I suspect the Nabisco plant in Chicago pulls about ~12 million therms worth of natural gas, at 30kwh per therm, that's pretty significant.
You asked about energy usage; but I have no idea as to how that bakery's natural gas usage affects the people surrounding it.
The smell of freshly baked fig newtons might offset the possible increased cost of gas-per-cubic-foot.
what makes this bakery comparable in terms of energy usage and pollution?
I don't think the conversion is as straightforward as they claimed. But they're also not claiming that they currently pull gigawatts of electricity.