Valero Energy is one of the largest independent refiners in the United States. It operates 15 refineries, with a total throughput capacity of 3.2 million barrels a day in the US, Canada, and the United Kingdom. Valero also owns 12 ethanol plants with capacity of 1.6 billion gallons a year and holds a 50% stake in Diamond Green Diesel, which can produce 1.2 billion gallons per year of renewable diesel.