A University of Utah project is progressing toward developing new geothermal technology that could make the renewable energy of the Earth’s interior more accessible. That’s according to scientists with the Utah FORGE project, a geothermal laboratory northeast of Milford, Utah recently featured in Science. Utah FORGE scientists briefed U President Taylor Randall on the project during the second leg of the president’s Utah Across Utah tour.

Led by Joseph Moore, a research professor in the Department of Civil and Environmental Engineering, the $218M project was awarded to the U’s Energy & Geosciences Institute after a three-year, five-way competition, and is the university’s largest-ever research grant.

“This is a unique facility,” said Clay Jones, a geologist with Utah FORGE and the Energy & Geosciences Institute, who provided the overview of the project. “There’s nothing else like this in the world.”

Mining heat

Randall and the U tour entourage met with Utah FORGE personnel and Milford city officials at the Blundell Geothermal Power Plant, a conventional geothermal power facility located 10 miles north of Milford and about a mile east of the Utah FORGE site.

The Utah FORGE site itself doesn’t look like much on the surface. When crews aren’t drilling or working in test wells, the site looks like little more than a few seven-inch standpipes sticking up in a sagebrush-dotted valley that also contains a wind farm, solar fields and hog farms.

A mile and a half beneath the surface, however, the team is exploring a new way to mine heat from the hot subsurface rocks. By drilling wells and opening up fractures in the subsurface granite, the project aims to circulate water through an artificial geothermal system and expand the capacity of this renewable, carbon-free energy source.

The heat beneath our feet is an enormous, inexhaustible resource. According to Cornell professor Jefferson Tester and colleagues, tapping just 2% of the heat available at a depth of two to four miles would provide more than 2,000 times the U.S.’ annual energy needs.

Currently, the only way to access that heat and produce electricity is through conventional geothermal power plants built near naturally occurring hot springs, where heated water rises to the surface. These plants tap the water from depths greater than about 5,000 ft to harness the heat the water contains. The Blundell geothermal plant, in operation since 1984, sits on the Roosevelt Hot Springs geothermal system and produces enough electricity to power 38,000 homes.

But hot springs are too rare for geothermal energy to be widely used for electricity production. Only a few dozen geothermal plants are in operation in the United States, producing 3.67 gigawatts of electricity—less than half of one percent of U.S. power production.

An engineered geothermal system, though, could create geothermal energy in many more places. The Utah FORGE site sits above a mass of granite that’s hot and dry. The plan is to drill a pair of wells; one for injecting water into the reservoir and the second for producing (extracting) the water after being heated by the hot rocks. The cold water pumped into the injection well will travel through the fractured rock between the wells where temperatures exceed 400 °F (204 °C). The hot produced water can be used for generating electricity or even directly for a variety of other uses including space heating, aquaculture and food processing.

Project status

With a core of the drilled granite sitting on the table of the presentation room, the group was briefed on the project’s current status. Since 2017, a total of six wells have been drilled, the deepest of which reaches a vertical depth of 9,500 feet. In early 2021, the first deep deviated well—the injection well—was drilled to a depth of 8,559 feet and a total length of 10,987 feet. The well’s trajectory is like a bent, upside-down drinking straw. Drilling such a highly deviated well has not been done before by the geothermal industry.

In April 2022, the well was “stimulated” by opening fractures in the granite using a perforating gun, which fires projectiles into the rock. Focused down-well seismic monitoring shows “microseismic clouds,” that expanded as the fractures opened and the water moved away from the well.

Coming next, in early 2023, the team will drill a second deep, deviated well to serve as the production well. It will intersect the fractures already formed at the base of the injection well. New drilling techniques and newly designed diamond-coated drill bits have allowed the team to increase drilling rates from 11 ft per hour to approximately 100 ft per hour, cutting drilling times by 50% over the previous rates. This is a significant advancement considering drill bit changes can take most of a day and drilling costs can account for one-half of the total project cost.

Once the second well is completed, the team will begin pumping water through the entire closed-loop system. They’ll use non-potable water from an aquifer beneath the site that’s unsuitable for human consumption or agricultural use.

A better bet

Utah FORGE funding currently extends through July 2025, but leaves several milestones uncompleted. An extension through at least 2030 has been submitted, and Moore recently traveled to Washington, D.C. to educate Utah’s Congressional delegation about the project and the need for continued funding.

”Continuing the project is important,” Jones noted. Utah FORGE is the only facility of its kind in the world where tools and technologies for enhanced geothermal systems development exist.

What happens to Utah FORGE after the project is completed is unclear. Private geothermal companies are already showing interest in Utah FORGE’s work and have begun leasing property surrounding the site. It may be that one of those organizations steps in and continues the work. Otherwise, Utah FORGE is required by the property owner, the State Institutional Trust Lands Administration, to plug and abandon the wells and restore the site to its original condition.

After the presentation, Randall recounted the history of another Department of Energy experimental laboratory which was developed to explore energy production from nuclear fusion. Decades of research and innovation by top scientists to overcome monumental technical hurdles have so far produced limited results, he said. “My guess is this is a better bet than that one.”

Read more about Utah FORGE in the University of Utah Magazine and at the project website.