Energy audits are highly useful tools that help determine whether your compressed air system is as efficient as possible. With energy expenses making up the largest share of a compressed air system’s costs, such an audit may save companies a lot of money.
In some cases, a full energy audit is not needed. That is especially true for simple compressed air systems for which a simple energy assessment may be sufficient. An audit is a much more thorough – and expensive – analysis of a compressed air system. It usually takes a few days or even weeks to complete and involves the use of special equipment. An assessment is more superficial and basically involves an expert “walking the line” while trying to identify inefficiencies during a visual inspection.
Regardless of which type of analysis you choose, there are some things you can do to make sure that your compressed air system is as efficient as possible, even before an energy audit or assessment is done.
Leaks are the main enemy of compressed air systems. In fact, research has shown that up to one-third of the compressed air that is generated is lost in leaks. That is a staggering amount if you think about it. Just imagine filling up your car and then watching 30% of your gasoline drip on the road through a leaky fuel line as soon as you start driving. While fixing leaks is important and can save large amounts of money (even a small leak can cost hundreds of dollars annually), you need to be careful when doing so: Especially old compressors may not be able to handle a suddenly reduced load. That is why any effort to plug leaks must be accompanied by measures that will allow the air generation to be reduced in line with the lower demand.
A well-designed piping system eliminates pressure losses and therefore saves you money. Conversely, old pipes, over- or undersized piping, or convoluted piping all contribute to an inefficient system that costs you money. This is especially a problem in the case of older compressed air networks as well as those that have been expanded over time. In addition, the material of the piping matters. Cast-iron piping, for example, will rust eventually, which may not only clog the pipes but could also degrade the air quality. Replacing these types with those made of other materials will pay off later – especially if the piping diameter is designed to supply the necessary airflow. While only experts can identify all of the inefficiencies of the piping, even a knowledgeable layperson should be able to look at the existing piping and identify major problems, e.g. pipes that seem to small or too large, inefficient pipe layout, etc.
When they are faced with capacity issues, some compressed air users increase their compressor pressure. That is not only an expensive “solution”, but it is also counterproductive. In many cases, a higher pressure may make things worse because, for example, leaks will only leak more air and compound inefficiencies.
Another major source of waste is a lack of awareness of how much compressed air an application actually needs. The operators of compressed air systems often overestimate the amount of pressure needed. In addition, compressed air users should always make sure whether their downstream equipment could run with less pressure than specified by the manufacturer. These optimizations alone could save thousands of dollars annually.
Large compressed air networks sometimes still include obsolete equipment, such as filters or separators that are no longer in use and only cause pressure drops. Replacing this downstream equipment will increase efficiency.
Just because compressed air is widely available in many production facilities does not mean that it should be used for everything. This is particularly true because compressed air costs nearly ten times as much as electricity. That means it is highly inefficient to use compressed air for tasks such as cleaning off a surface or keeping people cool.
Optimizing a compressed air network following an audit is smart, but not enough. You also have to make sure that the system continues to be well-maintained or the same efficiencies that were just eliminated will slowly return again. That not only means keeping an eye on the items on the list above but also regularly cleaning and maintaining filters, separators, and dryers. That is the only way your system can consistently and reliably deliver high-quality with utmost efficiency.
However, even if you take all of the steps, an energy audit is more than likely still worth it because trained experts will always be able to identify inefficiencies others will not be aware of. In addition, they will use sophisticated equipment that can pinpoint optimization potentials, so any business with a complex compressed air network should consider commissioning one.