Toronto Island Energy Storage Facility

Technical Demonstration, Research & Development

With the completion of the Toronto Island Demonstration Facility in 2015, Hydrostor developed the worlds first, grid connected adiabatic-CAES facility with utility host Toronto Hydro. The purpose of the facility was to demonstrate the technology and provide an ongoing testbed, with a potential long-term role as reserve power for Toronto Island. The facility was commissioned in 2015 and demonstrated A-CAES’ ability to play a significant role in the long-duration energy storage market globally. 



  • The viability and benefits of a hydrostatically compensated air storage, which includes a near constant pressure regardless of charge state and a reduced storage volume. For this purpose, the air was stored in underwater air storage vessels approximately 180 feet below the surface of Lake Ontario.
  • The ability to use standard, off the shelf compressors and turbines in a constant pressure compressed air energy storage process.
  • The performance of an adiabatic process in terms of round trip efficiency, response time, ramp rate, and cycle life.