It is thought to be fairly easy to save compressed air by addressing "low-hanging fruit"—that is, by finding and fixing leaks and eliminating wasted flow. Efforts in this area may not yield optimal results, however, unless you do some of the “hard stuff.” If your system is not controlled efficiently, reducing the flow many not significantly lower the system power consumption.
I cringe when I see energy incentives that are based solely on leak auditing. True, leak auditing is a good thing to do, and in a perfect world it should result in savings, but based on past experience I find that many compressed air systems have poor power turndown. This means that the reduction in flow may not appreciably reduce the compressor kilowatts because the compressor controls do not react in a linear manner.
Often the control strategy of multiple compressors is dictated by the service personnel working on your compressors. They may select operating modes that make their life easier, where compressors share the load or do not turn off when unloaded, or where pressures are maintained at levels high enough so there are never any complaints. But compressor operators' needs are not always your needs. Your plant needs to make a profit, and reducing wasteful energy consumption helps make it happen.
When leakage and waste reduction is combined with the systems approach where the full operation of the complete compressed air system, including compressor control, is considered, the results are optimized. But to do this is not always easy or inexpensive.
Nevertheless, dealing with the bigger system issues is often very fruitful. Doing things like reducing piping and component losses, installing large system storage receivers, implementing efficient multiple compressor control strategies, installing compressors with good turndown capabilities, and upgrading air dryers can result in a very nicely performing system that saves you money and delivers a clean, dry, and stable supply of compressed air.
Getting the most from your leak and inappropriate usage reductions strategies can yield very large savings that can pay for the more expensive improvement. This is especially relevant if there are local financial incentives that can help pay the cost.
Learn about the systems approach at a Compressed Air Challenge Fundamentals of Compressed Air Systems seminar near you. Our calendar of trainings is here.