A cunning plan to store energy underwater may help fulfil the promise of wind power
THE problem with wind power is that is cannot always be relied upon. The wind—and other transient, environmental energy sources such as solar—must either be used when it is harvested or stored expensively in batteries or specially designed hydroelectric schemes that use the resulting energy to pump water uphill. Alternatives would be extremely welcome. Alexander Slocum, of the Massachusetts Institute of Technology, thinks he has one. Observing that the fashion among wind-power fans is to build turbines out at sea, where the wind blows strongest, he proposes a pumped-storage system that uses seawater.
Dr Slocum’s scheme involves anchoring a hexagonal array of hollow, 31-metre-diameter concrete spheres to the ocean floor at a depth of approximately 350 metres. Floating turbines would be tethered to these spheres and surplus power from these turbines, generated during periods of high wind and low electrical demand, would be used to pump water out of the spheres, evacuating the central chamber. When the wind faltered or the lights went back on, water forced into the central chamber by the pressure of the surrounding ocean would pass through a turbine and generate electricity. Each sphere would provide a five megawatt turbine with four hours of storage capacity.
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