There was a time when I resumed commuting by bike after not having done it for several years. For the first few months, I noticed that my increased appetite increased my food costs by more than the savings in fuel for my car, so I was not saving money. We have an incentive to use fossil fuels because the costs are distorted. A gallon of gas has something like 31,000 calories, and it only costs about as much as a loaf of bread which has, what, I don't know, maybe 1,000 calories. We get gas cheap because we are borrowing from both our ancestors and descendants, and there are probably industrial subsidies, too.