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A-CAES Design and Feasibility Assessment Tools Development

Strategic Area

Smart Grid and Energy Storage




Sustainable Development Technologies Canada


Energy Innovation Program



EIP Contribution


Project Total

$ 2,048,468


Toronto, ON

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Hydrostor Inc.

Project Completion Public Report: Ontario A-CAES Project Development and General Design Advancement

Lead Proponent

Hydrostor Inc.

Project Background

This project advanced progress toward the final step in the Advanced Compressed Air Energy Storage (A-CAES) technology evolution. A-CAES is Hydrostor’s unique grid storage solution, which provides long-duration storage like pumped hydro, but has the key advantage of being able to be flexibly sited where the grid needs it, allowing the targeting of high-value and immediately available grid applications like transmission deferral and displacement of fossil-fuel based generation. The technology operates very similarly to a gas plant but is entirely non-emitting, is potentially much more cost-effective than batteries at scale with an estimated 50-year asset life, and is ideally suited to providing the long-duration storage resource necessary for decarbonizing the grid.

The main aim of this project was to advance critical technical development work associated with the deployment of a large-scale commercial A-CAES facility in Ontario. This involves design optimizations, development work, creating and validating broad feasibility assessment tools, advancing control strategy and plant controls optimization, and optimizing the topside and subsurface design and full-scale design basis.


A large utility owned site was chosen based on desktop geological studies, and a partial FEED was completed for the topside scope, advancing key FEED engineering deliverables including a Design Basis Memorandum (DBM), a permitting pathway outlining the permitting requirements, and a Class III Capital Cost Estimate. Vendor engagement for the turbomachinery equipment as well as other long lead items resulted in budgetary quotes and set the stage for a more efficient procurement process in the next phase of the project. One of the turbomachinery vendors engaged performed a turbomachinery engineering study which provided valuable inputs to the FEED. Using available desktop data, a preliminary subsurface feasibility report was completed, including a preliminary cavern design and cost and schedule estimate. These cumulative results provide a more informed and flexible reference design that will apply to potential A-CAES facilities going forward.

Benefits to Canada

Hydrostor is a proudly Canadian company and a leader in A-CAES. Hydrostor’s head office is located in Toronto and currently employs >30 full-time Canadian staff. Hydrostor’s existing projects have accounted for millions of dollars of economic development in Canada and the company has significant additional hiring and spending planned through its rapid growth, leading to job creation and employment of highly skilled labor. The outcomes from this project increased Hydrostor’s commercial readiness for wider deployment of a clean-energy technology that provides climate and health benefits through grid decarbonization and increased resiliency options. The development of a Canadian-grown technology and related Intellectual Property increases its export potential and attracts continued investment in a Canadian company from both outside and within Canada, which is demonstrated with projects currently in development in the United States, United Kingdom, Saudi Arabia, and Australia.

Next Steps

The work conducted on this project provides a strong foundation for future full-scale projects here in Canada, and abroad. The project learnings and deliverables have become an integral part of Hydrostor's commercial strategy and allow for a more efficient advancement of the development activities for future projects. For instance, to advance A-CAES technology and projects, the company is prioritizing the contracting of projects and development activities required to position these projects favorably to win contracting opportunities. The company is also undergoing an expansion of its team to ensure it can develop and deliver these projects successfully and continue to pursue commercial opportunities for A-CAES globally. Simultaneously, the company continues to focus on identifying technology and delivery improvements, continued advancement of a FEED, as well as the building out of its development pipeline such that the company can quickly accelerate its growth following the first facility reaching full commercial operation.

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