Things like this make me glad that I have a oil furnace. Lots of downsides of an old oil furnace (like the cost of the oil), but I can keep my house warm with it even if the power goes out. I hooked it up to a battery bank and when it runs the blower it also charges the batteries. Its not a huge amount of capacity, but its enough that it can keep the thermostat on and kick the furnace on when it gets too low.