I absolutely LOVE my Generac LP3250 propane-powered generator. [u=https://www.foragingtexas.com/2008/02/emergency-preparedness-generators.html]Let me count the ways![/u]

Pros:
1. Fuel Storage - these generators use a standard, 20lb propane bottle like your propane grill which are readily available (most of the time). Propane doesn't degrade so you can store multiple bottles for years if necessary.
2. Fuel Cost - Propane is generally much cheaper than cost of gasoline or diesel needed to produce an equal amount of power.
3. Fuel Safety - while propane is highly flammable it is non-toxic. If you accidentally release some it'll quickly dissipate without causing an environmental or health risk.
Runtime - a 20lb bottle will give 6-10 hours of run time depending on how much power you need from the generator. Three bottles will often be enough for most situations...but you can usually trade your neighbors electricity in exchange for their BBQ grill propane tank if the situation lasts longer than three days.
4. Power Output - propane is a high-energy fuel so it can produce a lot of electricity. They usually start at 3000 Watts and can be found up to double that.
5. Maintenance - since propane is a gas, when it evaporates it doesn't leave behind the gums and resins that gasoline or diesel do. This means lower carburetor maintenance! The carburetor is where the propane and air mix before going into the piston's ignition chamber (the part where propane is burned). Since the fuel is still unburned in the carburetor, when you turn off the generator fuel remains there. Gasoline and diesel will eventually evaporate form there, leaving behind goo which can prevent a carburetor from working the next time you need to run the generator. Propane doesn't leave goo behind!

But to be fair:
Cons
1. Size - to take full advantage of the power produced by propane the resulting generators are physically large. They will be up to 2-3 feet long and 2 feet wide.
2. Noise - most propane generators are made for construction sites where noise isn't a problem. They will be as loud as a standard gas-powered lawnmower so running them is noisy! This is especially problematic at night...or when you don't want thieves to know you have a generator.
3. Fuel Storage - keep in mind while propane tanks are safe to keep filled for long periods of time, the valve systems on the tanks have an expiration date. If the tank valve has expired, propane refillers won't refill it. This is really only a problem with the big, 50lb propane tanks that can't be swapped out for regular tanks at tank exchange locations, though.

-Blast