Podcast: Converting CO2 To Clean Fuel

In this episode, we dive into how MIT researchers have found a new way of efficiently leveraging the abundant carbon dioxide in the atmosphere to create clean, stable fuel capable of addressing Hydrogen’s shortcomings while still offering its core benefits!

EPISODE NOTES

(0:50) - Engineers develop an efficient process to make fuel from carbon dioxide

Transcript

In today's world, we hear a lot of talk around carbon dioxide being the villain, but this team from MIT and Harvard found a way to turn CO2 from the villain into this complex character that might help us solve our clean energy woes. So, if you're interested in that, let's jump right 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. 

Daniel: What's up everyone? Today we're talking about this team from MIT and Harvard that work together, were able to create fuel from carbon dioxide using this really interesting process. In my mind, it's like turning CO2 from the villain into maybe not the hero, but like a really interesting character in the clean energy saga, where we're able to use CO2 as a way to kind of stabilize and make a version of hydrogen fuel that's really stable, really useful, with an awesome shelf life, turning this yucky gas in the air that's been poisoning us and increasing the temperature of our Earth into a clean powder that can sit on a shelf for years, and we can use it to generate electricity whenever we need it. Kind of interesting. I think it's worth jumping into, but.

Farbod: And it's worth mentioning, making CO2 into something that's not bad has been, it's not like a new idea. People have been after this for some time. In fact, our last episode, we also talked about turning CO2 into something useful. And I don't know, out of both of the, you know, that's still fresh in my mind, out of both of the articles that we read, this one has the most potential in my opinion, and I'm excited to jump into it.

Daniel: Yeah, and I think one of the things that's interesting about what we talked about last episode is, if anyone didn't listen to it, or if they need a recap, you can go back and listen if you'd like. But it talked about using the sun to turn CO2 into syngas, which is like a precursor for things like jet fuel and stuff like that. But what we're talking about here is turning CO2 into formate, which is a nontoxic. It's a stable fuel and it doesn't need to be combusted. It's this powder that you can essentially mix with water in a fuel cell and generate electricity. So, in this case, we've got the ability to turn CO2 into something that stores in some ways, electricity, which is a lot more valuable for us when we're talking about electrifying a lot of the world around us. And it's much more meaningful in my mind to have formate with a fuel cell as something as like a backup generator for your house than it is to have a bunch of syngas that you need to process into kerosene and then burn in a generator to turn on the lights in your house. Formate, this product that we're talking about from this team from MIT and Harvard, is actually really, really useful when you are trying to create something that can be used to store and generate electricity.

Farbod: Yeah. Yeah, and I think it's worth mentioning, before we get into formate, what the current form of this carbon capture to turn into something useful has been like for the most part. Yeah. It's usually been like this two-stage process of you capture the carbon dioxide gas and you turn it into something that's solid. It looks like calcium carbonate is the go-to. And then once you have that solidified material, you heat it to drive off the carbon dioxide and convert it to a fuel feedstock like carbon monoxide. Now, the reason that this sucks is because the carbon monoxide, that feedstock, is actually what's leading you to get the fuel that you actually want. And that heating process is super inefficient, which means that you're roughly converting less than 20% of that carbon dioxide into that feedstock, which gives you the source. So, lossy.

Daniel: The big measurement they talk about here, the big metric is carbon efficiency. So how much carbon is being turned from this precursor material into the final fuel that you end up using? In this case, you're saying current state of the art is like 20%.

Farbod: Or less.

Daniel: Or less. That's not optimal. Yeah. Not by any means. And one of the other drawbacks I wanna talk about is every time we try to turn CO2 back into fuel, it generally not just as inefficient, it also ends up producing a fuel that's relatively hard to handle, or it's toxic, or it's flammable. Even syngas, like we talked about in the last episode, at least we've got infrastructure set up to be able to handle that type of gas, but it definitely fits the bill of something that's toxic and flammable. One of the things that we're talking about here though, and this team from MIT and Harvard is trying to achieve is, let's make something that's solid. Let's make something that's stable. Something that's relatively inert until you need to be able to use it again, but it's also still a very viable fuel to be used in a reaction to generate energy in the future. And it seems like they've been able to achieve that.

Farbod: And the cool thing about formate, by the way, is I didn't know this, not the exact composition that they're talking about here, but a form of it is commonly used as a de-icer. So, we're already familiar with what it takes to manufacture it to an extent, how to store it safely. And the fact that it's non-toxic has been proven over a long amount of time. So, it's not like this is a completely new chemical that we have to go through the trials and processes to figure out how bad actually is it for our environment? So that's, that's kind of reassuring to me. Now, do you want to start getting into the sauce or?

Daniel: Yeah, let's talk about their secret sauce, kind of the process of how they're turning carbon dioxide into formate. I think the, the first part of that is a bicarbonate cathode. That's the negative electrode used to handle bicarbonate, which is basically just CO2 dissolved in liquid. And then there's an intermediate buffer layer that helps maintain the right chemical environment for the reaction. Then the secret, secret sauce, I think, is this cation-exchange membrane. It's a selective barrier that only lets certain types of positively charged particles through. And then on the other side, there's a water anode with positive electrode where water split to help drive the reaction. Basically, what they're able to do is first can transform CO2 into liquid metal bicarbonate first and then at that point, they're able to selectively either turn that into potassium or sodium formate using a low carbon electricity source. And I want to dive a little bit more into that low carbon electricity source, but the big important part for everyone to understand here is they're able to turn CO2 into this output material, the only inputs that they need are a little bit of water, a little bit of CO2, and a little bit of electricity, and they're able to get this fuel. They're able to do this process at room temperature, at moderate pressures, so it's pretty safe, pretty energy efficient, and unlike many of the parallels we could draw to hydrogen processing, where everything needs to happen at an extremely low temperature or extremely high pressure, in this case, it seems like at standard room temperature and standard room pressure, we're able to do a lot of this process, which again, it helps, it lends credit towards the fact that we might be able to scale this in the future.

Farbod: Right, right. And you know, it's pretty easy to see now, but they've completely axed that second step of taking your precursor material and having to heat it up, which was super inefficient. Now you have this liquid potassium that, like you mentioned, there's some sort of low carbon energy source that you're going to use to get to your end material. And that's replacing that stage two that was so, so inefficient. Storage, all that good stuff is also a lot more viable for mass manufacturing, which makes it pretty exciting.

Daniel: Yeah. And again, the output here, you get a stable solid fuel that can be stored in a normal steel tank. Not like trying to store hydrogen where we've talked in the past around a lot of the limitations around extreme temperatures, extreme pressures, and over a long period of time, if you're trying to store liquid hydrogen in a pressurized tank, you actually need to let it off gas, otherwise the tank will explode. So, you lose hydrogen if you're trying to store it over a long period of time at room temperature. So that a lot of the challenges we experience with hydrogen which can be used in a very similar manner as formate, using it in a fuel cell, able to use it as a storage method for electricity. In this case, we're able to use formate in a similar manner, has slightly lower energy density than hydrogen, but much more stable, much more convenient, much more scalable because of all these constraints that are gone around temperature and pressure.

Farbod: Yeah. And while we haven't completely moved on from the topic of manufacturing. I think it's worth noting within their sauce, one of the bits that they've incorporated, which allowed them to be more streamlined than any other competition, is the membrane used to convert, during the process to convert from CO2 to the feedstock, the fuel feedstock. They had noticed that in other processes, this would get clogged up with byproducts of the process and it would change the pH. And by changing the pH of the membrane, you would not get the same quality of…

Daniel: You'd lose efficiency basically.

Farbod: You'd lose efficiency, correct. So, they noticed that that was happening and they implemented a change to make sure that the pH was consistent throughout the entire process. So that's, I guess, worth noting because if you're gonna scale, you're gonna be doing this a lot, you don't want any downtime to, you know, maintain that solution over and over again.

Daniel: Well, and I think it's, that's a great segue to talk about some of the statistics of their results, right? So, we talked about, you just talked about this efficiency thing, right? Are we able to operate over a long period of time without efficiency loss? Once they made that tweak to the cation-exchange membrane, they're able to operate for over 200 hours straight without any efficiency loss so that it showed 100% efficiency the whole time suitable for long-term operation. They're saying that this is scalable for you to do at an industrial level. They aren't concerned about the volume that's being processed or the amount of time that it's being processed. That's a really, really encouraging signal for something that you wanna be able to scale to become an industrial process, right? You don't want it to fade off after just a couple of weeks of operation. The other thing I wanted to highlight here is the carbon efficiency. So, we talked about the current state of the art is 20% or less carbon efficiency, this process has over 90% carbon efficiency, meaning 90% of the CO2 is being turned into useful fuel at the end of the day. It's not perfect, but that's a really strong signal there that they're working on something that has gone from 20 to 90% carbon efficiency. I'm sure they can continue to tweak it to get it closer to 95 or 100% efficiency over time.

Farbod: Yeah. I think it's worth talking about the actual fuel that we get out of it as well, right? So, you can get either potassium or sodium formate. We were looking at the actual molecule composition of sodium formate. Essentially, it's a hydrogen molecule bonded by carbon and oxygen. And that's what's giving it the extra stability in comparison to just storing hydrogen. In terms of things that make sense for us in our daily lives, I think the best example is something like a hydrogen fuel cell car. It seems very promising. It's very energy dense. But the problems that we've seen in the real world is that the transportation and storage of that liquid hydrogen is making it very difficult to scale this up rapidly. And as you store it in these tanks, the hydrogen starts to leak apparently at a rate of 1% per day. What you're seeing with this sodium formate is that it's not as energy dense. However, it's solid. So that means you can actually have more of it within the fuel cell than you would of the liquid and it is incredibly stable. It can stay in any normal steel tank for, I think you mentioned already, but like years, decades. And we have a lot of experience handling it, transporting it, storing it. So, there's that added level of safety as well.

Daniel: Yeah, I mean, and the shelf life is something that's really encouraging versus hydrogen, right? This 1% loss every day versus being pretty much 100% over weeks and years and months, et cetera. I do want to highlight what you said around energy density, right? Basically, it's a more stable packaged version of hydrogen. The hydrogen bond there is still the one that we're being used, still exploiting to either store or then later release energy. It's not great, the energy density here, because you've got basically dead weight of CO2 versus just hydrogen molecules, but I think we get a lot of convenience out of the dry powder. We get a lot of convenience out of the fact that it's a stable fuel and it doesn't need extreme temperature or pressure to be able to maintain it. So, one of the things that I think about separately from cars is like powering homes. In my home, it doesn't really matter to me how much a tank of fuel weighs. It's not actively impacting the efficiency of my home the way that it does in a car, you know, payload in a car costs a lot in terms of energy efficiency, in terms of fuel consumption. Payload in the house basically doesn't exist. I don't care if you put 100,000 pound brick in the corner, as long as it doesn't take up too much space. So, I see a potential future here using Formate as a fuel source for things like backup generators or maybe even local generators replacing the grid as a storage method for electricity that's being generated from renewable energy sources. The way that I think about it is like, if I had a wind turbine at my factory and the wind's not always blowing, but when it is, I wanna be able to store that electricity. Instead of storing that electricity in a battery or something that degrades over time or needs to be replaced, you could use Formate as an energy storage method. And as the turbines generate electricity, you're able to power this formate reaction, generate formate, and then you've got this stable inert dry powder. And when you want to use the electricity, you want to consume it, you just mix this with water inside a formate fuel cell, and then that generates electricity. So, think about a factory with a bunch of wind turbines, you're not actively using the wind turbines to keep the lights on. You need some sort of energy storage method. You could use formate as the replacement for lithium ion batteries or whatever it is that people are using for energy storage. And in this case, it becomes pretty much a carbon neutral exchange. You're taking carbon dioxide from the atmosphere to store the energy. And then when you're done consuming the energy, you release the carbon dioxide back. It's not the greatest solution. It's not completely sequestering carbon. But what it is doing is it's just borrowing carbon dioxide from the atmosphere and then putting it back. It's not contributing to additional carbon dioxide in the atmosphere.

Farbod: And like this entire process, there's two bits where you're gonna need energy input, right? You need it for converting the carbon dioxide in the atmosphere to the liquid metal bicarbonate. And that's when the article mentioned you can use low carbon fuel sources like energy sources, like solar, nuclear, or wind. That's what you were talking about. The next stage is drying that out. And they mentioned you could just utilize the sun, just kind of leave out the material to use it as the precursor for the potassium or the sodium. I'm blanking. Sodium.

Daniel: Formate.

Farbod: Formate, there it is. And both, like you said, if you're not in a rush for like how you want to handle your energy sources at a plant or at your home or whatever, they seem pretty doable. Like you have passive solar coming in. Battery probably doesn't make sense, at least not yet, because of how much it costs, and the capacity, and the degradation, and the recycling of it, the net environmental impact, yada, yada, yada. This could be a potential in-between approach that's feasible to store, burn, and just put the same carbon back into the atmosphere.

Daniel: Yeah, and like I said, this isn't turning CO2 from the villain into the hero, but it turns CO2 from the villain to this complex character that is a healthy, happy medium that is useful to us and is not further damaging the atmosphere and the environment as it has been to date. I think it's pretty compelling and like you said, out of most of the recent episodes, discussions we've been having around how do we make CO2 useful to us, this seems like one of the most promising out of any of the ones we've spoken to date.

Farbod: Yeah. And I’m pretty excited about hydrogen’s future and I see this as a good first step of making it widely available to get hydrogen fuel cells kind of going.

Daniel: Yeah, I agree. Yeah. All right, so before we wrap up, I want to do a quick recap.

Farbod: Yes.

Daniel: I'll try and run us through what we covered today. So here goes.

Farbod: Shoot.

Daniel: Imagine you can take carbon dioxide, this yucky gas that's in the air, been causing trouble for our planet for hundreds of years, and turn it into a special clean powder that can sit on a shelf for years. Later, whenever you need it, you can mix it with water and it creates energy to power homes or whole buildings. And it doesn't make the air any more dirty than it was before. It's net carbon neutral. So, this team from MIT and Harvard, these engineers have worked together, figured out a smart way to make this happen using some clean electricity and some clever science tricks. And essentially here, the fuel that we're talking about is we're able to turn CO2 into formate fuel. And that's what's being able to be used to generate electricity to power our homes, etc.

Farbod: Money. You got it.

Daniel: Thanks, dude.

Farbod: I'm always here for support. But yeah, I think I think that's the episode.

Daniel: Yeah, let's let's wrap it up here.

Farbod: All right, everyone. Thank you so much for listening. As always, we'll catch you in the next one.

Daniel: Peace.

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The Next Byte: We're two engineers on a mission to simplify complex science & technology, making it easy to understand. In each episode of our show, we dive into world-changing tech (such as AI, robotics, 3D printing, IoT, & much more), all while keeping it entertaining & engaging along the way.