The new proposal is open for public comment through July 5.

Congress last month extended valuable tax credits to producers of electricity from wind turbines and solar photovoltaic panels, a move that came as a relief to an industry that has experienced rapid growth in recent years.

The economics are interesting. Today, Block Island has no electrical connection to the mainland, so its power comes from expensive and environmentally unfriendly diesel generation, which the Block Island Power Company bills at 24 cents per kilowatt-hour in peak season.