Researchers at the University of Nottingham in the UK are currently testing the Energy Bag, a large inflatable energy storage device submerged in water’s off Scotland’s Orkney Islands.
Researchers at the Massachusetts Institute of Technology floated a similar idea last year using hollow concrete spheres instead of inflatable bags as a storage vessel. Now the idea of harnessing compressed air on the seafloor is going beyond the drawing board with the current testing off Orkney.
A company Thin Red Line is making the inflatable energy storage bags. They also make the inflatable structure for the Bigelow Aerospace space stations.
Thin Red Line Aerospace Design Engineer and CEO Maxim de Jong inspects the Energy Bag during initial test inflation (photo Keith Thomson/Thin Red Line Aerospace)
At a depth of 600meters, a 20meter-diameter bag could store around 70 megawatt hours of energy, the equivalent of roughly 14 hours of energy generation from one of the world’s largest offshore wind turbines.
Hydrostor, a Canadian company based in Toronto is currently developing similar underwater compressed air energy storage. The company plans to begin construction on a grid-connected, 4-megawatt-hour pilot project under Lake Ontario this summer.
Toronto-based startup Hydrostor ran a pilot of its underwater compressed air energy storage (CAES) technology last summer and with partner Toronto Hydro will construct a 1MW, 4MWh demonstration facility about 7 kilometers from Toronto’s shore later this year.
This rapidly deployed, low cost system uses non toxic substances with minimal environmental disturbances while offering 70% round trip efficiencies without the need for additional fossil fuel heat.