Genset? Works fine until your tank runs dry. How long is that? Days? A week or two? If you have a large tank, how,do you prevent the fuel from deteriorating?
Multi-fuel genset: gasoline/ natural gas/ diesel
gasoline with stabilizer
natural gas should last until supply in the line depletes out.
diesel in ground tank with stabilizer depends on how much land and what size tank you can afford (genset and vehicle usage)
There are fuel stabilizers that you mix in with your fuel supplies, before going into storage.