Coal Combustion is Increasing the Environmental Plastic Footprint


Livia Cabernard from ETH Zurich recently spoke to AZoCleantech to highlight the impacts of plastics on our environment and how coal combustion is increasing this footprint across the world.

How did you begin your research into the environmental footprint of plastics?

When I started my PhD thesis at ETH Zurich, my research focus was to analyze the supply chain of the Swiss gold trade, as Switzerland refines two-thirds of global gold. The origin of this gold is often critical. In this context, my first step was to develop a methodology to map global supply chains.

In the next step, we applied that method to assess the environmental impacts of global material, food and fuel production in the Global Resource Outlook 2019 of the United Nations.

Finally, I realized that the results are particularly interesting for the environmental footprint of plastics so I decided to dive deeper into this topic. I had a particular interest in the environmental effects of plastics as it was already a research focus in my master thesis – but from a different perspective: I focused on the pollution of microplastics in the environment. In this context, I have spent six months on an island in the North Sea called Helgoland to analyze the fate of small microplastics considered harmful to the environment and human health due to their mobility and ecotoxicity.

The carbon and particulate-matter-related health footprint of plastics has doubled since 1995. What is the cause of this and what effect does it have on our environment?

On the one hand, there has been an increase in the global demand for plastics – and thus the related environmental footprints. A key driver of the rising demand was the growing infrastructure in emerging economies. For example, plastics-related carbon footprints of China’s transportation, Indonesia’s electronics industry, and India’s construction sector have increased more than 50-fold since 1995.

On the other hand, the global market for plastics has become increasingly supplied with plastics produced in coal-based economies, such as China, Indonesia, and South Africa. This means that the energy to produce plastics – which is a highly energy-intensive process – has become increasingly supplied with coal, which causes climate and health impacts due to greenhouse gas and particulate matter emissions. By looking at the entire global plastics supply chain, we also found that high-income regions, such as the EU and USA, have contributed to the growing environmental footprint of plastics by outsourcing their plastics production to coal-based economies. This means that high-income regions increasingly consume plastics produced in coal-based economies (e.g.,  plastics embodied in electronics, machinery etc.). Consequently, plastics are responsible for 4.5% of global climate impacts. The vast majority (95%) of the climate and particulate-matter-related health footprint of plastics are related to the production stage (mainly coal combustion for electricity and heat supply).

How are coal-based emissions related to plastics-related carbon and particulate matter?

Due to the growth and shift of plastics production to coal-based economies, the energy to produce plastics is increasingly supplied with coal.

Image Credit: I. Noyan Yilmaz/Shutterstock.com

A total of 6% of global coal electricity is used for plastics production nowadays. The combustion of coal, either as electricity or heat to produce plastics, releases many greenhouse gas and particulate matter emissions. While greenhouse gas emissions from plastic production affect global climate change, particulate-matter emissions lead to local health impacts when inhaled due to respiratory issues.

What can be done to prevent this huge footprint on our environment?

We should reuse and recycle plastics to reduce primary plastics production, and strengthen efforts for a circular economy. However, a general ban on plastics is counter-productive as alternative materials often have higher environmental impacts. For example, if the plastics embodied in a car are replaced with steel, there is a higher climate impact, and additional weight during driving increases direct greenhouse gas emissions. Moreover, our study highlights the particularly strong leverage in the plastics production chain itself to reduce the climate and health footprint of plastics. Efficient measures include phasing out coal, transitioning to renewables and improving the energy efficiency in the plastics production process. As shown in our study for the past and future, decreasing the emissions in high-income regions as specified in the Paris Agreement is not sufficient. Such an approach even fosters a shift of plastics production to emerging regions with less-stringent environmental policies and limited economic power to implement state-of-the-art low-carbon technology. It is important that high-income regions invest in clean energy production throughout the supply chain. With regard to particulate-matter-related health impacts in India, Indonesia, and other Asian countries, the installation of advanced flue gas treatment could substantially reduce local health impacts due to plastic production.

Why are renewable energy investments throughout the plastics value chain vital for sustainable production and consumption of plastics?

We found that the vast majority (>95%) of the climate and particulate-matter-related health footprint of plastics is attributed to the production stage, mostly due to the supply of energy by coal (either electricity or heat), while the end-of-life stages such as incineration of plastics contribute to a minor fraction (<5%). Another striking result was that even twice as much fossil carbon is combusted as fuel for plastics production than contained as feedstock in plastics.

This means that the major issue is currently the energy supply for plastics production and not the feedstock. In this context, we also found that in a scenario where all plastics produced in 2015 were incinerated, this would increase the annual carbon footprint of plastics by 19% (subtracting credits from energy recovery). While the GHG emissions of plastics incineration are commonly known, our results show that even in a worst-case scenario in which all plastics were combusted, the major share of GHG emissions would still occur in the production phase due to energy supply (mostly coal energy). These are all reasons why the investment in renewable energy has such strong leverage to reduce both the climate particulate-matter-related health footprint of plastics.

What do you believe the future holds for global plastic demand?

I assume that the demand for plastics is increasing. Even if measures to avoid some plastics (e.g., one-way use bags in food stores) are implemented, the effect is small, as plastics find so many applications where it is hardly replaceable (and as mentioned above by the example of the car, substitution of plastics with other materials can result in even higher environmental impacts). Also, the current potential to recycle plastics is limited. One issue is the versatility of plastics, which makes it difficult to produce secondary plastics with the same functions as primary plastics. Another issue is the accumulation of harmful chemicals in plastics during the recycling process, which is a particular issue for plastics used in food packaging.

If global demand for plastics is only increasing, how is it possible for us to ensure we are not intensifying the impacts on the environment and human health? What key strategies must be considered to reduce the devastating effects the plastics industry has?

As discussed above, switching to clean energy is an efficient measure to reduce climate and particulate-matter-related health impacts during primary plastics production. In this context, it is important that high-income regions invest in clean energy production throughout the supply chain. Also, we should avoid, reuse and recycle plastics wherever possible to reduce primary plastics production and foster efforts toward a circular economy. To increase recycling rates, the product design needs to be improved with regard to more uniform plastics, as current recycling rates are also limited by the versatility of plastics. Concerning plastic waste in the environment, proper end-of-life treatment is critical. This requires the construction of recycling and incineration plants, especially in emerging economies (e.g., China, Indonesia, Vietnam, Philippines), where currently a lot of plastics ends up in the environment due to improper landfilling. Just recently, the UN Environment Assembly approved a plan for a legally binding treaty to reduce the environmental impacts of plastics, which is an important step in this direction.

Do you have any further research you are able to discuss?

Last October, I have finalized my PhD thesis entitled “Creating transparency in global value chains and their environmental impacts to support sustainability policies”. My thesis includes several case studies at the global and national scales to illustrate the potential of an improved method and database to map global supply chains. Besides the case study on plastics, the most recent case study was on resource use within the Group of 20 (G20). In this study, we found that nowadays, even half of global coal is used by the G20’s metals and construction material industry, mostly steel and cement produced in China. Similar to plastics, major drivers include China’s rising infrastructure and exports of metals embodied in machinery, transport, and electronics, while high-income regions such as the EU and USA contributed by their increasing reliance on coal-intensive metals produced in China. Also, our results underline the G20’s importance of switching to renewable energy, avoiding high-impact materials (e.g., cement and steel by sustainably sourced wood in construction), and improved supply chain management.

Where can readers find more information?

Brief video where I explain my research by the case study on plastics: https://www.youtube.com/watch?v=Bc9MJDCbe7c

Article on “Growing environmental footprint of plastics driven by coal combustion” https://doi.org/10.1038/s41893-021-00807-2

Study on “Limited utilization options for secondary plastics may restrict their circularity”: https://doi.org/10.1016/j.wasman.2022.01.002

Study on chemicals in plastics: https://pubs.acs.org/doi/10.1021/acs.est.1c00976

UN news on UNEA treaty to end plastics pollution: https://news.un.org/en/story/2022/03/1113142

My PhD thesis on “Creating transparency in global value chains and their environmental impacts to support sustainability policies”: https://doi.org/10.3929/ethz-b-000532983

Article on “Sustainability assessment of the G20’s supply chains of materials, fuels, and food”: https://doi.org/10.1088/1748-9326/ac52c7

Software tool and Database for mapping environmental impacts of global supply chains:

Software tool: http://dx.doi.org/10.17632/nddmgkm3cc.4

Database: https://zenodo.org/record/3993659#.YkmP_i-22Cc

UN Global Resource Outlook 2019, Chapter 3 on “Environmental impacts of Natural Resource Use”: https://doi.org/10.18356/64c3b469-en

About Livia Cabernard

I have been working as a post-doctoral researcher at the Institute of Environmental Engineering at ETH Zurich since 2021My research focuses on the improved sustainability assessment of global supply chains, particularly in the metals industry, the future bioeconomy, and with regard to the energy transition.

My goal is to bridge the information gap from the local scale of resource extraction to the international scale of processing, manufacturing, and final consumption while addressing the key environmental issues listed by the UN agenda. In my interdisciplinary research, I explore action to design more sustainable supply chains and final products to provide decision support for industry and policy.

I have completed my PhD studies at the Institute of Environmental Engineering and the Institute of Science, Technology and Policy at ETH ZurichIn my thesis, I focused on “Creating transparency in global value chains and their environmental impacts to support sustainability policies” and demonstrated the practical relevance through case studies at global and national scales, including the metal and building materials industry, food and agricultural systems, and global plastics production. My work has been published in Nature journals and reports of the European Commission Knowledge Centre for Bioeconomy, the United Nations Environment Program, and the International Resource Panel, including requests upon the G20 presidency.

My findings have been included in the UNEA guidelines, cited by the Swiss Federal Council, and achieved high media coverage. My work also supports industry and policy through the open-​source software and database that I created for improved sustainability assessment of global supply chains.

I also studied Environmental Sciences at ETH Zurich with a Major in Biochemical Cycles and Pollutant Dynamics. During my studies, I had a particular interest in microplastics research. For my master thesis, I spent six months at the Alfred Wegener Institute in Helgoland (Germany) to optimize an automated method based on Raman spectroscopy for microplastics analysis in the North Sea. As an intern at the Cantonal Office for the Environment (AWEL), I implemented a procedure to quantify microplastics in surface and sewage waters of Zurich. 

Disclaimer: The views expressed here are those of the interviewee and do not necessarily represent the views of AZoM.com Limited (T/A) AZoNetwork, the owner and operator of this website. This disclaimer forms part of the Terms and Conditions of use of this website.

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