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Aug 12, 2023

West Kern energy project would turn depleted oil reservoir into synthetic geothermal storage

Bakersfield-based Premier Resource Management LLC proposes to build a

Bakersfield-based Premier Resource Management LLC proposes to build a 10-megawatt, $100 million geothermal energy storage facility in western Kern, then expand it to generate 400 megawatts at a cost of $1.8 billion.

Western Kern's legacy oil fields have gained new interest recently as a place to bury carbon dioxide. But what about also using the area's ample underground geologic formations to store energy for the state power grid?

A Bakersfield company is working with federal scientists to develop a plant in Antelope Hills that would use parabolic mirrors to focus sunlight on groundwater that would be injected hot into an underground reservoir. Later, when the power is needed, steam from the hot water would run a turbine connected to an electrical substation nearby.

An initial, $100 million demonstration project planned to debut no sooner than 2025 would produce 10 megawatts of electrical power for five hours nightly. If all goes well, it could grow to 400 megawatts at a cost of $1.8 billion.

Premier Resource Management LLC's project could represent a novel innovation in Kern's increasingly diverse energy mix. The National Renewable Energy Laboratory, one of several partners on the project, notes similar geothermal power projects have worked in the United States and Europe for decades, but none have deployed a depleted oil and gas reservoir.

The company says the project would displace petroleum-fed "peaker" power plants with a zero emission, closed process that uses brackish groundwater already in place and creates minimal waste. If the concept were expanded across California oil fields, it says, the technology could shoulder a significant share of the state's power during times of peak demand.

"We believe the oil fields could meet roughly half California's 2045 long duration energy storage goals — with 45 gigawatts of potential on the west side (of Kern) alone," Mike Umbro, corporate development partner at Premier, said by email.

There are some limitations: It would take about 15 months to heat the reservoir enough to generate power efficiently. Also, if it were run nonstop for as long as 40 days, the operation would take months to reheat.

A March 9 post by NREL on its website spotlighted its partnership on the project, together with the U.S. Department of Energy's Geothermal Technologies Office, the Lawrence Berkeley National Laboratory and the Idaho National Laboratory. It said the work would help with decarbonization of the power sector while supporting diversity, equity and inclusion "if adopted in communities most impacted by high heating and cooling bills."

"Not only will utilizing this resource promote significant cost savings," NREL said in the post, "but it will also encourage oil and gas industries to participate in the transition to a decarbonized energy economy by leveraging existing capital and assets."

Kern County government's top energy permitting official, Lorelei Oviatt, said by email she had no applications for the project and withheld comment.

Premier said its biggest permitting concerns lie with the state's primary oil regulatory agency, the California Geologic Energy Management Division, whose project reviews it noted have slowed in recent times. The project as proposed would require aquifer exemptions and underground injection permits.

The company wants to put in 37 geothermal wells, a 60-acre solar array and a series of tanks for separating and cleaning water. It estimates the plant would last more than 50 years. The plan is to connect it to a nearby substation and power transmission line owned by Pacific Gas and Electric Co.

Unbro noted Premier started raised money in 2020 and continues to look for state and federal financial support.

"There are many private investors seeking clean energy projects, particularly with California's climate actions moving at an amazing pace," he wrote.

Energy storage has proved to be a tricky but critical element to meeting California's renewable energy goals. When solar and wind energy come offline with demand still peaking, the state wants more than just batteries to keep the lights on. Other forms of large-scale storage, like compressed air and pumped hydro — both of which have been proposed locally — come with hefty price tags and unique sets of pros and cons.

Geothermal energy has traditionally used steam from hot rocks to run turbines. While much capacity remains to be tapped, according to federal estimates, there are drawbacks such as unwanted emissions and limited transfer capacities.

Resource says a benefit of so-called geothermal energy storage, or GeoTES, such as the company proposes, is that it can store immense heat that can be transferred to electricity generation at a virtually unlimited rate.

It expects to complete environmental surveys and plan mitigation this year while beginning an aquifer exemption and injection permitting process it hopes to finish next year.

Business editor John Cox can be reached by phone at 661-395-7404.

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