The contract, for five Alstom 6MW Haliade turbines, was signed in the presence of US energy secretary Ernie Moniz and French industrial renewal minister Arnaud Monteburg. The turbines are scheduled for commissioning in 2016.
Alstom said the turbines would be manufactured at its new factories in Saint-Nazaire, northern France. Currently the deal is only for the Block Island project. Last October, Deepwater won a lease to develop up to 3.4GW off the coast of Rhode Island and Massachusetts after bidding $3.8 million.
This is not the first turbine agreement that has been made for Block Island. In 2011, Deepwater Wind publicised a deal with Siemens for its 6MW turbine, with Deepwater Wind CEO William Moore proclaiming the machine as the "future of offshore wind".
Speaking to Windpower Offshore in October 2013, Siemens revealed a deal was not in place with Deepwater Wind for Block Island, describing the earlier agreement as "pre-contract".
Siemens was unable to comment on the circumstances surrounding the collapse of the Deepwater deal. However, Deepwater's current CEO, Jeffrey Grybowski, said: "We executed a preferred supplier agreement with Siemens, which expired at the end of 2012. That agreement called for the parties to negotiate turbine supply and service agreements and also called for some degree of exclusivity.
"After that agreement expired, we continued to discuss an agreement with Siemens, but also began discussions with Alstom in 2013. We eventually came to an agreement with Alstom for a turbine supply and 15-year service contracts."
Grybowski was unable to give further details about why the Siemens deal fell through or whether it came down to price. However, he added that Deepwater had handed Alstom an initial multi-million instalment in order for the company to produce the turbines' blades.
Earlier this year, Block Island moved a step closer to reality, with state authorities offering no objection to the plans. Rhode Island Coastal Resources Management Council, the leading permitting agency for the project, issued a preliminary judgement.
The body urged the adoption of 17 measures, which include reducing any impacts on whales during construction, conducting regular reports on bird impact after the wind turbines are installed, and carrying out a study on the effects of the wind farm on recreational boating.
Despite this, the project has met with objections from locals, with developer Deepwater Wind being forced to look at changing the shore landing and buried land route for the wind farm as a result.
Deepwater intends to use the 30MW Block Island project to provide a test case for an offshore wind farm of up to 200 turbines in Rhode Island federal waters following its victory last week in an auction for leasing rights there.