Valero Energy Corporation is among the largest independent oil refiners in the United States. The company operates 15 refineries across the U.S., Canada, and the United Kingdom, with a combined throughput capacity of 3.2 million barrels per day. Valero also owns 12 ethanol plants with annual production capacity of 1.6 billion gallons and holds a 50% interest in Diamond Green Diesel, which has the capacity to produce 1.2 billion gallons of renewable diesel per year.