Energy Efficiency: A Little Knowledge Goes a Long Way

There has been a lot of talk in industry about energy efficiency in manufacturing facilities, but the realities of high cost and limited returns have stymied action. Some best practices, though, could tip cost calculations in favor of moving forward.

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For proof that knowledge really is power, look at the effect that greater insight into operations is having on Sasol Infrachem’s two steam-generation stations in Sasolburg, South Africa. Real-time accounting measures have empowered the operations staff there to make better-informed decisions about energy consumption. Not only has the company saved more than $3 million per year and reduced its impact on the local electrical grid, it has also improved its competitive position.

These results have put Sasol Infrachem into an elite group of manufacturers that have benefited from an important bit of knowledge: A variety of proven energy-saving technologies, ranging from right-sized motors and drives to energy-management software, can both reduce the environmental impact of operations and cut operating costs. In the process of deploying these technologies, these manufacturers and their automation suppliers have identified some best practices that can help others reap the benefits.

One of these practices is to tie energy efficiency to the goals of the business, which is what Sasol Infrachem has done. Working with consultants from Schneider Electric’s Process Automation business, Sasol’s staff now relies on measures that tie energy consumption to operational profitability.

But it’s important for manufacturers to realize that energy is just one of the key variables needed to increase the operational profitability of a plant, notes Peter Martin, Schneider’s vice president of innovation and marketing. “Many companies are finding that energy efficiency improvements, by themselves, do not help them realize the level of operational profitability improvements they expect,” he says, attributing sometimes lackluster results to companies ignoring other variables in the mix, such as safety, reliability and cybersecurity. “Focusing on any one of these variables without taking the others into account often reduces the operational profitability of the plant, even if that one variable is improving. These variables need to be managed and controlled under a unified strategy.”

Boilers, pumps and other equipment, therefore, must present the necessary information to plant personnel at the right time in an easily understood and actionable format that supports making optimal decisions. “We find that putting in real-time accounting measures first to establish a baseline and then to measure operational profitability enables establishing the appropriate balance among energy, material and production value that maximizes profitability—the ultimate measure of success,” Martin says.

Besides establishing the accounting measures, the development team for Sasol Infrachem identified the pertinent real-time performance measurements and created the necessary algorithms and financial models to connect operational measures to business goals. The team also found some unused computing capacity in each steam station’s distributed control system (DCS) to host the applications calculating the performance and accounting measures.

Now, operators, engineers and managers receive on their dashboards the information they need to maximize profit by reliably producing the cheapest steam in sufficient quantities at the required temperatures and pressures. As a result, the company has been able to generate savings in electricity, coal and other source materials.

“In general, companies that focus on measuring and maximizing their performance through real-time accounting can improve both their variable costs by 3-5 percent and production value by 1-3 percent,” Martin contends. “This can often pay for the investment in less than six months.”

Exploit integrated systems
A leading impediment to wider use of this approach has been the traditional separation between the business and operations domains. As the rise of the Industrial Internet of Things (IIoT) continues to dissolve the distinction between information technology (IT) and operating technology (OT), people and technology in these spheres have become increasingly interconnected. With the growing connections between these groups, “professionals now have the opportunity to expand their view beyond real-time control of processes to real-time control of total business performance,” Martin says.

Consequently, he advocates for a control strategy known as “asset control.” This view looks beyond the immediate process being controlled to include other variables that affect the success of the business. “An asset-centric approach aligns control functionality, including profitability measurement, with all the assets in industrial operations, from equipment assets all the way through units, areas, plants and enterprises,” he explains. “Our research shows that asset control enabled by the IIoT can help reduce energy consumption—and, subsequently, electrical spending—by up to 30 percent when integrated into a sound, overarching control strategy.”

Increasing interconnectivity has aroused renewed interest in energy consumption as a performance indicator. “It is an efficiency measure that can provide additional context to production operations,” explains Craig Winterland, business development manager for global solutions at Rockwell Automation. “The cost becomes more incremental as end users integrate energy-related data into other platforms and optimize production.” Some users have seen incremental savings as high as 10 percent from energy solutions, he reports.

Despite such results, only early innovators and thought leaders in manufacturing seem to be taking advantage of the technology to improve their energy efficiencies. One reason is that most facilities are not sufficiently instrumented to measure energy consumption, according to Winterland. “Although there are ways to calculate and allocate utilization across a site, there will always be a zero return investment to get the right infrastructure in place,” he says.

However, manufacturers already have some useful resources at their disposal, Winterland notes. One is the local power company. “The main incoming utilities should be the first place to start before investing in more advanced submetering solutions,” he says.

Another resource is the intelligence and other capabilities of today’s motors and drives. “Manufacturers can take advantage of intelligent motor control devices to start to use the virtual meters that already exist,” he advises.

Update motors and drives
Taking advantage of the latest advances in motors and drives has become another best practice—one that even poorly instrumented facilities can work into an energy-efficiency program. Just about every facility uses motors and drives, and the U.S. Department of Energy has already found that these devices are responsible for 70 percent of the energy consumed annually by U.S. industry.

To deal with this large source of energy consumption, automation suppliers like Bosch Rexroth recommend designing equipment to take advantage of the latest generation of energy-efficient motors and drives. For example, linear motors can cut friction in half, and the permanent magnets and enhanced stator wiring on synchronous motors can reduce energy consumption by about 3 percent.

“We have also been providing decentralized electric drive systems with cabinet-free technology,” says Dave Cameron, director of sales for Bosch Rexroth’s Electric Drives and Controls business. “This saves overall electrical energy and gets rid of common AC units on machinery.”

Decentralized drives also permit the recovery of excess energy through devices like accumulator charging circuits, electric or kinetic buffering modules, and servo drive controllers capable of recovering braking energy. Farmington, Conn.-based Trumpf is one machine builder that has incorporated these technologies into its highly dynamic punch presses. The smart energy mode on a drive package from Bosch Rexroth has cut the peak power drawn from the mains by these presses by half and reduced energy consumption by 30 percent.

The emergence of variable-speed electro-hydraulic pumps is perhaps the most important energy-saving development in motors and drives, according to Cameron. Because these pumps use servo motors and variable-speed frequency converters, they need not run at the same rate continuously. Not only can these pumps operate at slower speeds when processes are running at low capacity, they can also go into a standby mode when the equipment is idle.

As is the case with most energy-saving practices, manufacturers have been slow to adopt energy-efficient motors and drives. One reason is that the technology is not well known among users. Another is cost. “For existing equipment, much of the challenge is convincing the user that an upgrade will bring a return on investment,” Cameron explains. A similar problem exists for new equipment. “It’s just difficult for some people to be willing to spend the money up front to save later.”

Maintain your equipment
Yet another best practice for boosting energy efficiency is to consult the production monitoring and predictive maintenance software that you might already be using to keep equipment, especially motors, in good working order. The inefficiencies that result as equipment degrades often waste energy. Examples include bearing vibration and partial discharge in motors and generators.

“Partial-discharge monitoring can help the plant staff to establish a baseline for stable loads, which is critical for these types of electrical devices,” says Christian Laurenzano, a power-management account manager at Eaton’s Electrical Engineering Services and Systems Division. Monitoring load can then alert maintenance and operations when partial discharges begin to occur so they can schedule the necessary repairs.

Another class of useful monitoring applications is power management software. “It is impossible to reduce energy consumption without gaining insight into where energy is being used,” notes Bob Kirslis, data center and industrial marketing manager for Eaton’s Electrical Engineering Services and Systems Division. Power management software, combined with metering, can provide the real-time and historical data necessary for understanding where the facility is consuming power.

Analyses of the data can assist in right-sizing and fine-tuning equipment and suggest ways to modify habits and adjust production schedules to work around peak demand charges. It might even reveal opportunities for using newer technologies, such as microgrids and battery storage. “Battery storage can provide peak shaving and demand response to help in gaining further energy savings,” Kirslis says.

Advanced measurement and monitoring technologies used to be standalone, lab-type solutions, but not anymore. They can now be integrated into a conventional automation and I/O system. “The idea here is to integrate advanced measurement technology directly into the field level and much closer to the actual production floor, yet provide seamless connectivity from M2M [machine to machine] to higher-level systems, such as cloud databases,” says Andy Garrido, I/O market specialist at Beckhoff Automation.

He attributes this capability in part to smaller, more powerful integrated circuits. “We can now produce industrial I/O devices that can process more signals significantly faster than before,” he says. “These devices have become more precise, more compact, while maintaining a high level of repeatability.”

The precision of these devices is complemented by high-speed fieldbuses like EtherCAT. Besides offering higher speed and precision, these fieldbuses permit implementing technologies like advanced condition monitoring, predictive maintenance and seamless integration into cloud-based systems when combined with a PC-based control platform.

Garrido says that using I/O devices for monitoring energy efficiency is simple to do because EtherCAT-enabled systems have a variety of terminals available to measure all relevant electrical data directly. Some measurement terminals, for example, have a 690 V capacity to permit the direct monitoring of high-performance generators, such as those used in the wind power industry. Others are available for a three-phase AC or DC system. Particularly noteworthy are recently introduced I/O terminals that permit measuring to better than 100 ppm with a 24-bit resolution.

Although I/O hardware might not seem to be the most obvious place to begin looking for energy efficiencies, Garrido says, technology seems to have evolved to the point where it has become a good place to start.

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