Podcast: Solar Fuel Reactor Generates Energy Out of Thin Air

In this episode, we discuss a novel approach from ETH Zurich to remove a design bottleneck from solar reactors that enables power generation output that is 2X the current state of the art!

This podcast is sponsored by Mouser Electronics. 

(3:00) - 3D printed reactor core makes solar fuel production more efficient

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 learn more about how 3D printing will play a role in the next manufacturing revolution!

Transcript

When you think about solar energy, I bet the first thing that comes to your mind is solar panels. Well, folks, I'm here to tell you that solar reactors might actually be a pretty good in-between step until we can get solar panels at scale. If you're interested, if I got you curious, then buckle up and let's jump 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 we're talking about solar reactors. But before we jump into today's episode, let's talk about today's sponsor, Mouser Electronics. Now, you guys know Mouser, we love Mouser. They're one of the world's biggest electronic suppliers. And just given the nature of their business, they're actually very in touch with the different advancements that we're seeing in academia and industry. And therefore, they write articles about these things, they're called Mouser's technical resources. So, we're gonna talk about one of them today, specifically, it's about additive manufacturing. Hint hint, it gives us a little insight about what we're gonna be talking about today. You know, little teaser. But in this article, they're talking about how additive is gonna be a huge portion of the next industrial revolution. They talk about how Henry Ford, you know, we had the assembly line and that was a whole feat in itself, but now we're having additive manufacturing, it's making it more customizable. In some cases, for prototyping, it's even faster to get your prototype instantly with a 3D printer than ever before. And how, again, it's just going to revolutionize what manufacturing is. And what I think is relevant to today's episode is not only do you get the prototyping benefits, but you also get more complex designs now.

Daniel: That's what I was going to mention is there's a portion of manufacturing where traditional manufacturing tools, methods, et cetera, can't get you a complex geometry without having to split multiple parts and combine them together or spend a lot of money, having something being machined in a very specific manner. 3d printing allows for people to manufacture these complex geometries with a different method that actually turns a lot of things that used to not be feasible using other methods. When you use additive, you actually can make this new geometry. And I think that that's kind of what leads into our secret sauce of what we're talking about later today too.

Farbod: Absolutely. And to extend what you just said not only do we get these incredibly complex geometries now with additive manufacturing, as the technology has progressed, we're even getting more and more precision out of it. So that's quite nice when you're doing high precision engineering for let's say automotive or energy harvesting or solar fuel production. And what a great segue into today's article. Like we teased quite a bit, we're talking about solar reactors today. Specifically, this is an effort that's coming out of ETH Zurich. I feel like before we jump to anything, we got to talk about solar reactors. Yeah. Right. So as the name implies, you have solar, which is, you know, from the sun, and you're doing some sort of reaction typically for energy. In this case, the way that human beings have been utilizing this resource is by taking a solar, like basically mirrors intensifying the solar energy on some sort of reactor. And then taking energy, I mean molecules from the surrounding like carbon dioxide and water from the air, and then using it to come up with some sort of a fuel precursor. Now this approach is typically referred to as a net zero carbon, because you're gonna pull in carbon from the atmosphere, you're gonna make some sort of fuel, and then once that fuel burns, it's gonna release the exact same carbon back into the atmosphere, which you can, I mean, I think of it as something positive, right? Because carbon dioxide's just hanging on the air, kind of a negative, you know, this looming menace that we're trying to get rid of. And now you're able to sequester it into something that's actually useful. Yes, eventually it's going to go back out again, but at least you can start cycling it through instead of emitting more and more and more out there.

Daniel: Yeah. And generally speaking, here, when we use these solar reactors, the goal is to create this fuel precursor called syngas. When we were doing our research for this episode, we found out that syngas is actually used as a precursor for pretty much all types of fuels. So, when you're burning coal, and trying to turn it into petroleum to put in your car or you're taking natural gas and trying to turn it into petroleum for your car, something like that, right. Oil, et cetera, all these precursor fossil fuel materials. Almost all of them, when you're trying to make a fuel that you can use for aviation, for automotive, et cetera, at one point it becomes syngas. So, syngas is a mix of, I think it's carbon monoxide and hydrogen. And this mixed fuel syngas, it's short for synthetic gas. That's where we're able to create things like kerosene, et cetera, other useful fuels. The thing that I thought is interesting in this part here is like, we're able to use solar reactors to create the syngas material, which is already known, there's already an infrastructure set up to be able to turn syngas into useful fuels. So, they're not trying to create a whole new value chain. They're not trying to create a whole new economy around this new material. All they're doing is using the sun to create one of these precursor materials that the rest of the fuel industry is already built to use. So instead of sourcing our syngas from fossil fuels, we're gonna be sourcing our syngas from the air. Which again, like you said, carbon neutral versus adding more carbon to the atmosphere. It's definitely a step in the right direction.

Farbod: Yeah, no, I agree. But like as I was reading it, it's another one of those instances where you like this sounds too good to be true, why isn't a thing already? Yeah. Well, it turns out that there's like some design limitations here specifically like, we talked about the reactor a core portion of this reactor is this like ceramic structure that's funneling the solar energy to actually get the chemical process going. And this thing is they refer to it as an isotropic porous structure. Isotropic means it's like uniform all around. Porous, it's got a bunch of holes in it. Those holes are what's directing the sunlight in. Now the downfall of the structure is that, these pores whose job is to direct the sunlight in as the sunlight is traveling, they exponentially attenuate the solar radiation, which means that as it travels through the pores, you lose more and more of the solar energy. The more of the energy that you lose, the less of that energy is able to be converted into a higher temperature. The lower the temperature, the lower the overall yields of that syngas precursor that you're trying to go for via this chemical reaction. In general, what it means is that the core limiting factor here is that that ceramic structure is losing energy and not utilizing everything that's available to it.

Daniel: And because we want high temperatures, because we want a high energy reaction, if there were a way to optimize the design and the micro and macro structure of that core. And this is where, spoiler, this is where 3D printing comes in, but having the ability to fine tune both the micro structure and the macro structure of that core. In theory, and then we'll show that in reality, they also tested this as well, but in theory, it gives us the ability to perform this reaction at a much higher temperature with much higher energy, with much higher yields. It turns the solar reactor thing from something that works well in experiments and works well on paper into something that actually might produce a yield that's worthwhile of someone exploring in the real world and implementing in industry.

Farbod: Correct, yeah. So, let's get into the sauce. That's like our favorite part of every episode. And this sauce is no different. But what I love about this is that it really shows the first principles thinking that makes projects like this so successful. You mentioned it, if we can somehow resolve that limitation with the ceramic, it would make this process more viable for generating fuel. How did they go about it? Well, they said, let's just completely ditch this isotropic pore structure. That's been the norm in the industry. And it kind of makes sense when you first think about it, right? You're trying to focus all this solar energy, it would make sense to have a structure that can capture it from any angle that's coming in. They said, no, no, no, let's completely get rid of that and let's do a hierarchical porous channel, which like, I'm gonna try to explain it, chime in if I'm not explaining it the right way. But the visual I want you guys to think about is instead of holes everywhere, you have big holes at the opening that get progressively smaller and smaller and smaller as it gets to the back of the reactor. The idea there, as I understand it, is when you had these pores everywhere, you could have a lot of loss as the solar radiation is bouncing around with these hierarchical channels, you get to actually trap it more and more and more as the solar radiation is traveling down, which means you're not worried about loss as much as you were before, which means higher temperatures, which means you get more yield out of the entire process to begin with. That seems kind of, I don't know, straightforward, I guess, but it took some thinking to get into that. And again, they went against the norms and I thought that was pretty cool.

Daniel: And I think the challenge there is around not just being able to design something like that. I think just about anyone could design something like that. Again, knowing the first principles, knowing the constraints of the problem, knowing the solution that they're going for. But the challenge has been around manufacturing something that can do that effectively and that that's where additive comes in, right? Cause we've got the ability to use additive manufacturing to create something that is not only got this really, really high dimensional rigor, you can trust the dimensions that you print with 3D printing down to the fraction of a millimeter to make sure that these pores are the right size and make sure that the overall geometry is correct. But now we've got the ability to 3D print with some awesome materials as well, such as the ceramic here that they use in this case. We've got the ability to 3D print with materials with a little bit of post-processing, turn it into something that can withstand super high temperatures, not just like your dinky plastic 3d printing that sits on your desk. This is like using real high temperature, high pressure, like space grade alloy materials and you can 30 print them on your own.

Farbod: Yeah, yeah. And the team, to accomplish that, they have like a little sub-sauce to their main sauce where they're like, we have to create the structure. 3D printing is the approach because we can get that complex geometry out. But now we have to find the material to use here. And because this is like such a unique, I don't know, use case, they actually had to come up with the material of their own. And they generated this like specific ink that has I think it's serum oxide. That's what the original porous structures were completely made out of. It's a ceramic mixed in with a very low viscous liquid and that's what's getting printed as they extruded out line by line to make this entire structure. That serum oxide makes it so that as it's going through this intensive process of generating that syngas, it is very stable in instances of oxidation. So, the structure can be reused over and over again without worrying about reliability.

Daniel: I think that's awesome and I love that they were able to incorporate, you know, as someone who used to work at a 3D printing company, right, be able to incorporate in the material that you're using, that you're 3D printing with, incorporate the industry standard materials like cerium oxide. And as a part of that, also I think it's valuable for us to talk about the results here. Yeah. Right? So, they were able to 3D print this core that is in theory able to more efficiently produce solar fuel. They had these, remember this hierarchically channeled architecture to help direct sunlight more efficiently. What did it do, right? Was it 10% better or was it 20% better?

Farbod: It was twice, twice better. Like the yield that they got out of it was twice as high as the current best leading designs under the exact same conditions. Like this isn't like a baby step forward. This is a one giant leap in terms of solar generators. Yeah, or solar reactors, excuse me.

Daniel: No, I agree. And I think obviously seeing double the fuel production is a strong indicator I think on the podcast here, we can't tell you for sure whether something's going to make it out into the real world or not and actually impact your life but we can give you some signals that let you know, hey, this is a strong signal that this might make it out into the real world and might actually impact your life. One of them being the fact that this is just so impactful in terms of the previous industry standard, right? Being able to double fuel production compared to previous designs with the same sunlight concentration, all other things controlled their course twice as efficient, that's awesome. In addition to that, another signal that I want to say is like showing us that this might make it out in the real world, they've already patented this technology and they've already licensed it out to a company. To me that suggests that there's a path toward commercialization which is exciting.

Farbod: Absolutely!

Daniel: We always talk about on the podcast, but our pet peeve is when awesome technology sits on the shelf because no one thought to commercialize it. And make it, you know, bring it out to the world where it can make a real impact. This is a really strong sign here that this is already planned to be commercialized and industrialized to impact the rest of the world.

Farbod: Yeah. And to add a little bit more confidence boost there, one of the two companies that are, let me scratch that, there are two companies that are going after this technology for like further development and releasing it worldwide. Both of them are ETH Zurich spin-offs. That means folks that were at ETH Zurich saw this and they were like, this has so much potential that like I just can't keep staying here and researching anything else, I need to go and pursue this full time. And those two companies are Climeworks and Synhelion. I'm hoping I'm not butchering that name. But I think Climeworks is the one that officially got the license to start manufacturing these.

Daniel: Well, and I think it's super interesting, right? So, we talked about as more of the “so what” here to try and lend some significance to this. We know that it's twice as good at creating syngas, right? Syngas is as an example, one of the precursor materials for creating aviation fuel. We've talked a lot about sustainable aviation here in the podcast. This is one of the ways where we could get to a net carbon neutral aviation industry where we're able to pull carbon dioxide out of the atmosphere and then turn it into aviation fuel via syngas using this reactor. I think that this is a really, you know, just one example of where this could be useful but definitely a really interesting application of this technology because we've talked for many episodes around how it's really challenging to get renewable energy into the aviation sector. Hydrogen technology is just not quite ready yet. Battery technology doesn't quite make sense for most aviation impacts. Like this is one potential implementation where I could see it making a difference starting tomorrow.

Farbod: Yeah, without having to change pretty much anything else in the supply chain besides the fuel source.

Daniel: Yeah, and you can use existing airplanes. You don't have to change what fuel you're burning. You just change the source of the fuel, like you're saying, and be able to limit the impacts of aviation on our environment, which is, I think, outsized impacts for aviation based, you know, versus other industries.

Farbod: It's a win-win. It's rare to see those, but this is actually a win-win. Yeah. All right, so before we wrap it up, quick summary of what we just talked about. Solar reactors have been a hot topic for a while. Essentially, you use solar energy concentrated to a reactor, pulling resources from the atmosphere. I'm talking CO2 and water to get a precursor for a lot of gases. I'm talking like jet fuel, like kerosene, the fuel that goes into your car. Now the downside has been that these things have generally not been super-efficient because of these porous structures that are required to direct the sunlight in. Well, these folks at ETH Zurich, they were like, you know what, we're gonna turn this upside down, completely different than the norm. We're gonna do a hierarchical approach where we go from big holes at the top to progressively smaller and smaller as it gets to the reactor. What that means is that you can completely concentrate the solar energy, not let any of it escape, and get twice the yield that you normally can. All this to say that solar reactors are becoming more and more viable, and as a proof, there's two spin-offs from ET Zurich that are gonna pursue this full-time.

Daniel: Good, nailed it.

Farbod: Yeah, I try, what can I say? I do it for the fans. Now, I wanna give shout-outs to fans for all the support they've given us. We're getting closer and closer to January, which is always a great time because it means that another The Next Byte anniversary is coming up. We have some really fun things in the works for you guys. Hoping to release some teasers of that later this month, so please stay tuned. And in the meantime, feedback, questions, concerns, love, hate, anything you got, direct it our way at The Next Byte on Wevolver email, or Twitter, or X, I don't know what to call it anymore. TikTok, Instagram, smoke signals.

Daniel: Yeah, @NextBytePodcast on pretty much every social platform, thenextbyte@wevolver.com for email.

Farbod: For email, right.

Daniel: Hit us with your feedback. Again, it's an important time of year for us because we start thinking about, wow, we've been doing this for this many years. But also, any day of the week, any time of the year, if you've got feedback for us, we try to be receptive to it. And obviously it's a big part of why we keep doing what we're doing, the community that we're doing this with. And one of the ways that you can help leave an impact on the product that we deliver every single week is by giving us feedback, letting us know what we can do better or letting us know what we already do well and we can do more of. We appreciate hearing from everyone and obviously it encourages us to keep going and keep doing what we're doing.

Farbod: Definitely. Thanks for rocking with us. And as always, we'll catch you in the next one.

Daniel: Peace.

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

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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.