Eight steps to better refrigeration energy management
“A refrigeration system maintains setpoint temperature on the hottest day of the year,” Marcus Wilcox, president, Cascade Energy, Portland, Ore., says. “But every other day it runs at partial load and not optimally. Just because a system holds temperature and runs smoothly doesn’t mean it’s running efficiently.”
Systems can be made more efficient, but that effort must persist over time, Wilcox adds. “Entropy is everywhere. That applies to systems and the people charged with running them. Staff changes are made. New people are trained to run production but don’t have benefit of the energy-management program that ran six months ago.”
For many companies, energy may be their largest controllable expense, and for some, refrigeration can be one-half to two-thirds of energy costs. Cascade Energy, while active in several areas, has a longtime focus on refrigeration best practices. The company says it learned its craft over the course of 20 years’ work with ammonia and industrial refrigeration. It says it has applied energyefficiency programs to nearly 600 systems, and in the last several years to 200 to 250 systems, primarily in food distribution and public refrigerated warehouses.
Opportunities to reduce energy use in refrigeration systems range from capital projects to improved operations and maintenance practices. “But a company can’t expect to sustain and improve energy performance without designated leadership, clear goals, accountability, measurable results, and a continuous improvement philosophy,” Wilcox says.
Cascade Energy’s “Industrial Refrigeration: A Best Practices Guide” is considered by many to be the last word on the subject. Elements of a successful energy management program discussed in the guide include the following:
Gain upper management support—Besides providing clear goals and resources, management must convey that the energy program is real, a long-term effort, and that staff will be empowered and accountable.
“This executive audience is interested in saving money, of course, but also the competitiveness aspect, in that in a cost-sensitive market efficiency positions you to pursue newly profitable business,” Wilcox says. “Many companies want consumers to know they are energy conscious. Stockholders, corporate boards, and other influential groups want to see progress in sustainability and carbon footprint. This is a way to demonstrate that.”
Assign an energy champion—The energy champion establishes accountability, understands the project’s technical and financial aspects, and manages and motivates staff. There may be a champion for each technical system or department in the plant. The champion meets regularly with the team established to pursue stated goals.
“Our experience has been that even the most enthused operator doesn’t have the influence that leads to decisions to support real change,” Wilcox says. “We need to engage with engineers as well as operators in the engine room, but to drive real change you need executive support.”
Establish and track key performance indicators—Establishing energy-focused key-performance indicators (KPIs) allows a facility to track and benchmark performance of individual energy-related upgrades as well as for comprehensive energy management. KPIs ensure a facility sustains and improves upon advancements.
Industrial-refrigeration KPIs should provide quick, clear feedback on system performance that can be interpreted with minimal effort. KPIs that require burdensome data collection or complex processing will likely be abandoned over time. Effective KPIs allow a facility to develop a dashboard of system performance. With refrigeration systems, this often requires normalizing data, such as refrigeration energy, in relation to variables that strongly affect its use, such as production or outdoor ambient conditions.
Refrigeration system power (kW), system load (TR), power versus load (kW/TR), energy per unit production (kWh/lb), and energy per unit cold storage volume (kWk/cu ft) are just a few of the KPIs that can be used with an industrial refrigeration system.
Adopt a continuous improvement philosophy—One-time efforts to tune equipment and operating strategies can produce significant energy savings immediately. While this is a good starting point, these savings often erode over time when adequate procedures, measurements, and roles aren’t part of a continuous improvement program. Significant energy savings are achieved only by finding new opportunities, measuring KPIs and evaluating and increasing goals each year.
“There’s plenty of low-hanging fruit in industrial refrigeration. It uses a lot of energy. And so there are big opportunities for savings,” Wilcox says. “It’s a pyramid in that some things, like changing setpoints, cost almost nothing; others cost a little more, like fixing valves; and then capital upgrades that may involve significant investment. Doing the no-cost and low-cost stuff, given executive support, can deliver 10% to 15% energy savings. With capital projects involved, savings could amount to 30% to 40%.”
Participate in training—Training plant staff whose actions affect energy use is critical to success. Upper management, engineering staffs, operators, and maintenance staff all have different viewpoints but must share a common understanding of what is to be achieved.
“In larger corporations, for example, the operators’ world is in the engine room, which is very far away from the front office,” Wilcox says. “A yawning chasm exists between those operating the system, those paying the bills, and executives responsible for overall company profitability. The challenge is educating people in a common language across that broad spectrum.”
Reduce the cost of energy—Many utilities offer reduced rates when a facility agrees to an interruptible power-service option. Some utilities offer energy management software and training. This service can help you understand and manage factors that affect energy costs, such as time-of-day rate changes, peak-demand changes, and power-factor penalties. Be sure to find out whether alternate rate schedules are available from your existing utility provider.
“The first thing to do is set the baseline and KPIs. Set up a monitoring system and put in 2 years of utility bills. Monitor consumption on a real-time basis and see how energy usage changes as you make changes,” Wilcox says. “An engine room dashboard normalized for ambient conditions and production can track consumption day-to-day and do management reports that compare locations and aggregate across facilities. Besides getting a handle on actual costs, you can see who the leaders are and who needs additional training.”
Conduct proper cost and savings accounting—How project costs and savings are accounted for can help or hinder the results of an energy management program. To ensure success, incentive must be provided to those responsible for making improvements and meeting goals.
Document and replicate successes—Make sure the lessons learned as part of a successful energy management program can live on as plant operations and staff evolve and change. Companies with multiple facilities need to spread wealth—knowledge, best practices, and success stories—gained from site-to-site and department to- department. Although processes, system, equipment, and people are unique at each facility, dissemination of best practices is a great way to drive savings.
At end of day, energy efficiency must be managed for continuous improvement and not be just a one-time event, Wilcox says. “We’ve had clients who felt tracking and continuous improvement wasn’t necessary—that the savings would endure nevertheless. At the end of the day it’s about diligence and consistency. Without continuous processes, the progress they made just fades away.”
This is part of the Control Engineering December 2011 Industrial Energy Management supplement.