Google, ITOCHU subsidiary Tyr Energy and Sumitomo Corporation of America, will invest $500m in the 845MW Shepherds Flat wind project in Oregon, US.
The companies will join GE Energy Financial Services and developer Caithness Energy to jointly own the $2bn project.
On completion, the project will be capable of generating energy sufficient to power 235,000 average US homes, and will avoid about 1.5 million tons of carbon dioxide per year.
Construction is proceeding in three phases and involves installation of 338 GE Energy's 2.5xl wind turbines, along with development of 95 miles of roads and 167 miles of transmission lines.
Power generated from the plant will be sold to Southern California Edison, under a 20-year purchase agreement.