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With the Climate Change Levy now in place, it's a good time to look at your energy use and see where you can make savings. On a typical industrial site with a £150,000 annual electricity bill, £100,000 will be spent on running motors. For example, are any motors or fans running on full power all the time when they could be driven by demand? The answer is a professional energy audit. Undertaken by a trained engineer, an energy audit will identify those applications that would most benefit from the introduction of variable speed drives. The results, based on measured data from the application, will help you target your investment so that it produces the highest possible savings and gives you the best return. Four steps to an efficient audit An effective energy audit will have several characteristics. These will generally include: 1. Outlining the scope of supply The company will meet you and outline the benefits of the audit in detail, together with any assistance they might need required. This could include information on access to equipment and help in setting and connection of meters. He will also be interested in anything unusual that might during the audit affect the energy profile. 2. Collecting the data The data collection phase is an active phase. It involves an on-site appraisal with selected fans and pumps, to determine operating parameters such as voltage, current and power factor and the energy being used. This stage will usually be performed over a seven days to gain a complete picture of the plant's typical energy use. The energy auditor will look not only at your fixed speed drives but also any variable speed drives used, to see if the application is running at maximum efficiency. Your own staff may become involved at this stage although different auditors have different approaches. Some will train on-site staff during the initial appraisal others will do this subsequently. In either case the aim is that the site staff should be able to perform subsequent energy audits with minimal support. 3. Analysing the data Following the collection of the data, the findings will be analysed and potential savings identified using dedicated software. The finding will be methodically presented. Often tables or graphs will be created to help see where savings are likely to arise. 4. Recommendations The action plan will then be prepared, usually comprising an Executive summary and a detailed engineer's report, highlighting applications that can save the most. The figures will normally be translated into monthly savings, and there will be detailed recommendations for fitting particular drives or motors. Often the recommendations will show that variable speed drives can provide excellent savings in particular applications. The report should also clearly show the expected payback time on fitting new equipment. Implementation While not strictly part of the audit the aim is that the recommendations should be fully implemented. Once new equipment is fitted it is normal to track the actual savings against the predictions shown in the report. This will also help justify the investment in variable speed drives. Benefits Many audits will be performed by electrical distributors with a close link to a reputable manufacturer, so you will have the support of a large organisation behind your local contact. When choosing, who will perform the energy audit for you, look for these benefits: · Clearly identified energy savings · Complete audit results and energy saving calculations · History of other audits and associated energy savings · Proposed payback times · Degree of customer training given as part of the process There are other aspects to consider for example whether financial options are available and if your supplier offers a replacement drive scheme Audits in action It was just such an energy audit that produced spectacular benefits for a cooker factory, saving £17,000 on its annual energy bill. General Domestic Appliances Ltd, in Stoke on Trent Staffordshire, makes 12,000 cooking products a week for its market leading Creda, Hotpoint and Cannon brands. The company decided to look at the energy consumption of its wet fume plant, which extracts waste vitreous enamel from four paint booths. Some of the booths were not in constant use and were closed off by a mechanical shutter, yet the 132kW fan used to extract the waste enamel was run at a constant speed, wasting energy and money. Glen Hickman of Central Electrical carried out an energy appraisal on the plant. An energy analyser was connected to the fan motor and voltage, current, kWh consumption and power factor. Readings were taken every half-hour. The readings were taken over a typical working week for the factory, of 24 hours a day for five and half days a week. The report was presented to GDA's Plant Engineer Andy Rowe and senior management. "The report was easy to interpret. The way it was presented made it obvious what had been done and what the potential savings were," says Rowe. Central Electrical's calculations showed that the speed of the fan could be reduced by 20 percent and still achieve the necessary volume of air extraction, resulting in a 56 percent reduction in power from 118kW to 51kW and saving over 440,000 kWhrs a year. GDA's Plant Engineer Andy Rowe says: "The report concluded that the fan would consume £30,000 of electricity per annum if nothing was done. Central Electrical estimated we would save approximately £16,000 on the energy bill for the wet extraction plant in the first year if we adopted their recommendation of a ABB ACS 600 AC drive." GDA were impressed by the potential savings and decided to adopt the recommendations. The appraisal was repeated after the drive was commissioned to confirm the estimated savings figures. Andy Rowe says: "In fact we saved £17,000 and achieved a payback period of only four months." GDA have been pleased with the results they have achieved and are currently looking at other plant items with potential for saving energy. Further energy audits are definitely on the agenda. Top of the page |
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