I think there paying far more than 6cents per gallon.
Still, you forget generators are less than 100% efficient. At 30% that 30kW/hr = 9kW/hr for 6 cent. = 1.5 cents per kW/hr + cost of generator which is far from free.
For comparison I suspect you could easily get 1$ a gallon by just selling that gas. Using a mid sized fishing boat you could probably move ~1 to 10k gallons from the ships's fuel tank to a near by country without that seeming odd. Make that trip once a week and your living the good life without doing anything 'odd.' Hell I suspect you could simply meeting other fishing boats at sea fill their tanks for cash or even fish which would be next to impossible to catch.
Still, you forget generators are less than 100% efficient. At 30% that 30kW/hr = 9kW/hr for 6 cent. = 1.5 cents per kW/hr + cost of generator which is far from free.
Anyway, your far better off just selling the gas.