Compressed air to be used for energy storage

With green energy companies bursting with ideas to find an answer to our energy needs that don’t involve carbon combustion and greenhouse gases, the latest technology gaining attention is energy storage. Storing energy means it can be collected at times when renewable sources like wind turbines or solar farms are active and producing. The energy can then be released at high demand times when the wind isn’t blowing, or when the sun is hidden behind the clouds.

One Toronto company is proposing a new energy storage technology that uses compressed air to store energy. Hydrostor’s system uses large inflatable balloon-like bags to store the air under water. Said to be ideal for cities, which are often located near lakes and large bodies of water, the system entails transmitting surplus power, say at night, through an underwater transmission line to an offshore floating platform. The electricity compresses the air to the same pressure as near the seafloor and stores it in the submerged inflatable bags (“flexible accumulators”). These can be stored 50-500 metres below the surface. Any heat produced during the compression process is stored on the platform.

When the power is required, the process is reversed: the air is released, pushes upwards and drives a generator. About 70% of the input energy is recovered.

A Hydrostor demonstration planned for Toronto will produce 1 MW/4 MWh and is set to start in summer 2013. It will be located approximately 7 kilometres offshore.

Another company, General Compression, is working on a system that will store compressed air deep in underground caves or even old mines.

With Canada now attaining sixth place globally in terms of its total installed wind capacity (5,700 MW) — according to a just-released report by Industrial Info Resources — energy storage could become an important component of the energy industry.

See also an article about pumped hydro energy storage in the December 2012 issue of Canadian Consulting Engineer, written by Richard Donnelly and Francois Welt of Hatch. Click here