Electrical Systems / Energy Management

Wanted: wasted energy

How to capture the reward of higher efficiency.

By Paul Studebaker, CMRP, Editor in Chief

Many maintenance, operations and engineering managers argue that notwithstanding the recent hype, energy management has been on their agendas since the first energy crisis in 1973. Others say that much more has to be done in the name of corporate social responsibility, green, sustainability and saving our planet. Then, there are the pragmatists who need to see a payback as with any other project or capital purchase. Many need a push from government through regulatory pressures or demands from customers. Finally, some assert that energy-management initiatives are an excellent marketing or public relations opportunity targeting customers, employees, shareholders, suppliers, government, media, special interest or lobby groups, and the general public.

“The good news is that none of these are mutually exclusive,” says David Berger, P.Eng., partner, Western Management Consultants (www.wmc.on.ca). Some energy-reduction initiatives have always been there and will continue long into the future, like ensuring a building is well-insulated and properly sealed. These same measures benefit the environment by reducing waste, have a solid business case and are good for marketing purposes.

“So, it should come as no surprise that, regardless of your rationale, adopting an aggressive energy-management program is the right thing to do, independent of your industry, size or location,” Berger says. “And many of the possible initiatives under such a program are low-cost and easy to implement.”

Assemble a posse

The energy team will be different in every facility, but has some characteristics in common. “The team will be multidisciplinary and include production engineers, maintenance, financial, procurement, and production workers and supervisors,” says Peter Garforth, principal, Garforth International (www.garforthint.com). “The leader often will be someone who self-selects because of a personal passion about energy, and it’s not unusual for individuals on the team to have deeply held personal values around using it rationally.” Successful teams meet regularly, develop clear action plans that are updated regularly and learn to act as opportunities arise. They measure results, they engage as many employees as needed, and they understand that it’s about maintaining continuous focus.

“Often, people don’t try to stretch themselves or the people closest to the process don’t have the skill set. They become overwhelmed at the totality. They think, ‘What can I do?’” says Randall Witte, CEM, president, Emc2 ConServ Inc. (http://lighthouse-us-inc.com). “Stop and look at the system and ask, ‘What if?’

If you see something you question, ask about it. You might not have the whole answer, but don’t be afraid to challenge the status quo. Seek out others and ask.”

An overriding characteristic of a successful site energy team is an insatiable appetite to learn more about energy use and procurement and dig out the opportunities through creativity and focus. “Maintaining this passion creates a challenge to their leadership to make available educational tools, and most importantly, to reward and recognize team efforts,” Garforth adds. “Obviously, it also challenges leadership to consistently underline the importance of achieving energy breakthroughs through words and actions. Every senior manager visiting plants should ask energy questions and expect to see an energy progress update. As with safety, if the questions are asked often, the answers get better.”

Known whereabouts

Some energy-saving opportunities, such as lighting, are pretty obvious. Some can be readily identified by experts or consultants, for example, air compressor controls. Some, like motor management, give reliable results over time if you support a consistent program with a persistent leader. These relatively large, well-defined projects can be identified, quantified and executed by a small number of experts, engineers and managers.

In a typical facility, one-fourth of energy cost savings come from capital projects external experts identify and one-fourth from managing energy procurement more effectively, says Garforth,. One-fourth result from capital projects identified from within the plants themselves, “usually with returns in excess of 20%,” he says, and “in my experience, typically a quarter of the gains come from low-cost measures that pay back in less than a year.”

If 25% to 50% of energy savings are to come from within the plant, it makes sense to build energy awareness, gather ideas and recognize results on the floor. Good management supports plant-floor efforts with goals and rewards.

“That’s the first step to effective energy team building: establishing goals,” says Garforth. Based on breakthrough goals accepted by the senior leadership, consistent energy productivity goals should be clearly established at the visional and plant levels. “It’s crucial for senior management to underline that energy productivity is important now and forever,” he says. Like attention to safety, the signal has to be very strong that it’s not going to go away.

But a large percentage of potential energy savings won’t be realized unless you recruit and engage the plant-floor workforce. “Contrary to commonly held views, breakthrough energy productivity rarely comes from a few obvious magic bullets; it comes from capturing hundreds and thousands of small wins throughout the company,” says Garforth.

Hot on the trail

Those thousands of small wins range from control strategies to compressed air leaks, and finding them requires constant awareness, observation and communication. Build a system for submitting and encouraging questions and observations about anything that uses energy.

“I go into different facilities and see the same technology applied at several sites, too often without question,” says Witte. For example, it takes a lot more gas flow to transport powders horizontally than vertically. “To save energy, raise the powder to a suitable height, then slope the run through the horizontal distance to match the transport speed so the powder is in free fall throughout the run,” Witte says.

Many maintenance, operations and engineering managers argue that notwithstanding the recent hype, energy management has been on their agendas since the first energy crisis in 1973.

Pay attention to opportunities to recover heat and harness free cooling on chillers, cooling towers, boilers and turbines. “We designed and installed a 99%-efficient cogeneration system,” Witte says. “All the fuel and 21°F of ambient air temperature went into the process. The system saves more than 80% of the related CO2 and 97% of the related NOx of the replaced electricity and thermal energy from boilers. It pays for itself in two years to three years, depending on the cost of electricity.”

Make the invisible, visible. Take full advantage of existing power and flow metering, including untapped sources such as variable-speed drives. Add temporary metering where it makes sense, and make a plan to install a power monitoring system that lets you verify results and identify future changes in consumption patterns, malfunctions and deterioration.

“I always remember a particularly creative example of communicating the impact of energy use in a glass furnace to the financial staff,” Garforth says. “The plant energy team attached an ultrasonic flow meter to the gas line, and instead of calibrating in Gigajoules or cubic meters, they used dollars at the current tariff. When visitors walked past the large LED display showing thousands of dollars an hour going into the furnace, the question as to how to slow the meter quickly came to the fore.”

Closing in

Taking down a big energy waster is rewarding, but don’t overlook the small stuff. Parasitic losses as small as seal friction can add up, and alternatives are being designed to reduce seal energy consumption.

“We developed our P/S-II seal with Gylon — a restructured PTFE with a special grain structure — for applications where traditional carbide seals fail from heat or friction,” says Earl Rogalski, senior product manager, Klozure products, Garlock (www.garlock.com). Along with slipperier materials, it uses a rotary instead of a face-to-face motion to reduce friction.

Low-friction packing-type seals also are available. “We compared seal types on a test rig with a 1-3/4-in. shaft,” says Chris Boss, senior applications engineer, compression packing, Garlock. A typical braided seal drew 1 hp to 1.25 hp and mechanical seals 0.65 hp to 0.8 hp. “The Hydra-Just started out at about 1 hp, but after 30 minutes of break-in it went down to 0.63 hp,” Boss says.

In fluid-handling applications, seal-related energy losses from excessive flushing and process dilution can easily dwarf frictional losses. Comparing the energy consumed by mechanical seals to that consumed by compression packings on, for instance, slurry pumps, “There is a whole lot more energy associated with flushing systems than seal friction,” Boss says. “How the seal is flushed and the amount of flush water makes a huge difference.”

Cold water cools and lubricates the seal, but cools the process so it may have to be reheated. Water that enters the process will have to be removed later from, for example, a paper or ore slurry. Dewatering by evaporation or separation takes energy.

“These aspects are orders of magnitude greater than friction,” Boss says. “It helps to use compression packings that run with less water, like our 1333-G braid, that can run at lower leakage rates and with lower flushing rates than other braided packing materials.”

Pressure and flow meters can be used to control the flow, reduce flow rates and determine when seals need to be adjusted or repaired. “You want to maintain pressure at minimum flow,” Boss adds. “Some users monitor flow rate but not flush pressure. They use more flow than they need, and they have no idea how low the flush rate could be reduced.

Figure 1. Labyrinth seals consumed about half the power of a lip seal on this 3-hp test motor.
Figure 1. Labyrinth seals consumed about half the power of a lip seal on this 3-hp test motor.

Compared to radial-lip seals, non-contact labyrinth seals or isolators can save energy on motors (Figure 1). “Our tests on a 3-hp motor show a lip seal requires almost 700 W to start and 300 W to run, while an isolator uses about 300 W to start and less than 150 W to run,” says Rogalski.

In the United States, 14 million industrial motors 1 hp or larger consume 30% to 35% of total U.S. electric power. “When you add up the potential savings, it’s an enormous number,” Rogalski adds. “The labyrinth seal lasts nearly forever and is virtually drag-free compared to a contact seal, but it can be a tough sell, especially on lower-horsepower motors. Do a life-cycle analysis and consider the cost to replace seals, as well as the downtime.”

Be creative. Witte’s group has separated the control of humidity and temperature by means of a liquid desiccant system. “We designed a new style of air handler that removes moisture from the air independently of heating or cooling the air, saving 35% to 60% of the refrigeration energy and capacity compared to standard HVAC systems,” he says. “The system can also humidify the air without any other devices.” The system needs no drain and won’t freeze — it can supply air at -60°F — so it needs no reheat coils.

Finally, be relentlessly inquisitive. “If something seems not right or not the best, challenge the status quo even if you don’t have the answer yourself,” Witte suggests. “Get corporate engineering involved. It’s caused by a law of physics, but that doesn’t mean it has to happen.”