With the Government recently announcing that it would begin phasing out single-use plastic bags, it seems  like the perfect moment to share my thoughts on the matter.

The various campaigns to ban single-use plastic shopping bags and microbeads have been generally well received by the New Zealand public. Microbeads for instance (very small plastic particles added to cosmetics to offer mild abrasion)  are very likely to end up in the environment. This is based on the way that they are disposed of – down the drain. The beads float to the top in waste treatment plants, bypass their collection systems and end up in the greater environment. A simple ban of products containing microbeads coupled with public awareness is a very effective solution and prevent harm in the natural ecosystem.

Single-use plastic bags however have become an easy and convenient villain by the media and other well meaning entities. The main reason for this is easily conveyed – they are made of plastic. A holistic view of the use of plastic bags however shows that there are many advantages to using plastic bags and these should be considered also. Our use and disposal of plastic bags is more villainous than the actual material.

Single-use plastic bags are made of cheap commodity polymers, cost very little and are extremely strong for the amount of material used. Whilst they are  predominantly made from oil-derived hydrocarbons they also lead to less carbon dioxide being released into the environment during production than what are perceived as green alternatives. The Danish EPA investigated the life cycle of various grocery bag options and released a report in February this year. They tracked various grocery bag options throughout their lifecycle and included factors such as the environmental impact of transporting bags: their effect on ozone depletion; production of greenhouse gases and other factors. It is a very long and comprehensive report but I recommend reading the executive summary at least. It finds that simple LDPE bags that are reused once and disposed of as a bin liner have the lowest environmental impact of the carrier bag options. Cotton bags however would need to be re-used 52 times to have an equivalent environment impact when ozone depletion effects are discounted (for this they would need to be reused a staggering 7100 times to have an equivalent environmental impact as simple LDPE (light supermarket plastic bags).

If you walk down a beach you might see plastic waste in the form of discarded PET drink bottles or abandoned plastic bags. This has a great impact on their perception but questions arise – why are these items here? Plastic bags for instance may catch the wind and be lost whereas bottles could potentially float and find their way to beaches down stormwater drains. At some brief point in their long lifecycle responsibility for these products was given up. We need to better consider the behaviour of end-users too. If all plastics were suitably disposed of through recycling schemes or buried in landfills would they be perceived as being such a problem?

Whilst environmental impact can be considered in various ways, perhaps we should change the narrative. Should we be thinking about conventional plastics  in terms of resource conservation instead? Plastics are very useful but the oil they are derived from is a finite resource. They are not endlessly recyclable so perhaps we should make best use of them whilst they are available. Sending them to landfill seems like a wasted opportunity but perhaps that is a conversation for another time.

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Greg Storey

About Greg Storey

Senior Engineer at Blender Design. A technical whizz, turning ideas into actual working products with skill and experience.

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