1 gold coin buys you a nice silent 5.5 kw diesel generator with some diesel,
(enough for an electric heater, some lightbulbs and a laptop)
diesel has the advantage of being better storable than gasoline aka petrol aka benzine, and you can blend it with vegetable oils.
~ 2 liter per 5.5 kw/h
the model I watched has variable RPM, it adjusts to the workload (disuse)
bigger engines probably get better mileage.