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PET bottles greener than glass or aluminium - Study

By Rory Harrington , 21-Sep-2009

PET bottles are a greener alternative to glass or aluminium cans, according to a new study into the environmental impact of single use packaging.

The report by consultants Allied Development Corporation reached its conclusion after calculating the green credentials of each packing type by focussing on weight of materials, total energy consumption and total greenhouse gas release.

“A cradle-to-grave analysis was completed for each packaging scenario, including all materials, processing and transportation”, said the study authors.

Greenhouse gas emissions

The research, sponsored by Husky Injection Molding Systems, found PET production resulted in less greenhouse gas (GHG) emissions and used less energy than glass or aluminium cans.

The report said that PET had he lowest GHG emissions at 314.9lbs/1000 units. In contrast, aluminium cans racked up the highest GHG release of 570.9lbs/1000 units – some 81 per cent more than PET. Glass production, although given a greener rating than aluminium, resulted in 500.4lbs/1000.

“The chemical process associated with producing aluminium from bauxite releases a significant amount of GHG, which contributes to the high level of GHG for aluminium cans,” said the report.

PET bottles also registered the lowest energy consumption at 3,225MJ/1000 units. Glass had the highest energy consumption at 4,227MJ/1000 units – nearly a third more than PET. Aluminium cans used 21 per cent more energy than PET at 3,917MJ/1000 units.

“Compared to aluminium can and glass bottle, PET packaging for CSD applications within North America remains the best alternative from an environmental perspective”, the research concluded.

It added that boosting recycling rates and PCR content into new bottles would help reduce PET’s environmental footprint.

Methodology

The study defined ‘purchased materials’ as any used for the production of the primary package – including raw materials/packaging and pallet packing. Processing was taken to mean anything related to manufacture and filling of the primary and its components. The authors defined ‘transportation’ as anything related to the movement of the materials from one place to another.

All package types were considered to be best in class; The three types examined were: 23.9g PET bottle/355ml (2.3g HDPE closure); 200g glass bottle/355ml (2.1g metal closure) and 11.3g aluminium can/355ml (2.8g aluminium can end)

Assumptions

The study used a number of assumptions to reach its conclusions; Packing production and filing operations are found in the same facilities, thus minimising the impact of transport; It assumed the PCR content rates for packing and closure manufacture are: aluminium 46 per cent; glass bottle 39 per cent; PET bottle zero per cent.

A standard shipping distance of 800km to retail for all packing types was assumed. Only one way’ glass – instead of refillable glass - was considered as the authors said his was “typical” for the North American market.

Canadian outfit Husky produces PET bottles, closures and packing equipment. It said it hoped to use the results of the research in the company’s future product development strategy

“Husky is taking steps to support research to learn about the environmental footprint of beverage packaging,” said company marketing vice president Jeff MacDonald. “Our goal is to apply this knowledge to product development that will help improve sustainability.”

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