Look around the room you are in. Chances are that many of the objects within easy reach are made of plastic. Our lives are built on plastic and so is a burgeoning environmental problem. Most plastics are made from fossil fuels and end up in landfills, rivers or oceans where they can persist for centuries.

Bioplastics are one of the most promising solutions to this conundrum, but the term is often misunderstood and misused and this can lead to poor choices by both consumers and manufacturers. Let's try to set the record straight.

What is a bioplastic?

The term bioplastic is actually a catch-all for plastics that are bio-based, Biodegradable or both - and these are two entirely different things.

Bio-based refers to the origin of the material. The raw materials are biological, such as corn, sugarcane, cassava, potato starch, algae or even used cooking oil rather than crude oil.

Biodegradable refers to the end-of-life properties of the material. It means it can be broken down by microbes into water, carbon dioxide and biomass.

There are three families of bioplastics

The two characteristics are independent of each other, so there are three broad categories of bioplastics.

1. Those that are bio-based but not biodegradable.

These are bioplastics that are essentially plant-based equivalents of conventional plastics. They are made using bio-based feedstocks but have the same properties as their fossil fuel counterparts and are completely recyclable, but without using any fossil carbon in their production (Bio-PET, bio-polyethylene made from sugarcane ethanol) .

2. Those that are both bio-based and biodegradable.

They are made from renewable feedstocks (PLA, PHA, starch blends etc) and are biodegradable.

3. Those that are not bio-based but are biodegradable.

These are mostly petroleum-based polymers (PBAT, PCL etc) that have been tweaked to make them biodegradable.

A crucial thing to note about biodegradability is that it does not necessarily mean what most people think it means.

Most materials that are touted to be biodegradable usually require very specific conditions to do so. Usually, they need the heat and microbial help present in an industrial compost. Materials that are industrial compostable (such as PLA) often need temperatures of 58C before they can biodegrade - something that is rarely reached outside of a commercial compost. On the other hand, some polymers such as some PHAs are capable of degrading in marine or soil environments.

In order to find out if a plastic is truly biodegradable, it is necessary to check if it has been certified as such (EN 13432 or ASTM D6400). This is really the only reliable way of finding out if a material is really capable of biodegrading under certain conditions.

Why are bioplastics a good thing?

Lower use of fossil fuels

By using renewable resources, bioplastics can help lower the amount of fossil carbon used in the production of plastic and add diversity to the supply chain

Lower carbon footprint

Most bioplastics are capable of offsetting a sizeable chunk of the greenhouse gases that would have been emitted by petroleum-based plastics due to the ability of plants to absorb CO2 as they grow. It should also be noted however that bioplastics are not always significantly better from an environmental point of view than conventional plastics - it is highly dependant on the material and production method.

Superior end-of-life options

Compostable plastics can form an important component in closed-loop waste management systems by diverting food-contaminated packaging from landfill and returning it to the soil in the form of compost. This is really useful in places where food and plastic recycling cannot be separated

Less persistent pollution

Compostable plastics have the potential to reduce the amount of plastic pollution that persists in the environment for centuries, as they are much more likely to biodegrade, provided the correct conditions.

Innovation

Bioplastics are not just a feel-good alternative to conventional plastics - certain bioplastics can open up new opportunities in engineering and product design that traditional plastics cannot. Some bioplastics can be composted along with food waste or can be absorbed by the body for medical purposes.

What are bioplastics currently used for?

Packaging makes up the largest segment of the market for bioplastics - with bio-based flexible plastics being the largest single category. Bioplastics have been used in a wide variety of packaging formats including food packaging, stretch wrap, shopping bags, bottles, coffee pods etc. Compostable packaging is particularly useful for fresh food, takeaway containers and tea bags.

Agriculture and horticulture are also big users of bioplastics, particularly biodegradable mulch films that can be plowed back into the ground after use - thereby saving on the time and money needed to recover traditional plastic sheets. Similar principles apply to plant pots, clips and seed coatings.

Bioplastics are seeing an increase in use in food-contact packaging, such as cutlery, plates, cups, and straws, particularly in catering, where the packaging can often be composted along with any food waste.

Toys, phone cases, cosmetics packaging, razors and even athletic shoes are being made with bio-based polymers. Textiles are a growing market too, with bio-based PLA, and bio-polyamide fibres being used in clothing, carpets, and upholstery.

Automakers and electronics manufacturers are also using bioplastics to make interior panels and insulation to lower the carbon footprint of cars and consumer electronics. In the medical field, biodegradable sutures and drug capsules are also being developed that can safely be broken down by the body.

Challenges

The bioplastics industry is still relatively small, and it is important to discuss the limitations of the technology.

Plastic made from renewable resources tends to be more expensive than petroleum-based plastics, although this is not always the case, and the gap is closing as these materials become more widespread. There is also the challenge of balancing the need for bioplastics with the need to feed a growing population. Some bioplastics use starch as a feedstock, which is a concern since there is already a global shortage of starch. However, alternative feedstocks are being explored, including agricultural waste, algae and food by-products.

Industrial composting facilities are not available everywhere, and it can be very challenging to ensure that compostable plastics are not being contaminated by conventional plastics

The term biodegradable can be confusing, and it can lead to consumer misunderstanding about how exactly the material should be disposed of. There is also the challenge of ensuring that biodegradable plastics are not being inadvertently used in the recycling stream, since they can ruin the whole batch.

Conclusion

While bioplastics are not a magic bullet that solves all of plastic pollution at once, they are an important technology when it comes to building a circular economy. However, it is vital that bioplastics are used wisely, in the right applications where their benefits can be maximized. A crucial part of this is ensuring that bioplastics are being certified and disposed of correctly, and that consumers are aware of the differences between various bioplastics.