By Eric Crampton 13/08/2018 7


The Ministry for the Environment’s consultation document on banning plastic bags is out.

The key table, or at least the most interesting table, is in the appendix. It shows, from a Danish study, the number of times a reusable shopping bag would have to be reused to have less environmental impact than current disposable bags.

Source: Ministry for the Environment. 2018. Proposed mandatory phase out of single-use plastic shopping bags: Consultation document. 

The consultation document provides no cost-benefit assessment, but Question 8 asks those making submissions to assess whether the benefits might outweigh the costs.

I can only speak for our own household, but I doubt we’re that we’re that atypical.

We have a few reusable bags at home. The ones we have get reused a lot, because we use them on planned trips to the store. But most of our trips aren’t like that. Most of them are grabbing a few things on the way home after getting off the bus. Maybe other people are happy to carry around reusable grocery bags every day on the off chance that they might need to grab milk, bread, eggs and butter on the way home. I’m not. On those trips, we use the disposable plastic bags. Because what else are you going to do? Walk home, get a bag, walk back to the shop? It’s absurd.

The more likely outcome: buying the reusable bags on those trips, accumulating a stack of them at home, then finding some way of disposing of them down the line. The number of times these things get reused will be endogenous to whether disposable plastic bags exist. I’m expecting that the reuse rates will be dropping.

I also have a few hundred of the disposable bags now on order from Ali Baba because they’re too useful around the house to do without. It may also be fun to bring those to the market for use as shopping bags after the ban.

Oh – another depressing part. MfE includes this line.

Retailers will profit from not having to provide free bags and by selling alternative carriers, and are in a good position to help their customers to transition.

Not a lot of economic intuition on display here. If it’s true, it means that customers will choose stores based on whether bags are available. If that’s true, the value destroyed by banning them is substantial.


7 Responses to “Bag Ban: read the appendix”

  • I think this is largely consistent with other studies that show that over the production/consumption cycle of bags, single use plastic has an advantage. Nonetheless, what these studies typically ignore is the *later* disposal cost of plastics. I didn’t see in those 14 impacts (and this is typical) this metric. If plastics didn’t accumulate as a stock pollutant then this would be trivial. But they do, which does have implications for the control costs. (I’m putting aside as an issue for the moment, the volume of plastic allocated to plastic shopping bags over other plastic products).
    Fwiw, I keep spare shopping bags in my car and office for the occasional shopping trip, many of which are cotton tote bags given out at conferences over many years.

  • Hmm. I think this is the Danish study (english version).
    https://www2.mst.dk/Udgiv/publications/2018/02/978-87-93614-73-4.pdf

    It evaluates outcomes over three end-of-bag-life scenarios, including incineration, recycling, and re-use as waste bin bag. So all of the results on the 14 indicators were relative to plastic bags in three different disposal scenarios for the plastic bags, with the ‘reuse as bin bag’ being the scenario friendliest to disposable plastic bags. Check Table 23, where the dark blue LDPE EOL3 is the ‘plastic bags reused as bin liners’ scenario.

    The report considered littering effects to be negligible in Denmark though. If littering here is more substantial, then we’d need to worry more about it, but also worry whether there are other policy solutions that might reduce littering without banning bags.

  • I think we tend to use landfill a lot as our disposal mechanism. Nonetheless, the problem is we wouldn’t say, have dead whales washed up on beaches with stomachs loaded with plastic bags if disposal was a closed process. A lot is getting into the environment. That seems to be a cost that isn’t being factored in. Especially as plastic is more like a stock pollutant.

    I agree that it doesn’t mean a ban is necessarily the best policy solution. Good economists should consider all the options.

  • Brendan A major reason why we have so many landfills is a previous Labour government banned industrial incineration being considered. If those waste furnaces with supplementary gas firing had been installed (Meremere was an ideal site), then there would be a lot more recycling and the disposal problem be a lot less. And we would be getting significant electricity generation.

  • Chris, can you please provide some evidence foer your statement ‘Labour government banned industrial incineration’?? And how would that result in ‘a lot more recycling’, given that energy from waste is NOT recycling, and a likely outcome is that material would be diverted from existing kerbside recycling schemes to EfW?

  • Hi Eric,
    It’s interesting that as a highly educated individual (who is likely to hold strong environmental views) you hold such a stubborn view on using single-use plastic bags. I personally find it extremely easy to use re-usable bags. I store a few in my car, a couple in my home, and I have one of those fold up ones that I keep on my in my day bag. It simply requires that choice to change your habits.
    I’m sure that we might not be solving the issue overall (as we may start to accumulate many re-usable bags), but I think it’s the message that is more important. The opportunity is now arising where general members of the public can be more conscious of how their own actions and decisions affect something greater than themselves. This may then lead to other positive environmental choices down the line.

    • Hi Isis,

      I’m glad that you find it very easy and that the ban will not impose any particular cost on you. Others don’t and will bear costs. Banning things to send a message is a terrible precedent – and especially where the ban on its own really does no particular good.