Oregon wind turbinesGoogle is helping to create economies of scale for clean energy.Photo: T.J.Another day, another $100 million invested in clean energy.

Google has been on a green tech investment roll of late. Last week, the search giant put $168 million into BrightSource Energy’s 370-megawatt solar thermal power plant, currently the world’s largest solar project, which is under construction in the Southern California desert. And on Monday, Google announced it would invest $100 million in the 845-megawatt Shepherds Flat Wind Farm in Oregon. Shepherds Flat, being built near Arlington, Ore., will be the world’s largest turbine farm when completed, if it hasn’t been overtaken by another project by then.

“This project is exciting to us not only because of its size and scale, but also because it uses advanced technology,” Rick Needham, Google’s director of green business operations, wrote in a blog post. “This will be the first commercial wind farm in the U.S. to deploy, at scale, turbines that use permanent magnet generators — tech-speak for evolutionary turbine technology that will improve efficiency, reliability, and grid connection capabilities.”

“Though the technology has been installed outside the U.S., it’s an important, incremental step in lowering the cost of wind energy over the long term in the U.S.,” he added.

Other investors in the Oregon wind farm are General Electric, the nation’s biggest turbine maker, and Sumitomo Corporation.

Shepherds Flat has been something of a controversial project for the $1.3 billion federal loan guarantee its developer, Caithness Energy, has secured as well as state incentives for a wind farm that will create relatively few jobs.

But for Google, the investment is probably less about creating green jobs than generating green energy at scale as part of its corporate commitment to make carbon-free energy cheaper than that of coal-fired power.

The Silicon Valley giant says it has so far invested $350 million in clean energy projects. Two weeks ago, for instance, Google invested $5 million in a German photovoltaic power plant

“This facility will provide clean energy to more than 5,000 households in the area surrounding Brandenburg,” wrote Benjamin Kott, Google’s clean energy advocacy manager, in a blog post. “Until the early 90′s, the site was used as a training ground by the Russian military. We’re glad it has found a new use!”

The $350 million is just what Google has directly invested in projects. Its investment arm, Google Ventures, has put in tens of millions more in various governments, ranging from peer-to-peer car sharing ventures to biofuel firms to an Ag 2.0 startup.