Powerful measures

Energy bills are soaring: every plant manager knows that. Even so, the statistics are alarming. According to the latest figures from the Department of Energy and Climate Change, for instance, average industrial electricity prices increased in real terms by 5.2% between the first three months of 2011 and the first three months of 2012. Over the same period, industrial gas prices increased by 9.5% in real terms. So it's not surprising to see that energy efficiency initiatives are underway in large numbers of manufacturing plants. Simply put, cost increases on that scale equate to a significant proportion of overall gross margin. And in the present environment, opportunities to recover that lost margin through price increases are few and far between. Even so, many manufacturing plants are missing a trick, notes John Roberts, managing director at specialist manufacturing software firm Idhammar Systems. "'Switch-off' campaigns, sensors and installing sub-meters can only go so far," he notes. "The big driver for energy consumption is production – not kettles and lights – and most manufacturers track production-related energy consumption at too high a level to provide meaningful, actionable information." And a great deal of that meaningful, actionable information can come from comparing energy consumption with detailed production data, he asserts. In short, the sort of data provided by a typical manufacturing execution system (MES), or a specialist overall equipment effectiveness (OEE) system. "Typically, a manufacturer undertaking energy conservation measures might install sub-meters to capture the energy consumption of major pieces of plant," he notes. "But that will only provide an insight into the overall consumption of those pieces of plant – and not how that consumption translates, efficiently or otherwise, into actual production volumes." And with energy prices at today's levels, he stresses, something more is required if manufacturers are to achieve the step change improvement in energy efficiency that is so obviously called for. But where is such a step change to come from? Throw into the mix the data acquisition possibilities of MES and OEE, and it's not difficult to see opportunities. Take, for example, a fairly typical production line. The glue heaters might be turned on at 4am so that they are available for production at 6am, a move that also involves switching on lighting and other ancillaries. Production starts at 6am as planned, seeing energy consumption increase accordingly. But a mid-morning, hour-long breakdown sees zero production, yet almost unchanged energy consumption, with equipment left running while repairs are carried out – pure waste. Finally, when the shift ends at 2pm, the energy waste continues, with equipment again left running. Such data – not available through conventional energy-saving initiatives – immediately produces actionable insights on three levels, says Roberts. First, there are obvious quick fixes. Could the heaters be turned on later? Are there more energy-efficient heaters on the market? Can any assets be turned off during a breakdown? Is it possible to speed up the plant to make more products for the same amount of energy? Can end-of-shift power shutdown be automated? And knowing the full energy cost of a breakdown, are breakdowns being tackled with appropriate priority – that is, 'highest energy cost' first? Second, come more subtle measures. Knowing that energy is typically a plant's second-highest cost – and that the energy consumed while a plant or line isn't producing, or while it is producing scrap, is pure waste – what can be done to eliminate such waste? Could a slightly slower line speed minimise breakdowns, for instance? Would slightly looser tolerances reduce scrap, and the loss of the energy that has been 'embedded' in that scrap? And thirdly, concludes Roberts, there are more sweeping changes. Recognising low-cost tariffs, for instance, could enable certain products to be produced at night, when energy costs are lower. There would be a labour premium, for sure – but the savings on energy could vastly outweigh it. Again, might production processes be redesigned so as to, for example, optimise energy consumption, rather than (say) labour costs? "Such issues aren't simple, but without data, you can't even consider them," sums up Roberts. "Energy costs are high, and likely to remain so. In such an environment, encouraging people to switch off the lights only takes you so far. The real driver of energy consumption is production — and only OEE and MES give you the insights you need to link the two."