It’s Earth Day, so there isn’t a company on the Internet that isn’t trying to brandish its green image. Apple led the charge earlier this week and today, Google announced that it has inked a deal with MidAmerican Energy to supply its $1.5 billion Iowa data center with up to 407 megawatts of 100 percent renewable wind energy.

This is the company’s sixth and largest green energy power purchase agreement so far and brings its total amount of contracted renewable energy to over 1,000 MW. MidAmerican Energy will supply Google’s data center with power from a number of its wind farms, including its new Wind VIII site, which — once construction wraps up next year — will consist of 448 wind turbines.

“Google’s significant and growing presence within our service area, along with its long and demonstrated commitment to renewable energy, have been important factors in MidAmerican Energy’s pursuit of renewable power,” said Bill Fehrman, president and CEO of MidAmerican Energy, in a statement today. “In addition to increasing Google’s access to renewable energy, this agreement also reduces energy costs for our customers.”

Google previously signed a very similar agreement with an Oklahoma utility in 2012 and earlier this year, it announced that it had come to a similar agreement with a Swedish utility to power its Finnish data center. The company has also invested about $1 billion in 15 green energy projects around the world.

Iowa — just like Oregon — has become a magnet for data centers recently thanks in large part to the availability of generous tax breaks and access to affordable and renewable energy, with Google, Facebook and Microsoft making heavy investments in the area.