Compressed Air Systems in a Green World

Using this system could save a plant about 100 kilowatts annually.

How can an 8%-10% efficient utility be Green? The answer is that it can't, but improvements to Compressed Air Systems represent the single largest opportunity to reduce carbon emissions by reducing the fuel consumption of electric utilities. Transportation engine idling, lighting replacements, improved HVAC, insulation, thermal windows, etc., all recently recommended by our President Obama, are excellent opportunities, but they pale in comparison to the energy savings opportunities in Compressed Air Systems.

Compressed Air is used by virtually all manufacturing facilities. It is used because is it powerful and convenient, without the inherent challenges of electric wiring, and it is considered by many to be Free.

The problem is that because Compressed Air is so easy to use, it is generally poorly applied. When was the last time a cleanup crew asked an engineer to insure the Compressed Air System could support their blow nozzles? (Nobody likes using a broom.) I'll suggest that if their tools were electric they would have to insure the wiring and breakers were adequate, ground faults in place, and all is in compliance with all NEC codes. Conversely, no engineering is done to install a 3/8" coiled hose that requires an increase of 20 psi to operate the equipment at an additional increased cost of 10%. When this hose is attached close to a production machine, the machine may shut down since the air is not smart enough to know where it is really needed. Because of these common situations, Compressed Air is arguably the least efficient and the most costly utility in many manufacturing facilities. In poorly designed or deteriorated systems, the owner typically receives eight cents return for every dollar spent.

Why do Compressed Air Systems present this Green opportunity? End users must take a step back, and consider the entire Air System as a whole. Have you ever known a project manager to be accountable for a project ROI which is measured one year post commissioning? This is how it should be done because system cost and efficiency is what matters... not that of individual components. Unfortunately, we see that whole is not exactly the sum of the parts.

First we should recognize that the designers of air system components operate independently. They create cost efficient machines which can theoretically produce a given amount of work for a given energy input. Market competition for components (compressor, filters, dryers, valves, etc.) is often based upon published performance specifications, and is highly competitive. If you could draw a box around that component -- you would find that they usually have met their design goals. When multiple compressors are installed, as is the case with most manufacturing facilities, nobody bothers to look "outside their box" and think about how each machine interacts with the others.

Throw in the fact that very few systems are engineered, but rather "sold" based on an owner's specification and competitive bid. This causes systems that are overpowered and under-designed for performance. Undersized equipment sold by competitive bid such as filters, Compressed Air dryers, regulators, distribution piping, application tubing, etc., typically require an artificial increase of 20 psi in the Compressed Air System. Using Positive Displacement Rotary Screw Compressors, which are the most common in use today, results in a 10% increase in energy costs. When most of these compressors are running in a throttled, or modulated state, you are looking at an old fashioned mousetrap.

The recent introduction of Variable Frequency Driven Compressors (VFD) into the market has exacerbated this problem. The VFD Compressor can be useful when applied to the Air System, but realized Energy Savings target is suspect when you draw that box around one component.

How do we make Compressed Air Systems as Green as possible? Thanks to early efforts a couple of decades ago by a single minded engineer R. Scot Foss of Airsagas, Inc., and several like minded equipment and control suppliers, the idea of a well designed and operated Compressed Air System has taken hold. This thought process has been aided by substantial increases in electric rates, which in many cases have tripled in just the last few years.

This group known as the Airnet, supplied quality independent air audits followed up with suppliers more interested in a long term customer relationships than in the equipment they could sell. In the end this resulted in hundreds of major U.S. corporations improving their Compressed Air Systems. As this concept of an engineered Compressed Air System caught on, the compressor manufacturers themselves decided that they could supply these solutions.

In some cases, they do a good job, but it is probably best to invest in an independent audit conducted by someone who does not work for the local power utility, or sells equipment. It's hard to argue with the statement that,"The most efficient Air Compressor is the one that is Off!" The machines last for many years in this state, it doesn't require maintenance either.

If this is such a great opportunity to be GREEN, why isn't the government involved? The fact is that they are. Based on several years of meetings with the Airnet group, the Department of Energy began the Compressed Air Challenge. This group now certifies Air Auditors provided they attend a short class and pass an associated test. This is certainly a good starting point and any company receiving the standardized free Compressed Air Challenge Air Assessment will be better for it.

Results show though, that this is just a beginning and that more detailed engineering of both the compression side and the user side will result in substantially larger returns. After improving the performance of several thousand air systems, this author has learned that there are really only a select few who can get the most out of a Compressed Air System.

If we can focus on the prize we can make the world a Greener place -- one compressor System at a time. It is the big picture analysis which will uncover significant Energy Savings potential. One should remember that component specifications are the perception, and the ultimate system performance is the reality which will be measured.

Let's end with one energy savings comparison. If 333 homes replaced six lamps with high efficiency bulbs for a reduction of 50 watts each, for eight hours per day, the savings is 300 watts or 0.3 kilowatts per house. This author's experience shows an average reduction of 100 kilowatts in the typical U.S. manufacturing plant by improving the Compressed Air System. If the plant operates 24/7, it would take 1000 homes replacing their light bulbs for an equivalent energy reduction.

In our new Green world, per our own Government calculations, a reduction of 100 kilowatts reduces carbon emissions by 673 tons annually -- not bad for a few weeks effort. This is truly the Green gift that keeps on giving by reducing costs to manufacturers, extending the life of our available fossil fuels, and keeping our environment clean.

Chris Wagner is President of CAM Technologies, which is an industrial controls company, based in Baltimore, Md. The company specializes in delivering compressed air automation products and services to a wide-range of industries.

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