Toronto Hydro and energy storage company Hydrostor of Toronto are testing a unique underwater energy storage system that will use compressed air stored in balloons under Lake Ontario. The pilot project is expected to provide enough electricity to power 350 homes. Toronto Hydro said that it has been exploring new ways to power its grid and this was the most creative project the company has been involved with so far. It is being called the world’s first underwater energy storage system.
Compressed air is stored in balloon-like structures similar to ones used in salvaging shipwrecks. The balloons, or accumulators, are located three kilometres offshore from Toronto Island, 55 metres below the surface. Pipes have been laid connecting the balloons and allowing the stored air to be pumped back to land using hydrostatic pressure. The pressurized air then powers a turbine to generate electricity. The system is a variation on the so-called pumped hydro model in which water is pumped uphill, stored, and allowed to flow downhill to power a turbine when needed.
The Hydrostor system also uses heat exchangers to reduce the amount of energy lost as the air is stored in the cold water. No emissions are produced and no toxic substances are used in the system.
Hydrostor CEO Curtis VanWalleghem said that his system costs less than half as much as the best batteries available, and lasts twice as long. It can also be paired with wind or solar power systems which are notoriously dependent on atmospheric conditions to function.