Planning and scheduling are the core business functions whereby refiners adjust the entire manufacturing process to improve profits and achieve better results. Whether it’s used at a small refinery or a large one, planning and scheduling can have a major impact on profitability. A case in point is Valero Energy Corporation’s 14 refineries with crude and feedstock throughput ranging from 90,000 barrels per day (bpd) to over 300,000 bpd. Improved planning and scheduling can have a positive impact within the refinery as well as across the company’s supply chain. With today’s crude prices pushing past $100/bbl, a small “per barrel” impact can be very significant. Regardless of size and economies of scale, the specifics of planning and scheduling are applicable throughout the industry. This article will cover the challenges, solutions, results and benefits of planning and scheduling in refinery optimization.