Plastic Podcast Episode 13: Breaking Down Chemical Recycling with Dr. Julia Vogel
In this episode of Plastic Podcast, host Clark Marchese delves into the intricate world of chemical recycling with Dr. Julia Vogel, a chemical engineer from the German Federal Environmental Agency. They explore the nuances of chemical recycling, its comparison to mechanical recycling, the different methods of chemical recycling and their different outputs, and its potential role in the future of plastics management. This informative discussion breaks down complex recycling methods like pyrolysis, gasification, and solvolysis in a way that's accessible to all listeners.
Episode Guests: Dr. Julia Vogel
More information about Dr. Julia Vogel here
More information about the German Federal Environmental Agency and Chemical Recycling here.
Find Dr. Vogel’s article on chemical recycling here
More information about the episode and the Plastic Podcast
Episode Transcript and more information on the Pine Forest Media Website
Follow Pine Forest Media on Instagram @pineforestmedia
Hosted, produced, written, and edited by Clark Marchese
Cover art and PFM logo by Laurel Wong.
Theme music by Tadeo Cabellos
[00:00:09.920] - Clark
Hello, and welcome back to another episode of Plastic Podcast, the show that tells the science and the story of our relationship with plastic. I am your host, Clark Marchese, and today we are serving Plastic and Chemical Recycling. All right, before we jump into it, we always get started with the trivia question. The question for today is, which of the following is the name of an active volcano on Antarctica. I'm asking you this in honor of Pine Forest Media's latest series, South Pole, all about the science of Antarctica, which can be found wherever you stream your podcasts. Your choices are A, Mount Terror. Yes, that is a real name of a mountain on Antarctica, B, Mount Everest, C, Mount Everest, and D, Mount Murphy. Spotify listeners can answer directly on the episode page of the app, and everyone else can DM me on Instagram at Forrest Media for a chance to win a monthly prize. No cheating, and stick around to the end of the credits to hear the answer to last week's question and a lovely review from one of you. Okay, chemical recycling. That's what we're here for today. I got the chance to speak with Dr Julia Vogel, a chemical engineer working with the Federal Environmental Agency of Germany, also known in German, forgive me in advance, as the Umweltbundesamt.
[00:01:41.180] - Clark
We talked about what chemical recycling is, why we're doing it, and We also did an Are You Smarter Than A Fifth-Grader style, breaking down four different types of chemical recycling and how they work, and whether or not chemical recycling has a role to play in the future of our plastic problems. Now, I've been very curious about this topic ever since I started looking into plastics. One thing to keep in mind, however, when you're listening to this, is that I was a lot smarter at the end than I was at the beginning. This is usually the case when you're talking to an expert, but when I went into this interview, I didn't know as much about chemical recycling as I do now. I approach the topics trying to compare chemical recycling and mechanical recycling, which is the kind that most of us will be familiar with. But in hindsight, I think that wasn't the best way to go about it because they're not meant to compete with each other. You'll learn as go along that they have different intentions, different outcomes, and they're trying to solve different problems. I know that there are places to critique both types of recycling, but if anything, chemical recycling could be used most effectively to supplement mechanical recycling rather than replace it.
[00:02:45.140] - Clark
Okay, now we can go ahead and get started. All right. Hello, Dr. Vogel. Welcome to the show. The first question I have is if you could just introduce yourself and tell us a bit about your research.
[00:03:00.270] - Dr. Julia Vogel
Yeah, sure. I'm Julia Vogel, and I'm focused on work in the area of waste treatment. My main focus are thermal waste treatment processes, and lately, a very big part of that is chemical recycling. We recently finished a big research project that was carried out by the LWTHachen and the University of Mersetburg, and it has the title, Assessment of the Potentials and Evaluation of the Techniques of Thermochemical Plastics Recycling. We always have very long titles, I'm sorry. This research project focused on the evaluation of chemical recycling in terms of energy consumption and greenhouse gas production in comparison to mechanical recycling and energy recovery. The final report will be published very soon.
[00:03:48.360] - Clark
Well, it sounds like there's a lot of stuff in there, so it makes sense that the title is very long. I'm sure that we'll probably break down a lot of those words in there for listeners who might not have a science background, but that sounds like a very interesting project. When exactly is it going to be released?
[00:04:02.260] - Dr. Julia Vogel
Well, it's difficult to say, but I would say in two or three months, it should be available on our website.
[00:04:08.690] - Clark
Okay, well, we will keep an eye on that. Before we get into it, though, I'm just curious. Chemical engineering, that's a choice. When did you decide you wanted to become a chemical engineer?
[00:04:18.530] - Dr. Julia Vogel
Well, already when I finished school, I thought about what to do, and I decided I wanted to do something in relation to the environment as well. Things like the accident in Chernobyl or the so-called forest dying in Germany made very big impressions when I was a kid. I decided to study environmental engineering, and later I got a PhD in chemical engineering.
[00:04:41.610] - Clark
Wow. I can only imagine how much work that must have been. Okay, the This is a topic at hand, chemical recycling of plastics. I had never heard of what this is before I started this podcast. For anyone out there who was like, I was two months ago, what is that?
[00:04:56.980] - Dr. Julia Vogel
Well, first, there is no official definition chemical recycling, but it's widely agreed that it includes technologies like solvolysis, pyrolysis, liquefaction, and gasification. I think we'll go to these later in detail.
[00:05:13.200] - Clark
We sure will.
[00:05:14.540] - Dr. Julia Vogel
In this research project that I mentioned, we worked on a definition that could be used as a legal definition as well. There, we referred to chemical recycling as a process in which the polymers from the plastic are completely or partially broken often down into their components, and these then can be used for other processes in order to produce new polymers or other substances. However, fuel production from these processes is excluded from the term chemical recycling.
[00:05:46.200] - Clark
Okay, well, we're going to break down all of those words into their own polymers and monomers. Let's even start with those words polymer and monomer. A polymer is a chain of molecules, and a monomer can be thought of as one link in that chain. Our DNA is a polymer. The monomers of our DNA, if you can stretch your brain back to high school biology, you might remember the letters A, G, T, C, U. Those represent the different chemicals that make up our DNA. Plastic is also a polymer, at least the vast majority of them, and they're built up of a chain of many, many, many different kinds of chemicals. Also remembering there are many different kinds of plastics, and so the monomer chain will look different for each type. So not a lot of people have heard of chemical recycling. I'm wondering, when did we start using this process? How long has it been around?
[00:06:39.000] - Dr. Julia Vogel
Well, there is no such thing as a concrete discovery day for chemical recycling. The technologies that I mentioned before that are now used for chemical recycling have been known for centuries, but for other products like gasification or pyrolysis for coal or biomass, and even for waste. We've tried that for the last 20, 30, 40 years already. However, it hasn't been too successful, let's say it like this. There were successful projects like a gasification plant in Germany in the late '90s, early 2000s, but it wasn't successful due to the very high costs of the waste treatment that were applied there. I think the term chemical recycling as such appeared sometime before 2020, maybe 2015, 2018, something like that. Then it replaced other names such as feedstock recycling or raw material recycling that were around for a much longer time.
[00:07:37.550] - Clark
Okay, so still relatively recent in the way that we're using it today. Also, it sounds like I might be hearing in there if we were to compare chemical recycling and mechanical recycling based off of sheer amount, it seems like there's a lot less chemical recycling that happens. Is that correct?
[00:07:54.360] - Dr. Julia Vogel
Yes.
[00:07:55.550] - Clark
Maybe I'll also ask you quickly if we chemically recycle other things or just plastic.
[00:08:00.370] - Dr. Julia Vogel
No, we at least prefer if we would use the term chemical recycling only when we talk about plastics recycling.
[00:08:07.810] - Clark
Got it. Okay, so the plastic recycling that most people are familiar with is where you put your coffee cup into the properly-colored bin. If it's one of the lucky 9% of plastics out there, it gets taken somewhere and turned into another coffee cup or something else. Can you tell us how mechanical recycling and chemical recycling are different Mechanical recycling basically is you keep the material as it is.
[00:08:35.440] - Dr. Julia Vogel
So the polymer, plastics are always polymers, or not always, but plastics are polymers, and those are not broken down. Their structure is kept intact, and the material can just be used as plastics again. So basically the old plastic, to say it very simply, is multi and you can form new plastic from it. Whereas chemical recycling really breaks down the polymers, makes it smaller into smaller bits and pieces, and those can be used in general for any new product if you put it in the chemical industry.
[00:09:09.380] - Clark
Okay, so with chemical recycling, you're after the chemicals inside of the plastic. That makes total sense, actually. Wait, should I become a chemical engineer? I'm very much kidding. Anyways, once you have these chemicals, it sounds like you can do whatever you might want with them. They could even be made back into other plastics, but you could also send them off to other industries or sectors that use these chemicals. Do you know what the majority of chemicals that are produced from chemical recycling are used for?
[00:09:36.660] - Dr. Julia Vogel
We have to differentiate between the different types of chemical recycling. I'll start with solvolusis, and that produces the monomers, basically, from the polymers. That can be repolymerized into new plastics. It's basically the building blocks of the plastic polymers that are produced in solvolises. In pyrolysis or something similar, which is called liquefaction, production in an oil bar, they both produce an oil as the main product. And this oil can be used as a substitute for fossil-based oils in the chemical industry. And gasification, as the name already suggests, produces a gas. And this gas also can be used as a raw material for basic chemicals productions.
[00:10:19.630] - Clark
Okay. And then I guess for the oil and gas that is produced, its applications could be so wide-ranging. It's hard to know exactly what they might be used for.
[00:10:28.550] - Dr. Julia Vogel
Exactly. From those, you just use them as an input in the chemical industry where thousands of products are actually produced.
[00:10:36.520] - Clark
Let me ask another question, too, because one of the problems we face with mechanical recycling is that not all plastics can be recycled. Can all types of plastics be chemically recycled?
[00:10:47.490] - Dr. Julia Vogel
No, they can't. First of all, it depends on the type of chemical recycling because there are differences. Not every type of chemical recycling, like solvolices or gasification, can be used for all plastics. As in mechanical recycling, there are problems with very, let's say, dirty input, for example, or very mixed material, also depending on the type of chemical recycling, again.
[00:11:12.690] - Clark
Got it. What about in terms of energy expenditure? Is one type more efficient than the other?
[00:11:18.990] - Dr. Julia Vogel
Well, chemical recycling is much more energy-intensive than mechanical recycling, and therefore, also, greenhouse gas emissions are higher for chemical recycling than for mechanical recycling because it breaks the polymers down. So you start much earlier in this life cycle, basically, of plastics, and you have to go through more steps in order to produce a new plastic.
[00:11:40.440] - Clark
Okay, so more greenhouse gas emissions are generated in the process of chemical recycling, But maybe it's useful to look at the outcome. With chemical recycling, depending on the process, you're basically creating a fossil fuel substitute. So is chemical recycling more energy and greenhouse gas efficient than removing more fossil fuels from on the ground?
[00:12:00.910] - Dr. Julia Vogel
Yes, always. Recycling is always more efficient. However, if you look at, for example, greenhouse gas emissions from those two processes, it gets a bit tricky because you have to look at the whole process, not just the chemical recycling process. Our research project showed that if you use pyrolysis oil instead of raw oil for new plastics, if you just look at the greenhouse gas emissions, they don't defer so much. But in terms of energy efficiency and all the other aspects, Yes. Just substituting a material that you have to extract from nature is obviously much more efficient.
[00:12:37.000] - Clark
How about cost? Is one more expensive than the other?
[00:12:40.570] - Dr. Julia Vogel
That's always very tricky to answer, but in general, I believe that chemical recycling is more expensive because of the type of plants that you need to build.
[00:12:50.560] - Clark
Okay, so let's dig into these different types of methods. We have solvolysis, liquefaction, pyrolysis, gasification. Listeners Guys, don't worry too much. I'm going to be holding your hand through this, and Dr. Vogel is going to be holding mine. But maybe I'll first ask which of these is most commonly used.
[00:13:09.600] - Dr. Julia Vogel
At the moment, liquefaction and non-oil bath and pyrolysis are the ones that are Well, yeah, used the most or looked at the most. Solvolysis is very specialized for certain plastic types, and it's more on a laboratory scale at the moment.
[00:13:26.770] - Clark
I want to understand how each one works. Perhaps you can Try and explain it to me as if I were a fifth grader, because I think that might be where I'll need to start. One by one, how about gasification?
[00:13:37.430] - Dr. Julia Vogel
Okay, well, you chose the most complicated one to start with.
[00:13:42.420] - Clark
Perfect.
[00:13:44.370] - Dr. Julia Vogel
Gasification uses very high temperatures, more than a thousand degrees, in order to decompose the input material, in this case, plastic waste. A gasification agent that is either oxygen or steam normally. From that, a thin pathet gas is produced. This gas contains mainly hydrogen and carbon monoxide, but also methane, carbon carbon dioxide and nitrogen. This can be used then for further processing and cleaning in order to substitute raw material.
[00:14:24.460] - Clark
Okay, gasification, you turn a plastic into a gas. This is going well so far. How about pyrolysis.
[00:14:31.120] - Dr. Julia Vogel
Okay, pyrolysis. I'll start with pyrolysis and liquefaction in an oil bar together because they are similar in terms of their main product. They both produce an oil which is like a hydrocarbon mixture. This, again, has to be purified and then can be used as a raw material and input for the chemical industry. However, the technology itself is different. A pyrolysis reactor is heated and the plastics are decomposed through heat only. There's no oxygen present in this reactor. So pyrolysis works at temperature around 400 to 550 degrees, and it normally results in a gas that contains smaller molecules or parts from the polymers that are broken down. So this gas then can be cooled down and the gas condenses and a liquid, the so-called oil, is then produced. Some parts of the gas remain and can be used for energy recovery for the process itself, and also some solid parts are present that need to be disposed of.
[00:15:42.920] - Clark
Okay, pyro, like fire, heat, into a liquid, oil, liquefaction, also into a liquid, oil. This is clearly not the first time you've had to explain this to someone like me. We've got one more, solvolusis.
[00:15:57.040] - Dr. Julia Vogel
Okay, solvolusis is basically the the decomposition of the polymers into monomers by using a solvent. And that solvent is always specially tailored to the polymer. And here we look at different types of plastics like PET from bottles or polyurethane that is, for example, used in mattresses and stuff like that.
[00:16:22.300] - Clark
So this is the one where the final product can be turned into other conventional plastics.
[00:16:27.440] - Dr. Julia Vogel
Exactly. You get the monomers or building blocks of the plastics, and then you can just polymerize them as you would do when you produce these types of plastics from virgin material.
[00:16:41.080] - Clark
So this next question I'm asking is because I've read a paper of yours that was trying to get to the bottom of this very question, but are these chemical recycling plans that we have economically viable in current market conditions?
[00:16:53.940] - Dr. Julia Vogel
No, not really. The thing is, these types of not state-of-the-art technologies are always associated with a risk when you invest into them because you don't just yet know how the market will be and all those kinds of things. There's a risk, and obviously, they have a very high investment cost as well.
[00:17:19.720] - Clark
Okay, so just to make sure I understand or even to say it in different words, when we say it's not economically viable in current market situations, that means that it is still cheaper for companies to take raw materials from the Earth than it is to fund these plants, perhaps because of the sheer cost or also because the risk that investors do or do not want to take. Is that a good understanding?
[00:17:45.380] - Dr. Julia Vogel
Yes, I think that's perfectly right.
[00:17:47.630] - Clark
Okay. Then are we able to make a prediction as to whether or not these technologies will be able to obtain the necessary funding and investment to make them viable?
[00:17:57.260] - Dr. Julia Vogel
Well, the question is maybe also, do we as a society really want that? For example, if we have legislations that force producers to use recycling material, then we will also enforce any recycling Recycling, really, because then it's not a matter of cost, but the companies have to invest. They only would have to think about which technology they choose. If mechanical recycling is not able to actually reach what we ask as a goal, then they will have to invest into chemical recycling. At the moment, it's difficult to say what will happen because there are also other options where we could go. But a lot of companies are planning to invest into chemical recycling.
[00:18:48.420] - Clark
We mentioned that it is more ecologically costly to take raw fossil fuels from the ground than it is to chemically recycle, but there is a considerable amount of emissions associated with running these I'm wondering if there are any other ecological drawbacks than the greenhouse gas emissions we mentioned?
[00:19:07.140] - Dr. Julia Vogel
Not really. I think it's safe to say that, let's say, under sound environmental management in countries that have a sound system in place, it's very unlikely that it causes any environmental harm. As I said, it's more problematic in terms of CO₂ emissions or energy in general than mechanical recycling, but obviously it produces less CO₂ than incineration of plastic waste.
[00:19:34.820] - Clark
Another thing that the article you've written states is that there's still a need for future research to make final conclusions about the role of chemical recycling in the future. I'm wondering what knowledge gaps do we still have? What research questions do you think still need to be addressed?
[00:19:48.760] - Dr. Julia Vogel
That's a bit tricky, that question. Well, in general, I think we got a bit further with finishing our research project now that I mentioned before, because it shows that chemical recycling really can have a part in a circular economy and could have some positive impact as well, even if we still prefer mechanical recycling wherever possible. I think the questions that are still open are which waste streams are really suitable for chemical recycling and with which technology is it best to treat those waste streams. On the one hand, there are academic questions that can be a part of a research, but also the These questions are probably decided by a market situation or the political framework in the future.
[00:20:36.620] - Clark
Based off of the waste streams that you just mentioned, maybe I should have asked this earlier, but just to clarify, is the waste stream currently different from mechanical recycling, or can you use the same well-sorted, proper plastic type as you would for mechanical recycling as you would for chemical recycling?
[00:20:54.010] - Dr. Julia Vogel
Well, you could use it, but you shouldn't. It should be a stepwise process Basically, first, all the kinds of plastics that could be recycled. Mechanically, it should be recycled there because it's more efficient in all terms, cost energy and emission-wise. All that is not mechanical recyclable. Could or should then go into chemical recycling. But even there, not everything will be recyclable.
[00:21:22.580] - Clark
So this next question, I think based off of the discussion we had, the answer might be obvious, but I'm going to ask it anyway because I think It's important to mention. And it gets to what a lot of plastic researchers are telling me when I speak to them is that we will not recycle our way out of this problem. And they're referring to mechanical recycling. But for someone who's never heard of chemical recycling, we might think, Oh, there's this new state-of-the-art technology. Maybe that's the answer to all of our problems. Is that the case? Is chemical recycling our answer to the global problem of plastic?
[00:21:53.780] - Dr. Julia Vogel
Unfortunately not. The problem is it can be a part of a solution, but it's in general, very problematic to expect that the waste industry at the very end of a life cycle of a plastic product deals with all the problems that have been created before. We have to start much earlier in this, let's say, life cycle of a plastic product. We should really get the producers to take their responsibility in order, for example, to make products that are recyclable or to make producers responsible for the recycling recycling of their products themselves. There are many options to improve the circularity of products. In order to solve our plastic waste problem, we really have to start much earlier and we have to include many more stakeholders than just the waste industry.
[00:22:47.740] - Clark
Yeah, I mean, that tracks with what every other scientist is telling me. So thank you for reinforcing that. As we start to round out this conversation, maybe I'll ask if there's a piece of good news that you can share in your field or Is there something positive to end on?
[00:23:02.560] - Dr. Julia Vogel
I think I can say, and I think that is very positive, that a lot is happening in the waste industry at the moment. And in general, a lot of new things are coming up there. I think this is good news.
[00:23:14.490] - Clark
Okay. Then the final question is, is there anything we missed? What else do we need to mention when it comes to chemical recycling of plastics?
[00:23:21.800] - Dr. Julia Vogel
I don't think we really missed anything. I want to stress that it's much more complicated than introducing some new technologies that will fix everything. You always have to look at the big picture.
[00:23:34.990] - Clark
Okay, I think that's a perfect note to end on. The final question is, where can people find you and follow your work and access this report when it comes out?
[00:23:42.950] - Dr. Julia Vogel
The German Federal Environment Agency has a web page where you can find all our topics. It's very informative, and also all our reports are published there and can be downloaded for free. This is also where our most recent report will be published on chemical recycling. Also, you can have a newsletter or follow us on social media so that you're always on top of what we're doing.
[00:24:08.970] - Clark
Okay. Well, this is the part where I say thank you so much for taking the time to speak with me today. Thank you for teaching me about chemical recycling, and thank you for your really important work in this space.
[00:24:19.450] - Dr. Julia Vogel
Thank you for having me.
[00:24:28.810] - Clark
Okay, a major Thank you to Dr Julia Fugl. I hope you feel like you learned as much listening to her as I did speaking with her. It seems like the future of chemical recycling is unclear for the moment. Of course, we know that recycling, mechanical or chemical, isn't going to be the end-all solution to the plastic problem, but there could be other problems. Fossil fuels are finite, and of course, the fact that they will run out is not the only reason we need to be moving away from them. But it seems like this is a very moving space, so I'll be curious to see if chemical recycling is the direction we decide to move in or not. And I think our brains did enough work for today, so I think I will leave it there. You've been listening to Plastic Podcast. You can find more information about this week's guests and links to their work in the episode description. Cover art for the show was done by Laurel Wong, and the music you're listening to was done by Tadeo Gubejos. I am your host, Clark Marquesi, and this episode was produced, written, and engineered by me.
[00:25:37.030] - Clark
So if you found it interesting, send it to someone you know. Plastic Podcast is part of a larger network of sciencey podcast called Pine Forest Media. You can find more information about us in the episode description or on our website at pineforestpods. Com or on Instagram and TikTok at Pine Forest Media. We've got some exciting sciencey podcast coming out this year and a five-star rating across platforms, and a review on Apple podcast is one of the best things you can do to help the entire network to grow. Thank you to all of you who have made it this far. And today's review comes from Kieran from South Africa who says, Part of what's so nice about the way you've structured it is that it makes me feel really smart in the sense that you've explained it in a way that doesn't make me feel stupid, but it's just the right pitch of making me understand it without babying me. Anyways, it's an enjoyable experience. If you would like your review to be featured on the show, all you've got to do is leave one on Apple podcast and you will probably get picked. Now for the answer to last week's Trivia Question.
[00:26:38.790] - Clark
The answer was Paris, France. Paris was the place where countries from around the world met and agreed to work together to keep emissions from raising global temperatures above 1.5 degrees celsius. And this agreement is thusly named the Paris Agreement. All right, that's all I have for today, and we'll talk soon.
