INSIGHT: Bio-based and biodegradable plastics and their role in plastics circularity

Jia Hui


SINGAPORE (ICIS)–Multiple fast-moving consumer goods (FMCGs) producers and global brands have made clear their commitment to reduce the usage of conventional fossil-based plastics, with alternatives such as bio-based and biodegradable plastics have been gaining the industry’s interest.

However, are those materials the solution to plastics circularity? Confusion among terms like bio-based, biodegradable, and compostable plastics makes it hard to discern — and make — the optimum environmentally beneficial choice.

The decision of which material to use is not that simple, with several trade-offs to consider.

The term ‘bio-based’ refers to a material made from feedstocks that have come from renewable sources– referring to the beginning of the product’s life cycle. Examples include, but are not limited to, sugarcane, corn, or cellulose.

The term ’biodegradable’ refers to a material’s ability to decompose via microbial activity – referring to the product’s end-of-life. The process of biodegradation depends on the surrounding environmental conditions on the material, and on the application.

A combination of those properties can generate materials that can be classified into three main types:

1. Fully/partially bio-based but not biodegradable – e.g., bio-based polyethylene terephthalate (PET), bio-based polyethylene (PE)
2. Biodegradable but petroleum-based – e.g., polycaprolactone (PCL)
3. Both fully/partially bio-based and biodegradable – e.g., polylactic acid (PLA), polyhydroxyalkanoates (PHA) or starch blends

Industry stakeholders and governments recognise that fossil fuels are finite. Reducing the consumption of fossil-based resources is seen as necessary, and the industry is turning to recycled and renewable materials.

With sustainability targets looming, many brand-owners and producers have looked to alternative sources of plastics, including bio-based and biodegradable plastics. Demand is growing because the increase in mechanically recycled polymer supply lags the growth in demand for these alternatives, across many markets.

Although both bio-based and biodegradable plastics are commonly classified under the umbrella term bioplastics, each material has its unique properties and consequently its unique pros and cons from the sustainability point of view.

As bio-based plastics use renewable resources as feedstock, fossil resources are preserved. In addition, bio-based production not only avoids emissions of carbon dioxide but often captures carbon during its lifecycle.

However, end of life remains a challenge. Similar to virgin resins, products made of bio-based plastic can be recyclable, depending on its design and access to collection systems.

Likewise, sorting and collection remain a challenge to avoid plastic pollution as well as to secure availability and reliability of supply for the recycling value chain. Bio-based plastics can be used alone or blended with virgin or recycled resins and can still be recycled.

Biodegradable plastics, however, serve as an alternative to conventional plastics in order reduce plastic pollution. Nevertheless, biodegradation depends on certain conditions such as temperature, bioactivity of the location, and moisture levels.

That means that biodegradable plastics still need to be disposed of properly. Besides consumer education, investments in collection systems and infrastructure are needed to ensure its proper destination in order to actually biodegrade and to avoid contamination of recycling streams.

Materials that are both bio-based and biodegradable are likely to have a low carbon footprint, contributing to those seeking to achieve carbon goals, as well as reduce virgin plastics consumption and avoid plastic pollution, if the collection infrastructure is in place.

However, life cycle analyses (LCAs) remain disputed, and may not cover the entire cradle-to-grave life cycle.

Bio-based and biodegradable plastics currently represent only 1% of global plastics production, accroding to trade group European Bioplastics.

This number is set to grow with the shift in consumer preference coupled with brands and countries’ sustainability, including carbon and reduced fossil-based, feedstock targets.

China and Japan are set to become forerunners in Asia, investing millions into boosting domestic bio-based plastics production capabilities.

According to Greenpeace, citing Huaan Research, China has 36 upcoming bioplastics projects, creating a total of 4.4m tonnes of newly added production capacity.

The Japanese Ministry included $45m in the 2019 budget for developing products manufactured from bio-based plastics.

Regulatory advancements are observed in Australia, EU, and US – with new rules on labelling to help consumers see through false green claims.

In the US the Federal Trade Commission’s Green Guides are designed to help marketers avoid making environmental claims that mislead consumers.

Biodegradable claims must show evidence that the entire product or packaging will completely break down within a certain period, usually within one year.

Companies must identify specific materials and explain why it is renewable, refraining from use of general terms such as “eco-friendly” or “green”. Individual states in the country have their own independent regulations.

For instance, currently, terms such as “compostable,” “home compostable,” or “marine degradable” are prohibited in California unless the product meets the American Society for Testing and Materials (ASTM) standard specification, which is exceedingly difficult.

Similarly, the EU holds common views, with the new circular action plan intending to release a policy framework on bio-based, biodegradable, and compostable plastics. The Commission will assess where the use of bio-based feedstock leads to genuine environmental benefits, and not just reduce the use of fossil resources. The assessment is to be completed in 2021 as part of the new circular action plan and setting a criterion for these uses.

Australia and the EU have taken the first steps to ban oxo-degradables, oxo-biodegradable, enzyme mediated and landfill biodegradable products.

Apart from cost and economies of scale as a barrier to mass market adoption of bio-based and biodegradable plastics, proper disposal and end of life management is crucial.

While biodegradable plastics can theoretically shorten the life cycle of plastics and reduce environmental stress, they will not biodegrade when landfilled or left in the environment where conditions are not right.

Without enough oxygen to break them down, they can last for years and release methane, a greenhouse gas 23 times more potent than carbon dioxide.

PLA, one of the most common bio-based plastics, is conditionally biodegradable, requiring industrial composting conditions such as temperatures above 58°C.

Under the right circumstances, microbes can turn the material into carbon dioxide and water within a couple of weeks.

However, if it becomes litter or ends up in seawater, it does not biodegrade at all.

There are limited industrial scale composting facilities resulting in a lack of economies of scale, which provides no incentive for a separate collection stream for biodegradable plastics.

Many of those plastics that look the same as regular plastics end up in mechanical recycling streams. Consumers put them into recycling bins, interfering with, and contaminating batches of recycled plastic and harming the recycling infrastructure.

Bio-based plastics are also not necessarily more sustainable especially when the materials’ life cycle is taken into consideration.

Widespread production of bio-based plastics has fostered an open loop system where new resources are continually required to create new bio-based plastics. This puts a strain on the world’s finite amount of arable land, and even risks competition for agricultural resources.

The environmental impact of certain feedstock sources remains unknown. Plants such as sugar cane require a lot of irrigation and this could intensify water shortages.

Added to this, given the limited production sites of some bio-based feedstocks, the financial and environmental cost of moving material around could potentially outweigh the benefits of using it.

Globally, the infrastructure needed to process biodegradable plastics from collection through to high-temperature composting is still limited at industrial scale.

While bio-based plastics may transition parts of industry away from fossil-based materials, this will be limited due to the scale of supply.  Also brands and consumers must be careful to assess the complete life cycle and consider if they complement other circular alternatives.

Marketing campaigns can exploit misunderstandings or the lack of information in this area. It is important to note that switching from one type of plastic to another does not address the end-of-life management problem which has led to the existing plastic waste pollution crisis.

Insight article by Jia Hui Tan
ICIS Analyst, Plastics Recycling, Asia-Pacific

Additional reporting by Helen McGeough in London and Paula Leardini in Houston


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