Google will use the existing transmission lines at a soon-to-close coal-fired plant in Alabama to power a $600-million data center using renewable energy, in a deal with the Tennessee Valley Authority announced on June 24.

TVA said it still is working through details of the agreement, such as the amount and sources of power, but the idea of repurposing the Widows Creek plant to power the data center was attractive to Google, said Gary Demasi, its director of data-center energy and location strategy.

A Google spokesman said construction plans are still being finalized, but it expects to begin data-center work early next year. The northern Alabama site will be Google's 14th globally.

"Data centers need a lot of infrastructure to run 24/7, and there's a lot of potential in redeveloping large industrial sites like former coal-power plants," Patrick Gammons, a senior data center manager, said in an official Google blog. The arrangement will allow Google to scout renewable-energy projects and work with TVA to bring the power into its electric grid, Gammons said.

Google has become the world's largest corporate buyer of renewable energy and has bought the equivalent of more than 1.5% of installed U.S. wind capacity, he added.

"The Alabama data center will incorporate state-of-the-art energy-efficiency technologies," Gammons said. Google has said it can get 3.5 times the computing power out of the same amount of energy compared to five years ago. "Our data centers use 50% less energy than the typical data center," said the spokesman. "We raise the temperature to 80°F, use outside air for cooling and build custom servers."

Google is purchasing a permanent easement at the site, said a TVA spokesman, adding that the producer will provide power to Google directly and not through its local distributor. TVA is set to close by October the last remaining 470-MW coal-fired unit at Widows Creek.