Green myth busting: reusables vs single-use

In our new blog series, Green myth busting, I’ll be doing a deep-dive into assumptions we have around certain sustainable behaviours and choices, and teasing out some of the complexities. Last time we looked into the different ways of thinking about train travel versus car travel. Next up: reusables vs single-use.

The perception: Reusable products are better for the environment than single-use.

The facts:

Seems like a no-brainer, right? Single-use = bad and reusables = good. Well… it's actually a bit more complicated than that. Sensing a theme here?

While it’s absolutely true that single-use products are bad for the environment, their reusable counterparts often initially come with a higher carbon price tag.

However, every time we reuse our products, their environmental impact goes down. Therefore, our goal should be to reuse the products we’ve already got as many times as possible.

Let’s take a look at some examples, shall we?

Single-use plastic bags vs reusable bags

Single-use plastics bags have been public enemy no. 1 for a long time now, and for good reason. These lightweight plastic bags are made from high-density polyethylene (or HDPE to you and me), which is derived from fossil fuels.

Plastic bags can be recycled, but rarely are. In the UK, they currently can only be collected at supermarkets, so only 6% of flexible plastic packaging ends up being recycled (Wrap). The rest end up in landfill or as litter, where they can damage ecosystems and harm wildlife, or degrade into microplastics that pollute our air, water and soils.

However, plastic bags cost very little carbon to make. According to Mike Berners-Lee’s How Bad Are Bananas, a lightweight plastic bag costs about 3g CO2e to produce, with heavier supermarket bags clocking in at around 10g CO2e.

How do reusable options stack up? It depends on what kind of reusable bag you’re talking about, but almost all of them will have a much higher carbon footprint than plastic bags, as they use up more resources and/or more energy to manufacture.

In 2011, the UK’s environment agency determined that a paper bag had to be used three times in order for its climate impact to be below that of a single-use HDPE bag. A cotton bag? A whopping 131 times.

But the UK study was only looking at a product’s impact on the climate. A study conducted by the Danish government went even further to look at all the environmental impacts a carrier bag could have, including ozone and water depletion, ecosystem toxicity, etc.

The study then calculated how many times that bag would have to be reused in order for it to equal the environmental impact of a ‘bag for life’ that’s been reused as a bin liner:

Type of carrier bag	How many times it must be reused to equal the impact of a reused ‘bag for life’
Paper bag	43 times
Non-woven PP bag	52 times
Conventional cotton bag	7,100 times
Organic cotton bag	20,000 times

Basically, it all boils down to: reuse what you’ve already got as many times as possible. And the next time you’re buying your mushrooms loose at the supermarket, reconsider putting them in their paper bag if you’re only going to use that bag once.

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Single-use plastic bottles vs reusable bottles

Like bags, single-use plastic bottles are facing a reckoning. The most common material in plastic bottles is polyethylene terephthalate (PET), which is made from petroleum and natural gas.

Thankfully, plastic bottles are widely recyclable, but out of the 35.8 million plastic bottles used every day in the UK, only 55% are recycled. That’s 16 million bottles a day being added to landfill, littering our streets, or breaking up into microplastics in our oceans. (Psst… Norway recycles 97% of all their plastic bottles. Let’s take a leaf out of their book!)

Also, when a bottle does get recycled, virgin plastic usually gets mixed in to maintain the quality of the plastic; even then, plastic can only be recycled a finite number of times before it degrades to the point of being unusable (Nat Geo).

But what about their carbon footprint, and how does it compare to reusables bottles?

A litre-sized plastic bottle will have an average carbon footprint of approximately 103g CO2e, which comes from the PET and the energy necessary to mould it into its bottle shape (How Bad Are Bananas).

The carbon footprint of a reusable bottle will depend on what it’s made from. An MIT article found that a reusable bottle made out of virgin aluminium weighed in at 5.705kg CO2e per pound of material. The study goes on to estimate that it would take between 10 to 20 uses for a reusable bottle, depending on the material, to break even with the impact of a plastic bottle (when the source of the water is taken out of equation – that’s a whole ‘nother kettle of fish).

However, a New York Times article that examined the life cycle assessment (LCA) of a 300 gram stainless steel water bottle came up with a higher number. If the stainless steel bottle replaces 50 plastic bottles, it will have a lower carbon intensity than its plastic counterpart. But in order for it to beat plastic in all environmental impact categories, it’ll have to be used 500 times.

Also, though stainless steel and aluminium are 100% recyclable, bottles made from these materials tend to be also harder to recycle than plastic bottles, as they’re likely made up of several different kinds of materials fused together (for example, if there’s plastic embedded into the metal cap).

But unlike plastic, steel and aluminium can be recycled an infinite number of times, so if you need a reusable bottle, your best bet will be to get one that’s made entirely out of that material, to make it easier for you to recycle at the end of its life.

Conclusion: We need to ditch single-use products because they’re made from fossil fuels and, when improperly disposed of, can harm our natural environment. However, they do have a lower carbon footprint than reusable products. Therefore we need to reuse what we’ve already got as many times as we can and try to recycle it once we’re done with it.