The environmental effect of reusing and recycling a plastic-based packaging system

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Abstract

This Australian study presents the findings of a life-cycle assessment (LCA) that examined whether a re-use and recycle strategy for a plastic-based packaging that substantially reduces the quantity of waste to landfill would also reduce the overall environmental burden. The resources and environmental effects assessed over the life of each of the packagings included fossil fuel consumption, greenhouse gas emissions and photochemical oxidant precursors. The results demonstrate that recycle and reuse strategies for plastic-based products can yield significant environmental benefits. The study also includes some interesting findings regarding the relative contributions of transportation and construction energy, and the potential benefits of adjusting the impact assessment results to take into account the spatial variation in the significance of some environmental effects.

Introduction

To alleviate societal concerns over the increased rate of resource consumption and waste production, policy makers have encouraged recycling and reuse strategies to reduce the demand for raw materials and decrease the quantity of waste to landfill. However, these strategies have also been criticised because of their possible links to other types of resource and environmental impacts that are less obvious but no less important. For example, the environmental benefits of recycling paper have been questioned in light of studies that have shown increased fossil fuel consumption and greater emissions of greenhouse and acidifying gases [1].

The Australian company Email Ltd produces approximately 350,000 refrigerators per year in its factory in Orange in inland New South Wales, 300 km by road west of Sydney. These range in size from 140 to 650 l capacity. In 1990 a new style of packaging was successfully tested for the small 140 and 250 l refrigerators. This package consisted of expanded polystyrene (EPS) top and bottom caps moulded to fit the refrigerator snugly, plus EPS side-pieces, all enclosed in a tight heat-shrunk transparent polyethylene (PE) bag. The success of this trial prompted Email to investigate the possibility of extending this type of packaging system to larger refrigerators and freezers. Though Email was convinced of the performance benefits of the new packaging system they were, however, concerned that the additional plastic material would generate an unacceptable landfill burden. To address this concern, a variant on the original EPS/PE packaging system that incorporated recycling and reuse strategies was proposed.

To offset the additional cost of collecting the used packaging and investing in recycling technology, it was important that the packaging could be reused several times before the materials needed to be recycled. Though the current EPS/PE packaging is able to protect the refrigerator during transport and handling, the individual EPS components usually suffer enough damage to preclude reuse. Thus, the packaging was made even more resistant to accidental impact damage than the current system by bonding a layer of high-impact polystyrene (HIPS) onto the outside of the polystyrene foam top, bottom and side pieces before shrink-wrapping in polythene. Because the main motivation behind modifying the already successful EPS/PE packaging was the perceived environmental impact of waste disposal, we were interested to see how the environmental performance of this modified packaging system compared with the older style EPS/PE approach across its entire life-cycle.

To achieve this, we used a life-cycle assessment approach based on the ISO 14040 standards [2], [3], [4], [5] to investigate whether a recycle and reuse strategy for a plastic-based packaging system that substantially reduces the quantity of waste to landfill would also reduce its overall environmental burden.

Section snippets

Goal and scope of LCA

Our task is to compare the environmental performance of two plastic-based packaging systems. The packagings under examination are:

  • 1.

    the present system, which uses virgin material inputs, comprises moulded expanded polystyrene (EPS) components encased in a polyethylene (PE) heat-shrink wrap, and

  • 2.

    the proposed system, which employs some recycling and reuse of materials, comprises moulded expanded polystyrene (EPS) components fused to a HIPS coating sheet and encased in a polyethylene (PE) heat-shrink

Process descriptions and data sources

In this section we briefly describe the methods used in Australia to make the three major components of these two packagings: EPS; EPS-HIPS, and PE shrink-wrap. In particular we detail the assumptions made and the sources of data used for each of these materials. We will do this first for EPS, then EPS-HIPS and finally for PE.

Life cycle inventory

In this section we use the quantitative life-cycle inventory methods described in ISO 14041 [3] to calculate flows of materials and energy for the manufacture, use and disposal of refrigerator packaging made from EPS, EPS-HIPS and PE. Although the environmental impacts of concern here are all connected with material flows, it is essential to calculate all the energy flows as well, as the production of waste gases from the various processes is often dominated by the waste gases from the

Life cycle impact assessment

In this section we will use the results from the life-cycle inventory to assess the potential impacts of these two packagings. The first step is to assign the aggregated resource consumptions and waste emissions to the various categories of impacts chosen earlier for the base-case assumptions used to establish the inventories. These categories were the global problems of greenhouse gas emissions and the depletion of oil and gas, and the regional impact of photochemical oxidants. We then need to

Conclusions

The aim of the study was to use a life-cycle assessment approach to determine whether a recycle and reuse strategy for plastics-based packaging system that substantially reduces the quantity of waste to landfill would also reduce its overall environmental burden. Several important observations can now be made.

  • The life-cycle impacts in all impact categories examined in this study were less for the proposed EPS-HIPS/PE shrink-wrap packaging than for the present EPS/PE packaging. This is due to

Acknowledgements

This life-cycle assessment was commissioned by Email Ltd. For more detailed information regarding the specifications of the packaging system contact David Farrell, Supervisor Manufacturing Engineer, at email address: [email protected].

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