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Drilling for Geothermal: DOD Expands Next-Gen Tech

May 15, 2024 by John Nieman

The Department of Defense will partner with private companies to develop advanced geothermal systems near military installations, advancing net-zero goals.

Geothermal energy, created naturally from the Earth’s heat, has lagged behind other renewable sources. It produces just .4% of total U.S. electricity and about 1% of the world’s electricity. 

Traditionally, this carbon-neutral energy source has been limited to geographic locations where natural heat sources like volcanic activity have been present. Advanced geothermal installations can be built in regions without such unique components. However, next-generation geothermal technologies can be costly and often lack funding. 

With funding from the Department of Energy, the Department of Defense’s Innovation Unit (DIU) is partnering with private companies to develop three geothermal energy projects at Army and Air Force facilities in four states. The DIU already has projects underway at two Naval facilities and an Army base. The installations will help power the military facilities and provide insights into strengthening grid resilience.

 

Utah’s FORGE site, the largest geothermal research project.

Utah’s FORGE site, the largest geothermal research project. Image used courtesy of DOE

 

Drilling for Geothermal

Geothermal energy has been used for centuries in places like Iceland, where volcanic activity created hot springs and allowed easy electricity generation. 

The next wave of advanced geothermal energy has circumvented the need for unique geographical features like volcanoes. Instead, these geothermal technologies capture the natural heat from deep within the earth’s core, which is constant and reliable.

One primary obstacle to reaching this heat is the drilling process, which is not only cost-prohibitive but can also trigger seismic events if not done with careful precision.

Deep drilling and the injection of fluids at high pressures can cause seismic events, altering subsurface stresses and potentially triggering earthquakes. Another risk is environmental contamination. Drilling can breach natural hydrological barriers, leading to the unintended release of subsurface gases and minerals, including hazardous materials like arsenic and lead, into groundwater supplies. 

 

Next-Gen Geothermal Technologies 

Enhanced geothermal systems (EGS) involve creating or enhancing a geothermal reservoir within hot rock formations that are initially low in permeability and porosity. The key method used in EGS is hydraulic fracturing, which involves high-pressure injection of fluids to create or expand fractures in the rock. This increases the rock’s permeability, allowing water to circulate through the fractures and absorb heat from the surrounding rock. EGS can be implemented in geological settings where hot rock is available but lacks natural water flow or sufficient fractures.

 

EGS development process.

EGS development process. Image used courtesy of DOE

 

In contrast to EGS, advanced geothermal systems (AGS) can encompass EGS but also use other innovative technologies and methods to exploit geothermal energy. These might include using supercritical carbon dioxide instead of water as a working fluid to extract heat, employing novel drilling techniques to access deeper and hotter geothermal resources, or integrating geothermal energy extraction with other mineral recovery processes.

In a 2023 report, the Energy Institute of The University of Texas at Austin stated that constructing 15,000 geothermal wells yearly for four years would produce the electricity equivalent of the entire oil and gas industry. 

 

Transforming Geothermal Infrastructure

The Department of Defense’s funding initiative will prove critical for expanding institutional support to facilitate geothermal growth. 

Through its partnerships with technology companies, the DIU will create projects at the Naval Air Facility in El Centro, California, the Naval Air Station in Fallon, Nevada, and the Army’s Fort Bliss in Texas. One company, Fervo, reported reaching a milestone at its Utah site, which can produce 3.5 MW of geothermal power.

These projects will catalyze research growth and advance net-zero carbon emissions goals while avoiding the potential political weaknesses associated with convoluted international supply chain problems.

The potential for geothermal technology has always been apparent, but this new government investment will help realize this potential.