Energy Management in Plastics Processing - Part 2
Surveying Site Energy Use




A series of energy efficiency worksheets by Dr. Robin Kent for the Carbon Trust to help the plastics industry reduce costs through efficient use of energy.

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The rewards

Energy efficiency measures can improve your profits significantly for minimum effort and costs. For a plastics company with a turnover of £10 million per year and a net profit of 10% then the profit will be £1 million. The average electricity bill will be approximately £200,000 (between 1 and 3% of turnover). Simple no-cost or low-cost energy reduction practices can reduce this by a minimum of 10% (and up to 20%) and increase profits by at least 2%. This is the equivalent of adding sales of £200,000 to turnover and is a worthwhile investment by any standards.

The first part of this series gave details of the information needed to understand energy usage. This sheet shows how to carry out an initial site energy survey - the starting point for all improvement plans.

The initial site energy survey

The objective of the initial energy survey is to gain an overview of the general site energy use. It is a walk around the site with an energy managerís hat on. This will identify some rapid no-cost or low-cost improvements that can be made to save money.

The survey should be carried out as soon as possible - if energy is being wasted now, it is costing money now. The diagram shows the main areas of energy use in plastics processing. Use this as a guide during your walk-around to look for areas of high or unnecessary energy usage.

Energy uses in plastics processing

How do you do a site survey?

Take an unannounced walk around the site at around mid-shift. If there is no night shift it can also be profitable to take a walk around the factory when there is no production being carried out.

The questions to ask (and answer)

  • Which areas have the largest electrical load? (look for the largest machines, they will most likely also have the largest motors and create the largest load, when they are used).
  • Is the thermal insulation, if present, on all the machines in good condition? If there is no insulation then why not?
  • Look for signs of machines that are not in production but have motors or ancillary equipment running (e.g. conveyors, pumps, granulators, fans, machine heaters).
  • Are there any good reasons why machines need to be kept idling to be ready for the next production run?
  • Which motors are left running when not doing productive work?
  • Why are the motors the size they are and would a smaller motor be more efficient?
  • Which cooling water pumps (and chillers) and vacuum pumps are still running?
  • Is the airflow from fans being throttled back with dampers and could variable speed drives be used instead?

Look for areas of energy use where no productive work is being carried out and yet machines are running and using energy.

Look for water, air or steam leaks.

  • Where can you hear steam and compressed air leaks? 

The hissing noise you hear from leaks is costing real money. If there is no production being carried out then why is the compressed air system still running?

  • Is compressed air being used for expensive applications where other cheaper methods can be used? e.g. cleaning or drying.
  • Does the compressed air pressure need to be so high, or the vacuum so low?
  • Is the lighting dirty, broken?
  • What are the good, simple maintenance measures that can be adopted to reduce energy use?
  • Are Ďacceptedí practices wasting energy? Can they be modified at no cost at all?
  • Are there clear setting instructions for all machines and products and are they implemented when a machine is set up?

Turning the survey into energy savings

A site energy survey is useless unless action is taken as a result of the findings. Use the survey to estimate the excess energy usage of the site and arrange for an electrician to measure the factory electrical load and calculate the costs involved. Use the survey to identify operating practices that cost money and need to be changed. The results of the survey should be sent to the Managing Director and Production Director with full recommendations and costs for carrying them out.

Raising energy awareness

The cost savings possible from energy efficiency will only be achieved if there is a management commitment to actually carry out the work necessary and save the money. This is best ensured by having an energy policy that is as much a part of the overall company operations as the quality policy. 

The energy policy should ideally be part of a broader company environmental policy and, at the very least, should be formally adopted with top-level management commitment. The policy should be the responsibility of a designated Energy Manager who has clear responsibility for energy matters. 

There needs to be regular formal and informal communication with major users who are held accountable for their energy usage which should be monitored and targeted. The quantified savings from the implemented energy policy should be promoted within the company and used to create a favourable climate for investment treatment of other energy saving programmes.

Energy efficiency is a competitive advantage in any market and an initial site survey is the start of gaining the advantage for your company.

"Energy Management" Series.

The "Energy Management" series is designed to give plastics processors an insight into how to manage a valuable resource.

Download the complete series as an Adobe Acrobat file.

Last edited: 11/03/10  

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