Energy Efficiency in Process Plant Utilities

Abstract

This article highlights some aspects of utility systems design and operations for energy efficiency. After years of relative stability, the energy costs have risen substantially. Electricity rates vary by the hour and in some cases are tied to the price of natural gas. In a world of rising energy prices, it becomes important to optimize energy efficiency in design and operation of utility systems that typically run 24 hours a day, 365 days a year. Capital is critical and must be effectively used to purchase equipment. A financial guide for initial screening of investment ideas is often set as 4 years simple payback. During a more detailed analysis, the life cycle cost analysis or should be performed which includes costs arising from owning, operating, and maintaining, instead of a simple payback. The return for incremental investment should be equal to or higher than the minimum acceptable rate of return set by management. (Net present value should be positive) Energy conservation should be a part of the approval process for capital projects. Some of the ideas can be used for plant improvements to cut operating cost and gain competitive advantage in the marketplace. Energy optimization requires a team with the right blend of skills. However, most importantly, the success of the program will depend on the support and endorsement of top management. Following are suggested approaches to examine opportunities for improving energy efficiency in common utilities systems. Typically, in a process plant, the largest energy consumers are steam, compressed air, Refrigeration and HVAC, Cooling water, thermal oxidizers and electrical rotating equipment.