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Toronto Hydro and Hydrostor Inc. come together to launch the world's first underwater energy storage system


Technology harnesses the power of Lake Ontario to help boost electricity to the city

TORONTO, Nov. 18, 2015 /CNW/ - Located three kilometres off Toronto Island and in 55 metres of water, sits the first ever underwater compressed air energy storage system. Officially unveiled today, Hydrostor's system is connected to Toronto Hydro's electricity grid where it will remain until a two-year pilot study is complete. The project represents years of hard work designing and building the underwater storage unit and the onshore energy conversion centre. The system is expected to improve power quality and resiliency for island residents and engineers will be monitoring its performance through a variety of tests.

Hydrostor is a unique energy storage system as it uses compressed air and the pressure of water to run its system, and produces zero emissions. 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, made out of the same type of material used in marine lift bags to raise shipwrecks. When electricity is needed again, the weight of the water pushes the air to the surface through a large pipe and an expander converts the air back into electricity.

Energy storage systems are designed to store electricity during off-peak hours when demand is low and electricity is cheapest. Electricity can be released when the grid needs a boost, such as during times of high demand or during short-term power outages.

As Toronto Hydro is in the midst of a massive capital program to renew and upgrade its electricity system, the organization is actively exploring energy storage as a way to extend the life of some of its equipment. Hydrostor is the first energy storage project Toronto Hydro has been involved with that is located underwater.


  • At peak output the storage unit is capable of powering approximately 330 homes (660kW). Depending on how much power is drawn, the system can currently run for a little over an hour, although future expansion of the underwater air cavity will increase this duration.
  • The underwater compressed air energy storage system does not produce any carbon emissions and is expected to increase fish habitat.
  • Organizations involved in Hydrostor include:
    • Toronto Hydro
    • City of Toronto
    • ‎Ontario's Innovation Demonstration Fund
    • Sustainable Development Technology Canada
    • Ontario Centres of Excellence


Toronto Hydro owns and operates an electricity distribution system, which delivers electricity to approximately 747,000 customers located in the city of Toronto. It is the largest municipal electricity distribution company in Canada and distributes approximately 19% of the electricity consumed in the province of Ontario.

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"We're very excited to see this new technology in action.  Toronto Hydro has been very busy exploring new ways to power our grid, and I think this is the most creative project we've been involved in so far.  Supporting innovative solutions for Toronto's power needs will continue to be a focus for our organization."
-       Anthony Haines, President and CEO, Toronto Hydro

 "This event marks an important milestone for our company and we're thrilled to have the world's first underwater compressed air energy storage system in service. We're now focused on commercializing this technology globally to bring our green energy storage solution to countries around the world."
-       Curtis VanWalleghem, CEO, Hydrostor Inc.

"It's incredibly rewarding to see a technology and a company that we supported in the very early stages evolving the way Hydrostor has. This is truly a game-changing made-in Ontario system that has tremendous potential on a global scale."
-       Dr. Tom Corr, President and CEO, Ontario Centres of Excellence

"Hydrostor working with Toronto Hydro shows how utilities are beginning to re-imagine electrical distribution. Low–cost energy storage, situated in the downtown core, is a totally new kind of energy asset – one that enables a more responsive, efficient and intelligent grid."
-       Tom Rand, Senior Advisor, MaRS Cleantech and Managing Partner, ArcTern Ventures

"The world's first underwater compressed air energy storage system, which we're celebrating today, is a great example of the global impact Ontario-based companies can make when they have the support and resources they need to become world-leading innovators. We look forward to seeing the global reach of this innovative technology."
-       The Honourable Navdeep Bains, Minister of Innovation, Science and Economic Development


SOURCE Toronto Hydro Corporation


Video with caption: "Video: Underwater Energy Storage in Toronto". Video available at: https://www.youtube.com/watch?v=GicQwXbNnv0

Image with caption: "Air bag installation 2: Hydrostor prepares to install one of the air accumulators in Lake Ontario (CNW Group/Toronto Hydro Corporation)". Image available at: http://photos.newswire.ca/images/download/20151118_C8774_PHOTO_EN_548186.jpg

Image with caption: "Hydrostor energy conversion centre 2: Hydrostor’s on-shore energy conversion centre (CNW Group/Toronto Hydro Corporation)". Image available at: http://photos.newswire.ca/images/download/20151118_C8774_PHOTO_EN_548188.jpg

For further information: Tori Gass, Communications and Public Relations, 416-903-4037, media@torontohydro.com; 24-hours media line: 416-903-6845, media@torontohydro.com
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