FROZEN AIR 'BATTERY' STORES WIND TURBINE ENERGY

http://news.discovery.com/tech/liquid-air-powers-wind-turbine-121003.html

Liquid air, which can be frozen, stored and warmed later, could work better than batteries or fuel cells to store energy from wind turbines or other renewables.

The technology was originally developed by Peter Dearman, a garage inventor in Hertfordshire, U.K., to power vehicles. For the past several years, U.K. tech firm Highview Power Storage has been working to transfer Dearman's innovation to a system that can store energy for power grids.

Dearman's idea works like this: electricity generated by wind farms at night is used to chill air to -310 Farenheit -- its cryogenic state -- turning it into a liquid. The liquid air is then stored in a giant vacuum flask until it time to be used again. This is done at night when demand for electricity is low and the energy from wind would otherwise go wasted.

When demand increases during the day, the air can be warmed to ambient temperature. As it vaporizes, it drives a turbine to produce electricity, according to the BBC's Roger Harrabin.

In July, Highview Power Storage signed a commercial agreement with a German firm to develop "frozen air" plants in Sub-Saharan and South Africa. And it now has a pilot facility near a traditional gas-powered plant outside London. That way it takes advantage of the plant's waste heat to warm the liquid air, making the entire process more efficient and less costly. Company officials say their energy-storage system is best designed to help smooth out the peaks and valleys of energy production that often occur with wind, solar and other renewable energy project.