Energy makes up as much as 60 percent of the operating costs of batch and continuous-process plants. Many industrial companies interested in lowering energy consumption have already tackled much of the low-hanging fruit in their facilities, such as putting in more energy-efficient lighting, fixing compressed air leaks, tuning boilers or adding variable speed drives and energy-efficient motors. A more significant opportunity for savings, however, lies in better managing the energy consumed by production processes.
Taking that next step has long been a challenge because of process complexity and the lack of actionable information, but new energy management and control systems are making the job easier. By providing a window into production processes and energy consumption patterns, these systems give plant personnel new tools to manage energy use in the same way they manage other resources.
Batch and continuous process operations can also use these tools to reduce utility charges by avoiding peak demand penalties, using the most cost-effective sources of energy, and generating reliable consumption forecast models.
Managing the demand side
According to the U.S. Manufacturing Energy Consumption Survey (MECS), the process itself uses 84 process of all energy consumed by a process facility, on average. The proportion is even greater in certain industries, such as mining, metals and mineral processing, and water treatment.
What’s more, true process energy optimization often goes hand-in-hand with reduced maintenance costs, less downtime and increased throughput. After all, machines that run less frequently and at lower temperatures tend to break down less often, which essentially yields higher ROI.
Reducing energy costs from production processes requires managing the five most important factors that determine both utility charges and total energy consumption, says Robb Dussault, offer marketing manager with Schneider Electric's U.S. Industry Business. These factors are:
- Energy Event Management. Detection and analysis of process changes that cause consumption to exceed forecast
- Peak Demand Management. Minimizing peak demand, which triggers higher utility rates or penalties.
- Scheduled Demand Management. Minimizing costs by shifting demand to lower cost time periods.
- Idle State Management. Minimizing energy draw during idle process conditions.
- Demand/Response Management. Offering energy capacity back to the grid per request in exchange for incentives.
As an example of demand side management, Dussault cites the experience of a paper mill using blowers and dryers to reduce the water content of pulp injected into the production process. The blowers and dryers ran full-time, no matter the state of the pulp. By basing their operation instead on the condition of each batch of pulp as it entered the production line, the mill was able to reduce the temperature and speed of the equipment—and the amount of energy consumed.
Dussault also recommends involving people responsible for a company’s production processes in energy management activities. “The primary reason most companies focus their energy-saving activities on the facility is that facility management personnel are often given the responsibility for reducing energy costs. Not only is the facility in their comfort zone, but it’s often the only area where they have the institutional authority to make changes.”
Ironically, companies whose original goal was to improve control of their production processes often achieve the most significant energy savings.
Faribault Foods: Actionable information
A new control system gave Faribault Foods the tools it needed to live up to its commitment to implementing efficient processes that assure sustainable food production. The company is a member of the Sustainability Initiative Team, part of the Foundation for Strategic Sourcing. This group is comprised of executives from major consumer packaged goods, contract manufacturing and packaging supplier companies that work together to create industry standards to promote sustainability.
When Faribault Foods decided to modernize the production infrastructure at its rehydrated bean canning facility in Minnesota, it worked with Rockwell Automation to install a new control system that improves data collection from its processes, and better measures the consumption of water, air, gas, electric and steam (WAGES) resources.
By monitoring the entire production infrastructure in real time, including WAGES consumption, the control system allows Director of Engineering Phil Hines and his team to quickly identify opportunities for improvement and document each critical step of the process.
The plant’s new production process includes a state-of-the-art heat and energy-recovery system that reuses 100 percent of the can cooling process heat to warm city water for the soaking, blanching and cooking procedures. This reduces natural gas usage by 38.2 percent. The system also reuses cooled water to reduce the temperature of the cans in the cooking process, which cuts down on the company’s overall water usage by more than 100 million gallons each year.
The new system gives Faribault Foods access to an unprecedented level of process documentation, which has helped the company achieve Safe Quality Food (SQF) accreditation at all three of its processing plants. SQF standards require food processors to provide verifiable proof that robust food-safety control systems have been effectively implemented, properly validated and leverage continuous monitoring procedures.
“Without our new control system, we simply wouldn’t have possessed the documentation necessary to achieve SQF validation, which many of our customers today require,” explains Hines.
The plant is now producing the same amount of product in five days that previously used to take seven. When Hines first started the upgrade process, the plant was typically running at 75 percent of its maximum throughput. Now, the facility runs at 90 percent, with a better product quality.
“We knew from the start this wouldn’t be a one-time effort,” adds Hines. “The data lets us constantly improve our production processes, not only at our Faribault location but also at our Elk River and Cokato plants.”
UPM-Kymmene Paper Mills: Forecasting savings
Balancing energy demands and resources are critical to the profitability of UPM-Kymmene Corp., which operates 10 paper mills in Central Europe and nine in Finland. The company specializes in producing magazine papers.
Production is based on strong vertical integration as well as tight coordination of raw materials, energy and the production process. The company has long relied on energy management systems from ABB to predict its energy needs, optimize its energy sources and achieve significant savings.
“Taking care of our energy balance, the focus of the ABB system, involves balancing our time-dependent energy consumption, in real time, with respect to surpluses or deficits,” says Anja Silvennoinen, vice president of energy at UPM. In addition to energy generated by its own units, UPM-Kymmene purchases and sells energy to and from external partners and market operators.
Although the Finnish mills are self-sufficient in energy thanks to hydroelectric power, energy is often bought locally for the other facilities. Energy consumption information from mills in Austria, Germany, Wales, Scotland and France is consolidated in a control center system in Augsburg, Germany and is used to produce a total energy balance history and consumption forecast.
From there, the information is routed to Jämsänkoski, UPM’s Finnish energy management control center, which optimizes the use of energy resources and electricity trading for the Finnish mills. Jämsänkoski also controls the hydropower generation.
Prediction lies at the heart of this integrated system. Energy consumption is dependent on the operating mode of each mill, meaning how the paper machines and other units will be run. Once the operating schedule of the mill is known, its energy needs can be forecast based on history. This information can then be used to make real-time decisions on how to use, generate, purchase or sell energy.
A model that takes into account the available resources, their prices and various operational constraints supports the decision-making. A group of several mills can benefit from economies of scale to purchase and sell energy in the most effective way.
An essential step in the process involves feeding data—historical, real-time and forecasted—into one central database. This allows the operator to see what has been happening in production, how much energy has been used, and the amount required in the future.
The control center system compares the consumption forecast with available energy production capacity and existing purchase and sales contracts. It uses this information to help control center staff place bids on the electricity markets in preparation for energy purchases and sales.
The results of the energy supply calculations together with measured energy consumption can be used to internally allocate energy costs and bill users. They can also be used to verify external energy invoices.
The ABB energy management system allows UPM staff to simulate “what-if” scenarios by modifying energy system parameters without affecting the real system data. For example, new purchase or sales contracts can be simulated to assess their profitability. Mill operating schedules can also be changed to see how they affect related energy costs.
Explains Pasi Svinhufvud, who is in charge of implementing energy management systems at UPM, “We try to save energy, and now have the tools to monitor energy expenditure in real time. By keeping abreast of the situation, we can plan our operations to match our objectives. We use energy when it's cheapest and procure it from the sources that have the best market conditions for production.”
Beware the plateau
The danger for many companies undertaking an effort to reduce energy consumption—whether to lower costs or because of a commitment to sustainability goals—is that despite the successes achieved in the initial project, energy savings can settle into a plateau. This is particularly true if the energy management project was focused only on what was easiest to fix.
Here again, efforts to improve control of production processes may provide the leverage to take a more comprehensive approach to managing energy. Explains Product Marketing Manager Bill Schiel of automation systems vendor Invensys, “When a corporate energy manager can see real-time energy performance from the production process and is able to link that to the cost to produce a unit of product—like identifying the miles per gallon performance of a car—that’s a powerful incentive for action.”
Mary Burgoon of Rockwell Automation agrees. “So often, process improvements become the carrying vehicle for energy management efforts. People understand the need for improving production processes and how to do that. They’re not as certain about where to focus when it comes to reducing energy consumption. You need to know when, where and how you’re using energy, and what you’re spending on it, before you can identify a path forward.”
Discrete Examples of Energy Management
See how Skolnik Industries, Steelcase and Data Device Corp. take steps to reduce energy consumption.