How Manufacturers Can Uncover Hidden Energy Waste
In a manufacturing environment, fluctuations in energy usage are often tied to trends in production.
However, the production-to-energy relationship of a plant, process, or significant energy user (SEU) only tells part of the story.
The way machines are operated has a significant impact on the production/energy relationship. Careful review of the variability in the production/energy relationship of an operation can help improve overall efficiency.
Where Energy Spikes are Hiding
When production volume increases or decreases, energy usage typically follows. A common mistake is to take this at face value, without evaluating the extraneous contributors to variability in energy usage. As a result, costly energy waste often gets “lost in the noise,” and can drive up unidentified costs over time. Your energy usage may rise alongside a spike in production, but it may not have to be as high as it is.
Operational factors can drive up energy costs without contributing to production. Equipment could be left idling when it doesn’t need to be, for example. Poor maintenance of energy distribution systems, such as a steam distribution system, could result in leaks, or employees could fail to share or follow best practices for operating equipment.
Meanwhile, unreported reworks or a lack of accountability for variations in energy requirements for different products could leave energy consumption issues hidden from view.
Where Energy Reporting Often Falls Short
Many manufacturers are aware of these sorts of issues, though they may use different names for them (e.g. quality control, lean manufacturing, etc.). However, few consider their impact when reporting energy use as a function of production output.
In my experience, many sites use the overarching plant Energy Use Intensity (EUI) [unit of energy/production output] metric to track energy usage as it relates to production volume. EUI is an important metric that provides an overview of a plant’s efficiency.
However, this figure is not always the most useful when attempting to uncover specific and actionable opportunities to improve energy efficiency for a process or SEU. This is due to the sheer number of contributing factors, such as the examples above, rolled into a single value—or, in some cases, not captured at all. Without visibility into these factors, it proves impossible to determine how much each factor contributes to variability in energy use. You know what they say: you can’t improve what you don’t measure.
Gathering the Data, Conducting the Analysis
With the ever-decreasing cost of data collection and storage, manufacturers today have unprecedented visibility into performance of processes and even individual pieces of equipment. Unfortunately, many organizations collect data for the sake of collecting data, and lack a plan for putting that data to use. It’s important to come up with a process for collecting relevant data and putting it to use to identify operational improvements.
First, you will need to identify your SEUs and define measurement boundaries. A significant energy user can be a single piece of equipment or a collection of equipment or systems used for a single purpose. When determining the SEUs, consider the boundaries you will use to define inputs and outputs. Keeping your operations in mind, draw your boundaries in a way that makes it easy to understand the relationship between all inputs (e.g. electricity, natural gas, etc.) and outputs (e.g. product, steam, etc.). For example, if you are working to optimize your boiler plant, do not include steam end users in your SEU boundaries, as the additional variables will only confound your investigations of the boilers.
It’s important to consider the cost of metering and establish how you will measure and report each input and output separately. As a general rule of thumb, installing a permanent meter should not cost more than 10% of the annual cost of the energy source you’re measuring. Also, when determining where to begin optimizing a system, start at the end use and work backwards to the utility or energy source at the plant’s boundaries.
Have you considered the impact of energy waste on your perceived production requirements? Consider the aforementioned boiler plant example—if 30% of steam is lost to leaks in the distribution system, your boiler plant steam pressure set point may be higher than it needs to be. By identifying and fixing these kinds of issues, you can set more accurate requirements, saving money and time over the long term.
Once you have identified your SEUs and drawn the measurement boundaries, meter all inputs and outputs. All inputs and outputs must be measured separately; otherwise, it will prove difficult to determine what contributing factors resulted in variability in use for each energy source. In the boiler plant example, inputs may include natural gas, electricity, and water, while the output is steam.
Now that you have the data, what do you do with it? The key is putting the data into the hands of the people with the best understanding of the process or equipment.
To get a full view of your energy consumption across operations, you need to capture both the causes and the effects of energy waste. In the reports, be sure to include the input value, output value, and intensity rate (input value/output value) to see the energy usage effects of your equipment used in production, and align with the staff members who can provide context to explain what may have caused these issues. When designing these reports, provide a section where key staff can record their observations and comments.
It’s important to review these reports on a frequent basis, ideally at the end of every predefined reporting period. The better your staff can recall the events that occurred during the reporting period, the more insight you’ll be able to glean from the reports.
These reports could be extremely valuable in identifying opportunities for energy efficiency improvements. If a behavior emerges resulting in good performance, how can the behavior be captured as a best practice and repeated? If the behavior results in poor performance, how can it be avoided in the future?
And, finally, once an opportunity is identified, make sure the required behavior changes are documented, socialized among personnel, and baked into the facility’s standard operating procedures.