We've been running off propane for 35 years or so...being out in the country where there is no natural gas supply. For purposes of power supply for "off the grid" and survivalist kind of stuff it's a very versatile fuel with many options as far as appliances go. There's heat, obviously. We have central heat and air...heat run by propane. They make refrigerators and freezers that run off from propane, generators, stoves, ovens, grills, clothes dryers, water heaters, and even lights(think lanterns). They make stand alone heating units that require no venting and no electricity to run them whereas the central air unit requires electricity to run. We started off with the stand alone units when we lived in the other house on the farm. Never had to worry that the electricity going out to determine whether or not you stayed warm in the winter. Beat the hell out of burning wood! One could buy a tank and set their house up with all the amenities and be reliant on noone for "power" except the propane delivery once or twice a year.

I sound like Hank Hill from that cartoon sitcom from back in the 90's. Hank Hill Propane and propane accessories salesman.

You can get different size tanks depending on what all you are running off propane...300, 500, 1000 gallons. You can rent the tank or buy the tank. Renting requiring you buy propane only from the company you rent the tank from...it's their tank. Buy the tank and you can shop around for your propane and the prices can vary by a good bit but the quality of the propane can to.

Propane doesn't have the BTU's that natural gas does.

As far as duel fuel...maybe things have changed...but our central heat and air unit came with two sets of gas jets...one set for propane, one set for natural gas. You'd think they might have done something to keep from having to change the jets out for something like a modern generator but I do not know.