Energy Impacts of Productivity Improvements in Manufacturing

The complexity of industrial processes and the need to consider the interaction of various systems has led in many cases to the maturing of the “energy audit” in to a more sophisticated “industrial assessment.” The assessment team typically looks for potential improvements in energy use in concert with examination of waste streams and potential productivity improvements. The benefits of this new approach are substantial in particular with respect to productivity improvements. Such projects are much easier to interest management in than waste or pure energy ones. In many cases they may also require smaller capital investments as many of the projects involve changes in practices and procedures. In a large number of cases, the impact of productivity projects on energy use in the plant are ignored or underestimated. This is unfortunate as the appropriate tracking of energy impacts would lower implementation payback times and potentially lead to greenhouse gas reduction credits. This paper examines how energy impacts are currently tracked in productivity projects and suggests two techniques for dramatically improving the accuracy of these estimates. Experiences from the DOE Industrial Assessment Center program are used as well as data from the programs publicly available database. It is shown that in many of the recommended productivity improvements there is an associated absolute reduction in energy use. For example, it is common to recommend the elimination of steps in a process by improving quality control etc. Savings are tracked in terms of time and manpower, but the elimination of parts of the process normally results in a reduction in energy consumption. Often, this reduction is underreported. Also very common, however, is that case where a productivity recommendation leads to an increase of total energy use. For example better management of process equipment will lead to greater load factors. Handled incorrectly this can lead to a negative energy impact which could result in increased paybacks and misleading indications about energy efficiency. Analysis shows that even when there is an increase in energy use, the amount of energy per product unit goes down, making a process demonstrably more energy efficient. Arguments are presented why using an Energy Intensity Metric is critical in properly accounting for energy impact of productivity on plant energy use. We present a concept called Virtual Reduction in Operating Time and show how it can be used to improve accounting for energy impacts