How To Store Electricity In Air

The idea was created by a self taught engineer Peter Dearman in his garage in Bishop’s Stortford, Hertford. Here is how it goes.
You use excess electricity to compress and cool air in a tank. so it becomes liquid. You then warm the liquid back into a gas, and as it expands, it drives a motor turbine to create more electricity.
This method is used when the demand for electricity is high and when it is low, the excess electricity is used to cool the air. so its more of a way of storing electricity than making electricity.
The key innovation is to store the excess heat given out when the air is compressed and use it to re-heat the liquefied air when it is needed.
The firm Highview tried it at a small scale and it has announced to do a grid-scaled 50MW plant that will be built in the north of England.
The grid-scaled project will be able to supply electricity to about 25,000 homes for a day. although it will mostly be used to cover sudden electricity demand peaks.
This plant will help create a more stable electricity grid and will be very useful  for a 100% carbon free-energy future.
source:BBC