For typical biogas engine installation parameters see.[7] For parameters of a large gas engine CHP system, as fitted in a factory, see.[8] Gas engines are rarely used for standby applications, which remain largely the province of diesel engines. One exception to this is the small (<150 kW) emergency generator often installed by farms, museums, small businesses, and residences. Connected to either natural gas from the public utility or propane from on-site storage tanks, these generators can be arranged for automatic starting upon power failure.