How eco-friendly are compostable bags and coffee cups? 

As concern about plastic grows, more and more retailers and food vendors are looking to switch their packaging over to something more sustainable. But the world of “compostable” and “biodegradable” options can be a confusing one.

In this article, we look at how to dispose of compostable bags and cups, ask what conditions they need in order to break down, and examine the most eco-friendly options for consumers. 

What is compostable packaging? 

Compostable packaging is made from materials that can totally break down over time to produce organic matter. It has become a popular replacement for plastic, which never fully decomposes, but splits into smaller and smaller pieces that pollute rivers and seas.

Compostable bags are often made from vegetable matter like potato or corn starch. Compostable coffee cups and other food packaging can be made from materials like plant-based polymers, also produced from corn-starch or sugar cane, or from paper or cardboard.

However, compostable and biodegradable plastics can also be made from fossil fuels – just like conventional plastics.  

Is compostable packaging eco-friendly?

While compostable packaging is likely to be a better option than plastic (which we discuss in more detail below), it is not always as environmentally-friendly as it sounds.

All packaging requires materials and energy to produce, and as discussed above, compostable options can be made from fossil fuels, just like conventional plastic.

Even when produced with organic matter, the process often relies on new rather than recycled materials, such as wood. Paper packaging has repeatedly been linked to deforestation in countries like Indonesia, as well as in Europe.

Producing compostable packaging from natural materials also requires land, for example to grow corn used in cornstarch. With climate breakdown, land is becoming an increasingly vital resource, needed to grow food for human consumption or for re-naturing and capturing carbon through protection of forests and peatlands.

Compostable packaging also throws up issues when it comes to disposal. In theory, all compostable packaging can decompose into organic matter in an industrial composter. Under UK and EU law, for packaging to be labelled ‘compostable’, 90% must disintegrate within 3 months and biodegrade within 6 months.

However, in the UK, many composting facilities aren’t suitable for this kind of packaging. These facilities just do not have the right conditions for it to biodegrade, meaning that either it won’t break down or it will be removed alongside all other plastic at the start of the composting process.

Some packaging is home compostable, and we explain in more detail how to recognise this below, but this is currently rare in the UK.  

What is the most eco-friendly packaging option?

The best option, where possible, is to ditch single-use options altogether and reuse what you already have – including your existing plastic bags, coffee cups and cotton tote bags. You could consider keeping a fork and spoon in any bags you take travelling, for reuse, or storing a small fold-out shopping bag at the bottom of your rucksack.

It’s worth noting that reusable coffee cups and bags are heavier and therefore made from more material than disposable options. This means that, in order to be eco-friendly, they need to be reused multiple times.

A reusable plastic bag must be used somewhere between 4-20 times compared to a disposable one, in order to be more environmentally-friendly. 

For a cotton tote bag, the number is somewhere between 50 and several hundred times, depending on how they’re produced and eventually disposed of. 

Understanding labels on compostable packaging

The range of symbols on packaging can be confusing. 

Here are two you can look for if you want to know if the packaging is compostable.

The 'seedling' logo indicates that packaging is compostable. Never put this kind of packaging in with your recycling: it cannot be recycled and will just contaminate other recyclable plastics. 

Instead, check with your local authority whether you can put compostable packaging in your industrial composting caddy. Not all authorities have the right facilities for this. If your authority doesn’t allow composting of this kind of packaging, you will sadly have to bin it. 

The seedling logo is a registered trademark owned by European Bioplastics. It indicates the product is compostable in an industrial composting plant under controlled conditions such as temperature, moisture and time frame – leaving nothing behind but water, biomass and CO2.  

The OK compost HOME label by TÜV AUSTRIA indicates that the packaging can go into your home compost. If you do have a compost bin at home, that is the most ecological place to put it. (Note that the same logo without the word home is compostable only in industrial conditions.)

Some paper items will also be home compostable if they don’t have a bioplastic film on them. You can tell this from the texture: a shiny finish suggests they might have some kind of plastic film, while a matt one indicates they probably don’t. Most paper bags, for example, can be home composted. Cardboard takeaway food containers are often 'glossy' on the inside as this provides a layer to provide liquids and fats seeping through the material.

How do you dispose of compostable packaging? 

What you do with different items of compostable packaging varies. We cover the most common items, bags and coffee cups.

How to dispose of compostable bags

To work out how to compost your bags, first check out the symbols on them – which are explained above. Many compostable bags will only be suitable for industrial composting, in which case check with your local authority whether they have the right facilities for this, and if so, add them to your kitchen caddy collected by the council. If not, unfortunately, they have to go to general waste.

Some bags will also be compostable at home. For example, all Co-op bags are now home compostable. Check for the right symbol, and add them to your compost bin.

Even better, why not use your compostable bags to collect your other food waste? You could use them to line your kitchen caddy, giving them a second use before you dispose of them.

How to dispose of compostable coffee cups

As with compostable bags, start by looking for the right symbols on the coffee cup. Depending on what these say, either check with your local authority and add to your industrial food waste bin, or put in your home compost.

Can I put compostable packaging in the recycling bin?

Unlike plastic, compostable packaging cannot be recycled (with the exception of clean cardboard). Compostable plastics should therefore never be put in your plastic recycling bin. They could contaminate other recycling, meaning it has to be removed. 
 

Is compostable packaging more environmentally friendly than plastic? 

Compostable packaging is likely to be more environmentally friendly overall than conventional plastic. However, environmental experts warn that it is not a silver bullet solution to our plastic packaging crisis.

Bio-based plastics (which includes some compostable options) have a considerably lower carbon footprint through their lifecycle than conventional plastic. Unlike conventional plastic, compostable options can be made from natural, renewable materials rather than fossil fuels. As discussed above, though, compostable packaging still requires land and natural resources to produce.

Compostable packaging is single-use, while some plastic can be recycled a number of times. However, even where plastic can be recycled, it cannot be recycled indefinitely. Each time it goes through the process, the material is weakened and becomes poorer quality until it can no longer be reused, meaning that it eventually ends up in landfill.

Both conventional and compostable options also cause pollution. In 2020, a study found that bio-based plastic production actually resulted in greater amounts of pollutants, due to the use of pesticides and fertilisers for producing natural materials like cornstarch.

Once disposed of, however, conventional plastics are likely to be much worse than compostable options, due to the issue of microplastic pollution. Microplastics are created when plastic breaks down: they are tiny pieces of plastic that end up in rivers and seas and are ingested by animals, releasing toxins and affecting their reproductive systems.

Compostable alternatives may therefore be a useful substitute for plastic where disposable packaging is absolutely needed – but neither are free from problems and governments and businesses should also be looking at reducing packaging use overall. 

Is paper packaging more eco-friendly than plastic packaging?

Many companies are switching from plastic to paper, and a number of industry-funded studies have recently suggested that paper could be the most eco option – even better than reusables.  

However, academic studies have widely disagreed. The UN noted in 2021 that multiple studies suggested that paper bags could even be worse than plastic on some measures, including climate, depending on how they’re produced.

Paper packaging requires wood – meaning that ancient forests can be cut down and converted to industrial timber production. If all packaging was switched to this option, environmental activists warn that it could put massive strain on forests around the world.

Many supermarkets in the UK have switched from plastic to paper bags. But in 2020, the UK Environment Agency found that paper bag production required more materials and energy than plastic bags.  

Just like compostable packaging, then, paper is not a straightforward solution for reducing plastic consumption. 

In many cases, you may be forced to compromise depending on what you are buying. Where possible, use reusable packaging materials like bags, reusable cups, reusable (non plastic) water bottles, and avoid single-use packaging.