That UK LCA study of carrier bags

[walkitout]

Here is the link:

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/291023/scho0711buan-e-e.pdf

This is the source of the claim in coverage of the impact of California's ban on single use grocery store bags that a cotton reusable bag has to be used 131 times to be equivalent to a single use grocery store bag -- the claim that got me going on this project in the first place. Really? 131? Not 130? Are we not caring at all about significant digits, then? This isn't really science, then, is it?

Several things to note. The cotton bags they analyzed are the horrifyingly awful ones that hold very little. So, yuck. I don't use those; I use real totes instead, one of which is within the weight range of the cotton bags mentioned (upper end) the other of which blows way past it. FWIW, the upper end bag probably has 50% more capacity than the capacity listed. And the really big bag has probably 3x the upper end capacity. By volume. And I fill those fuckers, because I am never carrying them very far, unlike the hypothetical on-foot shopper in the UK study (I'm headed out to my car like a Normal Murrican; if I were doing this by bicycle, I would have brought the panniers in with me and filled those directly, and the bike would be parked even closer to the shop than the car can be).

Where was I?

Oh, yes. The study does understand that people put more in heavier weight plastic bags than lighter weight ones. And still more into the cotton bags (even the shitty ones they were analyzing). They figure one can get the same volume of groceries home in about half the number of bags if you are using cotton vs. single use bags. And that matches my experience with crappy cotton bags. My experience with my really large bag is that it holds 5+ cotton bags worth of groceries if packed correctly, which few baggers seem willing to do. Possibly they doubt their ability to transfer it packed from the table to the cart? It has great handles; I can just pick it up, pop it on a shoulder and bring it out to the car. Altho I then walk unevenly for a few minutes until I balance back out again.

Their analysis includes end of life stuff, which I find strikingly odd. Paper bags aren't even used in the UK in grocery stores any more, and they say no one uses them again for shopping, even tho they could be, and they include that in their analysis because. . .

"However, the inclusion of reuse for paper carrier bags is intended to illustrate how many times a
paper carrier bag would have to be reused to perform better than other bags, it is not a
statement that this reuse occurs or that it is feasible."

Honestly, it is a little startling. Back In the Day, I used to reuse paper bags as bin liners, but I don't get paper bags often enough to justify that, so not so much. Now, their primary reuse is as a container to drop clothes off at the Middle Class Guilt Reduction Station and, less and less often, transporting books I know longer want to own to the library for donation. I also use paper grocery bags to transport arts, crafts, food, etc. to parties.

Anyway. If my Really Big Bag is twice the size of their crappy cotton bags, then I'll assume that it will take 2x as many single use bags to justify its existence (since this is a by-weight of the input situation). My Really Big Bag needs to displace, thus, 262 (ha) single use bags. Since, when full, it replaces roughly 5 at a time, I need to use it about 50 times when I go to the store. Doesn't sound that hard -- it justifies its existence in a single year, if I use it once a week.

My purple packable bags are a little trickier calculation. They weigh 38 g. They are typically packed at about 1.5 times the capacity of a single use plastic bag, because baggers are chicken shit. I usually pack them about at 2x the capacity of a single use bag. They are made of this stuff:

https://www.chicobag.com/t-what-is-repete

That is post-consumer soda bottle plastic. I figure a chico bag beats a single use bag after no more than 6 uses -- even counting the carabiner, since a lot of that material is also recycled. Especially after you take a look at how they run their production and other sites (employees have their own towels in the loo and cloth napkins in the break room).

Comments

[ethelmay]

An article in the Atlantic claimed a while ago that each cotton tote bag would have to be used 327 times to be better than using a plastic bag twice (or a recycled polypropylene 26 times). Though apparently part of the problem is that there are too many tote bags being made for promotional purposes (which is a point I can well understand -- we have accumulated quite a lot ourselves, way more than we need).

same underlying LCA

[walkitout]

The Atlantic article is pointing to the _exact same study_ I referred to. They picked a different table / column in the table to come up with a number of times reuse -- they picked the column where the assumption is that ALL single-use plastic bags will be reused (100%) at end of life as bin liners AND that displaces bin liners that otherwise someone would have gone out and bought as new bags. This is precisely the kind of irritating subjective and honestly kind of unrealistic detail (100% of single use plastic bags? Really? And while I will line non kitchen bins with single use bags if I have them available, I often do not line if I don't have single use bags availabe -- I don't ever buy bin liners for non-kitchen bins, so even when I use them I am not displacing something else. I'm just trying to make the best of a bad situation. But this kind of underlying assumption winds up making it really hard to compete with single use plastic bags in terms of impact on the environment, because the single use bag is _assumed_ to actually have two uses -- halving its badness.