EERE Success Story—FORGE-ing Ahead with U.S. Geothermal

Geothermal energy, the “heat beneath our feet,” has the potential to provide enough power to supply more than 100 million U.S. homes around the clock. Most of that energy has been largely inaccessible, but that’s about to change.

American innovators and researchers are making progress exploring human-made geothermal reservoirs, which, along with technologies to capture and sustain this clean energy, are known as enhanced geothermal systems (EGS). Once mature, EGS technology will help the United States use a near-limitless resource across the country.

Conventional geothermal energy is typically harnessed where fluids, heat, and permeability—the ability for water to move through rock—coexist naturally in underground reservoirs. This combination is somewhat rare and restricted to certain geographic areas, but EGS technologies can produce energy nearly anywhere: Scientists could create a geothermal system wherever there is hot rock.

While EGS holds a lot of promise, it also faces technical challenges. That’s why the U.S. Department of Energy’s (DOE) Geothermal Technologies Office (GTO) established the Frontier Observatory for Research in Geothermal Energy (FORGE), a field laboratory in Milford, Utah, in 2018. At FORGE, researchers are  developing, testing, and improving technologies and techniques to create reliable EGS reservoirs.

In April, the Utah FORGE team conducted their first hydraulic stimulation. This process, which involves injecting fluid into rocks at high pressures to create new fractures, makes the rocks permeable and able to harness geothermal energy. Hydraulic stimulations are common in the oil and gas industry but have never been performed on a highly deviated well—a well at an angle exceeding 60 degrees for most of its depth—in the geothermal industry. Highly deviated wells enable better access to energy resources underground.

Though data is still being analyzed, initial results suggest the stimulation successfully created a geothermal reservoir. This is a key milestone in learning how to create a fully human-made geothermal reservoir that can be tapped to capture always-available electricity anywhere.

Once the precise boundaries of the new reservoir are located through data analysis, the FORGE team will drill a second full-size well in early 2023 into the new reservoir. The resulting well pairing is called a doublet; operators pump cold water down one well and hot water out of the other. The hot water pumped out of the reservoir carries the energy for electricity production. 

This doublet serves as the basis for the FORGE laboratory, where scientists can test their innovative EGS technologies and tools. In February 2021, DOE awarded $49 million to 17 research and development (R&D) projects to do just that, and projects are underway, as shown in the map below.

New R&D awards through FORGE fall into 5 categories: Devices suitable for use in high temperature wells Estimation of stress parameters Characterization of reservoir stimulation over time Specific stimulation and configuration at the FORGE site Integrating lab and modeling studies of the interactions among thermal, hydrological, mechanical and chemical processes.
FORGE R&D projects across the country

The FORGE initiative, including research, planning, drilling, and other site-specific development, is enabled by more than $200 million in federal investment, decades of public and private research, and the brilliant people working in geothermal energy. Geothermal energy is poised to make significant leaps with initiatives like FORGE and play a vital role in secure, domestic energy production. 

Learn more about the FORGE initiative and Utah FORGE site. For project updates and future FORGE research and development opportunities, sign up for The Drill Down, GTO’s monthly newsletter.

Source: U.S. Department of Energy, National Renewable Energy Laboratory

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