April 14, 2010
by Doug Waetjen
With all the talk about energy and carbon reduction, many manufacturers fail to realize there are incredible opportunities for cutting energy waste and carbon gases that are right under their noses. And it isn’t always necessary to commit to major capital-intensive programs that produce long-term returns on investment. There are plenty of inexpensive projects with short-term, almost immediate returns.
One of these is repairing leaks in compressed air and steam systems, which for some has translated into hundreds of thousands—even millions—of dollars in savings per year.
Many plant personnel think compressed air is free since it’s just air and used every day. And they think it doesn’t require much attention, even if there are obvious leaks. This is far from the truth. Compressed air is an extremely expensive utility. The US Department of Energy has estimated 30% of it is lost to leaks with an annual cost of around $3.2 billion. (No similar statistics for Canada).
Why so costly? It’s expensive to produce and inefficient to use. Of the energy required to produce compressed air, less than 20% of it is available for use. That means 80% of what you pay for is used up before the compressed air makes it into the distribution system. For example (see Air Leak Costs on page 2), one 1/64-inch leak can cost $48 a year. A 3/8-inch leak can cost more than $27,000. So imagine what hundreds of leaks of varying sizes will cost a plant.
One simple way to plug those costly leaks is to schedule routine compressed air audits and leak surveys.
While design and compressor efficiency are important factors to consider, there are two other contributing factors: misuse and waste. It’s not uncommon to walk through a plant and hear the hissing of leaks, which are often ignored as background noise. When they are loud enough to be annoying, the sound is muffled by rags or duct tape. Sometimes workers use air hoses to continually cool their working spaces. In one plant, an enclosed metal box was set up with an air hose running through the top to blow air on pop cans to keep them cool!
Clearing the air
Even engineers miss the inefficiency and cost associated with misusing compressed air. In some plants, it cools bearings or continuously blows on conveyors to clear dirt and debris.
A simple, inexpensive approach to reducing compressed air waste is to embark on an educational campaign. Use meetings to clear the air about the cost of energy waste and its impact on operating costs. Ask personnel to help identify misuse and encourage them to inform their co-workers. Motivational signs placed around the plant should illustrate wasteful behaviour and suggest changes. Use newsletters to promote a campaign and a suggestion box offering rewards or awards given to the most effective suggestion.