Catching a Breeze

June 4, 2017
By Damond Benningfield

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Offshore wind turbines in Germany. Credit: US Department of Energy

New wind-power turbines are popping up off the European coast so quickly these days that it’s hard to keep track of them. By the middle of 2016, more than 3300 offshore turbines had been connected to power grids, supplying enough energy to meet the needs of several million homes.

The main problem with these turbines, of course, is that when the ocean breeze dies down, the electricity is gone with the wind. But several groups are testing ways to store energy to keep the electrons flowing even when the wind isn’t.

A German company, for example, is testing a system that would store energy by using ocean water. It would store water in giant concrete spheres on the ocean floor.

When the wind is blowing, the wind turbines would power pumps to force the water from the spheres back into the ocean. But when the wind stopped blowing, valves would open to allow the water back in. The water would drive turbines in the spheres to replace some of the energy taken away by the calm winds. The spheres could be located at depths of almost half a mile, where the water pressure would drive the turbines at high speeds.

The company says that a sphere a hundred feet in diameter could store about 20 megawatt-hours, and each wind farm would consist of many spheres. A small-scale version of the system was tested in a lake in late 2016. That’s expected to be followed by a larger demonstration in the open ocean -- perhaps eventually leading to a way to catch the energy of an ocean breeze.