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.
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