Reuters: Legendary Texas oilman T. Boone Pickens has gone green with a plan to spend $10 billion to build the world’s biggest wind farm. But he’s not doing it out of generosity – he expects to turn a buck. The Southern octogenarian’s plans are as big as the Texas prairie, where he lives on a ranch with his horses, and entail fundamentally reworking how Americans use energy. Next month, Pickens’ company, Mesa Power, will begin buying land and ordering 2,700 wind turbines that will …