When you walk into a big industrial plant, it is easy to be overwhelmed by the question “where on earth is all the energy going?” When I was a young engineer, I certainly was overwhelmed and I spent a lot of time doing detailed work on unimportant things. With most things in life, the 80/20 rule is true and it is true for energy usage as well.
If you are adopting a systematic approach to energy management, you need to know:
- how much energy you buy in (your energy sources) and
- what is your end-use of that energy, and in particular, your significant energy uses (SEUs)
When you know the end uses of your energy in industrial processes or in buildings, you are in a position to make very dramatic energy reductions – instead of tinkering around in the utilities building.
In an ideal world:
- you would like to plot your Sankey (energy flow) diagram
- then identify your biggest energy saving opportunities by focusing on the significant energy uses
- In a breakfast cereal plant, we found that 70% of all of the energy was used in the drying of finished cereal. This made us focus on energy saving opportunities around the recovery of heat and latent heat from the dryer exhaust.
- In a high-end pharmaceutical manufacturing plant, we found that 80% of all of the end-use energy was used for climate control of clean rooms. This caused us to focus on HVAC, scheduling of clean room operation and re-examining regulatory requirements.
- In a university, we found that energy use was very widely fragmented and that most energy use was under the control of staff in local departments. This caused us to focus the energy management program around training and communication activities for employees and students.
- In a supermarket chain, we found that only 2% of energy was used for lighting of outdoor car parks. Before this analysis, some supermarkets had been investing time and effort on energy reduction in car park lighting because customers had complained about apparent energy wastage. After the analysis, the supermarkets re-focused on the bigger energy uses such as refrigeration, chilled displays and interior lighting.
When it comes to figuring out your end-use energy, the two common approaches are:
- Calculation – by energy specialists using the equipment power ratings, operating schedules, advanced calculation techniques, sometimes including simulation
- Metering – designing, tendering and substantially investing in automated metering systems
Both these approaches require a substantial investment of time and/or money – and this can delay your start on taking energy-saving actions.
The question is this: would you get better value for money by focusing on the most important energy uses from the start, rather than making an equal distribution of time and money across the entire plant?
If you are hiring energy analysis specialists, you could focus them on the biggest energy consumers.
Regarding metering, too many people “over- meter” too early and with the result that they have poorly designed and unbalanced metering systems – and they spend too much money on the wrong thing. For example, I very often see industrial plants that have hundreds of electrical meters and only one or two thermal meters – even though electrical /thermal energy use is split 50-50!
What is the value of guesstimation and visualization?
For different sectors within industry and buildings, there are research results available which will give a rough first estimate of the energy breakdown for your sector. So, why not search for results on the web and then apply the percentage breakdown to your site.
If you are in a very specialized industry, perhaps it is you who is the expert. Perhaps you have a rough idea yourself, from your experience.
Here is a Sankey diagram which shows all energy uses and clearly highlights significant energy uses (it also shows which of these are metered).
Now, can you visualize it? When you see your breakdown clearly, you can see what energy is “unaccounted” – i.e. you do not know where it is used! For example, I know of a manufacturing operation with long experience of making project-based energy-saving improvements. Only when they did a Sankey-style energy balance did they discover that 30% of their energy was being used in their water treatment plant at the back of their site (and “unaccounted”) – this demonstrates the importance of a top-down analysis of their energy use!
When you visualize, you can also decide which energy streams need extra metering and which ones just need an improved estimate – and depending on the size of the energy flow.
When you visualize, you can motivate your management by showing graphically key areas of energy cost reduction.
Bottom line: Yes – guesstimation will save you time and money. So, make your first guesstimate now, find a way to visualize it, and get focused on key areas for: saving energy now; improving your estimates; and investment in metering!
Paul F. Monaghan, Ph.D., is CEO of Enerit. Paul is a 30-year veteran of energy management throughout North America and Western Europe. As Enerit CEO, he is responsible for setting the strategic direction of Enerit energy software products. Enerit is a global leader in delivery of innovative systematic energy management system (EnMS) software to support Energy Star, ISO 50001, SEP and all EnMS based on the ISO 50001 approach. Enerit EnMS software is complementary to and integrates with monitoring and energy reporting software. Enerit software includes dynamic Sankey diagrams to make it easier to get started with a systematic EnMS approach.