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Scottish Plastics and Rubber Association Scottish Plastics and Rubber Association

Energy Management for Plastics Processors

The last SPRA technical lecture of the year saw Dr Robin Kent of Tangram Technology provide a very practical guide for plastics manufacturers on how to gain control over energy management and reduce energy costs. As a very engaging presenter, Dr Kent gave convincing arguments why energy efficiency has a major role to play in controlling global energy consumption and reducing carbon emission.

Typical energy costs for plastics processors
At a time when energy costs are rising, it is surprising that a lot of companies still do not measure their energy consumption especially as energy is now the 2nd or 3rd largest cost for a typical plastic processor. The areas of energy consumption and percentage of the total energy costs presented by Dr Kent are illustrated in the accompanying pie-chart.

There are basically two approaches for reducing energy costs;
• Reduce the £/kWh through purchase reduction – a temporary fix.
• Reduce the kW/kg through an energy management plan – a permanent fix.

The first key to an energy management strategy is to introduce a measuring system. This reportedly can bring instant 10% savings on energy bills with savings of 30% in ~ 18 months is not unreasonable from 10% maintenance, 10% management, 10% capital investment.
Dr Kent introduced a number of key actions that could be undertaken for companies starting out on an energy management programme including;

1. Develop a site energy map – count the motors, heaters, pumps, lights etc.
2. Prepare an the energy usage numbers
3. Start to measure and record – and turn into management information
4. Create a simple report – publish monthly and distribute
5. Check electrical bills against meter and monitor consumption trends
6. Benchmark machines internally
7. Calculate the base load to obtain a Performance Characteristic Line (PCL)
8. Use the PCL to predict usage from sales volume

9. Benchmark site externally
10. Benchmark machines internally
11. Buy the right kit – check energy efficiency, not the cheapest
12. Turn machines and ancillary equipment off when not in use
13. Use variable speed drives (VSD) – slowing by 20% can save 50% cost
14. Insulate hot and cold surfaces where possible
15. Reduce compressed air leaks
16. Reduce compressed air generation

If you missed the meeting and are concerned to keep energy costs down it is worth visiting the website at

where advice and information on energy management strategy is available together with spreadsheets to get you started. There are also a number of publications produced by Dr Kent for the BPF on this subject.

Report by Les Rose, SPRA Council Member December 2011

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