Just as prices at the gas pump have backed off a bit, word comes that this winter’s heating bills will rise sharply. The state’s largest utility, AmerenUE, has asked state regulators for permission to increase natural gas rates by as much as 30%. AmerenUE spokesman Mike Cleary says the cost of producing energy is going up. He says the cost of natural gas rises naturally with the cost of crude oil, which has been pushing gas prices up.