One of the first things I did to my house was install a wood stove. Turns out, it became very useful before the infrastructure collapsed. My normal furnace died twice on me. The wood stove kept the whole house warm. Later, I bought a rocket stove to cook on. This little beauty is amazing. It's very small yet sends a very high heat to the top where your pot or pan sits. It uses any available wood you can find. It can be twigs, branches, left over building material or small hardwood pieces, it doesn't care. It will easily fit in the trunk of your car. The one I bought isn't practical to carry in a bug out bag, but they make suitable ones for that. Then I bought a single burner propane stove, mostly for my beer hobby. It's very small but puts out a ton of heat. This could actually double as a space heater.