World's first underwater air energy storage system launched

New technology could address intermittent renewables supply

Canadian firm Hydrostor has installed the world’s first underwater compressed air energy storage system.

The technology, located 2.5 km offshore in Lake Ontario in Canada, with a mechanical facility on nearby Toronto Island, is designed to store electricity during off-peak hours when demand is low, and return the stored electricity during times of high demand or during short-term power outages. The technology is unique in that it uses compressed air and the pressure of water to run its system, and produces zero emissions, said Hydrostor.

The technology works by running electricity through a compressor and converting it into compressed air. The compressed air is sent underwater where it is stored in large balloon-like structures. When electricity is needed again, the weight of the water pushes the air to the surface through an airline to an expander which converts the air back into electricity.

Hydrostor said that advantages of the technology included capital costs less than half of competing li-ion battery technology, with over twice the cycle life, and far less environmental impact than pumped hydro. Hydrostor said it offered greater flexibility and substantially increased siting options compared to pumped hydro or cavern-based compressed air solutions, and was commercially available using proven equipment from 5MW/30MWh up to over 100MW/1,000MWh.

Curtis VanWalleghem, Hydrostor’s chief executive, said: “This demonstrates our ability to assist utilities in addressing peaking and reserve power requirements, as well as integrating intermittent renewable energy. The storage system combined with renewable energy provides an economically sound alternative to fossil fuel generation.”

Hydrostor will initially focus on developing projects in coastal cities, island nations and micro-grids. These projects could be stand-alone storage systems or combine storage with renewable generation.