The concept of “green” is a hot topic in packaging today, with companies constantly striving to win plaudits for their newer, more eco-friendly packages. But green, or sustainable, concerns are impacting the production side of the packaging equation as well, most obviously in the area of energy efficiency.

Discussions of production line energy efficiency typically begin (but nowadays don’t end) with a look at motors, and with good reason. Armory Lovins, chairman and chief scientist of the Rocky Mountain Institute, a resource policy think tank based in Snowmass, Colo., states that nationwide, the energy consumption of industrial electric motors can be cut by 50 percent. Other estimates vary, but it is clear that this is an area rife with huge energy saving potential.

In the quest for dramatic energy savings, switching to energy-efficient electric motors is generally a good place to start. This may include high-end NEMA Premium efficiency motors that meet guidelines established by the National Electrical Manufacturers Association. Though these motors typically cost 10 percent to 15 percent more than other energy-efficient motors, they frequently yield a quick payback on the investment. But that is just a start, because energy-efficient motors are only a piece, albeit an important one, of the puzzle.

“Making sure motor power ratings have been closely matched to the load or application (often referred to as sizing) is another way to ensure a motor is being used efficiently,” notes Corey Morton, product manager for automation supplier B&R Industrial Automation Corp., of Roswell, Ga. That’s because motors run most efficiently when operated at around 75 percent of their full load rating.

 “On new equipment, proper sizing may be relatively easy to implement,” observes Morton, “but often, for existing equipment, motor replacement may not be an option.” These cases are tailor-made for variable frequency drives (VFDs), with their ability to vary the motor’s energy output to match the load. Energy savings ranging from 3 percent up to a whopping 60 percent can result, depending on the application.

VFDs can pay off in other ways as well. “Starting an electric motor with full line voltage results in a large, inrush current that can be six to 10 times the motor’s full load current. For large-horsepower motors, this can be an enormous amount of current that may even result in momentary voltage sags on the facility’s distribution system,” says Morton. The result may be a large peak demand and inefficient operation of other equipment due to the momentary voltage sag. Depending on the company’s utility contract, it can also result in penalty pricing as well.

“A VFD can address both issues by slowly ramping the motor up to the desired speed,” continues Morton. “The starting current is reduced to levels required to accelerate the load to the desired speed, eliminating the voltage sags that would have resulted from the large inrush of current.”

More than motors

New motors or old motors, it’s a question of looking at the whole system, says Rich Mintz, national product manager for drives supplier SEW Eurodrive, of Lyman, S.C. “The goal is to get the most mechanical energy out of the least amount of electrical energy.”

The VFD can help in this regard. “The importance of the VFD is not just to limit the inrush of the motor. The most important thing to consider is that when a drive is employed, it provides the system with intelligence and flexibility.” He says that by providing the ability to control a motor’s starting, ramping, speed and other variables, it gives users the ability to manage energy consumption.

He cites for an example a plant with regenerative drives that return energy to the power system. Factor in drives with a control algorithm that monitors when other drives in a process or plant are starting or stopping, with some timed to operate only during periods of regeneration, resulting in a net power consumption of zero. “While a lot of applications can’t just sit around and wait to run, what about air compressors? Chillers? Pumps? Mixers, fillers or conveyors?  Will a start delay of a few seconds or even minutes really make much difference in these applications?” Mintz asks. “And when they do operate, is it OK to extend the ramp and maybe operate at a lower ‘full speed?’ ”

Mintz challenges other engineers to look for applications such as these, pursuing what he calls a holistic approach to energy issues. He adds, “These are the best ways to save energy: slow start, slower operating speed, shut off ...