plastic bottle blow moulding industrial energy efficiency.pdf

8/11/2019 plastic bottle blow moulding industrial energy efficiency.pdf

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Contents

1. Executive summary ...................................................................................................32. Background to the Industrial Energy Efficiency Accelerator.............................................43. Background to the plastic bottle blow moulding sector...................................................6

What the sector manufactures ....................................................................................6How the sector manufactures......................................................................................7Factors affecting business decisions .............................................................................9

Customer demands..........................................................................................9Legislation....................................................................................................10

Energy reduction incentives ......................................................................................104. Key findings ...........................................................................................................11

How energy is used in processing ..............................................................................11

Extrusion blow moulding ................................................................................11Injection stretch blow moulding.......................................................................12

Impact of bottle weight ............................................................................................12Impact of speed of production...................................................................................13Equipment idling .....................................................................................................14Heat loss ...............................................................................................................15Operator practice ....................................................................................................16Energy management ...............................................................................................17

5. Opportunities..........................................................................................................18Innovation in process control ....................................................................................18

Control of granulators (EBM)...........................................................................18Production planning (ISBM) ............................................................................18

Innovative equipment ..............................................................................................19Induction barrel heating (EBM)........................................................................19Barrel insulation (EBM) ..................................................................................20Infrared lamps (ISBM) ...................................................................................20

Summary of opportunities ........................................................................................216. Next steps .............................................................................................................22

Work together ........................................................................................................22Install smart metering .............................................................................................22Think strategically ...................................................................................................22Get support............................................................................................................22

7. Methodology...........................................................................................................238. Acknowledgements..................................................................................................25

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1. ExecutivesummaryOne way for industry to achieve significant CO2reductions is to improve energy efficiencyin sector-specific manufacturing processes. The Carbon Trust has been working with anumber of industry sectors, as part of its Industrial Energy Efficiency Accelerator (IEEA),to identify where savings can be made in each one. This novel approach aims to deliver

quick and substantial reductions in industrial process emissions by acceleratinginnovation in process control and the uptake of low carbon technologies.

The plastic bottle blow moulding industry in the UK processes more than 630,000 tonnes of polymera year through extrusion blow moulding (EBM) and injection stretch blow moulding (ISBM). Thesplit between the two processes is roughly 42% EBM and 58% ISBM. Products include containersfor food, medicine, soft and carbonated drinks, household and personal care products, automotive

products and industrial applications.

In the UK, there are approximately 154 blow moulding sites. The sector consumes around 755gigawatt hours (GWh) of energy each year and emits around 400,000 tonnes of CO2 (tCO2). Most ofits energy consumption is electricity, used in turning raw material into plastic.

We worked with the plastic bottle blow moulding sector in 2008 and 2009 to gain a betterunderstanding of energy use in the manufacturing process and to identify ways of improving energyefficiency.

We focused our investigation on EBM and ISBM because these processes account for most of theCO2 emissions of this sector.

The detailed data we collected reveals a number of opportunities for making significant reductions

in carbon emissions. These opportunities fall into two broad areas:

innovation in process control

innovative equipment.

The data we gathered indicates that taking action to become more energy efficient and to reducecarbon emissions can be a sound investment. Overall, the plastic bottle blow moulding sector couldtake a more strategic approach to reducing emissions. It could work more actively with customersand suppliers, and it could put itself in a better position to take advantage of the low carbon

economy.

In this report, we discuss the opportunities for energy efficiency and carbon reduction.

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2. BackgroundtotheIndustrialEnergy

Efficiency

Accelerator

Industry is responsible for 25% of the UKs total CO2emissions1. Experience at the

Carbon Trust supports the view of the Committee on Climate Change, which indicatedthat savings of between four and six million tonnes (Mt) of CO2(up to 4% of current UKemissions) should be realistically achievable in industry with appropriate interventions.

We believe that CO2savings far beyond those set in current policy targets are possible by working

more directly with organisations to clarify the opportunities. The impact of policy can also beaccelerated and increased if industry sectors are helped to understand their energy use and how tomake significant changes in a short timeframe, rather than gradually reduce their emissions over

time. Whats more, direct intervention can help embed a culture of innovation and good energymanagement, resulting in a greater long-term impact.

Significant CO2reductions in industry are possible by working with those medium-sized industrysectors that are outside of the EU Emission Trading System (EU ETS) but are affected by eitherClimate Change Agreements (CCAs) or the Carbon Reduction Commitment (CRC) Energy EfficiencyScheme. These industries are moderately energy intensive and, in total, account for 84MtCO2emissions per year2.

The Carbon Trust currently works with industry by supporting companies to reduce their carbonemissions. The approach is applied across a range of industries but does not offer detailed adviceon sector-specific manufacturing processes. More energy intensive industries frequently cite the fact

that survey recommendations do not address the bulk of their energy use as a reason for notimplementing them. Between 50% and 90% of a sites energy consumption could typically be usedby a sector-specific manufacturing process.

In addition, the Carbon Trust Applied Research Scheme has supported the development of anumber of industry-related technologies. This scheme is offered in response to applications for

support, rather than targeting specific technologies.

Recognising the challenge of reducing CO2emissions from industry, and the carbon reductionpotential of sector-specific manufacturing processes, we looked at how we could best engage with

industry to significantly increase the rate of carbon reduction beyond that delivered by carbonsurveys. As a result, we developed the IEEA approach, which was launched as a pilot in 2008.

The IEEA approach focuses on identifying and addressing the reasons why opportunities to reduce

emissions in industrial processes are not put into action. It is a three-stage process:

1Committee on Climate Change Report, December 2008.2Source: DECC CRC Presentation, Westminster Energy Forum, January 2009.

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In 2008/09 we undertook the investigation and solution identification stage with three pilot industrysectors: animal feed milling, asphalt manufacture and plastic bottle blow moulding. This reportdetails the results and key findings from the investigation into the plastic bottle blow mouldingsector.

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3. Backgroundtotheplasticbottleblow

moulding

sector

The UKs plastic bottle blow moulding industry processes more than 630,000 tonnes of

polymer a year through EBM and ISBM. There are around 154 blow moulding sites, whichconsume around 755GWh a year and emit around 400,000tCO2. Most of the sectorsenergy consumption is electricity, used to turn raw material into plastic.

The sector is represented by the British Plastics Federation (BPF), although blow moulders make upa very small proportion of BPF membership. The sector has had a CCA since October 2009.

What the sector manufactures

The plastic blow moulding industry produces containers for foods, medicine, soft and carbonateddrinks, household and personal care products, automotive products and industrial applications.

In this study, we have concentrated on EBM and ISBM.These processes are described in moredetail in the following section. The split between the two processes is roughly 42% EBM and 58%ISBM.

ISBM containers are generally made from polyethylene terephthalate (PET), though other polyesterpolymers may be used for specialised applications such as babies bottles. PET containers have aclarity similar to glass and a very low gas permeability, which means they can be used forcarbonated drinks.

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How the sector manufactures

The EBM and ISBM processes are made up of a number of stages. A simplified diagram of the EBMprocess is shown in Figure 1, and the ISBM process in Figure 2.

Figure 1: Flow diagram showing the main stages of the extrusion blow moulding

process and the major energy demands

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Factors affecting business decisions

As in all businesses, the decisions made by plastic bottle blow moulders are influenced by a numberof key factors. Figure 3 shows some of the most important factors that affect business decisions in

this sector.

Figure 3: Factors affecting business decisions in the plastic bottle blow mouldingsector

Customer demands

Immediate customers are usually drinks manufacturers or manufacturers of other liquid products.Supermarkets and consumers, however, have an indirect but increasingly important impact onsuppliers, for example, through the carbon footprinting of products such as bottles of milk.

To minimise transport costs, many bottle blow moulding plants are located on filling sites owned bydrinks manufacturers, such as dairies. Often the bottle blow moulding company pays the siteowner, rather than the energy supplier, for the energy they use, and they pass the cost back tothem in the price of each bottle. So, if the bottle blow moulding company reduced its energy use,the site owner would expect a lower price per bottle. This is clearly a disincentive for bottle blow

moulding companies to reduce their energy use.

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Legislation

The plastic bottle blow moulding industry pays the Climate Change Levy (CCL). The BPF, on behalf

of the plastics sector as a whole, negotiated a CCA with the Government that began in October2009. This gives participating companies 80% of the CCL back, subject to meeting energy efficiencytargets. In 2008, the CCL cost the blow moulding sector 3.5m.

The industry will also be affected by the CRC. Many sites use more than the 6,000 megawatt hours(MWh) minimum for inclusion in the CRC and are included unless they are part of the CCA. Somecompanies on the borderline for inclusion had an extra incentive to reduce their emissions beforethe scheme began.

Energy reduction incentivesEnergy use costs plastic bottle manufacturers a significant amount around 20% of overall

operating costs. The specific energy consumption for each site falls in the region of 1.5kWh/kg to2kWh/kg. However, energy efficiency has not previously been a high priority for the sector.

Some companies have received advice and audits from the Carbon Trust, but most have not. The

industry argues that tight profit margins mean its focus must always be on cost management ratherthan carbon management. This suggests a lack of awareness of the direct financial benefits of

carbon management within the sector.

It doesnt help that there is very little data for production and energy use within the manufacturingprocess. Submetering of the process is poor or non-existent. Where data exists, there are no

resources to analyse or understand its implications.

Although the sector is increasingly willing to think about energy efficiency issues, there is a lack ofcoordination and impetus. Many companies feel they are not getting the advice they need about the

impact of climate change legislation.

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4. KeyfindingsWe measured the typical energy use for both EBM and ISBM processes and found widevariations depending on the way equipment was used, the size and schedule ofproduction and how operators carried out their work.

How energy is used in processing

Extrusion blow moulding

Figure 4 shows the energy flow through a typical extrusion blow moulding machine during normaloperation.

Figure 4: A breakdown of electricity consumption for an extrusion blow mouldingmachine

This process uses electricity, and most of that energy is used to power the extrusion drive motorand the motor that runs the hydraulic system used in machine movements.

The plastic material is melted using the heater bands on the outside of the extruder and byfrictional heat produced as the material passes through the extruder. Where the report refers to

other uses of energy in the process, this includes power for conveyors, material handling systemsand other ancillary equipment.

Although compressed air and water for cooling are also used in the process, we havent included

them in this study because energy efficiency improvements for compressors and chillers are widelydocumented and are available from our website.

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Injection stretch blow moulding

Figure 5 shows the energy flow through an injection stretch blow moulding machine.

Figure 5: A breakdown of electricity consumption during the blow stage of injectionstretch blow moulding

This process uses electricity, and more than 90% of that energy is used to heat the pre-forms

above their glass transition temperature (around 100C), so that they can be blown to the requiredshape. The rest of the power is used for motion the direct electric motor that powers conveyors to

move the pre-forms and bottles around the machine; and for ventilation motors used to extracthot air from the ovens, draw cooler ambient air into the machine or circulate air in the ovens.

Other resources include high- and low-pressure compressed air for blowing the pre-forms, and

water to extract heat from the blown bottles and keep the neck area cool in the ovens.

Impact of bottle weight

Figure 6 shows the variance in energy consumed per unit of material for the different sub-processes, when different weight bottles are manufactured on the same machine.

The weight of the bottle has a significant impact on the energy used by the extruder and theamount of heating required heavier bottles generally consume more energy per unit of material intheir manufacture. A process called light weighting, which reduces material and energy costs, iscarried out in consultation with the customer who sells the filled bottle.

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Figure 6: Effect of different bottle weights on energy consumption for extrusion blowmoulding processes

Impact of speed of production

It was thought that the weight of material extruded per hour would affect the amount of electricityconsumed by the extruder and the heater bands. Surprisingly, the considerable variation in energyused, even though extrusion rates stay the same, shows there is no correlation between energy use

and the amount of material being processed. This may well point to poor process setting.

Figure 7: The relationship between extrusion rate and power consumption of extruderand heater

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Equipment idling

Figures 8 and 9 show the total energy consumption of an extrusion and injection blow mouldingmachine over time.

There are stoppages throughout the period and, in general, these are due to mechanicalbreakdowns. The larger gaps may indicate that the machine has been switched off because there isno operator available or production is not required. Bottle production often has to match the fillingrate, and problems at the filling line have an impact on the consistent operation of the bottle

production line. Another possible factor is that the speeds of the blowing machine and filling linemay be poorly matched.

However, even when the machine is stopped there is background power use from the heating

elements and ancillary equipment. The ISBM process can be more easily stopped and started than

the EBM process, which has advantages when the blowing machine has to match speed with thefilling line.

Figure 8: Power consumption (kW) of an EBM machine

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Figure 9: Power consumption (kW) of an ISBM machine

Over 21 hours of monitoring, the machine operated for only 1.5 hours, but the heaters andancillaries were left on continuously. Switching off the granulator and other ancillary equipmentwould have saved 150kWh of electricity. If the heaters had been switched off, a further 83kWhwould have been saved. Annually, that could add up to a cost saving of 1,900 for just onemachine.

The reason for leaving the heaters on was the length of time needed to heat up the barrel to astable condition. However, better production planning would allow ancillary equipment to beswitched off when not in use without disrupting production when the machine was needed again.

Another factor is that when a change of bottle size occurs, the change-over for the blowingequipment is completed more quickly than the filling line change-over. This leads to a period of fouror five hours when the blowing machine is run sporadically, waiting for the filling line to be ready.

Reducing the change-over time would reduce energy use and, again, could be achieved with betterproduction planning.

Heat loss

On injection stretch blow moulding machines, heat is lost as hot air from the top of the oven.

Temperature and energy flow measurements showed this to be at a rate of around 30kW.

The extruder and the motors on the extrusion blow moulding machine radiate the most heat.

Between 30% and 60% of energy may be lost in this way, depending on machine size. Infraredimages of these areas during operation show temperatures of up to 110C. In Figure 10, the bluezones represent areas of lower radiant temperature and move up the spectrum to red and white forareas of higher radiant temperature.

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Figure 10: Thermal image showing heat radiating from a motor

Operator practice

Although a number of factors affect energy use in these processes, operators are more likely to use

settings that are familiar, rather than tuning the machine for optimum energy and productionperformance. This is due to a lack of technical knowledge in the industry, and a lack of data to

demonstrate links between operations and energy saving.

Figures 11, 12 and 13 show there is no correlation between bottle weight and energy consumptionor between extrusion rate and energy consumption, where a relationship would usually be

expected. Since most energy use is in heating and plasticising the material, lower material loadsshould reduce energy. This suggests poor process control and a lack of awareness of energyconsumption when setting up processes.

Figure 11: Energy consumption of extrusion blow moulding machines for different bottleweights

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Figure 12: Energy consumption of injection stretch blow moulding machines fordifferent bottle weights

Figure 13: Energy consumption of extrusion blow moulding machines by rate ofextrusion

Energy management

There are few dedicated energy managers in the plastic blow moulding sector and there is littlespecialist and independent support available. Sites capture little production information, and there

tends to be no energy use information at process level to inform energy management decisions andmeasure improvements in performance. Managers are not generally aware of opportunities forenergy reduction and dont have the data to build a strong business case for change.

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5. OpportunitiesBefore we carried out this study as part of the IEEA, very few plastic blow moulding siteshad been surveyed from the Carbon Trust. Most werent familiar with conventionalenergy efficiency measures such as energy efficient motors, variable speed drives(VSDs), efficient lighting and plant and pipe lagging.

The majority could certainly benefit from these measures. However, most of the energy use onblow moulding sites is related to the actual process of producing plastic bottles. This study hasidentified several other opportunities for process control innovations and innovative equipmentspecific to bottle production.

Innovation in process control

These opportunities tend to be cheaper, have a shorter payback period than other types and tendto be fairly straightforward to implement. For these reasons, they are also the most popular withthe industry.

Control of granulators (EBM)

The EBM process was monitored for more than 1,450 hours on a number of sites and machines. Wefound that for 10.5% of the time when machines werent working, the granulators and ancillary

equipment were still running. It would cost nothing to make staff more aware of this and, byturning off this equipment, save both energy and money. Alternatively, an automatic sensor could

be fitted to each granulator to switch it off when the machine was not producing bottles.

More than 80% of blow moulding sites could take this opportunity, leading to savings of around

11,000tCO2a year.

Cost

The cost of installing granulator control is around 2,000 a machine. The saving would be around1,900 per machine per year, giving a payback time of just over a year.

Barriers

Lack of awareness and involvement of machine operators stands in the way of adopting bettergranulator control. This could be easily addressed with an energy saving campaign and by sharingbest practice across the organisation.

Production planning (ISBM)When the bottle size is changed on the filling line and blowing machine, it takes an average of eighthours to reach a steady state of production. During this time, the blowing machine is left running

and still consumes energy at around half its full speed rate. During monitoring of 588 runninghours, energy wasted in this way amounted to 600kWh.

Bringing in better production planning at just half the UKs sites could save 35,000tCO2a year.

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Cost

Better production planning should cost companies nothing and give immediate payback.Barriers

The main barrier is the shortage of time and skills to educate and train staff. Changing operationalpractices for energy saving reasons is often disregarded because meeting production targets is seenas more important. This shows that companies dont recognise that energy efficiency actually bringsfinancial and operational benefits.

Innovative equipment

These options tend to involve capital outlay, so businesses need solid evidence to be able to drawup a case for adopting them. Because equipment isnt renewed very often in this industry, it wouldalso take longer for a significant impact to be felt in the sector as a whole.

Induction barrel heating (EBM)

Our monitoring shows that around 8%-10% of energy consumption in bottle blow moulding is usedin heating the barrel. The injection moulding industry has brought in a new method of barrel

heating that cuts energy use by between 50% and 70%. This induction heating method isillustrated in Figure 14.

Figure 14: Heating the barrel using induction energy

Around 80% of plastic bottle blow moulding sites in the UK could adopt induction heating leadingto savings for the whole sector of around 50,000tCO2a year.

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Cost

The estimated cost of adopting induction barrel heating is 16,500 per machine. The paybackperiod should be just less than two years.

Barriers

Transferring induction heating technology to extrusion blow moulding isnt a simple processbecause of the use of cooling fans at the front of the barrel. Its also not clear what level of CO2savings can be achieved, which makes it difficult to build a business case for investment. This

technology would need to be tested and adapted for extrusion blow moulding before wider adoptionin the sector.

Barrel insulation (EBM)

Clip-on barrel insulation is used in the extrusion blow moulding industry and can save up to 45% ofthe energy use. However, it has to be removed whenever operators need access to the heaterbands, and is rarely replaced after removal. The solution would be integrated units with insulatedheater bands.

Around 80% of plastic bottle blow moulding sites in the UK could take up this option leading tosavings for the whole sector of around 32,000tCO2a year.

Cost

The estimated cost of integrated barrel insulation is 3,500 per machine. The payback periodshould be 18 months.

Barriers

The main barrier is lack of awareness among operators of the energy and cost saving benefits.

Infrared lamps (ISBM)

Improving infrared lamp technology could bring significant savings in energy consumption in the

ISBM process. Making the lamps more reflective and lowering power consumption are target areasfor some manufacturers and, if implemented, could save around 15% of energy.

If just half the sector adopted these improvements, there could be a saving of 4,000tCO2a year.

Cost

The cost of improved infrared lamps is around 10,000 and could have a payback of around two

years. It is more likely, though, that the lamps would be replaced only when the whole machinewas replaced.

Barriers

When manufacturers specify new blow moulding machinery, the energy efficiency of the infraredlamps is only one of several factors and unlikely to take priority.

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Summary of opportunities

Figure 15 summarises the financial case for the major opportunities identified for reducing carbonemissions in plastic bottle blow moulding.

Opportunity Cost per machine Payback Annual C02savings (tonnes)

Production planning (ISBM) Minimal Immediate 35,000

Control of granulators (EBM) 2,000


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6. NextstepsGenerally speaking, the level of awareness of the need to save energy in the plastic bottle blowmoulding sector could be improved. Comparison to other industrial sectors suggests that thesectors CCA will raise that awareness and be an incentive for energy efficiency. However,companies in the blow moulding sector still need to do more to get staff involved and raise

awareness of the opportunities to improve energy efficiency and save money. Companies need todevelop a culture in which accepted practices are challenged.

Work together

Cross-sector collaboration, particularly between machine suppliers and manufacturing companies,could lead to the development and adoption of more energy efficient equipment. Companies couldalso benefit from cross-sector training and sharing best practice. The CCA gives the BPF the

mandate to bring the sector together in this way.

Install smart metering

All companies in the sector would benefit from detailed submetering of the manufacturing processat their sites. This would give them information for more efficient day-to-day operation of theprocess, as well as providing evidence to justify investment in more significant energy savingopportunities.

Think strategically

The low carbon economy offers opportunities for manufacturers. Customers buying decisions may

change, and supermarkets are already measuring the carbon footprint of some of their products.Managers of plastic bottle blow moulding companies need to think strategically about how the low

carbon economy will affect them and how they can position their business to take advantage of thisnew business environment.

They need to work more closely with customers to understand how purchasing decisions may

change and to influence those decisions. There is a real opportunity to increase market share byreducing energy use and then using this fact as a selling point.

Get support

Companies should ensure they are taking advantage of all the available support and financialincentives to help them reduce energy and carbon emissions now. We offer a range of support to all

sizes of business, and there is more information about our range of services on our website atwww.carbontrust.co.uk.

The sector should also continue to work with the Carbon Trust as part of the IEEA to maximiseenergy savings from the manufacturing process.

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heating (kW)

total (kW).These readings were taken every half-hour to get an accurate breakdown of power consumptionwithout generating unwieldy data sets. Capturing data at 10-minute intervals and to the nearest

0.1kW instead of 1kW would have given greater detail to allow further investigation. As well ascontinuous monitoring, the flow rate of the cooling water on some of the machines was alsorecorded, along with the incoming and outgoing water temperatures. Thermal images of some ofthe machinery were also taken.

Host sites provided production data on the number of bottles produced and run times, and this waschecked for anomalies in comparison with the energy data.

A workshop was held to get more people from the plastic blow moulding sector involved indiscussing energy saving opportunities and the barriers to taking up energy efficiency opportunities.

Although no representatives from the BPF were able to attend, the Polymer MachineryManufacturers and Distribution Association and several member companies were represented.

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8.

Acknowledgements

This report has been produced by the Carbon Trust with support from AEA Technology Ltd, DavidWhite Consulting, Atkins, the Plastics Machinery Manufacturers and Distributors Association, Britvic,Highland Spring, RPC Containers Ltd and McBride.

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The Carbon Trust receives funding from Government including the Department of Energy and Climate Change, the Department for Transport,the Scottish Government, the Welsh Assembly Government and Invest Northern Ireland.

Whilst reasonable steps have been taken to ensure that the information contained within this publication

is correct, the authors, the Carbon Trust, its agents, contractors and sub-contractors give no warrantyand make no representation as to its accuracy and accept no liability for any errors or omissions.

Carbon Trust trademarks, service marks or logos used in this publication, and copyright in it, are the property

of the Carbon Trust. Nothing in this publication shall be construed as granting any licence or right to useor reproduce Carbon Trust trademarks, service marks, logos, copyright or any proprietary information in

any way without the Carbon Trusts prior written permission. The Carbon Trust enforces infringementsof its intellectual property rights to the full extent permitted by law.

The Carbon Trust is a company limited by guarantee and registered in England and Wales under

Company number 4190230 with its Registered Office at: 6th Floor, 5 New Street Square, London, EC4A 3BF.

CTG019

The Carbon Trust 2010. All rights reserved.

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plastic bottle blow moulding industrial energy efficiency.pdf