The beauty of propane is that it last a long-long time in a tank. If the tank was clean and dry when filled it will last years. The beauty of a diesel generator is the fuel will lubricate the upper cylinder area and the engines will last for many years. Fuel oil goes skanky though, and won't last as long as propane.
We just pulled out 2 - 10,000 gallon oil tanks at work (alternate fuel source for heating) and replaced them with a 12,000 propane tank filled to 80% (9600 gallons) @ $1.58 a gallon. The price for a tanker load of propane has gone from $1.40 to $1.58 a gallon in 3 weeks. Ouch...
The alternate fuel source is to qualify for the interuptable natural gas rates from our supplier. We didn't get "interupted" very often and had to burn up the oil just to keep it from going south on us. We swapped out the gas/ oil boilers for 3- 3,000,000 btu Aerco high efficiency boilers that run on natural gas or propane that is run through a propane air mixer to make it the same specific gravity as natural gas. The propane, if we don't use it, will still be good after many- many years. The fuel oil (#2 diesel) would not last that long. Microbes start to break down the oil after a while and it plugs things up and you can also have problems with condensation in the storage tank.
You don't have condensation problems with a propane tank. The tank we just installed was used - made in 1959 and is an uderground tank to boot.
If you get a gasoline gen-set, you can put an auxillary propane carb on it and have a dual fuel option.
If you heat your house with fuel oil (ouch again) you can use the same tank for your gen set and have fresh fuel.
Of course oif you live where you don't have to heat you house then...
