PROVIDENCE, R.I. (AP) — Utility National Grid has agreed to a 20-year contract for power from a proposed 400-megawatt wind farm project in Rhode Island Sound.

Under the agreement announced Thursday, National Grid would pay Danish-based Orsted U.S. Offshore Wind 9.8 cents per kilowatt hour for power from its Revolution Wind Farm.

The Block Island project was originally developed by Deepwater Wind, which was acquired by Orsted last year.

The project is estimated to generate enough power for 270,000 homes.

Orsted Co-CEO Jeff Grybowski says National Grid estimates the project will lower the average household’s electric bill by 50 cents a month over the life of the contract.

The state Public Utilities Commission will decide whether to approve the contract in the next four months.