WASHINGTON — Google and the subsidiaries of two Japanese companies are investing $500 million in a wind farm being built in the northwestern US state of Oregon.

Google said in a blog post Monday it was investing $100 million in the Shepherds Flat Wind Farm, expected to be the largest in the world when it is completed in 2012.

Google said the wind farm is intended to produce 845 megawatts of energy, enough to power more than 235,000 homes.

Co-investors in the $2 billion project are Sumitomo Corp. of America, a subsidiary of Japan's Sumitomo Corporation, and Tyr Energy, a subsidiary of Japan's ITOCHU Corp.

General Electric unit GE Energy Financial Services and developer Caithness Energy are among the other owners of the wind farm under construction near Arlington, Oregon.

"The new investors contribute a wealth of energy expertise, innovation and strong financial profiles to the landmark Shepherds Flat wind farm project," Les Gelber, a partner at Caithness Energy, said in a statement.

Google said the electricity produced at Shepherds Flat will be sold to Southern California Edison.

The Mountain View, California-based Internet company said the Shepherds Flat investment brings Google's total investment in clean energy to more than $350 million.

Google last month announced it has invested $168 million to help complete the construction of one of the world's biggest solar energy power plants in California's Mojave Desert.

"We remain on the lookout for more projects that make business sense and will help all of us take advantage of clean, renewable energy," Rick Needham, Google's director of green business operations said.