On 15 June, Carcieri signed bill H8083subA, which authorizes utility Narragansett Electric to enter into a power purchase agreement (PPA) with developer Deepwater Wind.
The new law requires the two parties to file a new PPA with the state Public Utilities Commission, and requires the commission to make a decision within 45 days.
The parties had agreed a PPA but it was rejected in March by the state Public Utilities Commission (PUC), which said the agreed price was too high.
Carcieri said: "Today, we are taking another step forward in our efforts to be the first state in the nation to construct an offshore wind farm."
Rhode Island faces competition in that arena. Massachusetts' Cape Wind is so far the only offshore project in the US with federal approval.
The new law requires Deepwater Wind to disclose its construction and development costs. If the developer achieves any capital cost savings during development, this will translate into a lower power purchase price, Carcieri's office said.
Deepwater Wind plans to build the 20MW wind farm to prove the viability of a larger project off the Rhode Island shore, with a capacity of at least 350MW.
The developer and state signed a legally binding joint development agreement for the larger wind project in 2009.