In praise of plastic

Categories: The Great Plastic Debate

Published: 15 Mar 2018

—

(Featured image: by Marco Verch, CC BY 2.0)

Edit, October 2019: People are still reading this post 18 months after I wrote it. In case it’s not obvious it’s actually part of a series. All my posts relating to plastic are linked to from here.

Lately, my facebook feed has been full of petitions to sign about creating plastic free towns, alongside posts from people excited to have found somewhere that sells milk in glass bottles. Meanwhile, Michael Gove, not known for his eco-warrior tendencies, is reported as being ‘haunted’ by images of plastic waste on Blue Planet II, and the Government has unveiled a 25 year environment plan which includes measures to reduce plastic waste. Our current preoccupation with plastic seems to mostly relate to marine litter and I looked into this in a previous post here. In essence, if it is entanglement of wildlife that concerns you about marine litter, the answer is regulating the fishing industry. If it’s the total volumes of plastic in the ocean, then the answer is investments in waste management infrastructure in developing nations; over 80% of the annual discharge of plastic into the oceans comes from just 20 countries. But read that blog post if you want the detail.

Much as with the rush toward diesel cars (better for climate change, worse for air pollution), there is more than one bit of the environment we need to worry about when it comes to plastic. So how do the alternatives to plastic do when considered in relation to climate change? Banning single use plastics and replacing them with something else could easily do more harm than good.

40% of plastic produced is used in packaging, and this is generally single use, with a short lifespan. So can we simply reduce packaging? Sadly for most food, the answer is no. Packaging provides protection from physical damage, reduces contamination risk, and stops the product going off. It often makes the product easier to handle, transport, stack and display, and provides us with the product in a suitable quantity. Granted, packaging also provides a blank canvass for marketing and promotional information which may be less welcome, but the importance of packaging in protecting the product is critical. Nobody buys the bruised apples that are loose at the bottom of the box, a browning lettuce or a limp cucumber. I’ve written about the importance of packaging in preventing fruit and veg decay here, and the results may suprise you.

The greenhouse gas emissions of the food itself are almost without exception larger than the packaging it comes in; between twice and two hundred times greater according to studies on a range of food in the US. Meanwhile, global estimates suggest that 28% of agricultural land is used to produce food that is never eaten. Whilst its customary to blame supermarkets for this, in the EU, 53% of food waste occurs in the household, with just 5% being at the wholesale and retail stage of the supply chain. We therefore need to think about packaging in the context of its potential role in reducing food waste. There are more imaginative ways of doing this than seem to be common at teh moment. Packaging could be better designed to provide us with the quantity of food that we need rather than an excess, or in a way that allows the quality of the remaining food to be preserved, for example via vacuum sealed pouches.

It’s not about the plastic bags…

If we accept that some packaging is necessary, the obvious question is what that packaging should be made from to most effectively perform its functions. When looked at in life cycle assessment terms, the answer in the majority of cases, is plastic. The Environment Agency did a study on bags made from high density polyethylene (HDPE, the usual carrier bag plastic), and compared them to paper, biodegradable plastics, ‘bags for life’ made of LDPE (low density polyethylene), and reusable cotton bags. Conventional plastic bags came out on top. For all types of bag, the production and resource use elements of the life cycle dominated the impacts; whether or not a bag was recycled had little effect on the results. Because producing the bag in the first place is where the impact is, the most important thing that we as individuals can do is reuse the bag, whatever it’s made from. To do better than a conventional ‘single use’ carrier bag, a paper bag would need to be reused 3 times, and the equivalent figures for LDPE bags for life and cotton bags were 4 times and 131 times respectively. And this is all assuming that the ‘single use’ bag was only used once; obviously if it’s reused itself, it is environmentally even more advantageous compared to paper, cotton and LDPE. The results of life cycle assessment studies are always sensitive to their underlying assumptions so it’s not worth being too hung up on the exact number of reuses of a bag is required, but the underlying data is robust in terms of favouring the humble 5p checkout bag. It’s also important to note that this study was of carrier bags, not of the packaging in direct contact with food.

Plastic bottles are pretty good too!

Similar conclusions about the desirability of plastic are reached in studies on bottles. Those of us with greying hair will remember waking up to the clinking of milk bottles and doorstep delivery by the local milkman. But a glass milk bottle is only reused an average of 10-16 times before disposal. This is partly due to wear and tear (nobody likes a clear glass bottle that is so scuffed that it’s beginning to be opaque), and partly due to the fact that not all are returned. Glass is energy intensive to produce and has a very poor strength:weight ratio. At a basic level it would make sense to design a piece of packaging that held the amount of product that you wanted; this is why most milk is sold in large plastic bottles holding several pints. And yet glass milk bottles are typically still pint sized; if you’re buying more than a single pint in a glass bottle, your product is seriously overpackaged…

Other beverage containers have also been subjected to life cycle assessment. Beer and wine producers have commissioned numerous studies demonstrating that plastic or aluminium packaging has a lower environmental impact than glass. Some have responded by making glass bottles lighter, and others have moved some of their product lines into aluminium cans. But much of the problem here is consumer perception of materials and its relationship to product quality; would you buy wine in a plastic bottle?

Proponents of glass bottles will say that they are easier to reuse than plastic (true), and easier to recycle (also true). There will certainly be circumstances in which a reusable glass bottle system is environmentally superior, but those proposing these schemes in the UK have yet to provide the numbers demonstrating this, and the question requires further analysis before investing in such a system.

In my less charitable moments I can’t help but think that the current hysteria about packaging is simply blame shifting in order to deflect attention from our own individual decisions; we are addicted to consumption, so we let food rot in our fridge and drink as many bottles of fizzy pop as we please, but we want governments and supermarkets to somehow make this environmentally friendly. The environmental impact of our own consumption is something that makes many of us deeply uncomfortable – we know that the world cannot support a rising population of people who are like us. I get this – consumption is an overwhelmingly big and messy problem to think about compared to the allure of one less plastic bottle in the ocean. But the idea that we will completely decouple consumption from resource use is flawed, and we cannot afford to ignore the impacts on climate change. So calculate your carbon footprint and make some changes that matter (I’ve discussed what these might be here). Get the bus, cycle, eat less meat, don’t fly on holiday, but above all, consume less. Agonising about plastic is missing the point.