Food & drinks sector must address energy challenges

Article by Chris Evans, marketing & operations group manager of Mitsubishi Electric UK:

Many customers tell us that one of their biggest business costs is energy, so it would seem obvious that tackling and improving the problem would be the natural thing to do.

However, this ignores the pressure of producing product and satisfying customer’s demands, which all food and beverage manufacturers face on a daily basis.

An argument often heard is that the energy bill is seen as a “sunk cost” or that it is the necessary evil endemic in the production process and that “it is what it is.”

20% of the UK’s total energy usage centres on industrial processes and 60% of that energy is consumed by electric motors

The solution is often seen as merely negotiating the best tariff from the supply authority but this approach fails to recognise the opportunities that lie dormant within the existing automation control architecture to identify areas for improvement and with some investment in energy management, to deliver significant energy and cost savings.

Some of the perceived obstacles to implementing an energy management system include cost, ROI and disruption to the production process. Indeed it is seen that this perception alone is enough to prevent any further discussion in favour of continuous production needs.

The counter argument to this must be that it is widely reported that adopting a holistic approach to energy management can return savings of up to 30%, surely this possibility cannot be ignored.

Another interesting fact is that it is reported that 20% of the UK’s total energy usage centres on industrial processes and that 60% of that energy is consumed by electric motors.

A typical food and beverage production plant consists of a variety of machines often containing electric motors of various sizes and these are usually linked together by conveyors and handling systems, again brimming with electric motors.

It is a well-trodden argument that says fitting variable speed drives (inverters) to electric motors will save energy but this is easier to see on a mixer or compressor where the motors tend to be larger but on a conveyor the motors tend to be much smaller and the effect harder to see.

If this argument is indeed accepted then why is it that many motors on many plants do not adopt any form of energy reduction techniques?

It is a well-trodden argument that says fitting variable speed drives (inverters) to electric motors will save energy

Implementing intelligent control of plant equipment will create the possibility to dictate how it operates. This illustrates the difference between energy saving and energy management.

Fitting an inverter to a mixer motor will save energy but understanding the energy usage of the production line, leads to the possibility of implementing an energy management control strategy.

How often are conveyors left to run during production downtimes or during extended breaks?

Fitting an inverter to a conveyor and controlling the inverter from the line control system means that decisions can be made to, for example reduce the conveyor speed during downtimes (reducing speed saves energy) or switch off completely if that is the most appropriate decision.

These decisions can be made intuitively by the overall control system and could be linked to production planning if we take it to the next stage.

Getting to the lofty heights of total energy management will seem a long and expensive road to anyone who has minimum or zero energy saving already implemented but like all good strategies it can be implemented in stages, evaluating the cost/benefit analysis along the way.

The first place to start is to know what the current situation looks like. To implement this stage will certainly require some investment and this will depend on the control level network architecture that already exists. PLCs, inverter drives and other control equipment are perfectly capable of offering up a raft of energy information.

They may not have been programmed to deliver this when installed but by engineering over and above the existing control program the information can be easily accessed. This extra engineering can be non-intrusive and does not have to affect the control program already present.

Communication of this information can then be transferred across the control level network to a dedicated energy monitoring package, where full analysis can take place.

What if no control level network exists? The choices are in essence either implement one, or deploy metering on the perceived “hotspots” to directly feedback the energy information.

A properly thought out and costed strategy will no doubt include both of these techniques, in whole or in part. The importance of this monitoring phase cannot be underestimated as this information will be vital in determining the next phase of the project.

Simply implementing a procedural change can often give immediate improvements and cost savings.

It is also highly likely during this phase that some behavioural problems will come to light, perhaps a particular shift tends to leave machines running and others don’t. Simply implementing a procedural change can often give immediate improvements and cost savings.

Even if this approach seems rather piece meal, it should be implemented as part of the “bigger picture” from the beginning as taking the holistic view will deliver the best results and the greater savings long term.

Problem areas will be defined from this analysis and suitable actions can be taken, this will range from fitting inverters, as previously discussed, to implementing a full energy management control strategy and all points in between.

It is vital that you engage with an automation supplier who can provide audits, proposals and have the capability of delivering a total solution.