Francois’ 5 key tips for reducing industrial energy costs

The target of this blog is to highlight common mistakes manufacturers make which increase energy and waste costs associated with their production and to pinpoint ways to avoid them. These tips apply to all industrial plants across manufacturing processes, from snack producers to industrial cement producers using chemical plants. Basically, anywhere where fuel is required to transform a raw material to a finished good.

This is where EnerTherm Engineering have pioneered in eliminating problems that impair production and have helped businesses optimize their operations whilst minimizing costs relating to energy and waste. Having designed manufacturing solutions across a range of industries including food production, medical equipment, chemical, process, and nuclear power plants, EnerTherm Engineering holds a wealth of experience designing solutions for a range of customer types. All of whom share a common goal of seeking to reduce energy output and costs and all of whom have learnt from the 5 mistakes we have identified during our energy audits.

We have categorized the root cause of increased energy cost into five key categories, (i) non-optimum production, (ii) process issues, (iii) poor or lack of maintenance, (iv) inadequate or lack of measurement, and finally (v) poor or inadequate design. To break this down using real-life examples, we have explored each of these common mistakes further below:

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1. Non-Optimised Production.

Production facilities are highly complex these days and many aspects can affect the overall production and cost of energy and waste. Logistics and planning are key components of making these factories work efficiently.

Non-optimised production starts at the beginning of the journey of producing a finish good. When raw material comes in, it has to be stored appropriately at the right temperature etc in the appropriate location.

However simple this may seem, we have seen customers storing fat or chocolate for biscuit production in cold stores, where energy is required later to warm it up. An unnecessary step given there are plenty of low-grade heat losses which can be utilised to maintain the raw material at the right temperature.

Sometimes factories are just not used to taking the right measures to save energy because that’s not how they have operated over the last 20 years..and processes have continued on in the same way. During our work with a large bakery in the UK, we found that they were leaving their oven running during gaps in production/break down cycles. The rationale from the factory manager was that in doing so, they would conserve energy by comparison with re-starting the oven. This may be true where production is halted for up to an hour, however often we see ovens left running for a matter of hours or even days straight in high fire where no output is being generated.

In many factories we have visited, we have seen a clear lack of visibility when it comes to metering and energy/waste display. In fact, several modern-day factories still only have global site meters and are not capable of evaluating equipment efficiency or energy usage and probably even less capturing waste data. This is where our team of specialist engineers can assist in conducting energy audits to evaluate energy usage/output ratios.

Metering is at the heart of evaluating non-optimum production and if it is not available then there is very little that the factory can do to intervene. It will also help to evaluate your next CAPEX and consider how greater savings can be made through new investment.

Top Tips:

  • Ensure you can measure your energy and waste on site accurately.
  • Make it a target in your KPI.
  • Ensure adequate SOP and training related to waste and energy.
      • Create procedure checks for all staff targeting energy related issues.
            1. Understand your root cause and make sure co-workers understand how to intervene.
            2. Make sure there is a champion whose job is to target energy and waste
            3. Make sure this is at the heart of the business goals/mission statement and gain buy-in from top level management to support the activity
            4. Cherish and nurture the fact that energy and waste reduction will lead to increased profitability.
  • Evaluate better ways to re-utilise energy and waste within the factory.
      • Employ an energy auditor to pinpoint factory wide issues.
      • Utilise tool such as Pinch Integration to quantify running cost versus capital cost.

2. Process Issues

This is a whole topic in itself. However we feel it can be split into two separate sections, (i) Process equipment issues and (ii) Process Control issues).

Process Equipment issues:

There is a lot to say about general running of process equipment and there are many cases where the equipment is not working because the equipment setting is incorrect. This can be caused by (i) overall wear and tear (e.g. a damper is stuck in one position, a burner air valve is warn out). (ii) inadequate setting used for a particular product (this can be because the setting isn’t right for that particular product and / or the process has not been adjusted to suit; e.g. wrong flow rate into a heat exchanger will lead to inefficiency and waste energy and potential waste ). (iii) It can simply be because the equipment has not been designed properly and does not run optimally.

Top Tips:

  • Make sure the equipment has been designed adequately and check whenever there are changes to your processes that the equipment is still valid and still operates within working ranges. This is often the case if the process plant has been upgraded upstream but has been overlooked downstream. An example of this would be where new increased throughput with a larger dryer does not have the packaging capacity to deal with increased throughput.
  • Ensure SOP for maintenance are put in place and followed with regular checks, refer to manual of operation or supplier info.
  • Always ensure there is adequate information to recognize that the process does not work optimally whether it is part of your KPI or not.
  • Put in place a process flow chart to help the operator to make informed decisions and ensure that process adjustments are only made when required. This is often over-looked in day-night shift, where one of the shifts creates adjustments to the process unnecessarily. Ensure all process changes are recorded electronically (ideally in a database to monitor change control).

Process Control Issues:

Control system can be very simple e.g. on/off control, or more complex with PID loops or APC, Neural Net and AI controllers.

However, process control always relies on sensing equipment which if faulty will lead to sub-optimal control at best, but can lead to catastrophic failure causing downtime, waste and energy loss.

Top Tips:

  • As with process equipment, keeping a close eye on process changes is key as well as ensuring your control system can handle the changes. It may well be that your control strategy needs adjusting to deal with a larger range of throughput.
  • Make sure you maintain those instruments which are crucial to your process control. Calibration should also be part of regular maintenance as some sensors have a tendency to deviate.
  • Finally, when all is well, there are still improvements than can be made to tweak the last few percentages of energy and waste reduction. You may want to get a specialist to help you to optimize your process, e.g. for developing a new control strategy/ new control system with improved instrumentation.

3. Maintenance

More often than not poor maintenance is at the heart of increased energy and waste. Equipment devaluates at a certain rate and good maintenance ensures the equipment is kept close to its original ‘readiness’. With increased breakdowns, costly raw materials are wasted and final goods are not produced to spec. They then very often end up in waste bins, landfill or at best recycled..

To minimise energy usage and waste, any process equipment should have both preventative (before failure occurs) and corrective (after failure occurs) maintenance. There is plenty of material online, such as: (https://www.roadtoreliability.com/types-of-maintenance/) which outlines how to put in place appropriate maintenance to suit your factory needs.

Let’s think for a minute of the actual costs of not having a maintenance plan in place. Wear and tear is the most obvious one and of course with repetitive movements, mechanical or electrical items will certainly need repairing or replacing. We have seen poorly maintained burners in operation where mechanical linkage on a gas fired burner was out of sync and excess air was affected leading to very high emission. This lead to increased energy usage due to improper combustion. In this particular case, overall process efficiency had dropped by 3-8% with equivalent energy usage increasing from £20K-£40K per annum, resulting in an increased carbon footprint.

On a survey visit to a plant in Egypt mechanical wear of burner parts and poor air filtration to the fresh air intake saw the level of CO soar above 1,000 ppm.  There had also been leaks within the factory environment. In this instance, the issue was not only cost but dangerous levels of CO meaning clear health and safety issues. In any factory where dust or dirt is an issue, preventative maintenance is key. A poorly maintained sensor in a crisp factory resulted in over-predicting final oil and moisture content in the final good which led to both increased waste and customer complaints.  As demonstrated in the above examples, whether the factory uses air filtration, operating valves or sensors, maintenance is essential to minimising running costs.

Unfortunately, in difficult times the maintenance budget is often trimmed and the costs associated with output, waste, health and safety and reputation are prioritised far above the maintenance budget.

Top Tips:

  • Create an appropriate maintenance strategy for your business.
  • Ensure there is a log of maintenance and repair so you can plan your logistics for part ordering.
  • Make sure you can measure and quantify the impact on energy and waste of carrying out maintenance.
  • Ensure you create enough internal flags or alarms to warn staff of when maintenance is required.

4. Measurement:

Dr. Deming quoted “if you can’t measure it, you can’t manage it” and his statement says it all in the context of this blog. Without measuring energy, waste, or process information there is no baseline and as such there is no way for anyone to improve it. Being able to accurately quantify energy/waste ratios for all appliances within a factory is key for senior management who require visibility and clarity to generate OPEX/CAPEX for business development.

This alone should be reason enough to ensure adequate measurement and instrumentations are put in place, yet it is often questioned in discussions with senior managers. More often than not they do not understand the true value of measurement and believe this is a nice to have rather than a necessary internal procedure. Too often therefore we see our customers hit a brick wall when asked the awkward question of, “so how much energy is used in your factory ?”. In 80% of cases the answer is quantified which is a good start, however when the second question is asked as to “Where do you spend most of the energy in the factory?”, only 20-30% can give an answer.

Targeting the equipment which has the highest specific energy usage (kWh/kg or kWh/unit produced) is prime and ensures the quickest ROI.

Quality data output and consistent data monitoring is so important of course and yet we often see data systems which are not linked to any database, with only spot readings available. Historical data from a database is crucial in understanding deviation and trends. Many factory managers also believe that data logging and storing data is expensive but this isn’t the case these days..(Check our future blog on this topic).

Measuring energy and waste is at the root of optimising your fuel bills and minimising your factory waste but general instrumentation (pressure, temperature, flow rates, moisture…etc) are also very important in order to understand the root cause of high energy costs. Multi-variate analysis utilising process variable instrumentation allows for correlating directly to fuel and energy cost. We have solved many energy and waste issues by simply studying and interpreting comprehensive data sets from factories (Check our future blogs on this topic).

Top Tips:

  • Ensure adequate instrumentation and data logging is used to collect data and make sure you can store historical data.
  • Use data monitoring to create a dashboard of running energy, waste and other key process variables.
  • Produce daily / weekly reports of energy and specific energy indicators which can guide and help you to make more informed decisions.
  • Use your own energy champions to interpret data collected or employ a specialist firm to analyse the data for you.

5. Design

It may seem strange to add design as a key variable in explaining cost increase with energy and waste but if the design isn’t right/optimum or whereby processes have changed and the original design isn’t fit for purpose anymore, it can have a significant impact on fuel and waste.

Working with many manufacturers within the food industry where heat exchangers are used to heat up fluid (e.g. oil, water) for their process, we have seen high exhaust temperature often being the sign of inefficiency and fuel waste. Here’s just two examples: (a) in Saudi-Arabia our customer was recording a high temperature of their exhaust emissions due to a bad set-up with their diesel burner. Large amounts of soot were generated in the gas stream which smothered the heat exchange tubes and drastically reduced the heat transfer to the fluid, resulting in reduced throughput. The design of this heat exchanger didn’t allow for fouling and was incapable of coping with the additional heat transfer requirement. (b) Our customer installed a fan to extract exhaust gas from a cement plant to be mixed with chemicals in order to capture CO2. The duct work was made of 200 mm pipe and a 2.1 kW motor. They realised when switching the motor on that no air flow was coming through the mixer. Our customer hadn’t sized the fan properly nor had they taken account of pressure drop within the duct system and density changer. The solution to this was to increase the duct diameter and increase the fan size to 50kW.

Top Tips:

  • Specialist calculations are often required to solve design problems and you must ensure that you are taking all process variables into consideration. Think of it as a cause-and-effect situation whereby one process variable may affect another.
  • If you do not have internal skills to perform the necessary calculations or the task becomes too complex, we recommend that you use an external consultant to help you. This will generate significant cost savings as well as reduce health and safety risks.
  • If your process is not performing as well as it used to be, think of the reasons as to why this may be: (i) Maintenance related issues, (ii) different plant requirements to those of the original design.

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