Cave ‘batteries’ will store wind power

For Uninterrupted Supply, Air Compressed Into Special Caverns Will Run Turbines Even When It’s Less Windy

Dominic O’Connell

Promoters of wind-power projects tout them as the feel-good alternative to burning fossil fuels. Energy secretary Ed Miliband seems to agree, saying last week that it should become “socially unacceptable” to oppose new windfarm developments in your area.

Wind power has an Achilles Heel, however. It is fickle — as fickle as the wind. Energy planners who have to make sure the lights don’t go out cannot guarantee power will arrive, no matter how many turbines are built. Conventional power plants, probably run on coal or gas, have to be ready to pick up the slack if the wind doesn’t blow. Now two British companies are putting money into a technology that could overcome this problem. Electricity from wind farms will be used to compress air, which will be stored in caverns below ground. When power is needed, the compressed air will be released, driving turbines to generate electricity.

If the technology works, energy planners will be able to rely on power from wind farms when it comes to planning the next day’s output — and the plants that burn fossil fuel can be stood down. Such a development could be critical to Britain, which wants to increase wind power tenfold by 2020, as part of the government's plan to have 35% of electricity generated from renewable sources.

The compressed-air technique may sound far-fetched, but it is already in operation. At Huntdorf in Germany, a 290MW plant — powerful enough to run 290,000 homes — has been running for 25 years. A 110MW facility at McIntosh, Alabama, opened in 1991. Neither stores wind power, but excess production from conventional stations. They were built to store electricity generated at periods of low demand, with it being sold to the local grid when whenever demand surged.

Sirius Exploration, a group quoted on the Alternative Investment Market, London’s junior stock market, has a huge stake in an ambitious power-storage project in North Dakota. The state is America’s windiest, and power from the it is destined for mid-western cities, including Chicago.

Sirius has invested in an American company, Dakota Salts, which has a lease on 5,000 acres of salt pan. It plans to mine potash found in deposits beneath the surface, leaving behind caverns that have the ideal geology to store compressed air. The technique will allow wind farms to take on the characteristics of conventional power plants. SUNDAY TIMES

WINDFALL: Underground caverns to hoard energy will allow wind farms to take on the characteristics of conventional power plants