Pros and cons of biodegradable plastics (bioplastics)

3 gennaio 2019 Magnus Jern

What are the pros and cons of biodegradable plastics? Are biodegradable plastics (bioplastics) good for the planet? Are the waste management systems prepared for biodegradable plastic waste? How fast do biodegradable plastics break down? We’ve spend a lot of time researching and pondering these topics. In this blog we will attempt to answer the most common questions on use of bioplastics.

Could we give up single use plastic?

The best thing would be if we could simply give up single use plastics. Refuse, reduce and reuse should always be the priority. Examples of success in reducing use of plastic include

charging for or banning plastic bags as there are good alternatives
making customers ask for straws for drinks in fast food places
reducing plastic packaging of fruit and vegetables in grocery stores
drinking tap water or filtered tap water in restaurants when served for free

But for every success story there are 10 failures.

Changing behaviour to reduce plastic use is hard

To change behaviour in a way that is perceived as worse or a sacrifice is hard though. Generally humans don’t like change.

Here are a few examples of refusing and reducing plastic that have proven to be difficult

switching from paper-plastic diapers to cloth diapers
drinking tap water in places where it doesn’t taste particularly good (e.g. Brighton, Barcelona or Dallas)
bringing a refillable cup for the morning coffee takeout place
avoiding takeout places with plastic containers

These changes require effort or even sacrifice by people. Therefore only the most passionate environmental supporters make the change.

Simply put most people will only change behaviour if everyone else does or if it’s convenient.

This is why TAPP Water chose to use biodegradable plastics for the filter cartridges for TAPP 2. We believe that it's the easiest way to get people to give up bottled water in an environmentally friendly way.

How can we avoid bad plastics with minimal effort?

This is where biodegradable plastics can play an important role. Instead of giving up e.g. straws, single use cups or water filters we replace the existing products with something similar. The only decision or change required is to make select products with biodegradable plastic.

What are biodegradable plastics made of?

Generally bioplastics are made of corn starch, cooking oil, algae or sugar although there are lots of other materials.

Source: Appliance Design 2018

These are then turned into plastics using various different methods with the most common and seemingly promising being:

Polyactic acid (PLA) synthesised from starch extracted from crops like corn, cassava and sugar canes.
Polyhydroxyalkoates (PHA) synthesised by having bacteria feed on vegetable oils or sugars from food crop.
Various bioplastics made from algae (found abundantly in seawater) using heating and cooling methods as well as mixing with e.g. calcium carbonate.

We also expect to see a lot more innovation in the coming years enabling e.g. foodwaste to be turned into bioplastics.

Cost of Biodegradable plastics

Currently bioplastics such as PLA are about 20 to 50 percent more costly than comparable traditional plastic materials. However, prices are slowly coming down as the technology improves. As demand and production volumes increase the cost should eventually be similar to conventional plastics.

For the time being though products using bioplastics will generally be a bit more expensive.

What’s the environmental impact of biodegradable plastics?

Every technology has its pros and cons. The main criticisms of biodegradable plastics are

A. Farm land use Require a lot of farm land for the raw material. Some even claim that this will divert land from foodstock and thereby create a food crisis. The counter argument is that the land required to satisfy all the demand for plastic, would only use 10 per cent of agricultural land. If you consider the potential to use sidestream or by-products from the food industry, the land use will be considerably less.

B. Water use to grow the crops for the raw material This is often one of the main arguments as the water usage figures for all crops look so extreme. See study in sources below.

But what these studies forget to mention is that the water doesn’t just disappear (it’s part of a circular system) and that crops are often grown in places with abundant water. Having said this water use should be considered when choosing where to source the crop.

C. Fertilizer, pesticides and other chemicals Several studies have shown that bioplastics production resulted in greater amounts of pollutants. This is due to the fertilizers and pesticides used in growing the crops and the chemical processing needed to turn organic material into plastic. But just like for other foodstock there are eco-friendly alternatives today that can be used.

D. Methane gas release In the ideal scenario all bioplastics end up in an industrial compost but realistically this is not the case in the short term. Some bioplastics will inevitably end up in landfills where, deprived of oxygen, they may release methane. This is a greenhouse gas 23 times more potent than carbon dioxide.

E. Recycling challenges When bioplastics enter the conventional plastic recycling stream they may contaminate the recycling process. Therefore separate recycling streams are necessary to be able to properly discard bioplastics that are not composted.

How do we dispose biodegradable plastics?

Biodegradable" implies that the decomposition happens in weeks to months. Bioplastics that don't biodegrade that quickly are called "durable".

With most bioplastics, decomposition is fast in industrial composting facilities but may take years in the natural environment. Therefore consumers need to ensure that bioplastics are disposed correctly.

To support this it’s also critical that governments and industries provide the infrastructure for industrial composting. However, even if bioplastics end up somewhere else such as a landfill or nature they still have an advantage. They will break down into their natural constituents over time and cause less harm.

What about other materials such as glass as an alternative to plastic?

This is where environmental impact analysis gets particularly complicated. Based on most studies plastic have a lower CO2 footprint due to weight and transportation. The only exception is when the glass and content is produced locally which is unusual. Therefore glass is not necessarily better than plastics.

Summary

Bioplastics are not a silver bullet for plastic pollution but they are part of the solution just like electrical cars for transportation.

Here are the key things to consider when :

Given the choice it’s almost always better if we can avoid packaging such as plastics entirely (refuse, reduce and reuse)
Bioplastics are a good alternative when packaging is required such as garbage bags, disposable cups for big events, diapers and water filter cartridges as in the case of TAPP
Make sure bioplastic materials are sourced to have minimal environmental impact
Always dispose bioplastics to the most appropriate waste management stream, typically industrial composting (ask your local waste provider if you are unsure)

Hope you find this useful. Please contact us for questions, comments and suggestions.