Sunday, October 07, 2007
The Way the Wind Blows
How could we store surplus wind power? There is a solution right under our feet.
No wind: As I was travelling on the train along the North Wales coast last Friday, I had a fine view out to the North Hoyle Offshore Wind Farm. It's a great sight all these turbines, each rated at 2 megawatts, like rows of white statues far out in Liverpool Bay. But there was a problem: it was a fine sunny day and no wind at all. The sea was like a millpond and the turbines were indeed like statues for they were motionless. Electrical output zero.
Achilles Heel: And that is wind power's big problem. It only works when the wind blows so if we relied upon wind power, on fine calm days, there'd be no power at all. This is unacceptable, of course, in our modern, energy-hungry world. But now, there's a solution and its name is CAES: compressed air energy storage. Put simply, when the wind blows during the night, wind turbines generate power which is not needed since most people are asleep. If you use that power to pump air at high pressure deep into the ground, that high pressure air can be stored and later released when power is needed, driving modified gas turbines and generators.
It works too! If you think this is unlikely to work, it already does, and much more is underway. The first CAES plant came on stream in 1978 in Huntorf, Germany and a second much larger one was commissioned in 1991 in Alabama, USA. It stores its compressed air in a mined-out salt dome 80 metres across and 300 metres tall, lying 450 metres below ground, and can use the air to supply a turbine generating 110 megawatts of electrical power continuously for some 26 hours.
Giant battery: So just like hydroelectric pumped storage, wind powered compressed air storage could act like a giant battery, evening out fluctuations in demand by topping up the grid when needed. There are plenty of geologically-suitable locations all over the world so maybe we should push politicians and utilities to get moving on CAES. To find out more, read this New Scientist article and this Treehugger piece.