On the same day that Greenpeace released a report highlighting coal-based power consumption by 10 technology companies’ data centers, Google (one of the 10 firms) announced it had secured a high-capacity wind-power purchase to power its new data center in Oklahoma.

Google said on 21 April it had contracted to buy all power generated by a 100.8MW wind farm going up in the state for the next 20 years.

NextEra Energy Resources is building the wind farm, named Mico II. Google said the farm is being built directly as a result of the internet company’s agreement to buy the power it generates.

Construction of both the wind farm and Google’s data center in Mayes County is expected to be completed by the end of 2011, according to a blog post by Gary Demasi, a member of Google’s Global Infrastructure team.

This is a second large wind-power purchase for Google in less than one year. In July 2010 the company signed an agreement with NextEra similar in size and structure for power from a wind farm in Ames, Iowa, to be used by its data center in Council Bluffs, Iowa.

Mico II power will not be fed directly to the data center in Oklahoma. It will be fed into the electrical transmission grid, and the data center will take power from the grid.

There is a number of reasons the company cannot plug its data center directly into the wind farm, and Bill Weihl, Google’s green energy czar, said regulation was one of those reasons. By law, he said during a presentation at the GreenNet conference in San Francisco on 21 April, the company is required to buy power from the local utility in Oklahoma.

Another big reason is intermittency of wind power. Renewable-energy sources like wind and solar have to be backed up by traditional power plants to sustain constant load for consumers.

In a whitepaper that explains its renewable-energy purchasing activities, Google writes, "The plain truth is that the electric grid, with its mix of renewable and fossil generation, is an extremely useful and important tool for a data center operator, and with current technologies, renewable energy alone is not sufficiently reliable to power a data center."

Since it is buying all Mico II power, Google will sell it into the grid at local wholesale prices. The set-up is the same in Iowa.

Google is able to play in the wholesale energy market through its subsidiary Google Energy, an entity it registered as a power utility in January 2010.

In the aforementioned whitepaper, the company concedes that it may be selling wind power at a "slight net loss", because renewable energy is more expensive than energy generated from coal or other traditional fuels.

Google hopes that in the future, however, the contract will become profitable, as price of traditional grid power surpasses that of renewable power.

To ensure the renewable energy it paid for applies to its data centers, the company keeps renewable-energy credits (RECs) it gets through buying wind energy and applies those RECs to energy consumed by the facilities.