Podcast: Burning Paper Bags For Sustainability

author avatar
Podcast: Burning Paper Bags For Sustainability

In this episode, we discuss how Penn state researchers accidentally discovered that heat treatment of paper bags could make them stronger - especially when wet - thereby increasing their reusability significantly.

In this episode, we discuss how Penn state researchers accidentally discovered that heat treatment of paper bags could make them stronger - especially when wet - thereby increasing their reusability significantly. They also demonstrated impressive biofuel extraction potential with their approach making the product’s life cycle useful and environmentally sustainable.   

This podcast is sponsored by Mouser Electronics.     

(3:20) - Stronger paper bags, reused repeatedly then recycled for biofuel could be future🛍♻️

This episode was brought to you by Mouser, our favorite place to get electronics parts for any project, whether it be a hobby at home or a prototype for work. Click HERE to check out the step by step guide on creating your own garden monitor/manager!


What's going on, folks? Welcome back to the NextByte Podcast. Hey, did you know that the US throws away 100 billion plastic bags every year? Well, if you want to figure out how we can potentially solve that problem, then buckle up because this one is the episode for you. Let's get into it.

I'm Daniel, and I'm Farbod. And this is the NextByte Podcast. Every week, we explore interesting and impactful tech and engineering content from Wevolver.com and deliver it to you in bite sized episodes that are easy to understand, regardless of your background.

Farbod: All right, folks, today's episode is very environmentally focused. So, it makes complete sense that we're going to start off by talking about our sponsor, Mouser Electronics. You guys know we love Mouser. They are one of the world's biggest electronics suppliers. And that really comes into play here because they wrote this article. You guys know we love sharing like Mouser's technical resources. Well, they really knocked out of the park with this one. They're writing about how Arduino, it's this super small microcontroller that you can adapt to any kind of project you want. But in this specific resource that they made, they walk you step by step on how you can leverage this technology for managing your own garden. And that really resonates with me on multiple fronts. One, there's this hobbyist electronics engineering aspect that I love.

Daniel: We're makers. We love making.

Farbod: Exactly. And they share like the code. They share like the hardware configuration, the 3D printed files that you can use to print your own housing and stuff like that. But then there's the concept of managing your own garden and making sure the amount of sunlight you're getting, the moisture levels yields the most crops. That's just interesting in general. But as a somewhat new homeowner who wants to set up his own little garden for tomatoes and stuff, that really scratches an inch for me. And at the same time, again, we're talking about the environmental side of things, making sure that you're getting the most out of the environmental resources you're using in your own home. What could be better? This is a hat trick of interest for me.

Daniel: I'm with you, man. Along those lines, the ability to create or to grow better food more efficiently at a lower cost in your own backyard is sweet. And it's made better by the fact that they give you the full blueprint on how to do the whole thing. They give you the bill of materials, step -by -step instructions, all the associated technical information. Like we said, we're both makers and Mouser knows that. And Mouser loves makers. I think they're a bunch of makers too. And it's like a perfect harmony.

Farbod: Absolutely. And again, that's one of the cool things about Mouser because they’re one of the world’s biggest electronics suppliers, they know what kind of tools are in the market. So, if you want to develop a certain project, they probably know what's going to work best for you with a specific budget, with specific outcomes, et cetera, et cetera. So, it's really cool that they kind of provided a little taster, a little sample of what that looks like, what their knowledge looks like when put in action with this technical resource. And yeah, I don't know. I had a lot of fun reading it, we’re going to link in the show notes. Folks, if you’re interested in gardening, if you’re interested in doing a quick weekend project. You should definitely check this out.

Daniel: Yeah, I'm with it, man. And what, what do you do with your produce, right? Like you go to the store, you're buying your produce. What do you put it in?

Farbod: You put it in a paper bag. We put it in a paper bag. Well, if you're environmentally conscious, you put it in a paper bag, right? We got to clarify that.

Daniel: That's the case, right? So today we're talking about stronger paper bags and the kind of overarching premise here. It's a research coming out of Penn State. We've got like a strong team working on this from a cross -functional area. So, we've got professors that are in the agricultural and biological engineering school. We've got Jaya Tripathi, who's a doctoral degree candidate in bio-renewable systems, as well as a teaching professor of chemistry. So, we've got chemistry, bio-renewable systems, agricultural and biological engineering, all coming together to work on paper bags. To me, it sounds like a lot of firepower to work on something that's not that important. But when we look at the big picture here, it's actually really impactful. So as a world, we're trying to use less plastic, especially single -use plastic bags. Those are the things that have been demonized as public enemy number one, right? I mean, a lot of local legislations stuff like that, they charge you now if you want to use aplastic bag to try and encourage reuse of bags or some places you go like Trader Joe's, you can only use a paper bag. So according to the UN environmental program, 5 trillion plastic bags are produced worldwide annually. It takes over 1000 years for each of those bags to disintegrate completely. They wreak havoc on the environment. Americans throw away 100 billion bags annually. All those end up in landfills or in the ocean. That's equivalent to dumping nearly 12 million barrels of crude oil into the ocean or into the landfills. So, the alternative we've often had for these awful, evil plastic bags is paper bags, right? They sound great. But the problem is they're not very strong when they're wet. I don't know if you've ever used a paper bag. It's like really frustrating for me whenever I go to Trader Joe's and it's raining because if I didn't bring my reusable bag, I know it's going to rain. The paper bag is going to get wet. It's going to rip out the bottom. My food's going to fall. Like it's a known outcome and it sucks.

Farbod: Absolutely. And like one of the things that this article pointed out about these paper bags is for them to negate the environmental impact of their production because everything has a cost. They would have to be used more than once. And in a lot of cases, we only use paper bags once because again, like you're saying, if it gets wet, you don't really have a use for it anyways. It's just going to tear away. So, you use it, you get it from the grocery shop, you come in and then like what I use it for is my recycling. I put all my cans and stuff in there and then I just throw it out. That's the end of the story. I don't think about it twice. I don't ever look at a paper bag and go, oh, I can take that with me shopping again. And that way I can save like, I don't know, four or five, six more paper bag usages. So, with that in mind, like the solution is kind of like clear in terms of not using plastic bags, right? Like if you're going to do something else, paper is better. So then can we make paper stronger? And technically you can. You can chemically process this thing, hence the involvement of chemistry people in this research effort. But if you do that, then you start introducing elements like actual materials into the paper bag that is environmentally dangerous. Like it can't degrade as quickly as if it was just paper, right? Like you can add coatings and stuff like that to it, but then you kind of start getting the worst of both worlds. You're kind of getting something reusable, but it's not as reasonable as a plastic bag, but it still has plastic. So, it's going to take a long time to degrade. It's really not a win. So, like, what can you do? Can you really just take this standalone product and just make it inherently better? So, spoiler, yeah, you can. And that's what these folks cracked. And the coolest thing to me, like we love a good story. This was a total accident. You mentioned earlier, one of the lead researchers of this paper, Jaya Tripathi, was actually working on biofuels. Like making paper bag stronger was not really top of the mind. And there's this process of, I had never heard about it before. It's very like unique and niche, I guess, Torrification. Like we've talked about carbonization before, and it's something Daniel, you and I have a lot of experience with given, you know, I don't know how many years ago I graduated at this point, four years ago, we worked on graphene research together. Carbonization is the process of carbonizing something. Basically, you get rid of all the other organic materials that you're just left with carbon. Now, carbonization happens at above 400 degrees by heat processing something. Torrification is kind of the same process. It's pyrolysis. So, heating something without oxygen, but it happens in the two to 300 degrees Celsius range. Now, the reason I think this is important is because Torrification is usually used for making organic materials more dense. So, you get a more carbon dense end product.

Daniel: It cooks off the water. It cooks off the volatile organic compounds. What you're left with is like, they usually use it as like pre -processing for creating like biomass fuels, right? They're trying to concentrate down to just the organic solids in there so they can go create fuel out of it. Exactly. One note there, I've never heard about it before researching for this episode as well but I think it's pronounced torrefaction, not Torrification.

Farbod: Oh my God. Torrefaction? I think I mistyped it. I think I mistyped it. Does it not have the F -I -C -A -T -I -O -N? I think it's torrefaction, dude. English is my second language. Torrefaction it is. That works. I took ESL. That's cool. But yeah, so torrefaction, that was the main goal here. They were trying to understand like, can we use like paper bags to get biofuel out of it? And understanding that the tensile strength of this increase was just like a complete accident. It was like, oh, shoot. Like I was just trying to make this more, again, like energy dense. I didn't really care about tensile strength, but this is actually stronger. And so that's something they started investigating. And they did some experiments to see like just how much better it could get when wet. By the way, something else I forgot to mention. When you go through the process of torrefaction, you make the material hydrophobic. So that's where I think the light bulb kind of went off and they're like, ooh, what if we like wet this thing? Does the tensile strength still hold? And it does. So, they ran these experiments where they were like, let's go through the process at different temperatures and see what the increase in tensile strength is, in comparison to our baseline which is no torrefaction processing. And they saw increases at a minimum of 557% all the way up to almost 2300%.

Daniel: Yeah. So, they made paper bags almost like 22 times stronger when they're wet. Just figuring this out on accident, right? Doing torrefaction to try and use paper bags as like biomass fuel. They accidentally discovered that they can increase the paper's wet tensile strength up to 22 .3 times. That's incredible. The challenge there then being post torrefaction, they were like, all right, let's cool. Let's test this for the biofuel production. Like we originally intended the paper actually showed a lower glucose yield than before they had treated it. So, they're like, man, what's going on here? Like, can we solve this problem? Because what they want is like these two headed approach, where one, the paper bags are stronger to where we can use them and reuse them well, like utilize them during their first life to get everything we can out of it to reduce our impact on the environment. And then the second life here is where you break this down and turn it into biofuel that can be combusted in an engine or something like that. So, they made the first life a lot less stronger. And then it compromised the second life. And they figured out that by treating the paper post torrefaction with a sodium hydroxide solution, this helped increase the glucose yield. And for me, I was like, okay, cool. What does glucose yield mean? Why is it important to the second life? The second life being we want to break this paper down. We want to turn it into a fuel that we can use for energy. Glucose yield matters because cellulose, this is paper, the paper fibers. You wash this with acid and enzymes that breaks the cellulose down into simple sugars, that's glucose. Those simple sugars can then be fermented. Think about the way that we produce alcohol. You can ferment these sugars. And in this case, we're trying to produce ethanol, which is a type of sugar alcohol that ethanol is distilled and then can be used as a combustible fuel. So, what they're doing here is they're trying to figure out how to turn paper into sugar. And they’re going to turn that sugar into fuel. So, what they did is they used a sodium hydroxide treatment on this paper after torrefaction. So, after they made it much stronger, they also were able to treat it with this corrosive alkali treatment. And it increased the glucose yield from 69% post torrefaction originally to as much as 93%. So basically 93 % of the paper fibers that they put into this biomass fuel creation process, 93 % of those paper fibers were turned into sugar by mass, making it a much better source for biofuel production. And again, I was like, cool, 93%. Is that great? Is that not that good? Like what's the context? Yeah. Compared to the industry standard for office paper or for newspaper, office paper gets an 82% yield, newspaper gets an average 17% yield. So basically, what they're saying here is they've created a paper bag that's 22 times stronger when it's wet than it used to be. And they also created this, you know, the same bag, the paper, the way that they've treated it is actually better at becoming biofuel than your normal office paper or your normal newspaper. So, they've kind of created a super paper bag here. And then takes me back to the beginning of the episode when I was like, seems like a really high-powered team to be just working on something as simple as paper bags. Now you can see what they did here. They turned paper bags from like this, this menial thing that we use sometimes and we get pissed when it rips in the rain to this thing that's 22 times stronger and is better at generating fuel than all the other papers sitting on your desk or sitting in your home. To me, it's like, dude, this is incredible.

Farbod: This, I think you hit the nail on the head earlier when you were talking about how it's a two headed approach, right? Like the original goal of this research that they were doing was like, how do we make good biofuel out of paper bags? And then they were like, oh shoot, like this is getting kind of stronger. Can we like optimize for that as well? And instead of compromising, they just went like optimize both during use life cycle and then after use life cycle, right? So then now while you're using it, you can get more use out of it because it's stronger. And then once you're done using it, you can get more value out of it as an energy source, which is just such a total win. Now I was curious again, because Torrefaction, I had not heard about it before, ever. So, I wanted to dig into it more and see like, what's the downside? You know, like, it seems like such a good solution. I'm just wondering like, why hasn't it just taken off? And it's, it's this common downfall of all these amazing things that we see in material science and like really every industry, and it all comes down to production. So, when you want to like do mass manufacturing, that's where you start to run into process. Interestingly enough, it's not like a capital issue. And it's not a potential issue like this. There's potential in it. It's actually pretty affordable. But when you think about processing these things at scale, one of the big problems is that with the Torrefaction process, the output isn't just a product, it's the product and all the other volatile compounds that you're trying to get rid of, the gasses that you cooked off. And those gases include carbon monoxide, carbon dioxide. So, people have been trying to figure out like, what is the best solution here with this volatile gas that now we have available to us? And a very logical answer is, let's just use it as the heat source again. Like, let's just keep burning it to process more material. And that's a great idea. But remember, Torrefaction is a version of pyrolysis, which means little to no oxygen needs to be in the chamber as this is like reacting. So, to actually burn off that excess gas, you need to introduce more air. And if you use too much air, then you combust all the material instead of Torrefacting it. I think that's the word. Which isn't really useful. So, then other companies, other startups over the past two decades, apparently, have been trying to solve this problem. And they've come up with some really novel solutions, like taking these gases into heat exchangers, cycling them, and then trying to like, when it builds over time, then trying to burn it slowly. But what's really unfortunate is that as these gases cycle, condensation can happen, and they can turn into oils that stick on every surface, which will result in like required maintenance, like you might be able to process this stuff for a couple hours, and then you have to shut everything down, and then get someone to like scrub inside of there, and then resume processing again, which just does not scale well, it doesn't make financial sense, it doesn't make, you know, probably sense on the energy side, either with the amount of effort you're putting in. So that that's been the limiting factor. And that's interesting to me, because it seems like everything that's related to the actual product is resolved. But the processing end is where we're getting caught up.

Daniel: That's like, that's super keen that you dove into that. I wouldn't have thought to go there. Where my head was after all this is like, all right, let's go back to the big picture, right? We want our bags to be convenient, we want them to be strong, but we also don't want them to have a poor impact on the environment. So, that the original goal here is nice, like let's make a strong paper bag. Let's also make a bag that at the end of its life, once it ripped, or once it's been used a couple times, and you know, people are limiting their waste by reusing things, we've got the ability to turn this into biofuel instead of just like littering it and putting in the ground or whatever. Right. Both of those sound better on the paper, like one call, you know, one tick in the column for the paper bag versus plastic bags. But then it brings me back to what we talked about the very beginning, which was like a paper bag already must be reused several times to reduce its global warming potential to below that of the condensed, the conventional high -density polyethylene bag. So, on the littering front, paper bags are obviously better right off the bat. But if you're talking about global warming, potential emissions, etcetera, if you're going to use it only once, plastic bags are actually better for the air, for the atmosphere, than paper bags are. And one of the concerns that this brought me, and I haven't done the math to figure it out, right? You're talking about pyrolysis or torrefaction. You know, they’re baking the paper for these paper bags at 392 to 500 degrees Fahrenheit for an extended period of time. That is also, in my mind, a lot of energy required to generate an oven that's that hot to do the processing. I wonder how much extra global warming potential there is or carbon, green, you know, greenhouse gas emissions during that torrefaction process, you know, just even to create the energy to burn the oven that hot. How many more times would I need to use this paper bag to cancel out its global warming potential? I'm not sure. It's just another question I would love to consider as the big picture of this, because we do a lot of greenwashing in today's society where we say, you know, the paper bag is better because, you know, a sea turtle won't eat it and think it's a jellyfish. Well, that's great. Good for the sea turtle. But if you're only using the paper bag once, you're actually putting more carbon in the atmosphere than you were if you're using plastic bags. So, is there a way for us to consider the holistic impact here? I think one of the things that you mentioned in the torrefaction process is really interesting, right? We basically can't figure out what to do with this waste. It's a nightmare to figure out what to do with the waste from the torrefaction process. I'm not sure about the energy associated with the processing. That being said, if we're able to address two of those and there's some data to prove, like, yes, if you're, you know, this makes it the paper bag strong enough that you can use it 10 times. And because you can use it 10 times, it actually cancels out all the greenhouse gas emissions as if you were going to use 10 paper bags because they break a lot. Or, you know what, we actually figured out a way to sustainably dispose of the waste gas from the torrefaction process. Once we get that full picture analyzed, and I'm sure it's something that, you know, this team can do, and I think it's really interesting, Jaya Tripathi is going on to a career after finishing the, you know, I think it's a PhD degree. Like going into industry to try and solve problems like this. I think this is a really important key in understanding that is like, yes, you made an awesome innovation up front. I'm a huge fan. Honestly, I'm a huge fan. Can we look at the whole picture and understand, like, is this going to impact the way that we renewably interact with the planet? And I think no one's better than them. Coming out of their PhD in bio-renewable systems to figure out the problem.

Farbod: Yeah. And that's not something I had thought of, but that's a really good point. And again, just to reiterate, we're both like, we're interested in this. And the reason we're bringing these questions up is because we're also interested in the problems themselves. When I dug into this and saw the manufacturing site, I'm like, how do we solve it? We've been stuck on this for a while. What's the silver bullet here? And that's what you're saying is when you see someone that worked on this research and proved out its benefits, and now they're moving on to industry, that's where I'm really getting excited. Someone taking this knowledge from academia and seeing how do we make this something that actually solves the real-world problem. Now, I have one more thing that I wanted to talk about in terms of potential negatives with this technology. They really harped on the tensile strength increase throughout the paper, which is great because when you put stuff in a paper bag, you're holding it straight, stuff is pushing it down straight. It's awesome. But I am wondering, does the sheer strength get compromised whatsoever as you start, not carbonizing, because again, carbonization happens at a higher temperature, but you're getting rid of more of the stuff that, and then you're getting left with more carbon. Carbon is a typically more fragile material. And now that the other components are getting kind of cooked off, I’m wondering does that play factor in terms of how reusable that bag is going to be, like getting crumpled here and there, maybe it's susceptible to tears from the side now.

Daniel: Yeah. Is it more brittle? I don't know. That's an interesting question. And I think what you're right. Like the wet tensile strength is just one part of the picture in the material strength equation.

Farbod: You know, I'm the kind of person that hates doing more than one trip. So, I end up loading stuff on my arm and I'm swinging around. Does that mean like one wrong swing? And then my yogurt is going to splatter over the floor. I don't know. Just thought I put that out there, something I was thinking about.

Daniel: Oh, that's interesting. Yeah. Would you mind like giving us a succinct explain like I'm five or too long didn't read summary of what we talked about today?

Farbod: Absolutely. Well, I'm going to try my best. How about that? All right. So, we're going to start of by talking about the big plastic bag problem, we produce 5 trillion plastic bags every single year, and it takes about a thousand years for those bags to decompose. So that's a big problem. In the U S alone, we're using about a hundred billion bags every year, which is the equivalent of dumping 12 million barrels of oil. That's crazy. So, paper bags have been a great alternative, but unfortunately, we need to use them actually quite more than once for it to be like worthwhile, the manufacturing energy and the environmental damage that goes into developing it. So, if we could do something that allows us to use it more than once, it'd be great. Chemically processing it, unfortunately makes it more environmentally damaging. So still not great. What can we do? Well, this amazing team at Penn State has looked into this process of Torrefaction, which is essentially heat processing the paper bag to make it much stronger when wet, which is the big problem with paper bags. In fact, in some of the research that they ran, the strength can increase anywhere from 550% to almost 2300%, which is crazy. So, this is kind of paving the way towards a future where we can have much stronger paper bags that we can use more than once instead of getting it once from Trader Joe's and then using it as a recycling bin. But there are some problems as of right now, torrefaction when it comes to manufacturing, it's been difficult to scale up and we need to consider the amount of in. But what's amazing is that these folks are actually putting a lot of resources into figuring out not just what it takes to discover something like this, but down the road, how do we scale it and how do we make it a possibility so that we can all benefit from it? How do I do?

Daniel: Is your name the hammer? Cause you just nailed it.

Farbod: I mean, I don't know if you want to make that a nickname, I'm all for it.

Daniel: I don't know. You have to earn that one, buddy.

Farbod: You can't just tease me like that and take it away. That's so unfair, but you know what? I'll earn it. All right. I think that's a good spot to end the episode on. We've been negligent on giving out shout outs, right? We owe a couple of shout outs. I think we were trending in Canada, right? Yeah. We were trending in Germany, I believe. What am I missing?

Daniel: I think top 150 in both of those countries. Top 150. We cracked the top 100 in Azerbaijan again.

Farbod: I mean, you guys leave us speechless every time. What am I going to say? Thank you. It's just, it's not sufficient, you know? But if you want to connect with us on Twitter, TikTok, Instagram, Email, and we could personally thank you by, I don't know, if you got suggestions for episodes, we could talk about it. If you want to tell us how you're liking the episodes or how much you're hating it or what you think about our intro song, because Dan really seems to hate it, definitely do that, you know?

Daniel: We're not like these really unapproachable, inaccessible voices in the sky that speak to you through your headphones. We're real people. We love to interact with everyone. We love to see that this is a community, not just an audience. And we love being a part of this community and interacting with everyone. So why don't you reach out to us? We're on pretty much every single platform you could imagine.

Farbod: We've enjoyed that. You can send us smoke signals and we'll pick it up. We'll try our best. We really will. We really will. All right. And on that note, thank you so much for listening. And as always, we'll catch you in the next one.

Daniel: Peace.


That's all for today The NextByte Podcast is produced by Wevolver, and to learn more about the topics with discussed today visit Wevolver.com.

If you enjoyed this episode, please review and subscribe, via Apple podcasts Spotify or one of your favorite platforms. I'm Farbod and I'm Daniel. Thank you for listening and we'll see you in the next episode.

As always, you can find these and other interesting & impactful engineering articles on Wevolver.com.

To learn more about this show, please visit our shows page. By following the page, you will get automatic updates by email when a new show is published. Be sure to give us a follow and review on Apple podcasts, Spotify, and most of your favorite podcast platforms!


The Next Byte Newsletter

Fuel your tech-savvy curiosity with “byte” sized digests of tech breakthroughs.