Google’s checkbook is wide open this week. Not only did it buy 3D interface startup BumpTop, and invest in mobile payments company Corduro, but it also just put $38.8 million into a wind farm in North Dakota. The $190 million project is being put together by NextEra Energy Resources, will produce 170 megawatts of power (enough for 55,000 homes), and will be called Peace Garden Wind. Cue the Zen meditation harp.

When it comes to renewable energy investments, Google uses a lot of solar energy itself, and has invested in startups such as AltaRock (geothermal), eSolar, and Makani Power (high-altitude wind). But this is the first time it has ever invested in an energy project rather than in a company.

Also, the money is not coming from Google Ventures, or its philanthropic arm Google.org. Rather, it is coming straight from Google’s treasury, a company spokesman tells me: “You can think of it as a way to diversify our cash holdings while investing in an area that we think is important to support.” Google has $26.5 billion in cash, so it needs to find something to do with all of that money. Perhaps there are some tax advantages to investing the money directly rather than through its investment arm, Google Ventures.