pellets stoves can run for atleast 24 hours on 40lb bag..... many hoppers can hold 120lbs or more. you can leave the house for a few days and not worry.... back up electric heaters in case of a failure.
A 40lb bag of pellets is about $3.50-$5.
Most modern pellet stoves have thermostats and the stove turns off and auto re ignites when needed.
If you are in Michigan bulk pellets or cherry pits by the ton are very cheap.
My next greenhouse will have corn/pellet boiler to heat the floors
