My younger daughter works as a sustainability analyst for brewers Molson Coors and she covers a great many environmental issues in her work. She recently told me that the Enviroment Agency has published a research report into the impact of ‘environmentally friendly’ shopping bags.
What this reveals is that the carrier bag issue is not as simple as it would seem. There is more to this than just ‘single use bad, bag for life good’. It seems to be down to the resources used, where they are made and – for natural products like cotton and paper – the high levels of inputs required to grow and process the raw materials.
This chart from the report shows the number of times the various types of bags need to be used to be a more favourable solution to the ordinary single-use high-density polythene (HDPE) bags.
Impact of HDPE bags when compared to “sustainable” alternatives
| Type of carrier | HDPE bag (No secondary reuse) | HDPE bag reused as bin liners | HDPE bag (used 3 times) |
|---|---|---|---|
| Paper bag | 3 | 7 | 9 |
| LDPE bag | 4 | 9 | 12 |
| Non-woven PP bag | 11 | 26 | 33 |
| Cotton bag | 131 | 327 | 393 |
The amount of primary use required to take reusable bags below the global warming potential of HDPE bags with and without secondary reuse
The science up to now has not been clear enough for me to stop using the single use bags, but this report certainly helps. Knowing for instance that the single use bags our customers take away are often used as bin liners adds to the confidence that we have in continuing to provide them. We also offer the ‘Bag for Life’ style that a minority of customers have taken up. We previously sold hemp carriers for a while, but no longer do so.
I think that the biggest surprise from this research is that the carriers made from cotton are potentially the least environmentally friendly in terms of Global Warming impact. The chart shows that if the ‘single use’ bags find three uses the cotton bags need to be use nearly 400 times before they match the ‘friendliness’ of the plastic variety.
The two key statements from the reports executive summary are:
Whatever type of bag is used, the key to reducing the impacts is to reuse it as many times as possible and where reuse for shopping is not practicable, other reuse, e.g. to replace bin liners, is beneficial.
The reuse of conventional HDPE and other lightweight carrier bags for shopping and/or as bin-liners is pivotal to their environmental performance and reuse as bin liners produces greater benefits than recycling bags.
So with this in mind should these HDPE bags have a message printed on them to that effect?
This Environment Agency report has been long in preparation – it was commissioned in 2005 – but it does provide a sound basis on how to proceed with the carrier bag issue. Like many sustainability issues the answer isn’t clear-cut and is down to how we as consumers use a product as well as how it has been made.
Paul Keys
25/03/2011
A thorny issue indeed. Some time ago, in conversation with a lecturer from one of the Sheffield universities, I was informed of the following. (I should point out that I have no way of verifying the voracity of these ‘facts’, but neither do I have any reason to disbelieve them)
Single use carrier bags are one of the most successful ever inventions, when you consider what they are for. A strong vessel for people to carry home often heavy shopping, with confidence that the bag will not usually break, and yet adds virtually no weight to the shoppers burden. It is extremely inexpensive, in fiscal terms,when compared to every other alternative, none of which offer the same strength/weight advantages.
The manufacture of these bags uses waste product from the petro-chemical industry, which aside from the production of moth balls, has few other alternative uses, and if not employed in this manner, would probably be burned at source.
This in turn leads to the suggestion that if single use bags are taxed out of existance, then the core ingredients used in the production of them, would have to be burned, thus resulting in pollution. However, with the use of catalytic technology, this pollution can not only be controlled, but also the process of destruction could be used as a fuel source. It could therefore be argued that the bags themselves, could be burned after use, offering no more pollution to the environment, than if they had not been created in the first place. It would stop the problems associated with sending them to landfill, and the argument that something that had probably only had a useful life of, at the most, a few hours, which then take thousands of years to decompose, would also be dissipated.
It is possible, more than possible, that all of the above is nonsense, I do not have the skills to decide. But perhaps those that do, should make their cases more clearly.
Jai Singh
29/03/2011
I too have looked at this and have made some enquiries regarding woven bags. I have had many customers wishing to use these as opposed to the Plastic alternative.
Has anyone successfully implemented this and have you seen cutomers opt to re-use rather than use the Plastic bags. Also how many retailers charge for bags as I currently do not?