Fuels: Natural Gas, Directed Biogas
Input fuel pressure: 15 psig
Electrical efficiency (LHV net AC): > 50%
If that's the case, then it seems to me that relying on something other than the grid would be a smart move.
Beyond that, the cost comes down to availability. There are parts of the world where every single house has a natural gas line for heating (water and air). I've heard that in Japan, small/clean/quiet (relatively) generators are installed in some apartments and provide electricity.
This article has some information on natural gas usage in California. It seems like most of it come from out of state (or country):