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Quick wins for energy saving


There are a number of ways in which the energy consumption of automated systems can be reduced. Robin Putman, Energy and Technical Services Director of COFELY explains how to get a fast return on investment.

Faced with commercial and environmental imperatives to reduce energy consumption, many operators of automated systems are looking for ‘quick wins’ that deliver significant savings with a fast payback. Frequently such measures will also open the door for further cost savings through condition-based maintenance regimes.

For example, in a recent situation we encountered all of the baggage conveyors for an airport check-in area were running constantly while the check-in desks were open – more than 18 hours a day. However, passengers were typically checking their luggage in waves, rather than continuously; and only a small proportion of the conveyors were required for each flight.

The relatively simple remedial action was to install sensors that would switch off conveyors when no baggage was loaded for five minutes. In addition, the strategy ensured that only the conveyors needed for each flight were in use, while others remained off. The result was a payback of just four months – with ongoing benefits to the bottom line thereafter!

Similarly, in warehouse applications there is often considerable energy wastage when conveyor deliveries are delayed by between two and five minutes, waiting for tilt tray sorters to re-set themselves, during which time conveyors continue to run without achieving anything. In one such application we reduced the re-set times to just six seconds, increasing productivity, cutting energy wastage and reducing the decision time required for system components to ‘wake’. The result was a more efficient start sequence which ultimately reduced energy consumption further.

Another relatively simple enhancement is to switch to newer, lower friction materials. Replacing existing equipment in one automated logistics environment recently reduced energy consumption by 30% for one of our customers.

In many systems, downstream processing errors result in frequent stops and starts of upstream conveyors - increasing energy consumption and wear and tear and potentially jarring goods out of position. Fitting speed control inverters addresses these issues by providing a soft start and stop that minimises wear and tear and minimises risk of load slippage.

A further benefit of inverters is that the speed of the conveyors can be optimised to provide maximum energy efficiency in relation to the types of loads being moved. However, such a strategy has to be implemented in the context of the operational needs, so it’s important that the service provider has a good understanding of both operating and maintaining automated systems. So, for example, suggestions might incorporate control enhancements that increase flexibility and make it easier for staff to switch systems on and off and alter energy saving timers in response to unexpected events, such as a flight being cancelled or production run changes.

Where operation and/or maintenance services are outsourced to a third party this may also bring in fresh ideas that have been tried and tested in the service provider’s other contracts.

For instance, when sensors need to be replaced there is a tendency to simply replace like with like – each market sector often having a ‘standard’ option that may be different to the ‘standard’ option in other sectors. Unfortunately this product selection will often owe more to tradition than sourcing the most cost-effective and technically suitable solution. In contrast, a service provider with a breadth of experience across disparate sectors can provide ‘cross-fertilisation’ of ideas based on all available options.

Tradition will also play a role in many maintenance strategies, using calendar-based servicing frequency irrespective of actual usage. In light of the reduced run-times achieved by the measures described above, it often makes sense to move to condition-based maintenance. This is also true where products have the ability to be ‘routed’ through a system, either through planning, operator preference or redundancy routing. Where elements of the system experience more frequent stop/starts and run hours than others it is necessary to tailor maintenance strategies to suit.

This will harmonise the maintenance intervals for each item of equipment with actual usage – typically based on run times or stop/start frequencies, without impacting on overall performance. Equipment used less frequently will still be subject to visual, acoustic and thermal imagery monitoring to detect emerging problems, while the maintenance team’s efforts and expertise can be focused on the harder working or more mission-critical equipment.

In addition, the maintenance provider should also be able to provide advice on other ways of saving energy within the spaces the automated systems occupy. An obvious example is upgrading lighting to more efficient light sources that also enable more sophisticated occupancy and daylight control can also deliver significant savings with a sensible payback.

While these are just some of the ways in which energy savings can be achieved, they serve to illustrate the most important principle – namely that it’s important to look at the detail and take every opportunity to fine-tune systems. Calling on specialists with a broad range of experience will also help to ensure all options are considered.

www.cofely.co.uk