Visualizing Energy Consumption

Having a clear view of your plant floor operations—knowing what to look for and instrumenting what you can—can cut industrial energy costs. Metering is the best and most accurate method, but mathematical models can help as well.

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How much energy does it take to make your product, and what does that add to its cost? Does it reflect optimal operation, or are there avoidable energy losses in a machine, a production line, or in a plant-wide system? Clearly, these are not minor matters; rather, they add up to serious bottom-line issues. As Bob Sabin, industrial energy consulting engineer for automation vendor Emerson Process Management (www3.emersonprocess.com), notes, “Energy efficiency is being recognized as a key element in economic competitiveness and business success.”

Unfortunately, a great many companies still have only a rudimentary understanding of their energy consumption patterns, so an energy audit is required. This may sound like a daunting task, but experts say there is a simple and direct way to begin the process: Walk around. This walkabout, or visual inspection, can reveal many of the ways in which your plant is using—and misusing—energy.

Though electricity use is generally the chief concern, don’t forget WAGES, an acronym that stands for water, air, gas, electricity and steam. Waste in any of these categories translates into lost dollars, so be alert for compressed air or steam leaks, as well as low-efficiency lighting and other potential trouble spots.

A fresh pair of eyes can be a useful addition here. Your maintenance personnel and other in-house staff are used to thinking in normative terms; that is, is this the way in which this machine or system normally works, so if it’s working normally, what’s the problem? To a trusted vendor or other knowledgeable outsider, it might be clear that your personnel have come to accept sub-optimal performance as normal.

While walking through the plant is both easy and largely cost-free, as Bob Gates of GE Intelligent Platforms (GE-IP, www.ge-ip.com) stresses, it’s only a start: “Just walking through the plant isn’t enough. It is impractical to assume you can monitor energy use in any large facility without some sort of sensor-based, automated system.” GE-IP supplies energy management systems as part of its Proficy suite of manufacturing software.

Before wrestling with issues of sensor placement and system upgrades, however, it is important to complete the energy audit. This includes looking at your motors, typically the biggest source of energy use, and waste, in an industrial facility. Are they sized correctly for the jobs they are expected to do? Have variable-speed drives been installed where appropriate, such as on high-energy-consuming equipment like cooling towers, where motors are often running too fast or too slow for the equipment’s varying requirements? Choosing the right cooling fan motors also impacts energy use and operational costs.

“A cooling DC fan motor could theoretically be in operation around the clock and in place for a longer overall lifespan than most other industrial equipment,” notes Sam Pelonis, president of Pelonis Technologies (www.pelonistechnologies.com), a manufacturer of AC and DC fans and motors. “Finding the right balance of power and cooling ability, counterpoised by energy efficiency and maintenance cost, is key.” (See “Using the Performance Curve to ‘See’ Energy Consumption,” opposite page.)

When it comes to cooling towers, technology now exists to closely match energy consumption to actual needs. This includes things like automated air dampers and, most importantly, programmable or “smart” thermostats.

“Programmable thermostats raise and lower target temperature zones based on user-programmed profiles,” says Pelonis. “But in the last two to three years, the programmable thermostat has become part of the cloud.” These thermostats can be directly linked to a Wi-Fi network, and through that to the Internet and then to remote mobile apps on phones, tablets and computers. These thermostats can use sensors, algorithms and cloud computing technologies so that, over time, they begin to “learn” the owner’s habits.

“They can also be integrated with online weather sources and calendar apps,” says Pelonis. “By doing this, they can determine when the owner might alter the schedule and, if the weather is changing, adjust the environment accordingly.” Thus, smart sensors may not only make sure the building is comfortable when it is occupied and more energy-efficient when it is not occupied, but they can also choose the most effective and energy-efficient manner within their programmable profiles for reaching those targets.

For example, modern bulbs and fixtures can remedy part of the problem of low-efficiency lighting, but since lighting accounts for a large chunk of a plant’s electric bill (some say more than a third), it pays to investigate other measures as well, such as automatic controls that turn lights down, or off, when rooms are unoccupied.

Companies seeking to save energy also need to closely study their utility contract and their monthly utility bills. Power companies typically charge more for power delivered during hours of peak demand. Knowing that, companies can weigh the feasibility of staggering start times or rescheduling certain operations for non-peak times. Savings from this process can in many cases be considerable.

Planning and visibility
As is obvious by now, the questions asked during an energy audit will suggest the range of corrective action available. But corrective action by itself is not energy management. Energy management entails establishing a consumption baseline against which future gains and losses can be measured, and the development of a prioritized plan for phased-in corrective action. As a necessary precondition, it requires visibility into the plant’s energy usage.

“The first step is to be able to visualize where energy is being consumed,” stresses Marc Leroux, chief technology evangelist for collaborative production management at automation vendor ABB (http://new.abb.com/us). “And providing visualization is fairly straightforward.” It’s a matter of metering the equipment’s energy usage, and then linking that data into a plant-level system that can facilitate analysis and action.

One problem, however, is the fact that “equipment that is typically inefficient is also likely to be older equipment, which does not have any metering associated with it. This is the point where many manufacturers stop attempting to use a plant-level visualization system,” Leroux says. “Of course, metering is the best and most accurate way to understand energy consumption, but it is possible to get a reasonable picture of performance using mathematical models.”

Emerson’s Sabin agrees, saying, “Most plants don’t have enough granularity in terms of energy measurement. They often need more instrumentation if they hope to provide themselves with a real-time tool for energy and cost savings.”

This situation is rapidly changing thanks to declining prices for sensors and other instrumentation and, more importantly, to the advent of wireless technology. “Wireless technology has really matured in the last five to 10 years,” Sabin notes. “The growth of wireless has changed the game. A wireless instrument can typically be installed for a fraction of the cost of a wired instrument, and wireless measurement is now being brought to bear on instruments and processes that previously were impractical to measure.”

Sabin cites “a simple device called a steam trap monitor” that was formerly found on a few strategically selected steam traps in process plants. “We are now seeing plants that put them on most of their steam traps. The energy [savings], and thus cost savings, from this pervasive sensing make it almost a no-brainer,” he says.

With wireless technology, says Sabin, “we are seeing in some cases as much as 40 percent more instrumentation being put into processing plants—particularly on important equipment around production operations that in the past was largely unmonitored. This is facilitating a new level of reliability and energy performance.”

GE’s Gates concurs on the importance of wireless: “Providing your people with access to real-time information on energy consumption is a key part of successful energy management. And thanks to wireless technology, you can now get this data not only at the HMI but also on your cell phone or other handheld device.”

Automated systems
As good as this ability is, it is not enough: It’s great to have a clear picture of a tree, but one needs to be able to see the entire forest as well. That’s where automated energy management systems come in. Provided you have the sensing infrastructure in place, an automated energy management system will give you the big picture and the ability to manage it. A variety of systems compete in this sphere, including PROFIenergy, a system from the network protocol organization PI North America (us.profinet.com). According to Carl Henning, deputy director for PI North America, PROFIenergy enables control devices like PLCs to command energy-consuming units to switch into energy-conservation mode during breaks, such as lunch breaks or random stoppages.

This strategy is used by other energy management systems as well. According to Daniel Liu, business development manager for Moxa Americas (www.moxa.com), “By implementing an energy monitoring system, the cost savings on energy is said to range from 15 percent to approximately 25 percent—just by switching off the unused machines and equipment.” At first glance, that claim appears startling, but it seems less so when one considers estimates that say robotic cells, lasers and drives can rack up close to 60 percent of their total energy consumption during pauses.

Liu goes on to observe that “energy monitoring systems and asset management systems of course have a pretty high overlapping rate in terms of equipment and techniques used.” Sabin puts it thusly: “When is an industrial site normally performing worst as far as energy efficiency? When equipment is performing sub-optimally.”

Gates adds, “When you monitor a line’s energy figures over time, you get a glimpse of the fact that something must not be running right; something is in need of proactive maintenance.” Clearly, energy management and asset management are two sides of the same coin.

The key to effective asset management is to use energy consumption figures and the host of other data that real-time monitoring and smart devices can provide to decrease unplanned downtime. Here again, an automated system is crucial. Such a system should not only be able to monitor key parameters and track those parameters over time, but also be able to analyze the results and indicate possible corrective actions.

However, despite this high degree of autonomy, an automated energy or asset management system remains a tool, and typically a rather expensive one, cautions Ahmed Mahmoud, senior group manager for embedded systems marketing for National Instruments (www.ni.com). It’s cost-driven, in part, by the need to customize these tools to fit the needs of the specific plant.

Still, says Mahmoud, larger facilities are finding these systems increasingly attractive because of the complexity of their operations and the fact that an aging workforce means there are fewer people on the plant floor with the skills and experience to make energy or asset management decisions manually. “Ultimately,” he adds, “it all comes down to profitability and to driving innovation in your process.”

The new ISO 55000 Asset Management Systems standard offers some guidance on the subject of energy management. The effect of this standard will probably be minimal for some time to come, though, unless major customers and insurance companies begin insisting on it. Still, it would be wise for those involved in energy management to familiarize themselves with the standard. This can be easily done by visiting the ISO website (www.iso.org) or Mitsubishi Electric Automation’s new energy management website, www.mitsubishienergy.com.

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