As for power, whether electricity or heat, that’s more challenging to come by – and more expensive – than on the mainland. The average going rate per kilowatt hour in Maine was 15 cents in August, but on an island like Monhegan, far from the reach of the grid, it’s usually about 70 cents. The difference in price for No. 2 heating oil, which 80 percent of Maine’s islands are dependent on? Typically $1 more per gallon than on the mainland.