Dear Readers, welcome back to my blog! Here's a series of blogs which will take you through my very exciting research which I did in the past year - my Master Thesis! This is the seminal project of the start of my academic career.
If someone asks to say what my thesis is in brief, it would be investigating an alternative method for recycling mixed plastics.
So, what is this alternative method you might ask?
Well. Before we get into the nitty gritty of what is this alternative method. Let's talk about plastics.
Annual global plastic production has reached 367 million tonnes in 2020 (Tiseo, 2021). Plastics consumption is twenty times more than what it was in 1950s, which was when plastics started to really take off. Let's take a moment to think about it. Plastics have become a material of convenience, found in every facet of our lives - mostly but not limited to packaging. Hmm let's see, shampoo, cream, toothpaste, laptops, all vehicles, phones, insulation. They are EVERYWHERE!!! And they are GROWING. So, it's horrible that we still, after over 75 years, don't have a way to dispose of them which doesn't involve dumping them on landfills. Since a majority of the plastic waste management systems around the world can be classified as “Early stage” and “Transitional” (McKinsey, 2018), over 62% of plastics are still landfilled* and only ~6% recycled* and the rest are incinerated. Like think about it. People are struggling to find land TO LIVE and growing crops and we're finding land to dump our garbage.
Now that that's out of the way, let's look at how recycling is done normally.
Normally, plastic is recycled in what is called mechanical recycling. That means plastic is broken down, mechanically, into smaller bits. Now mechanical recycling can be broken down into open loop and closed loop recycling. Closed loop usually takes pure streams of plastics with little to no additives. Think about the large 1.5l bottles you might deposit in a supermarket. Closed loop recycling is the closest to a circular economy because the recycled plastic is a similar quality as virgin plastics made from crude oil. Open loop recycling is done for most of the plastic which is recycled. Here, plastics with dyes and additives are broken down and made into products which are different from its original use. These are usually lower grade items and unlike products from closed loop recycling, can't be recycled repeatedly. So what happens to them? Once they cannot be recycled anymore, they are either burned or landfilled. So there's the problem with recycling. So it's all nice and all that companies are making shoes and clothes out of polyester fibres from recycled PET bottles. But its not like u can recycled those jackets and shoes to make more jackets and shoes.
So how DO we recycle?
Well, that's what I'm trying to investigate.
Small scale pyrolysis reactor I used at Uni
I'm looking at a technology called pyrolysis. See, the basic building blocks of plastic are strings of carbon and hydrogen bonds bound together. Pyrolysis is essentially breaking down plastic in the absence of oxygen in an airtight container so that the chemical bonds of the plastics break apart into smaller stringed molecules. The output of this process is called pyrolysis oil which basically is a concoction of fuel and multitudes of chemicals. We can use catalysts to speed up reactions AND to direct the reaction to get a particular product, like naphtha - which can be used to produce many other chemicals. Michelin for example, are pyrolysing plastic waste to extract chemicals which can be used in tyre making.
See, on a university campus, we generate a lot of plastic waste too. From food packaging to lab waste. My job is to find out what types of plastic waste we have on campus, what sort of fuel and chemicals can we extract from this process and what is the environmental impact of the life cycle of this process. All this to see if there is a potential for Utrecht University to manage its own plastic waste without having to contract an external company.
Now how is this relevant outside of this case?
Let's think.
A Pyrolysis reactor is quite flexible in terms of its scale. You can make a tiny one to fit in a lab and take a few grams of plastic or build a massive plant to take in hundreds of kilograms per hour. Most importantly, plastics can be managed through pyrolysis in a decentralised fashion. Which means, you can set it up in a neighbourhood, in a small remote village or a beach so that you can manage the plastic waste. The most important potential I see is the potential for making a new form of chemical industry around it. Sure, you can make fuel out of it, which might be useful in some contexts. But a truly circular system here will be made if you merge chemical recycling with research and industry in the chemical field. This would allow innovations like what Michelin is doing - making tyres out of pyrolysed plastic waste.
Now I am well aware of the downsides of chemical recycling. Going into this research, I was aware that despite this tech being over 50 years old, there is yet to be a large scale, commercially viable use for chemical recycling. Billions have been pumped into this field with little to show (Rollinson & Oladejo et al., 2018). The main reason being that plastic waste is so messy, as you will see in this diary series. Different plastic give rise to different pyrolysis oil mixes and we still haven't cracked the code to predict what sort of products we can get. What I intend to investigate is the products which we can get from different plastic mixes and the environmental impacts of such a small scale system based at university. This is an exploration into a very contested topic in a time where many European governments and large corporations are touting chemical recycling as the end all, be all for plastics waste management.
Let us see how that turns out shall we?
*based on weighted average
McKinsey report: Plastics Recycling – No time to Waste, 2019, Plastics Europe Conference
Michelin tyre pyrolysis: https://www.michelin.com/en/press-releases/michelin-and-enviro-partner-to-develop-an-innovative-technology-to-transform-used-tires-into-raw-materials/
Rollinson, A., & Oladejo, J. (2020). Chemical recycling: Status, sustainability, and environmental impacts. Global Alliance for Incinerator Alternatives, 1-45
Tiseo, I. (2021). Global plastic production 1950–2020. Statista, September, 20
Cover image source: japantimes.co.jp Creator: TORU HANAI | Credit: REUTERS
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