I thought about Kerosene but I have a 500gal propane tank for backup heat for the heat pump that could be connected to the propane heater if the power outage is longer than 30lb propane tanks can support. I'm calculating 1.3 lbs / hour when run continuously which isn't likely to be the case since it does have a thermostat and produces a lot of heat. Probably cycles about 25% on in the garage. Kerosene also requires rotation since it has a 2-5 year "shelf life." It's probably not an issue if you are using it regularly anyway though.
Ahhh...having a 500 gallon propane tank changes the situation. When we did a house renovation a few years ago, I had a single 100 gal tank installed to fuel 2 fireplaces and the range cooktop. I've considered adding a second one beside the first to provide more on-site storage if it were ever needed, but that idea's been residing on the 'round to it' list for a while. My other thought was to wait until the current HVAC air handler with electric resistance heat fails. Then, at that time, install a new gas furnace and upgrade the tank capacity.
JoeR