State has tripled its supply of renewable energy in the last two years. : PROVIDENCE, R.I. — Rhode Island electric customers are already using power from the first offshore wind farm in the nation, a 30-megawatt project off Block Island — and plans are in place to buy another 400 megawatts of offshore wind. Now, developers are proposing to sell an additional 350 megawatts of offshore wind power to the Ocean State.