A new study by Penn State researchers proposes enhancing compressed-air energy storage (CAES) by utilizing geothermal heat from depleted oil and gas wells. The simulation study found that the geothermal-assisted CAES system improves efficiency by 9.5% compared to existing methods, allowing for greater energy recovery and potentially increasing profitability.
By repurposing abandoned oil and gas wells, of which the US has an estimated 3.9 million, this approach eliminates the high upfront costs of drilling new wells, making CAES more feasible. The natural heat from underground rock formations raises the temperature and pressure of the stored compressed air, allowing the system to store and release energy more efficiently. When electricity demand is high, the stored air is released to drive a turbine, generating power.
According to lead researcher Arash Dahi Taleghani, SPE, this method addresses key economic and technical barriers to CAES adoption. Additionally, repurposing old wells could help prevent methane leaks from improperly sealed sites, reducing environmental hazards. This strategy also presents economic opportunities by maintaining jobs in regions with established energy industries.
The study, conducted under Penn State’s Repurposing Center for Energy Transition and supported by the US Department of Energy, highlights how integrating geothermal energy with CAES can enhance grid stability and support the renewable energy transition. The findings were published in the Journal of Energy Storage.
“If we use existing wells, we are basically hitting two birds with one stone,” Taleghani said. “First, we are sealing these wells. That stops any potential leaks. And then if we are repurposing these wells for energy storage, we are still using the infrastructure that is in place in these communities. It can potentially maintain employment in the area and allow communities to be part of the energy future.”
Research contributors from Penn State include Derek Elsworth, G. Albert Shoemaker Chair in mineral engineering and professor of energy and geo-environmental engineering, and Qitao Zhang, SPE, a postdoctoral scholar, both in the John and Willie Leone Family Department of Energy and Mineral Engineering.