Google announced Tuesday that it has signed a deal with MidAmerican Energy to supply up to 407 megawatts of renewable wind energy to its Iowa data center.

The deal is the search engine's sixth and biggest green energy acquisition to date, according to TechCrunch.

The data center will receive power from many of MidAmerican Energy's wind farms, which includes the company's new Wind VIII site. The site will feature 448 wind turbines once its construction ends in 2015.

"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," Bill Fehrman, president and CEO of MidAmerican Energy, said in a statement on Tuesday. "In addition to increasing Google's access to renewable energy, this agreement also reduces energy costs for our customers."

The deal covers Google's current facilities, along with future expansions that will use the renewable energy. This agreement has brought Google's total amount of contracted renewable energy to over one gigawatt, or 1,000 megawatts, PC Magazine reported.

"We've entered into a few different kinds of agreements over the years," Neha Palmer, head of energy strategy and development at Google, and Sam Arons, energy program manager, wrote in a blog post. "Sometimes signing power purchase agreements (PPAs) with wind farm developers and sometimes working with our local utility partners."

The Wind VIII program will help MidAmerican Energy generate over 3.3 gigawatts of clean energy through wind, PC Magazine reported.

"But it's not just our own operations we want to green: Google has also invested over $1 billion in 15 renewable energy investments around the world, in an effort to put more renewable energy on the grid and reduce global greenhouse gas emissions," Palmer and Aarons said.

Google's previous moves towards clean energy include singing a similar deal for its Oklahoma data center in 2012 and investing almost $1 billion in 15 green energy projects all over the world, TechCrunch reported.

Access to cheap and renewable energy has made Iowa a valuable area for companies such as Google, Microsoft and Facebook to build their data centers.