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Case Studies

Analysis Proves Viability of ‘Green’ Compressed Air Energy Storage

Sproule constructed a 3D geologic model and 3D numerical simulation model to study the performance of a compressed air energy storage (CAES) project located in California. The project was completed on behalf of Worley Parsons and Pacific Gas & Electric Company (PG&E), along with funding from the US Department of Energy (DOE).

Project Highlights

  • The analysis involved a 9-step reservoir screening process for potential sites in California
  • Sproule created a full field model to simulate air injection and withdrawal in a depleted natural gas reservoir
  • The team designed, permitted and predicted performance of the CAES field-testing program, and analyzed the field test results and environmental impacts


  • PG&E wanted to understand the viability of storing compressed air underground. This process would use low-cost, off-peak electricity to compress air into a storage system in an underground space such as a permeable rock formation or salt cavern. When electricity is needed, the compressed air is withdrawn and used to drive a generator for electricity production.
  • The clients wanted to accurately predict withdrawal air/gas mixtures to avoid explosive compositions.


  • Sproule screened 12 potential sites to find the top two candidates
  • The Sproule evaluation used compositional reservoir simulation to model the mixture of injected air with in-situ methane remaining in a depleted gas field
  • The team built and calibrated two independent 3D simulation models for the top depleted reservoir candidates
  • They then prepared and ran the reservoir simulations for a 300-MW-by-10-hour CAES facility


  • The evaluation determined that this option provides an alternative ‘green’ energy solution for storing solar and wind power for Californians
Alan Burzlaff, P.E.
Senior Manager, Engineering

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