Google has agreed to buy an additional 48MW of wind power for its Oklahoma data center, which is already slated to get more than 100MW of wind power through a prior deal.

Unlike its previous deal where it would buy the power directly from a private wind-farm developer, in this agreement Google will pay a premium for wind power generated by the local electric utility. In the first deal, Google has to sell the wind power it buys into the electrical grid (having stripped green credits from it) and then buy power from the grid as usual to power the data center.

“Although both options can make sense depending on the circumstances, we’re excited about this collaboration because it makes the most of our respective strengths,” Gary Demasi, director of Google’s global infrastructure team, wrote in a post on the official Google blog.

The power in the most recent deal will be generated by the Grand River Dam Authority’s (the utility’s) first ever wind-energy project called Canadian Hills. Google expects the wind farm to come online later this year.

Canadian Hills power, power from the 2011 deal with NextEra Energy Sources (developer of the 100MW wind farm, all of whose capacity Google has committed to buying for the next 20 years), and power from another NextEra wind farm in Iowa, which Google contracted for in 2010 in a similar deal, makes total wind-power capacity the Internet giant now has access to about 260MW.

Google has committed to making sure its operations are carbon neutral in 2007. In addition to buying clean energy, the company invests in clean-energy development projects buys green credits to achieve that neutrality.

The announcement comes against the backdrop of strong backlash by the data center industry in response to a series of New York Times articles that accuse the industry of wasting energy while painting a picture of itself as green and efficient.

Here are comments on the NYTimes article from some of our bloggers: Ian Bitterlin’s post and Julius Neudorfer’s post