Google has received federal approval to buy and sell energy on the open market, giving it more options for the way it powers its data centers and opening the door to a potential move into the energy-trading business. Google applied for the authorization last December through a wholly owned subsidiary called Google Energy. The U.S. Federal Energy Regulatory Commission (FERC) approved its application Thursday, granting Google "market-based rate authorization," or the authority to buy and sell energy on a wholesale basis.