Can Wind Power Be Stored?

Wind farms typically generate most of their energy at night, when most electricity demand is lowest. So a lot of that “green” energy is wasted.

So the big question is: How do you bottle that power for air conditioners and other appliances that are busiest during the day?
There are many companies moving to fill the energy gap. Using federal loan guarantees and $4 billion in “smart grid” stimulus cash, they are working on utility-scale storage units that they hope will help balance intermittent renewable sources like wind and solar and let electric grid operators match power supplies with demand.

Among the leaders is a Massachusetts company that plans to use hundreds of “flywheels” to store 20 megawatts of electricity, enough to power 200 homes for a day. Beacon Power Corp. is working with a $43 million federal loan guarantee for its $69 million storage project in Stephentown, N.Y., which is scheduled to break ground by year’s end.

The plant would store cheap “off peak” electricity in 2,500-pound flywheels that turn faster than the speed of sound. When the electricity prices rise — or when winds die — energy can be withdrawn from the wheels and sold to the grid at a premium rate.

“It will signal a dramatic shift to a cleaner, more sustainable method of providing frequency regulation on the grid,” Beacon CEO Bill Capp told the GridWeek conference in Washington last week.

Scientific American