Variable Speed Drive Technology Supplies Power When Needed

This article is the final in a three-part series that examines ways to reduce compressed air energy costs. Part one outlined 10 ways to reduce energy costs. Part two suggests ways to reduce energy costs through heat recovery.

The simple economic model of matching supply to meet demand optimizes productivity and helps control costs. This makes sense not only in the economic world, but also when considering compressed air production and use in a manufacturing facility.

Compressed air systems are critical to a number of functions within a food manufacturing facility. But poorly designed and maintained compressed air systems, by some estimates, account for up to $3.2 billion in wasted utility payments in the United States every year. One quick and easy way to ensure your facility isn’t squandering energy in its compressed air production process is to consider the benefits that can be provided by a variable speed drive compressor.  

While many plants require continuous, round-the-clock operations seven days a week, there are likely cycles where lulls in production present opportunities for energy savings. For example, there are 168 hours in a week and most compressed air systems only require anything near full capacity between 60 and 100 hours, or about half the time. When an air compressor runs at 100 percent to accommodate demand that represents only 50 percent of the compressor’s maximum output, then half of the energy required to power that compressor is immediately wasted. Variable speed drive air compressors continually and automatically vary the production and output of compressed air to meet fluctuating power requirements.

Statistics compiled through compressed air system assessments and performance analysis show that nine out of every 10 air compressor applications are ideal for VSD. Compared to a fixed drive compressor, a VSD compressor sized for the same end use requires on average 35 percent less power to operate – simple math shows that this can cut a manufacturer’s compressed air costs by one-third.

Energy costs, already on the rise in recent years, have garnered additional attention of late as facility managers are continually charged with finding new ways to cut costs.

Look at one case where a manufacturer was running a 200 horsepower air compressor 24 hours a day at 3 cents per kWh. These energy costs have doubled in the last five years, increasing in some areas to 8 cents per kWh or more. The annual cost to operate that compressor at 3 cents per kWh was $41,273. Today, at 8 cents per kWh, that same compressor costs $110,062 to operate every year, or more than $550,000 over five years. Staying with this example, switching to a VSD compressor could potentially save this facility $38,521 annually or $192,608 over five years.

Combine these savings with the greater efficiency that is realized when you replace the older equipment with newer, more efficient infrastructure and the return on investment is often realized within two years. By varying output to meet compressed air demands, manufacturers who choose to include a VSD compressor as part of their infrastructure can realize immediate energy savings that will only compound over time.

For more information about Atlas Copco Compressors visit For a free copy of Atlas Copco's 156-page Compressed Air Best Practices Guide, please send an e-mail to and put "Manual—Food Manufacturing" in the subject line and provide your delivery address in the body of the e-mail, and Atlas Copco will send you a complimentary copy.