Sunday, October 07, 2007

The Way the Wind Blows

How it all works, from Treehugger

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.


Derek said...

A nice solution, much more efficient than generating hydrogen.
I'm a little uneasy about putting lots of pressure underground though.
I remember a clever car-jack that consists of a heavy plastic bag that attaches to one's exhaust. Whatever the weight of the vehicle, an idle engine will lift it.
I fear this may either change the landscape, or create cracks that will allow the air to escape.

Hydro has many potential benefits. eg.
- pumping to where it could be drawn off as drinking or irrigation water,
- the storage area (if large enough) will reduce temperature extremes in desert-like areas
- the water could also be released when rivers are getting low so as to preserve aquaculture.


Bry Lynas said...

Pressure underground is not a problem with properly-chosen sites. Remember that trillions of cubic metres of natural gas have been sealed underground naturally and often at very high pressures for millions of years. We're using these stored reservoirs now, of course, and a great deal is known about how to get gas (or air) in and out without loss. It's even possible to use the hydrostatic pressure of water (which usually naturally occurs below gas and oil in reservoirs) to keep the gas pressure constant. Pumping air in drives the water deeper; releasing it to drive turbines means the water rises again, maintaining the pressure. Very useful.

Umah said...

So wind turbines only work if there's wind. If not, nada, kaput zero! So why are global warming alarmists pushing for alternative fuels. Its not efficient!

kelley said...

LOVE the idea! with all the conveniences like time shifted tv viewing. It's like having a huge capacitor to store the energy for future use. Who thinks of this stuff?
Hey, we just launched a green site of our own! Check out our blog 'The WormFarm Chronicles'... Right now we're talking about worm composting in the dining room with her permission --