A switch in time….
04 February 2010
The industry and government are constantly urging us to fit inverter drives and save energy. But is all this hype clouding that other important method of controlling energy usage – simple industrial controls? Jeff Whiting says we should not underestimate the power of this sister technology; even the simple switch can have a significant impact……
Disciplines we learn in one field can sometimes be applied in other areas and yield really useful results. In recent weeks, for instance, I have been focused on the latest Machinery Directive to identify some of the design requirement of industrial equipment to minimise risk and make the equipment safe. The standard process is well defined and I feel that some of the assessment approach outlined could be modified and apply to minimising energy within our processes.
BS EN ISO 14121 (Risk Assessment) encourages a three-stage process to safety. First, design out as many safety problems as possible; then those that can’t be removed through mechanical and control design are brought under control with a safety option – a light curtain, guard or similar. The final approach is through user information, such as instructions, limitations of use and training.
This process is very sensible and in principle could be applied to energy engineering. The assessment process would then become, to design out energy consumption where possible through the mechanical and control philosophy. Secondly to apply energy saving technologies such as inverter drives. Finally, to provide user information and training to minimise any other energy requirements that may require localised input.
More and more people are recognising the value of energy saving technologies - stage two in my analogy - but what about designing out unnecessary losses in the first place? When you think about it, many elements of a machine are left running for major parts of their duty cycle without any useful function taking place. In a lot of cases it would be possible to switch them off when they are not actually operating; powering them up just before they are actually needed.
The main culprits include lights, fans and pumps. To this you can add HMIs and other unmanned display/control panels, possibly chillers or air conditioning, conveyors and so on. At first it may feel like the level of energy savings will not warrant the effort required. But some rough calculations on the back of an old envelope may well change your mind rather quickly.
When designing a machine engineers primarily think functionally: what are we making; how can we do that; what processes are involved? Energy considerations, where they are considered, usually come somewhere low down the list of goals.
But it costs nothing to think about energy as a primary part of the project brief. If heat is involved, can a smaller amount be applied more accurately. If cooling is required, can this be done intermittently rather than constantly? Can the length of conveyor runs be reduced, or its speeds be slowed without impacting overall productivity? Would reversing a plant’s layout change lifting operations into lowering ones? How many lights on the machine could be left off for long periods of time?
Many of these questions could also be asked of existing machinery, but this brings up a universal problem. People generally don’t like change. They would rather muddle on as they are, using the well-known mantra, “If it ain’t broke, don’t fix it!” Creative efforts are often reserved for things perceived as new and exciting. People easily come up with all sorts of reasons for not undertaking change. But a good manager will make the effort to work through these and properly assess how change can unlock potential.
The same observation is true with new build. Design teams will generally have established ways of working and may not welcome the further dimension to the project in trying to ‘sort out the energy before the machine is built’. Rationally they know it can be done and that it should be done, but it may be a new trick too far for some old dogs.
Jeff Whiting is energy spokesman for Mitsubishi Electric’s Energy Centre
John Houston responds:
Jeff Whiting’s comments about designing in energy conservation are to be applauded. By and large he is correct in presuming that when considering new designs then incorporating energy economy costs nothing. That is, if one accepts that it takes no longer to design an efficient system than an inefficient one.
However, there remains a price to pay in having more sophisticated controls or additional components such as variable speed drives, HMIs et al. Here, we confront that thorny old chestnut of price versus cost. Apart from possibly cars, how many of us really consider the on-going costs of the products we buy? If we did, we would all be using energy saving compact fluorescent lamps, A-rated energy efficient kitchen appliances and the like.
In practicality, we tend to buy washing machines and other products that have the features, colour or styling we desire. If we find one that meets those criteria and also has a high efficiency rating, it simply vindicates our decision – a bit like putting a few coins in the charity collection box. In other words, for most of us, energy efficiency is not among our top priorities in making purchasing decisions.
This is even truer when it comes to making commercial purchases. The hapless plant engineer is faced with sourcing equipment that is first and foremost fit for purpose. If he or she is charged with making more widgets from a constrained capital equipment budget, then that is the task they focus on. That is irrespective of the effect the purchase may have on running costs through energy consumption.
If the public, that pays its own energy bills, cannot be easily persuaded to consider running costs alongside price, how can we expect those in industry, who don’t as individuals pay the bills, to do otherwise?
It remains the case that there is little or no cohesive thinking or collaboration in commerce and industry when it comes to equipment procurement. Imagine our same plant engineer being told they have a capital equipment budget of £X that would rise to £X+Y, if Y equates to the annual energy saving of any equipment specified. Yes, I know it’s not an argument seen much in practice, but if it were, one can imagine the shifting imperative on OEMs to produce energy efficient equipment.
However, I believe the only way to change commercial attitudes towards equipment design is to impose it. This is difficult. I remember sitting on a Defra committee investigating energy efficient electric motors a few years ago with the prospect of outlawing motors below Eff-2 ratings. It failed because it was generally held that the buyers would not stand for the higher priced motors. Considering that electric motors can cost about 300 times their price in running costs over a lifetime, there is no better example of the price/cost argument! Nobody likes legislative interference, but we do rather bring it upon ourselves don’t we?
[Our apologies for providing the wrong photograph in the newsletter. This was not Jeff Whiting, as indicated in the first paragraph of the newsletter article introduction, but Les Hunt, editor. Jeff's picture is on PSB's home page ]
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