As you know, Apple built a large data center in North Carolina to support iCloud. The company is now working on extensions as indicated on the flight photo below obtained by Wired . Areas named "2" and "3" are the current 'in constrution' locations.
According to Wired and previous rumors, it could be the future biogas-powered power generator as well as the solar power farm that Apple is aiming to built to be as green as possible for its regarding power consumption of its data center.
