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Implementing a Holistic Energy and Utilities Evaluation to Improve Sustainable Production
By: Doug Burns, Practice Lead, Sustainable Production, Rockwell Automation
Posted: July 7, 2009
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Each of the opportunities identified in an energy audit can generally be classified as one of three changes to the manufacturing process:
- Behavioral changes: Behavioral changes are simple, low- or no-cost solutions that can significantly impact the bottom line, such as changes in the time of day certain equipment is used, or timing power-up sequencing for off-peak hours. Payback for behavioral changes is generally immediate and the savings drops straight to the bottom line.
- Programming changes: Programming changes are relatively low-cost changes to the facility’s energy-consuming assets that can provide a quicker payback. On the plant floor, these changes can take the form of improving controls or upgrading older equipment for more effective use of energy resources. Payback for programming changes is generally realized in less than one year.
- Capital investments: Capital investments can include boilers with advanced process control that helps optimize fuel usage; installing solar panels or other alternative energy systems to power manufacturing machinery; and building an entirely new, more sustainable plant. While these are the most expensive options—payback can stretch beyond one year—the long-term ROI also can be the most rewarding.
Examples from an audit conducted for a large batch manufacturer can illustrate the different categories and typical actions pertaining to each. As part of audit process, Rockwell Automation recommended behavioral changes as simple as instituting an energy consumption awareness program with their workforce. The analysis recommended setting easily identifiable metrics for success, including a 1% reduction in overall energy consumption. It was estimated that these small improvements—ranging from just 1-5% improvements, in most cases—could help the company save significantly on energy costs year over year.
The audit also identified potential savings resulting from shifting time-of-day operation for equipment to off-peak hours to reduce peak demand charges. By charging the batteries used to power their forklifts at night instead of in the middle of the day, the company could realize $35,000 in demand charge savings annually.
The programming changes identified for this same batch manufacturer included several updates to their compressed air system, which was comprised of two 750 standard cubic feet per minute, 150-horsepower air compressors. These compressors ran 24/7 at full power—even when the plant was in a down condition on the weekends or during holidays.
Recommended programming changes to this system included reducing line pressure to the minimum psi required by non-operating devices when the plant was in a down condition, and powering those devices that must stay on during weekends and holidays with smaller, dedicated compressors. The audit analysis also recommended reducing the line pressure during operational periods to the minimum level necessary to complete the manufacturing process. All told, these programming changes had the potential to save the manufacturer almost $50,000 annually.