Quick wins for energy
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
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
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.