You are fairly limited when living in an apartment. A kerosine heater may work OK and be fairly economical. We have had one for years (bought at a yard sale). Does anyone know how long kerosine can be stored? I have some that is 20+ years old. I should dig it out and fire it up to see if it still works. I am ashamed to say that I am not as prepared as I should be with that item.

I have heard of some propane heaters that can be used indoors, but do not have any experience with them.

I have used a fireplace insert as my main source of suplimentary heat. It is a triple walled Buck stove with a thermostat for the fan control. A marine battery and power inverter keep the fan running when the power is off. When the battery runs out (hasn't yet), I can open the doors and put the screen in. With the doors closed and the fan running I can heat the house. With the doors open, I can heat the 12 feet in front of it. I try to keep the battery charged!!