At a Glance: Valero Energy Corp. Valero operates 16 refineries and seven ethanol plants stretching from California to Canada to the Caribbean. The San Antonio-based operator generated more than $119 billion in revenues in 2008 with total assets of $34.3 billion. Other company highlights include: •Number of Employees: Approximately 22,000 •Refining Throughput Capacity: 3.1 million…