By DIRK LAMMERSSIOUX FALLS, South Dakota (AP) ¿ Valero Energy will buy seven ethanol plants from VeraSun Energy for $477 million, the largest biofuel buyout in terms of production capacity. VeraSun, the second largest U.S. ethanol producer, filed for bankruptcy protection in October and on Wednesday, a Delaware bankruptcy court approved the sale. Valero won an auction for the assets in court on Tuesday. The sale is expected to close in April. Also involved in the bidding was agribusiness giant Archer Daniels Midland Co. Valero becomes the first traditional refiner to cross over into ethanol production. The sale could give other major energy companies a benchmark price for the assets of ethanol producers now under tremendous financial strain. Ethanol industry leader Poet LLC is also shopping around. Valero Energy Corp., the largest U.S. independent oil refiner, will acquire plants in Aurora, South Darkota; Charles City, Fort Dodge, and Hartley, Iowa; Welcome, Minnesota; Albion, Nebraska; and a development site in Reynolds, Indiana.