PROVIDENCE (AP) — The developers of a new offshore wind farm say their power contract has been approved by Rhode Island regulators.

Danish-based Orsted U.S. Offshore Wind and Eversource say the Rhode Island Public Utilities Commission approved their 20-year power purchase agreement with National Grid Tuesday.

Orsted and Eversource are co-owners of the 400-megawatt wind farm, called Revolution Wind. The plans call for up to 50 turbines in federal waters south of Martha's Vineyard, Mass.

The turbines are expected to generate enough energy to power about 270,000 homes, roughly a quarter of the homes in Rhode Island. Local construction could start in Rhode Island in 2020 with commercial operations by 2023.

Connecticut separately plans to purchase power from turbines at the same federal lease site.

Orsted is planning several more U.S. wind farms.