Toronto Hydro Pilots World’s First Offshore Compressed-Air Energy Storage Project
A set of pipes running nearly two miles out into Lake Ontario are part of a novel project to help Toronto Hydro extend the life of its distribution equipment.
The two-year pilot is not another tidal energy project — it’s the first test of an underwater compressed-air energy storage system by Ontario-based startup Hydrostor. The company uses off-the-shelf technology to pump air into underwater balloons. When energy is needed, the air can be released from balloons and expanded to create electricity.
The pilot project will help Toronto Hydro defer distribution investment by providing peak electricity. But the near-term market opportunity for Hydrostor is in displacing backup and peak generation sources like diesel or coal. Depending on the success of the Toronto pilot in the next few months, Aruba also has a pending contract for Hydrostor’s technology.
“We are able to work more like a developer,” said Curtis VanWalleghem, CEO and co-founder of Hydrostor. “We can make a brisk business doing a few projects a year.”
By not manufacturing anything, VanWalleghem said Hydrostor’s costs are far lower than other compressed-air energy storage startups, such asLightSail.
The company uses drilling techniques that reduce the demand for boats and cranes at the surface to deploy the pipes and balloons. VanWalleghem said the installation of the underwater balloons, which are slight modifications of the ones used for marine salvage, requires only one tugboat. Although Hydrostor has streamlined the installation and reduced costs, it requires some serious permitting. The pilot in Toronto, for example, required 17 permits.
Back on land, electricity runs a compressor to produce the compressed air. During that process, waste heat is captured and could be used to increase the round-trip efficiency from about 60 percent to as high as 80 percent.
The compressed air is pressurized to match the pressure at the ocean floor where the balloons are located. The air is then pumped down to fill those balloons. When electricity is needed, the system goes into reverse mode and the weight of the water pushes the air back to land, where it is converted back into energy.
The balloons will come with at least a 10-year warranty, and that could be expanded to up to 20 years after the pilot.
