Nicor Gas stores about 150 million cubic feet of gas every year for use in the winter. 
Spokesman Bernie Anderson says the company buys it in the summer when the rates are lowest. It’s pumped into the ground in places like Troy Grove.

Anderson says on peak use days, like this week when temperatures were below minus-ten, the stored gas fills customer demand. Nicor says about a third of the gas it delivers over the winter has been stored since summer.