Tuesday, 29 January 2019

Which type of Grocery Bag is the most Environmentally Friendly?

Which type of Grocery Bag (shopping bag) is the most Environmentally Friendly? 

This is not a simple choice. Each of the below grocery or shopping bag options has its own problems. The choice will boil down to whether you want to prevent global warming or prevent plastic pollution. Plastic pollution despite being a very visual problem, is a small problem compared to global warming. 

Conclusion: The most important factor with a shopping bag / grocery bag is that is is reusable. You should look for a bag that will last a long time, and is easy to make. This is unlikely to be a paper bag, they do not last very long. There is no problem with plastic bag provided it is re-used multiple times, and recycled at the end of use.

Plastic or paper? 

Paper is better right? No not really. A life cycle comparison conducted by NASA (you know rocket scientists), have shown that  really there is little to pick between paper or plastic in terms of environmental credibility. Below image courtesy of NASA. 

Bag for Life?

A very simple "bag for life" option for a super market may well be a very good option, a 20c / 10p heavy duty plastic carrier bags will last for perhaps 100 uses and is very easy to make and recycle. 

But even with reusable bag you have to be careful with you choice.  Some heavily made reusable bags such as cotton totes bags have to be used 1000's of times before they are better than a normal plastic grocery bag. Why is this? . . .

It is because normal plastic grocery or shopping bag is very quick and easy to make. A complicated fancy looking bag for life is complicated to make, you need to grow cotton, wash the cotton, feed the workers, spin the cotton, weave the cloth, stitch the bag together, transport the bags in trucks. Each of these stages produces CO2 and a complicated bag will produce a lot more CO2 than a simple one. 

The best option might be to reuse a bog standard carrier bag. Just make sure you dispose of it properly. 


A compostable plastic carrier bag is an excellent choice if you actually intend to compost it at home in you well managed compost heap. But is is not a good choice if it ends up in the normal rubbish bin, or mixed with normal bags for recycling. 

No Bag

Perhaps the best option is no bag at all. But this only works for just a few items. But if you are wearing a coat, why not put the stuff in your pockets. 

Card Board Box

Many stores provide a used cardboard box, in which to put groceries. Provided this is recycled or composted after use, this might also be a good option.

In Depth 

The below table comes from a report published by the Environment Agency of UK. It shows the number of times you have to reuse a carrier bag, for it to become comparable with a certain alternative.

A conventional HDPE bag is very easy to make, and creates little environmental impact. Re-use for best option. A paper bag would have to be used 3 times to be comparable. But I doubt you would be able to re-use a paer bag 3 times. An LDPE bag need only be used 4 times to be comparable, it is entirely feasible that an LDPE bag could be reused 4 times, and as such this is the best option.

Below is a table showing the types of bag, so as to avoid confusion regarding types.

Based on the CO2 footprint of manufacture the below graph is derived. This is just one part of the life cycle analysis that was carried out.

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