Energy efficiency starts with knowing how your facility is using its power
With the industrial sector consuming more than one-third of all the energy used in the United States, it's easy to see why facility managers are constantly seeking ways to reduce energy costs without compromising their production lines. Today, thanks to emerging technology and energy-efficient equipment, the real costs and return on investment can be easily calculated. According to the U.S. Department of Energy, implementing best practices for energy management and energy-efficient equipment, as well as plant-wide energy audit recommendations, can reduce a plant's annual energy costs by 10% to 15%.
As a first step, energy audits or detailed walk-throughs by energy management professionals are useful tools for identifying potential energy conservation measures (ECM) and savings opportunities in the facility. Based on what is learned about a particular plant's inefficiencies and potential cost savings, measures such as lighting retrofits, infrared scanning of heavy equipment, advanced metering, or an enterprise energy management system (EEMS) are all possibilities.
Why EEMSs are useful
Unfortunately, many plant operators only gain insight into their energy usage after a head-turning event, when consumption has increased or decreased during the month based on ebbs and flows in production. An EEMS ties all of a facility's energy usage data together, providing manufacturers with details of their daily energy usage (Photo 1). Where making products is the first priority, saving money can be an easy second by employing an EEMS to:
Chart energy usage;
Compare energy usage by day, week, month, or year;
Monitor all utility services, including electricity, gas, water, and steam;
Schedule energy data collections to occur automatically;
Evaluate the impact of critical load-shedding activities in real time;
Determine specific processes that are not energy efficient; and/or
Identify poor performers by benchmarking energy levels at multiple facilities.
Manufacturers and plant operators can immediately realize some of the benefits of predictive maintenance, energy efficiency, and cost reduction by using accurate, real-time status feedback to evaluate the performance of pumps, compressors, heaters, chillers, conveyors, and other electrically powered equipment. If energy usage or a particular load shows an increase above the normal level, equipment might be deteriorating or prematurely developing problems.
A study conducted by the Alliance to Save Energy, based in Washington, D.C., reports that the connection between energy choices and cost is not always made. In the study's example, “compressed air leaks are often overlooked because ‘air is free,’ although this conclusion ignores the fact that 5 horsepower of electricity is consumed to generate one horsepower of compressed air. Steam system management is susceptible to similar thinking. Plant operators who assume that scrap rates are of no importance ‘because scrap can be melted down and used again’ are not considering the excess energy consumption that this practice requires.”
In one real-world example, a facility manager noticed unusual data in the form of rapidly sequential electrical load changes when he was working on a totally different project. No one was aware of it, but the facility's HVAC equipment was “short cycling,” or cycling off and on too frequently, due to a loss of coolant in the system. Warned by the abnormal data, he was able to repair the equipment before it had a chance to break down and cause unnecessary downtime and an even more costly headache.
EEMS equipment elements
The technical components of an EEMS typically include interval data recorders (IDRs), advanced meters, and energy intelligence software. Each of these elements is critical for learning when, where, and how energy is being used in a particular facility. By analyzing the data, an operator might learn that a piece of equipment is not being shut down at the end of a shift as planned — or unnecessary equipment might be running during peak hours (when electricity costs more to generate). The solution might be as easy as shifting specific equipment usage to non-peak hours, when energy is cheaper, resulting in the potential savings of thousands of dollars.
The first EEMS element, IDRs, are data collectors designed to track and record energy consumption, typically in 15-minute increments. IDRs send the information to an in-house computer or a secure Web site that allows manufacturers to analyze the information in real time or historically. Plant engineers and managers can track total load within a facility to benchmark usage patterns and uncover “out-of-tolerance” energy use at individual points. Knowing the real costs, managers can adjust their power use accordingly.
Advanced meters (Photo 2), the second element, are installed to measure actual electric, gas, and water use behind the main utility meter. Advanced meters are instrumental in managing utility costs and determining the drivers of excess usage, and can be used to measure consumption (kWh), demand (kW), real-time kW load, volts and amps per phase, and other parameters. The demand reading will show the highest peak demand and the date and time the peak occurred based on a time period consistent with the local utility's billing tariff. This is ideal for applications where kW peak demand charges become an issue. Where poor power factor is penalized, kVAR data provides the analytics needed for correction.
Technological advancements have mitigated the physical requirements for installing advanced meters. Previously, they required large and bulky peripheral equipment that took up valuable space within an industrial facility. Now, advanced meters take up far less space and do not require an interruption of service. They can be installed with 0-2V output split-core current sensors placed around the conductors of the circuit being monitored (Photo 3). This ease of installation allows them to be placed on virtually any load in the building, providing increased data on energy consumption throughout any given day and making them beneficial for manufacturers facing kW peak demand charges.
The final EEMS element, energy intelligence software, allows plant managers to read and monitor energy consumption easily and effectively via on-site or off-site computers, the typical system requirements of which include:
10 megabyte minimum hard drive space available
RS-232 serial port
Microsoft Windows 2000 or higher
Energy intelligence software systems generate energy usage graphs and profiles for demand analysis and power-reduction consideration in selectable time sampling rates. Itemized electrical bills for departmental allocation and usage verification are also easily created. Another useful function is determining the coincidental peak demand date and time for multiple facilities or loads. Most software will read meters either on-site or off-site (via cellular or telephone modem, intranet, Internet, and/or remote computers).
Making a difference
A plant's energy management system (EMS), also known as a building management system, uses multiple methods to control energy usage. Its controls can be selected to manage HVAC, lighting, or equipment — or used to control all three. Control criteria can be based on time, temperature, light, and actual load data. With the data obtained from the EEMS, the EMS can be tuned to a facility's real requirements to obtain the maximum savings. Advanced meters can often be directly connected to the EMS for use in optimizing its ability to control the energy usage.
Energy efficiency starts with the detailed knowledge of how the facility is using its energy. Getting started is as easy as analyzing your company's priorities and payback guidelines, creating an action plan, and getting corporate buy-in. Next, determine the goal for implementing an EEMS, whether it is for energy conservation, cost savings, or reducing power factor penalties. Then, schedule an energy audit with energy management professionals. They should be able to discuss the use of an EEMS as a viable solution to meet your needs. Finally, request a cost-benefit analysis and an estimated date for your return on investment for each recommendation.
Bovankovich is vice president of engineering for E-Mon, LLC, Langhorne, Pa.
Sidebar: EEMS Communications Options
Ethernet — meters are connected to secure servers via broadband connection.
ModBus — industry communications standard developed for meters (and other industrial equipment) to communicate information.
Industrial cellular phone — allows meters to stay in contact with EEMS servers where landlines are not available.
Traditional telephone (ADSL POTS) landline — sharing a landline is sometimes the most effective way for meters to communicate with servers, if broadband networks are not in place in the area.
Sidebar: EEMS in Action
Enterprise energy management systems (EEMS) can provide significant cost savings — just take a look at these real-world examples. In one case, a food manufacturer processed one of its more popular snack brands from a single building within a much larger manufacturing complex. Each tenant paid for energy based on an estimated percentage of complex-wide energy usage. The snack food facility manager suspected that his operation's portion of the energy bill was too high and decided he needed a better way to allocate true energy usage costs.
After installing energy meters and analyzing the data, the manager's suspicions were confirmed when he learned that actual energy use was less than the amount for which the product line was being billed. The result was a reduction in his electric bill from an estimated 11% of the overall facility electricity bill to an actual 7% (an effective 36% reduction). For a relatively small investment in metering equipment and software, the snack food line was able to save thousands of dollars per month in energy costs. As a result, the investment paid for itself within 60 days.
In another example, a manufacturing facility shared a location with a sister division and also split the energy bill. One of the divisions was experiencing unusually high energy costs compared to other corporate facilities that manufactured the same products with similar equipment. As a result, the corporate office made preliminary plans to shut down the division and move the manufacturing operation to a facility located in another area of the country that had lower tariffs for electrical power. In an attempt to solve the problem without having to move the business elsewhere, managers installed energy meters to separate the energy usage of the two divisions and an interval data recorder (IDR) to measure usage of specific equipment and processes.
Managers found that the division paying for 60% of the electricity bill was actually using less than 41% of the complex's total energy. The IDR also showed that a heat-treating process used once a week was causing a 175kW spike in energy usage. The division worked with the corporate accounting department to re-allocate its percentage of the energy bill and moved its heat-treating process to a day when overall demand was not as high. In this way, the division saved $2,100 per month just by eliminating the spike in electrical usage for the heat-treating process. As a result, the division reduced its energy allocation by $324,000 per year. Needless to say, plant closure plans were cancelled.