Utah geothermal project hits a milestone, pumping water through deep granite

Utah FORGE scientists connect two deep wells that could one day generate a continuous flow of hot water to produce power.

(Rick Egan | The Salt Lake Tribune) The Drill site for Utah FORGE, the nation's largest geothermal experiment, north of Milford, in Beaver County, on Thursday, July 6, 2023.

This story is part of The Salt Lake Tribune’s ongoing commitment to identify solutions to Utah’s biggest challenges through the work of the Innovation Lab.

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Utah FORGE, the nation’s most advanced effort to produce energy from the earth’s core, reached a significant milestone this week when it successfully pushed water through an underground reservoir 1½ miles below the surface.

The University of Utah-managed project north of Milford in Beaver County, funded by more than $200 million from the U.S. Department of Energy, is DOE’s foremost experiment in what is termed “enhanced geothermal systems.” Geothermal energy from hot springs has been captured to produce electricity for decades, but that can only be used where hot springs are available.

Enhanced geothermal systems require drilling deep into hot, dry rock to pull some of that heat out. If such systems can be made practical and affordable, there are locations worldwide where the geology is favorable. Ten miles north of Milford is one of the best.

Utah FORGE researchers drilled two deep wells and then broke up the rock between the two wells using fracking technology from the oil and gas industry.

After fracturing rock from both wells, the scientists for the first time this week were able to push water down one well into the fractures and see water come up through the second well.

“We do have some connectivity between the two wells,” said John McLennan, a University of Utah chemical engineering professor and a co-principal investigator of Utah FORGE, during a tour of the site Wednesday.

(Rick Egan | The Salt Lake Tribune) John McLennan talks about Utah FORGE, the nation's largest geothermal experiment, north of Milford, in Beaver County, on Thursday, July 6, 2023.

The news brings the project one step closer to the goal of providing a continuous flow of hot water that can produce electricity.

Utah FORGE sits in an area of Beaver County that has become a hotbed of renewable energy. Farther up the hill is PacifiCorp’s Blundell plant, a conventional geothermal project fed by a hot spring. Surrounding the site are solar farms and windmills, and a private company, Fervo Energy, is also pursuing an enhanced geothermal project a short distance away. Even the nearby pig farms produce energy by extracting methane from the waste.

“I don’t think there’s another place like this in the world,” said Joseph N. Moore, a U of U civil and environmental engineering professor who oversees Utah FORGE.

The site was chosen six years ago after a national competition because it had lots of dry granite sitting above a large pool of magma. Nearby are long-dead volcanoes and Roosevelt Hot Springs. It also has access to water that, because of its mineral content, can’t be consumed by humans or animals but can be used to pump into the ground and capture heat.

(Rick Egan | The Salt Lake Tribune) Joseph N. Moore describes the work done to drill through more than a mile of hot granite. Thursday, July 6, 2023.

Moore describes FORGE as a “de-risking” laboratory, and all experimental data is made public in an effort to encourage more development. There are no large-scale working enhanced geothermal systems, and that is because of huge costs involved in drilling into granite with diamond-tipped drill rigs that cost $70,000 a day to operate.

Because the temperatures exceed what are normally seen in an oil and gas drilling project, Utah FORGE also has to develop new equipment and materials that can handle temperatures reaching more than 400 degrees. The heat has destroyed the plugs and seals normally used in drill projects.

“Fracking” is shorthand for hydraulic fracturing, a process that has dramatically increased U.S. production of oil and gas, turning the nation into an oil and gas exporter instead of importer. Fracking means pumping high-pressure fluids into wells to fracture the rock. The drilling crew working on the FORGE site this week will be moving to an oil and gas drilling operation elsewhere in Utah in a few weeks.

(Rick Egan | The Salt Lake Tribune) Workers connect segments on the drill site for Utah FORGE, the nation's largest geothermal experiment, north of the town Milford, in Beaver County, on Thursday, July 6, 2023.

But fracking for heat is substantially cleaner than oil and gas fracking, which produces massive amounts of wastewater while also greasing underground plates, causing earthquakes. Seismicity is closely monitored at the site, but only tiny movements have been recorded.

Fracking is especially fruitful when combined combined with another recent technology, horizontal drilling. Instead of just going straight down, drill rigs can now go down and turn sideways, meaning a well can pull more oil and gas from a shallow but wide underground deposit.

Both technologies are in use at Utah FORGE. The two wells go down 5,000 feet, and then bend 65 degrees and continue down to 8,500 feet. The whole length of the wells is about 11,000 feet. The “reservoir” is the extensive system of cracks produced from the fracking but still isolated from any outside water by surrounding rock. And the water pumped through can be reused continuously in a closed-loop system.

Derisking has also meant learning how to drill faster. They have tested various drill bits, and are now chewing through granite five times faster than they were when they started, McLennan said.

(Rick Egan | The Salt Lake Tribune) One of the early, rotating drill bits at the drill site for Utah FORGE, the nation's largest geothermal experiment, north of Milford, in Beaver County, on Thursday, July 6, 2023. Later non-rotating bit models were found to drill much faster.

In this week’s test, the scientists pushed a few thousand gallons of water in. For the system to be commercially viable, they will need to get to hundreds of gallons per minute, Moore said. Current DOE funding continues through 2025, and Moore expects they will apply for more to continue after that.