Massachusetts Department of Public Utilities (DPU) in the US has approved a 15-year power purchase agreement that will allow National Grid to buy Cape Wind’s energy, capacity and renewable energy credits.

The Cape Wind facility will offer “significant benefits not currently available from any other renewable resources, which outweigh the costs of the project,” the department said its approval statement.

Cape Wind proposes to build America’s first offshore wind farm with a 420MW capacity on Horseshoe Shoal in Nantucket Sound, which will feature 130 turbines.

The wind farm would provide for three quarters of Cape Cod and the Island’s electricity needs, thereby reducing this region’s need to import oil, coal and gas.

The DPU decision culminates a comprehensive six-month review of unprecedented scope.