Energy is the most important cost factor in the U.S petrochemical industry, defined in this guide as the chemical industry sectors producing large volume basic and intermediate organic chemicals as well as large volume plastics. The sector spent about $10 billion (68 billion yuan or RMB) on fuels and electricity in 20041. Energy efficiency improvement is an important way to reduce these costs and to increase predictable earnings, especially in times of high energy price volatility. There are a variety of opportunities available at individual plants in the U.S. petrochemical industry to reduce energy consumption in a cost-effective manner. This Energy Guide discusses energy efficiency practices and energy efficient technologies that can be implemented at the component, process, facility, and organizational levels. A discussion of the trends, structure, and energy consumption characteristics of the petrochemical industry is provided along with a description of the major process technologies used within the industry. Next, a wide variety of energy efficiency measures are described. Many measure descriptions include expected savings in energy and energy-related costs, based on case study data from real-world applications in the petrochemical and related industries worldwide. Typical measure payback periods and references to further information in the technical literature are also provided, when available. The information in this Energy Guide is intended to help energy and plant managers in the U.S. petrochemical industry reduce energy consumption in a cost-effective manner while maintaining the quality of products manufactured. Further research on the economics of all measures—and on their applicability to different production practices—is needed to assess their cost effectiveness at individual plants.