential objects that have not yet been found, it is difficult to understand where they are. And in much of the eastern United States and many other parts of the world, underground rocks are not the right type for traditional plants to work, or the water is not there.

Some researchers and start-ups are trying to expand geothermal energy to new locations. With EGS, they try to project what is underground by pumping liquid down into an impermeable rock to open cracks. This creates a space where water can move freely and heat up, producing the steam needed for power. The process has the potential to cause earthquakes, as early projects in South Korea and Switzerland have shown. However, EGS is similar to fracking, which is widespread in the United States and the risks are likely to be manageable in most places, Robbins said.

This approach can extend geothermal energy to places that do not have the groundwater or rock types needed for traditional plants.

However, accessing these resources will not be easy. Commercial drilling usually does not go much deeper than seven kilometers (four miles) – for cost reasons, often even less than that – and many places that could benefit from geothermal energy are not enough hot at this depth to reach 150 ° C required for economical electricity generation. Reaching sufficient temperatures can mean deeper, which will require new techniques and technologies that can withstand high heat and pressure.

Courtesy of DOE Geothermal Technologies Office

Fervo is developing some of these details in its own projects, including one announced earlier this year by Google to install geothermal power near the company’s Nevada data centers. He also recently joined a DOE project in central Utah called FORGE (Frontier Observatory for Research in Geothermal Energy).

FORGE’s academic and industrial researchers are trying to find best practices for implementing EGS, including drilling and reservoir maintenance. The site was chosen because its geology is quite representative of the locations where other EGS installations can be built in the United States, said Lauren Boyd, EGS program manager at DOE’s Geothermal Technology Service.

With the new funding from the Infrastructure Bill, DOE will fund four additional demonstration sites. This will broaden the researchers’ understanding of the creation of EGS facilities, as they will be able to work in different places and with different types of rocks. At least one plant will be built in the eastern United States, where geothermal energy is less common.

But technological barriers are not all that have slowed the progress of geothermal energy, said Susan Hamm, director of DOE’s Geothermal Technology Service. The construction of a geothermal power plant can take up to a decade due to all the necessary permits. Streamlining this documentation could almost halve this time and double the projected geothermal capacity by 2050.

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