The U.S. Air Force has awarded its first contract to determine whether a power plant using geopressured geothermal systems, or GGS, can generate the clean energy needed for a base to achieve energy resilience.
The contract awards Sage Geosystems a grant of $1.9 million, which the company will match with its own funding, to develop a demonstration project at an off-site test well in Starr County, Texas, in 2025.
Unlike traditional geothermal techniques that rely on geological formations of hot water and steam that limit their use, GGS repurpose fracking technology to extract thermal energy from miles below the Earth’s surface.
If successful, the demonstration could lead to a full-scale project at Ellington Field Joint Air Reserve Base in Houston, Texas. Sage has been working with the University of Texas to develop its technology and study the geologic feasibility of a power plant at Ellington Field.
“This initial contract is a step forward in the Department of the Air Force’s push for energy resilience,” said Kirk Phillips, Director of the Air Force Office of Energy Assurance. The OEA is managed by the Air Force Civil Engineer Center, a primary subordinate unit of the Air Force Installation and Mission Support Center.
“If the demonstration proves successful, this project could help improve Ellington Field’s ability to maintain operations during electrical grid outages. The installation has the potential to be completely self-sufficient for its energy needs,” Phillips said. “This project, and the future projects it could pave the way for, could help ensure that national security needs are met by our installations during critical emergencies.”
With GGS, power plants can harvest not only the heat energy from the water in the fracture, but also the energy created by pressure as water is pumped into the fracture. Ellington Field’s 147th Attack Wing is eager to be the first to take advantage of the new technology.
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“The wing is excited to demonstrate the first Geopressured Geothermal System in the Air Force,” said Lt. Col. Christian Campbell, Commander of the 147th Civil Engineer Squadron. “To be 100 percent resilient and carbon free would be an amazing feat. For the 147th Attack Wing to be the baseline, and showcase this amazing technology to the DoD, makes us proud.”
It wont be Sage’s first foray into Electric Reliability Council of Texas (ERCOT) territory. Last month, the company announced the location of its “first-of-its-kind” project, which would be the first geothermal project in ERCOT territory.
Sage entered into a land use agreement with San Miguel Electric Cooperative Inc. (SMECI) for the 3 MW GGS energy storage facility. The 3 MW EarthStore system will be in Christine, Texas near the SMECI lignite coal power plant. Sage will operate as a merchant, buying and selling electricity to the ERCOT grid. Later this year, Sage will launch the EarthStore facility, which it says will utilize the earth’s “natural capacity for energy storage” to produce dispatchable electricity on demand through a power source that works independent of weather conditions.
The facility will use Sage’s proprietary technology to store energy, targeting 6-to-10-hour storage durations and delivering a round-trip efficiency (RTE) of 70-75%, Sage said. In addition, water losses are targeted to be less than 2%. At scale, this energy storage system will be paired with renewable energy to provide baseload and dispatchable power to the electric grid. When combined with solar power, Sage’s EarthStore facility enables 24/7 electricity generation at a blended Levelized Cost of Energy (LCOE) well under $0.10/kWh, it said.
Sage has been making moves outside of Texas as well. The company also just announced the signing of a Memorandum of Understanding (MOU) to establish a collaborative framework for pursuing commercial projects and joint funding opportunities related to subsurface energy storage and geothermal power generation in California. The strategic partnership between Sage and CRC will focus on developing clean and reliable energy solutions in the State of California.
Geothermal electricity generation taps high-energy-content steam at temperatures of 300-700 degrees Fahrenheit and requires drilling to depths that are as much as tens of thousands of feet below the surface.
The process works by drilling sets of both injection wells and production wells. Cold water is pumped down the injection well and then flows through the geothermal reservoir to the production well. The water returns to the surface at a high enough temperature for the energy to be captured at the surface and enter an electric generation cycle.
Originally published in Power Engineering.
