Li Shen: We should ensure the sustainability of bio-based products before they hit the market
With the way things are currently set up, biodegradable plastic is often not broken down like it should be. Why does this happen, and what can we do about it?
Dr Li Shen is an assistant professor at the Copernicus Institute of Sustainable Development at Utrecht University. In this interview she tells us about her work towards achieving a sustainable bio-based economy.
Firstly, how is a bio-based economy different from the current fossil fuel economy?
In a fossil fuel economy, substances like gasoline, fuel oil, diesel, naphtha and kerosene are converted to energy, chemical products and materials. With a biobased economy its biological substances such as wood, sugars, vegetable oil and natural fibres that serve as the raw materials. We are in the process of transitioning away from this fossil fuel economy to an economy that is at least partly bio-based.
A lot of your work is on bio-based plastics. What’s the story here?
As we transition to a carbon-neutral economy, we need replacements for plastics made from fossil fuels. Bio-based plastics - plastics derived from renewable biological resources, have been a major focus of innovation of the last few decades. But despite leaps in innovation, transitioning to bio-based plastics is not necessarily straightforward or sustainable. My work looks at how we can indeed do this sustainably.
Innovators don’t think about waste management during the process of innovation, so we end up with bio-based plastics not suited to what we have
How is the transition to bio-based plastics challenging?
Bioplastics are completely different to fossil fuel-based plastics in the way they are produced, used, and disposed of. Our infrastructure is only geared up to traditional plastics. Innovators don’t think about waste management during the process of innovation, so we end up with bio-based plastics not suited to what we have.
Do you have an example of how this can be a problem?
In the Educatorium here at Utrecht Science Park we have single use cups made from polylactic acid (PLA), a transparent bio-based and biodegradable plastic made from corn or sugarcane. Research by a group of my students showed that despite being certified biodegradable, these cups are not actually able to degrade in Dutch industrial composting facilities.
Biodegradable plastic cups that are not biodegradable! How is this possible?
PLA degrades in a controlled environment, needing a specific temperature, amount of time and moisture. The norm says that 90% will degrade under these conditions within six months, but in Dutch industrial composting facilities organic waste is only treated for two to three weeks. As is often the case, there has been no thought into waste management during the process of innovation. We’re left with a product that is potentially sustainable, but will end up in the environment - not too different than with a fossil-fuel-based plastic.
How could we get around this problem and make sure “biodegradable” items like these plastic cups are a sustainable alternative?
In my work I collaborate with the developers of novel materials and processes to assess the sustainability of novel technologies when they are still in the development stage, before they even reach the market. The idea is that the products come to the market that are either suited to the waste management infrastructure we already have, or that we are able to adapt our infrastructure to enough in advance.
I collaborate with the developers of novel materials and processes to assess the sustainability of novel technologies when they are still in the development stage, before they even reach the market.
But companies are not obliged to think about waste management of their products. How will we see lasting change?
We need good governance across countries, the EU, and the whole world. Sustainability solutions don’t only come from innovation. Legislation often reacts very slowly - at the moment it’s only damage control. The legislation around bio-based products like bio-plastics should be in place before they start causing a problem - we really need to push this. As with climate change, we’re acting too late.
Further reading
Corona, B., Shen, L., Reike, D., Rosales Carreon, J. & Worrell, E. (2019). Towards sustainable development through the circular economy - A review and critical assessment on current circularity metrics. Resources, Conservation and Recycling, 151.
Broeren, M.L.M., Zijp, M.C., Waaijers-van der Loop, S.L., Heugens, E.H.W., Posthuma, L., Worrell, E. & Shen, L. (2017). Environmental assessment of bio-based chemicals in early-stage development - A review of methods and indicators. Biofuels, Bioproducts and Biorefining, 11(4), 701-718.
Shen, L., Worrell, E. & Patel, M.K. (2010). Present and future development in plastics from biomass. Biofuels, Bioproducts and Biorefining, 4(1), 25-40.
Shen, L., Worrell, E. & Patel, M.K. (2010). Open-loop recycling: A LCA case study of PET bottle-to-fibre recycling. Resources, Conservation and Recycling, 55(1), 34-52.