There is a temptation to believe that science and technology will save us from climate change, while we continue business as usual. But we have already emitted huge levels of CO2 into the atmosphere, and it’s going to take both carbon capture at the source and direct air capture (DAC) from ambient air to make a dent in the record atmospheric concentration of 415ppm we hit in 2019.
Dr. Jennifer Wilcox is the James H. Manning Chaired Professor of Chemical Engineering at Worcester Polytechnic Institute and the author of the first textbook on carbon capture. Today, Dr. Wilcox joins Ross and Christophe to discuss the distinction between carbon capture in general and direct air capture specifically and explain why we need both strategies to succeed in reversing climate change.
Dr. Wilcox goes on to describe the two leading DAC technologies, solvents and solid sorbents, sharing how we might decide where to build plants and what tech to use in a given situation. Listen in for Dr. Wilcox’s insight on conducting a techno-economic assessment on systems that have yet to be deployed and learn how you can get involved in the ongoing advancement of carbon management.
Resources:
‘Cost Analysis of Carbon Capture and Sequestration of Process Emissions from the US Industrial Sector’ in Environmental Science & Technology
‘Cost Analysis of Carbon Capture and Sequestration from US Natural Gas-Fired Power Plants’ in Environmental Science & Technology
‘Cost Analysis of Direct Air Capture and Sequestration Coupled to Low-Carbon Thermal Energy in the United States’ in Environmental Science & Technology
American Physical Society 2011 Report
Lenfest Center for Sustainable Energy
Full Transcript
Ross Kenyon: Hey everyone! Welcome to Season 2 of Reversing Climate Change. We are doing that podcast thing now and launching a Patreon. You can find it at patreon. com slash noripodcasts. There are various tiers with different types of goodies available. Do you want to receive a special newsletter digest of what norinauts are reading that week? Be a part of a nori book club? Get special access to nori events? Go take a look at patreon. com slash noripodcasts for what we’re offering. And in that spirit of being lean in that startup kind of way that, you know, we like to do, this list of goodies is subject to change and we’d very much like your feedback.
Is there something that you’d really like to see but it isn’t listed here? Honest feedback does a lot to help us shape what we offer to you. You can send an email to podcast. nori. com or fill out our podcast survey anonymously in our newsletter which you can find at nori. com slash subscribe. And thank you so much for listening to another season of Reversing Climate Change. Hello and welcome to the Reversing Climate Change Podcast. I’m Ross Kenyon. I am here with Christophe Jospe. You’re back. It’s good to have you back because we’re doing a deep dive on direct air capture today.
I needed backup. We’re talking about LCAs, Lifecycle Assessment. So we have the distinct pleasure of having Dr. Jen Wilcox, Professor of Chemical Engineering at Worcester Polytechnic Institute. And thank you for instructing me how to say it. Yeah, thanks. Thanks for being here. Jen also wrote the first textbook on carbon capture. So yeah, Jen, you are a direct air capture celebrity. Thank you for being here.
Dr. Jen Wilcox: Excited to be here. Thanks for having me.
Ross Kenyon: Yeah, it’s a lot of fun for us to be able to dig into these things because we never do nearly enough direct air capture shows. And there’s certainly a lot to talk about. It’s been getting more and more attention. But as Christoph likes to say, we like to start with people’s stories. So what was the path that got you to speaking about DAC on a TED stage? How did your life align to get you to that point?
Dr. Jen Wilcox: Well, I actually didn’t know I was going to be speaking on direct air capture at TED. I was invited by science curator David Biello. It was just before Christmas time in 2017. And he asked me to speak on carbon capture. And that was 2017. I wrote my textbook on 2012. I’d been studying direct air capture for, you know, probably since 2008, 2009. In my textbook, I purposely have a thread of direct air capture throughout to understand the difficulties in doing direct air capture compared to more concentrated sources. When I was asked to speak at TED on carbon capture, I said yes.
It felt like a Christmas gift coming just in time for Christmas to be able to like Share this knowledge that I had in this topic that I wrote a book on to a broader audience. And so I wrote my speech and then I delivered it practice and I guess it was in February in front of others ahead of, I think it’s in April when the actual event was in Vancouver. At that practice, the group was like, that’s not what we’re asking you to talk about. Because I talked about all carbon capture.
I talked about avoiding carbon emissions in the first place, which is just a lot easier to do than waiting until it gets into the atmosphere and it’s so dilute and then you have to actually separate it out of the atmosphere. And how we just need to really do a lot of deep decarbonization ahead of that. And so in that moment, I was like, wait a minute. You know, I realized in real time in February during my practice that I was really being asked to talk about direct air capture, not carbon capture.
And to me, it was, I said, you know, at that time and still, I’m pretty critical about the comparison of the two because one is just cheaper and easier to do than the other. And we’re not doing it at the scale we need to. And so at first, I was not excited to do a TED Talk on direct air capture. And I explained that. And I said, well, I’m not going to get up there and tell you that this is something that’s easy to do. And they said, well, that’s why we’re asking you to do it.
Because it’s not easy and we get it. And that’s not what we want. That’s not what we want to hear. We want to talk about why it’s difficult. What makes it difficult? What makes it expensive? And yet, why do we need to do this? Why is this so important? And why does it have to be part of the portfolio? And so that night, I wrote my talk. I didn’t sleep. I stayed up all night and redid my entire presentation. And the next morning gave it to David Biello and he was like, wow, that was fast.
And so that was what I ended up presenting at TED was that because that was something that I thought about a lot, you know, the challenges and the difficulty. And so then it became very easy for me at that point to do this.
Ross Kenyon: Your comments are interesting because we also, as supportive as we try to be of direct air capture, many of us have roots or it was the thing that caught our attention about carbon removal and climate change as being a possibility to solve this in some sort of discrete way. Why is direct air capture so subject to magical thinking or a sort of wild euphoria? That being said, soil also has a lot of wild euphoria. Is this just carbon removal in general is the realm of euphoria? Yeah.
Dr. Jen Wilcox: I’ve heard people say, hey, can technology and science save us? And the answer is no. But there is this temptation, I think, to think that it could. And something like direct air capture means that, hey, let’s build, and I don’t like the term machines, but let’s build these chemical plants and take carbon out of the atmosphere and maybe there’s a perspective that allows us to keep doing what we’re doing, irresponsibly burning fossil fuels 24-7 to pull it back out. And so there’s, I’m sure, a perspective that thinks, well, hey, that sounds pretty good because we don’t have to change, you know, and that sounds pretty easy.
But that’s probably where the magical thinking might come is just the temptation to think that we don’t have to work. That we can just rely on science and technology to solve the problems that we’ve got ourselves into because of need for energy, I suppose. But that’s where I come in. I think in my work, you know, how much land does it take? Can you really build one of these plants anywhere? No. But people like to say that. You know, there are a lot of benefits compared to some of the other strategies.
But we need so much avoided carbon. We need now so much carbon removal that not one of these technologies is able to do it on its own. And so direct air capture is going to be part of the portfolio. It’s gotten some excitement and interest because it’s like, hey, we can build it. And now we can get ourselves out of this mess. But it’s important to understand what it takes to build it.
Christophe Jospe: So, Jen, I love where you’re going. And I also love to geek out on some of the more philosophical questions on deep decarbonization or carbon management. But before going there, I think it would be useful for our listeners to get some definitions so we’re all on the same page. You’ve mentioned now carbon capture, direct air capture. What are the difference between the two? How do they work theoretically? What are we even talking about here?
Dr. Jen Wilcox: Sure. So I’ll start by saying, you know, when I first got into this field about, you know, 2008, 2009, something like the carving capture in general, it was, you know, we kind of think carving captures in 1. 0. And thinking about it, where would you even do carbon capture? A decade ago, I would say we do it everywhere we possibly can. And what does that mean, carbon capture? It means retrofitting a power plant. It means retrofitting a cement plant, an iron and steel facility, so that you’re avoiding the emissions of CO2 in the atmosphere to begin with.
And so carbon capture kind of 1. 0 is like thinking about where are all of the streams in which CO2 is born, right? And before we allow it to get into the atmosphere, into its very dilute state, let’s try and capture it before we allow it to get there. Avoid its emissions to start. And from a chemical engineering perspective, it’s easier to do that just from an energy perspective because the CO2 is more concentrated. And those sources, once it gets into the atmosphere, it’s 100, 300 times more dilute. And so carbon capture is really just thinking about retrofitting existing facilities where we actually combust fossil fuels.
Or use fossil fuels in a process, like even in cement production, it’s a combination of fossil fuels, but also calcining carbonate that we mine out of the earth to chemically produce CO2. And so it’s like all of those sources of CO2 being able to have a chemical process, a separation process that you build, that you retrofit onto those plants so that the CO2 never gets into the atmosphere. Whereas direct air capture is, we’ve been emitting CO2 since the start of the Industrial Revolution. The natural systems like the oceans and the terrestrial biosphere uptake roughly half of that every year.
But in the absence of those natural sinks, it’s been steadily accumulating the other half in the atmosphere. And we’re at a point... Where deep decarbonization is no longer enough to meet our climate goals, so now we don’t have a choice and we have to take it back out of the atmosphere. And that’s a different separation process. That’s direct air capture because we’re pulling the CO2 out of the atmosphere rather than avoiding it from going into the atmosphere to begin with. And that’s a much more difficult problem.
Christophe Jospe: And the question of scale immediately comes up too, because when you’re looking at some of the plants you described, whether it’s a power plant or a cement plant, steal quite a bit of CO2, right? Whereas direct air capture, And I’m really glad we’ve got a chemical engineer on the Because it brings me back to this concept, and I’m sure you’ve come across of it as Sherwood’s rule, right? Where Sherwood came and said costs tend to scale linearly with dilution, meaning if you have something at 4% or 12% concentration, it’s a lot easier than 0.
04%, which is about the concentration of CO2 in the atmosphere. Why is or isn’t that true in the world that we’re looking at? And by the world we’re looking at, I mean carbon management.
Dr. Jen Wilcox: Yeah. So Thomas Sherwood is a chemical engineer. So absolutely that the more dilute systems get, the more energy really it takes to do the separation. And so the reason for that is because you’re having to deal with all of the inert particles. The more inert molecules, in this case, nitrogen, say, and oxygen that we’re having to touch... The more inefficient your process is going to be, right? And so that is absolutely the case. I mean, this is not any different than Sherwood’s rule in that direct air capture, ultimately, when you look at the energy required to do the separation from a more dilute system, it’s going to be significantly greater compared to a more concentrated system or a system more concentrated in CO2.
Now, the energy is just part of the story. And so the other piece of that, though, before I get into the other part, so costs are related to both operating, which is associated strongly with this energy, and costs are also associated with the capital, like how big does the contactor have to be? What are the different components of the separation process? But back to Sherwood, if you’re having to deal with More particles that actually aren’t of interest, for instance, more nitrogen over CO2, then the actual efficiency of the process will decrease as well.
Just intuitively, you can kind of think about that, right? Because of that, what that means is if you have a concentrated system, say, from the exhaust of a power plant, the energy, it’s going to actually be lower, right, than from an airstream from the atmosphere, but the efficiency is going to be higher too. And that’s another piece because what we’re talking about right now when we talk about something like Sherwood is we’re talking about minimum thermodynamic work in terms of an energy separation process. But when you talk about efficiency, it’s a little bit different.
And so the fact is, it’s like the real process that you actually have to put your finger on that you’re deciding to use to do the separations, whether it’s carbon engineering plant or whether it’s a Climeworks plant. When you make a decision on choosing a technology, That’s when the efficiency starts to come into play. How many units do you have in that? You might have something that has to regenerate the sorbent that you use for separation. You might have a compressor. You might have a system of fans. Every one of these units has its own inherent inefficiency associated with it.
And the more units you have, the more inefficient your process is going to be. And it turns out that when you look at a system that’s more concentrated, you just have less of those units. You have less material that you have to process that is unwanted, that is inert, you know, in more concentrated systems. Is you get these losses in efficiency as you get some more dilute systems. You get an increase in cost then associated with the energy. And then the other piece is the contactors. If you have a system like a power plant, a natural gas-fired power plant, for instance, is 100 times more concentrated in CO2 than the atmosphere.
And if you want to design a system that captures the equivalent CO2 from that unit as you would from the atmosphere, Your direct air capture has to have 100 times the surface area. That contactor has to be just 100 times greater. That directly translates to an increase in capital costs. So, you know, in this case, it’s not that difficult to see how both the energy and the capital costs are increased for a system like direct air capture compared to the more concentrated sources.
Christophe Jospe: It sounds to me like you’re saying the debate is settled, but I’m not so sure it is. In some cases, yes, okay, perhaps it takes more surface area, but it doesn’t necessarily mean that unit sizes... When I think about a visit I took a few years ago to a global thermostat plant, they had a way of basically filtering a lot of air through a contactor in a more efficient way. So it didn’t have to necessarily be 100 times larger for something 100 times more dilute per se. But I’m not here to necessarily spar with you on that.
I think I’m more interested.
Dr. Jen Wilcox: I would be happy to spar with you on that. When have we ever taken a solid sorbent technology like Climeworks and applied it to a concentrated source? Tell me. Ball’s in your court.
Christophe Jospe: I don’t know if I want to answer that question, but I’m going to answer a different question. Because the answer is we don’t have one.
Dr. Jen Wilcox: Oh, that’s always... Are you on a dissertation? Are you defending your PhD dissertation right now? Because that’s a perfect way to respond. No, but the answer is there isn’t one. So I would love for a company like Climeworks to take that wonderful technology that you just talked about that says we have this wonderful idea that allows less surface area and get the same amount of CO2 interaction with our binding materials. It’s like, great, let’s apply it to a more concentrated stream. We will get the same benefit. But the thing is, is we don’t do that today.
So we’ll just step back for a moment and talk about what we do today for more concentrated streams. So we have projects where we use a mean scrubbing, and it’s a solvent. It’s a liquid base separation process. And in liquid-based separations, we can use a weak base, you know, because in those separations, we’re looking at more concentrated streams. So like taking an example like Petronova, before it recently stopped operating because of the price of oil, but that’s a whole different conversation. But when it was operating, it was able to capture about 1.
4 million tonnes of CO2 per year. And in doing that, it was capturing it from an exhaust stream that was 300 times more concentrated than CO2 in the atmosphere. And it did it using a pretty weak base, amines, in 30 weight percent in water. Take a step back and look what Carbon Engineering is doing. Are they using amines for their solvent? No, they’re not. They’re using potassium hydroxide. They have to use a very, very strong base. And this goes into the inherent differences between the two leading technologies in direct air capture today.
One being solvents, and the fact is that they have to use a strong base, and I’ll explain why in a minute. And the other one is using solid sorbents, and they can get away with using a weak base. Okay? Okay. And the truth is, is that we haven’t figured out or it’s just hasn’t been cost effective yet to take adsorption or solid sorbent based technologies and apply them on a power plant exhaust. And that’s one of the challenges that we can talk about in a little bit. But going just to the chemistry for a moment.
So why is it when you think of a solvent and you think of separations, what does it look like? You have a contactor that doesn’t actually look that different from carbon engineering versus global thermostat or Climeworks. You have these large contactors. And then in carbon engineering system, they have packing material inside. Okay, it’s based on a PVC type of packing. And they flow the solvent down the packing. And the goal is that the solvent has to coat the packing and have a very thin layer. And the idea is you want to maximize So when you bubble your air through using that fan, when you push the air with the CO2 through the material and you bubble it through, you want intimate contact.
You want to maximize, because CO2 is so dilute, you want to maximize the CO2 interaction with the chemistry in the solvent that, by the way, is only at 30 weight percent across all that packing. If you were to just take a meter cubed, like a little bit of a volume in that packing, and you ask yourself, How many opportunities do I have for CO2 to bind with my chemical? And you just take that for a moment in your meter cubed volume basis. Take it off to the side. Now let’s go to Climeworks, right?
They’re using solid sorbents. The monoliths don’t look that different from your catalytic converter in your automobile, right? And so your catalytic converter is like this honeycomb Monolithic structure, and you can coat the walls of that with the chemistry, but then the question is what does that look like? It’s micromesoporous materials. Microporous are like less than two nanometers. So these are very small pores. A gram of this material will have the surface area of a football field. That’s why you can get away with weak bases because you get to just coat this stuff with amines.
So now you take your meter cubed, how many binding sites do you have for CO2? A gazillion compared to the solvents, okay? So there’s just a lot more interaction A lot more opportunity. So sure, they have some creative airflow designs, but it’s really the technology. It’s the solid sorbent technology. But today, when you look at all of the scales of solid sorbents, catalysts, activated carbon, zeolites, we haven’t done this ever before on a gigaton scale that we have to capture carbon today. If you look at this, we just haven’t done it.
And the materials that they’re using are like metal organic frameworks, very designer. We’ve got to figure out how to scale them up. And that’s one of the challenges right now. They’re doing it and we’re making it work. Companies like BASF, you know, who know how to make catalysts, who know how to make chemicals. We just need to get all of these guys on board and make this stuff and make it happen. Because that to me is a great idea, you know, but it’s like the solvents can scale. We don’t have a problem, but they each will have their pros and cons, you know?
And so hopefully that gives you a little bit Better watch out, Jen.
Christophe Jospe: You can just have your students listen to this podcast and they’ll start skipping your class. There was so much beautiful context there and I think a lot of really important points. And it also goes back to... Following processes that we know, we know how to work and things that are a little bit more theoretical and this concept of scale. You know, you mentioned quite a few companies, including Climeworks and Carbon Engineering. It’s worth noting, they’re still on the 1 to 3 to 10 tonnes a day. Whereas you mentioned Petronova, which is shut down.
And man, would I love to go down that rabbit hole in that tangent, because I think there are a bunch of reasons, but we won’t. We’ll save that for another time. Listener, you’ll just have to wait. The next one. I just want to make a couple of points on top of your points to maybe bring us back to make sure that our listener gets something, some takeaway so they can sound really smart at a cocktail party when they’re talking about the difference between carbon capture and direct air capture. Yes, that is the goal.
Dr. Jen Wilcox: You’re right. You’re right. Let’s get back on track.
Christophe Jospe: So effectively, we’re trying to grab some stuff. Maybe it’s concentrated, maybe it’s dilute. We want to grab it using the least amount of energy. In some cases, we can get fancy on how we can grab that energy. And in Climework’s case, they got really fancy by saying, hey, you know, we’re going to go find geothermal and this thermal energy. That’s coming out of the flip side of that is many of the plants that we’re looking at are just dumping CO2 directly in the atmosphere, which we know is a bad thing that is exacerbating the greenhouse effect.
So we as a globe should do everything we can to avoid those emissions from going into the atmosphere as long as we need to keep running those plants, which hopefully reduces their lifetime. You know, I would make a comment that when these plants were originally designed, it wasn’t with the mind of saying, we’re going to use this resource as efficiently as possible. It was more like, oh, wow, coal, super cheap. Let’s just burn it and cheaper. Burn it super inefficiently. So the idea of even retrofitting is you’re making it harder on yourself if you were to completely redesign a plant where you see groups like NetPower doing really innovative work to say, how can we more efficiently use some process with a view in carbon management?
All of which brings us to the question of when to do what and where and why and how. And so I was wondering if you can give us a sense of when to capture CO2 from ambient air. When does that even make sense? And it seems like we’re in agreement when to capture from a point source at all opportunities possible because we want to reduce those. No, I need to fix that statement. Right.
Dr. Jen Wilcox: That was 1. 0. See, I talked too much and I never got to 2. 0. Uh-oh. Uh-oh. No, so 1. 0 is like 10 years ago, everywhere possible, avoid. But we just recently did a study on trying to figure out, yeah, what are the priorities for conventional carbon capture? Not direct air capture, but just avoiding CO2 in the first place. And just, you know, surveying kind of the landscape, it doesn’t make a lot of sense, as you pointed out, to retrofit a coal-fired power plant. Turns out 53% of the coal-fired power plants in the United States are actually past their expiration date, but they’re still running, we’re still pushing them, they’re still operating.
And then you also look at, there’s a lot of exciting activities in terms of like, I was in Colorado for a bit and in Pueblo, Colorado, retiring coal-fired power plants and replacing them with photovoltaics. They got approval, I think recently too, to early retire a plant in Arizona. So it’s like, it’s pretty exciting to see all of this. So to me, it’s like, we get a lot of natural gas, right? Cheap, super abundant natural gas in the United States. And it’s like, that’s not carbon-free. It’s about half the emissions of a coal-fired power plant, so fuel switching will get us some of the way forward.
But we need to be thinking about that. I see absolutely first and foremost just displacing coal-fired power plants with low-carbon energy. First and foremost is a mode of decarbonization and getting us forward. But where to do carbon capture would not be, in my opinion, on those. We just could displace them with renewables, provided it’s local and available. But with natural gas, there’s a lot of opportunity to look at carbon capture with natural gas firepower plants. The other piece that we looked into specifically is the industrial sector. So this is oftentimes a very difficult to deal with sector.
And when folks talk about direct air capture and in general carbon dioxide removal technologies, we think, well, not only do we need to start pulling the CO2 out of the atmosphere, but we also need to deal with the fact that there’s just emissions that are really difficult to avoid, like the agricultural sector, the transportation sector, and then the industrial sector always falls into that category. And so what we did is, again, a big study. This all just came out just a few weeks ago in the Environmental Science and Technology Journal.
It was a three-part series, the first one being on natural gas. The second one is the industrial sector. And we looked at the potential of We looked at every single industrial facility in the United States that would even make sense to add carbon capture to. So we looked at every steel plant. We looked at every cement plant. We looked at everywhere where you make hydrogen in the US today, you know, from natural gas. And so we looked at all of these opportunities to try and understand how much potential could we get, you know, from this sector.
And it comes out to like 0. 7 gigatons, you know, if you were to retrofit all of that sector with carbon capture. And so to me, yeah, what’s that?
Ross Kenyon: That’s per year.
Dr. Jen Wilcox: And so to me, it’s not the whole footprint. And there’s a bunch of reasons because a lot of the industrial sector has to do with heat. And it’s like, that’s a different conversation is like, Low carbon heat, right? Like it’s like, okay, well, we have to think of, you know, you have to think of biofuels or hydrogen or, you know, some of these other strategies to doing that. Because it turns out like if you look at a refinery and 50% of their footprint is associated with kind of process emissions from a catalytic cracker and chemically generating CO2, and the other half is heat, it’s like they may have 200 different heaters on site.
And they’re not necessarily going to want to go with like electric heating. So probably like hydrogen makes sense, you know, maybe for some of the iron and steel plants, electric arc furnaces could make sense. For the cement industry, oxygen fired kilns in the future might make sense, but there’s not a single one of them in the United States today. So we look... We looked at the ages of the entire fleet of each of these, and we thought about when does it make sense to even do carbon capture? Because if you’ve got, for instance, a cement facility that is going to be retiring within the next decade, maybe you don’t spend the money to do carbon capture.
Maybe there’s something else you do. And same with an iron plant. Maybe you do direct reduction of iron use and hydrogen. Maybe that makes sense instead of like retrofitting with carbon capture. So a lot of the work we’re doing is kind of like surveying it to answer that question of where does it make sense? We don’t want to like spend the resources, spend the money in a place that just doesn’t really make sense to invest. And not to mention, we’re not going to do it all in one day. And so there has to be a little bit of a priority.
And so by doing this, these landscaping studies that we’ve done, it provides a bit of a blueprint of what would you do first? What would you do in the next five years or 10 years?
Ross Kenyon: Jen, you make a really strong case for focusing on decarbonization and capturing from the point of emissions. But what do we do with the trillion plus tonnes of carbon dioxide already in the atmosphere? Clearly, some sort of DAC is going to play a role here. Or do you actually think other methodologies might be a better place to look?
Dr. Jen Wilcox: DAC is definitely going to play a role. Part of a big focus of my work is figuring out where best it makes sense to do DAC and how.
Christophe Jospe: What’s the DAC up plan?
Dr. Jen Wilcox: Did you say DACA plan?
Christophe Jospe: Yeah, what’s the DACA plan? That’s great. I like that one.
Dr. Jen Wilcox: I like that one too. I’ll just say before I get into the DACA plan, the details of the DACA plan, the elephant in the room is we avoid all this CO2. We pull all this CO2 out of the air, gigatons. What are we going to do with it? Where is it going to go? You know, if we really care about making a dent and removing it from the atmosphere and not putting it back, then we need to think about permanent removal. And permanent removal, to me, is back in the geosphere.
That’s permanent. That’s for sure. You know, if you’re going to bet on it, right? And so it’s like, well, you’ve got two options. You’ve got sedimentary basins, and some of them are associated with oil, and that’s maybe another podcast. And then some of them are not. And then some of them are minerals, right? And minerals are interesting. People seem to be comfortable with rocks, I’ve noticed. You know, the technological readiness level of mineralization is not as far along. As sedimentary basin storage. And so, but that’s where a lot of my work has been lately is figuring out strategies on how to look at mineralization of CO2.
But then the DACUP plan, Isn’t just about what you do with the CO2. It’s about where are you going to build these plants and what technology are you going to decide to use? And I do not think it’s a winner. You know, I’m a firm believer in kind of lots of different buckets, you know, and because you just never know which one’s really going to pan out in the end either. And I’m not saying like we dilute resources because we think there’s going to be failures. I don’t think that any of the plans out there in terms of the leading technologies today With direct air capture, I think they’re going to succeed.
I think that they have amazing people working at these companies who are extremely stubborn. And want to make it work no matter what. And it’s technically feasible. So like, let’s just do it, right? And so the thing I’ll say of like moving forward with the solid sorbents, I think it makes a lot of sense. Christoph, you had mentioned geothermal. And so in our DACA plan, you know, in our third paper in the series of three, was looking at coupling in part to geothermal energy resources in the United States. One of the things that we did isn’t just about geothermal that hasn’t been tapped yet, but existing geothermal power plants today.
Every geothermal power plant has a condensing unit. At the end, before you put the ground, you condense it first, and you’re really maximizing the thermodynamic efficiency of the whole process. Imagine re-envisioning that whole power plant strategy and thinking of the DAC plant as the condensing unit. We can promise you. That working fluid is going to go in at 100 and come out at 60. And so that could be your opportunity for regenerating the material. Problem is, is that geothermal isn’t often perfectly cited with where you want to store the CO2.
And so in formations like basalts, like in carb fix in Iceland, it’s a beautiful synergy. You’ve got a lot of water so that the kinetics are favorable for the mineralization in the basalts. You have geothermal. And so it makes sense. And there are other opportunities for bringing all of the convergence of those pieces together to do more carb fixes. But what we looked at is geothermal, but we also looked at nuclear. And then you imagine that these energy resources today, these businesses, these utilities that are producing carbon-free electricity, imagine if they were instead producing carbon-negative electricity to help offset some of the difficult sectors that are hard to avoid or to help thinking about removing from the atmosphere as well.
And so... That’s what we looked at in that study. But I’ll just mention that part of direct air capture and the two different technologies that I’ve been talking about today, the solid sorbents rely on low quality heat pretty much. It’s like 100 degrees C. So it allows you to couple with waste heat. It allows you to couple with geothermal resources. And even the nuclear, we are using their steam, but we’re not using their high quality steam. We’re using their low quality steam. So they’re able to get some electricity out still.
And so with the solvent-based approach and that very strong acid that I talked about, potassium hydroxide, which you need, right? You need that base. But that potassium hydroxide base, that strong base that you need to react with CO2, in the end, you’re ultimately, through that whole process, you’re ultimately forming a carbonate mineral that you’re regenerating. And it requires roughly 900 degrees C heat. To generate that feedstock and to recycle that process back through. And so that isn’t going to necessarily couple with these low quality heats. But the difference is, is that the scale of those plants, you know, the cost in those cases is dominated by large pieces of equipment.
And so it makes sense to build them at, say, a million tonnes a year removal, where the Climeworks type plants are on the order of thousands of tonnes per year removal scale. So they’re just really two different scales, right?
Christophe Jospe: Totally. And just for all the DAC enthusiasts out there, what you’re spelling out is a really important distinction, which probably means that there is no one size fits all when describing direct air capture technology. And so when looking at some of The liquid sorbents, we then understand why Oxy Petroleum has invested in carbon engineering and is using such a plant to capture 1 million tonnes a year. And it even gets into some of the questions around how they can make certain assumptions on cost, but they’re following something that ultimately, like you said, is heating up to 900 degrees Celsius.
And I believe the process is very similar to what might be used in a paper mill. So you’re We’re used to seeing certain estimations on process economics, whereas what Climax is pursuing is something that’s more modular. And so I guess to create an analog, it might be fair to say, you know, this is like rooftop solar versus concentrated solar power. They’re both using energy from the sun in the same way we’re both sucking CO2 from the atmosphere, but the way in which you go about building energy. These plants is going to look completely different.
And the assumptions going into the costs and the process economics are completely different, which gets me to my next question. But maybe just to back up, you know, there’s this obsession with dollars per ton in CO2. So there’s this word thrown around in the field we all work in called TEA. Techno-economic assessment. There’s a report, and I remember reading this report multiple times because I was working with Dr. Klaus Lackner and Dr. Alyssa Park at the Lenfest Center, which was the American Physical Society report of 2011.
Dr. Jen Wilcox: Oh, such a famous report, yes. Or infamous, I should say.
Christophe Jospe: Which is a beautiful entry into thinking about direct air capture and views that people have about it and the TEAs that go into it. Let’s see. There’s a question in here, I promise. I bet I can guess it. Yeah, well, it’s a process economics question. How does one, as a chemical engineer and or a physicist or someone who’s thinking about these things, how do you get into process economics on a technology that hasn’t really scaled yet?
Dr. Jen Wilcox: Well, okay, let me explain. In 2011, this report came out by the American Physical Society, and I was a co-author of that report. And really, it was looking at, you know, what are the costs of direct air capture using chemicals? And how do you do a TEA on a system that hasn’t been deployed yet, right? And it’s like, you can look at each of these, one of these parts, and you hear folks from Carbon Engineering talk about this, is that all of these items that go into their system are off the shelf and commercially available today.
And so you can buy these pieces, but they’ve never really been integrated ever for the purpose of direct air capture. And so bringing components together for the first time and asking those components to work in this way to do DAC is not straightforward. And so the way that we costed those numbers and the way that we did that assessment back in 2011, it’s really started in 2009, by the way, and it took a couple years to be done, is that we had to base it on existing systems. And so what do existing systems look like for carbon capture?
A weak base like amine. Like we knew that much. And we knew that there was enough out there in terms of the kinetics and the solvents and understanding the thermodynamics and the capacities of things like sodium and potassium hydroxide. So like we had that kind of data and those kinds of experiments had been done on a pretty small scale at that stage. But in terms of how to design the contactor so that you can then cost that out, The packing material, these types of contactors, I mean, they were invented by Bottoms.
The first patent was by Bottoms in 1930 for packing material, for absorption, for scrubbing CO2. So we’ve actually known this technology for a very long time using amines. And the purpose was to create high purity CO2 for the food and beverage industry. So we’ve been doing it for years. And so what we did is we took a pretty standard system. So what it looks like is it’s a tower, right? And because... Typically, like in a Petronova type of system, you know, you want very tall towers, right? And you have this driving force because your CO2 is 300 times more concentrated in that system.
So you can imagine a tall, thin tower. And the taller the tower, the more opportunities you have to capture CO2. So in other words, the taller the tower, the more carbon you take out. And so what that means though, is the taller the tower, the more energy required to push your gas through that tower. And so the towers that we had to design in this, if you made them too tall, you end up putting more carbon in the atmosphere in terms of blowing power Then carbon you take out in terms of DAC, right?
And so it’s like there’s an optimization there. We couldn’t do tall towers. We had to kind of do short towers, which means you don’t capture as much CO2. But we use these vertical, what we call squat towers, to do the analysis. Now, at that time, carbon engineering was really getting started. A lot of the data and the work that they had was proprietary, so we couldn’t really access. But we learned later that, you know, they did not use a kind of a squat power approach. They used more of like this other approach, right, which is all the pictures we see of DAC today, which in the end, it’s like your solvent’s flowing down and your air is Instead of being a cross flow to the solvent, instead of being a counter flow, your air is a cross flow.
It’s like hitting it kind of horizontally on, right, as the solvent is vertically flowing down. That’s a very different design than what we designed. Now, the other piece is that direct air capture is kind of an open system, right? And so in our system, we didn’t really look at it that way. It was more of a closed system, which again is more conventional. The other piece that’s quite different is we said, we’re going to use the standard metal packing material that’s been We know it works well against these caustic materials.
But it turns out the pressure drops higher, and it’s more expensive to make those metal packing materials. But again, that pressure drop being higher means more fan power to push your gas through. So what we did in APS was more closely related to the technologies that we know today for using separations for CO2. Now what a company like Carbon Engineering was doing was thinking ahead. They were thinking, how can we use different types of packing material that can have a lower pressure drop? What about PVC? So that’s what they’re doing.
They’re trying PVC. It’s cheaper to make. The pressure drops lower, which translates to lower electricity costs because the fan power goes down. But the question is, is it going to work? For how long? Will it degrade over time? We just don’t know until they actually deploy it and run it for a while. The other piece is that rather than... Counterflow, the crossflow design, is also something that’s unique. And so these types of things, in my mind, was just like a company that’s forward thinking. It’s very different from a group of scientists to getting together and saying, what do we know?
What do we know for sure if we’re going to do this techno-economic analysis, right? Right. We can’t just take things out of the air and we can’t ask, this company can’t divulge information that’s proprietary. So we have to do the best we can to kind of piece these parts together that we do know well. And in the end, we estimated a cost of roughly $600 a ton. And we know from a company like Climeworks, although it’s a very different technology, they are doing it today about $600 a ton. They have a view that they think in the next 5 to 10 years they could get it to $200 or $300 a ton for their system.
And so it’ll be wonderful to see how that pans out and if we can make that work. We don’t know what it’s going to cost to do it on the solvent-based approach until the plant is actually built in an integrated way and we can actually see those costs realized.
Christophe Jospe: So just to be clear, the costs you are describing are simply the cost of capture, correct?
Dr. Jen Wilcox: So ultimately, in the end, it would be not what you do with the CO2. It’s only the cost of capture, but we also look at what’s called the net removed costs. So $600 a ton, and that is also looking at, in this whole process, are there any flows of CO2 that go back into the air from doing it? And if there are, those have to be subtracted out. If you design a plant that’s to capture a million tonnes, right, but half of that goes back in the air, then you’ve just doubled your cost for that plant.
Christophe Jospe: Right.
Dr. Jen Wilcox: So we do take those flows into account.
Christophe Jospe: There’s this pesky issue of leakage. If you’re producing chemicals that’s emitting a bunch of CO2 or if you are using natural gas to power it but not capturing that CO2, your costs go up even higher. And in some cases, that may mean do nothing is actually the best answer. And that’s why some of these TEAs help.
Dr. Jen Wilcox: Absolutely. The TEAs help. We recently... Submitted a paper that’s under review right now where we look at if you were to use natural gas as your fuel, and particularly in the Permian Basin, which has some of the highest reported leakage rates for natural gas, it drastically increases the cost of net removal. And it does not even economically make sense to do it until those systems are leak-tight. So you’re absolutely right.
Christophe Jospe: So Jen, I want to put a magic wand in your hand and you wave it. And everything that you think needs to be researched to advance this agenda of carbon management is happening. What have you done?
Dr. Jen Wilcox: Yeah. So magic wand. I think there’s still a lot of work to be done in terms of if we think about the technologies themselves, you know, and we want to see these costs come down, what does that mean? It means we need to go along that learning curve too, right? Like, and what does that mean? How do we do that? How do we learn? We learn by building. And so it’s like, we often think about waving magic wand. And what does that mean? Does that really mean like dollars that go into research and development?
Like, Scientists like me working in our labs and like figuring out like new ideas. I think it’s actually going to be across a lot of different parts of the problem. And one part is actually just more funds associated with deploying more plants, getting more carbon removal happening today. So that companies like getting like a thousand more Climeworks would be a great start. A thousand more carbon engineering would be a great start. To me, it’s like A lack of human capital today in order to get to the gigaton scale that we need.
And so first off is just building these things and like stop asking all these questions. It’s technically feasible. Let’s just get the steel in the ground and get them built and learn. It’s not bickering about what if $200 or $300, like who cares? Get it built, figure it out, build another one, figure it out, learn. And eventually, they will come. The more chemical companies will come and figure out how to scale this. We’ll do better at building oxygen fired kilns that could also be used for other industries like cement and glass making, for instance.
Like all the technology advances that we learn by doing in this field will absolutely be synergistic into other sectors as well. So first and foremost, we just need a lot more of what we’re doing today. Second, I think that we also need to be able to today, it’s like EOR is like such a hot button topic. I personally feel like I mean, I’m all about defossilization all the way. Completely transparent about that. But the truth of the matter is, it’s a slippery slope. Because with the EOR, it’s like there’s a green light, you know?
And I think a lot of people don’t realize is that when you... You use CO2 for enhancing oil recovery. That CO2 ends up staying underground. And we get it. We understand it because we’ve been doing it since 1972. Never had an accident. We haven’t had CO2 leakage. Why? Because it’s the same trapping mechanisms that have been trapping oil and gas for millions of years. We get it. We understand the physics. But at the same time, it’s hard for us because it also means more oil is produced. And so it’s like if there were incentives to maximize the storage throughout the recovery of their oil production, which they absolutely physically and technically can do, then that would be a step forward.
It would not be a reliance on fossil. It would be a bridge. Now, that’s one story. But the other piece is like, well, why aren’t we able to do more in dedicated geologic storage and saline aquifers, you know, where there’s not necessarily depleted oil and gas? It’s like, well, We need to understand them as well as the oil and gas reservoirs. So there needs to be more characterization, right? We need to go there and understand those formations. And so there needs to be more research dollars going to actually understanding and characterizing those formations so that there is a green light for them.
First and foremost, it’s like, well, where’s the carbon going? So we need to figure those out. But then we also just need more projects so that we can figure out the R&D directions that we actually need to go by making mistakes and learning.
Ross Kenyon: Jen, I want to close us out on what may prove to be a bit of a controversial question. What would have to happen for direct-to-air capture in order for us to be able to continue business as usual? Like you emit one, you pull one out, we don’t decarbonize at all. How good does DAC have to be to make that a reality?
Dr. Jen Wilcox: I mean, I think it’s not possible, right? Because it’s like we are already at devastating levels of carbon in the atmosphere, right? And so it needs to come out. And so what your question is, is how do we... And from our Academy of Sciences study, what we estimated is assuming that we have deep decarbonization on the order of, say, you know, which is intense, right? Like 20 gigatons of CO2 per year. Because think about it, right? It’s like if the natural... Sinks are taking up half of what we emit, just say, rough estimate of 40 gigatons a year, and they’re taking up 20.
Then we don’t even start dipping into that 410 ppm concentration until we deep decarbonize at least 20 gigatons of CO2 per year, right? And so if our goal is to decrease from 410 to get somewhere interesting, that could be good for us, then we need to do 20 gigatons to Because if you’re saying we’re not going to deep decarbonize because we’re going to just keep driving our Hummers, right? So if that’s what’s going to happen, we need to do 20 gigatons of CO2 per year plus this estimated removal that we need in order to somehow get the PPM down low as well.
So I would say that it’s probably going to be another 10 gigatons. I mean, that’s a lot, right? So that’s a lot of negative emissions. And I mean, are you further asking, I really don’t like this. It’s not comfortable for me.
Ross Kenyon: Yeah, a little bit of dancing around it.
Dr. Jen Wilcox: Yeah, I mean, come on.
Ross Kenyon: Tell the Hummer drivers listening out there what they need to do to make that a reality.
Dr. Jen Wilcox: Yeah.
Ross Kenyon: Hummers in perpetuity.
Dr. Jen Wilcox: I suppose, I mean, this is what it’s all about. You know, when I teach my class, I... I don’t want my students to get depressed, you know, and I often tell them, I’m like, a little bit of depression is healthy. You need to be motivated. We need everybody here to be excited and motivated. Not super depressed, but a little bit. It’s a dose of reality. We’re in trouble and there is an urgency and we need more human capital to help figure this thing out.
Ross Kenyon: I think Nori, especially in the early days, tended to focus on rhetoric that was a bit closer to that of not wanting people, not needing to rely on people to have a spiritual change or change their consumer habits radically because we think that’s unlikely to happen for many people. And also it causes political fights that are not productive for climate action. I don’t know to what degree we hold that these days, Kristoff. I don’t know how you feel about that.
Christophe Jospe: I mean, I can only speak for myself and my own spiritual transformation. I produce less CO2 waste, for sure.
Ross Kenyon: This guy reads a couple Wendell Berry books from Charles Eisenstein, and he becomes a guru, I think is what happened.
Christophe Jospe: Rath, consider yourself a conservationist, techno-optimist, permaculturalist, like all of those things. It all fits together. I mean, I like to think of CO2 as waste, and we just don’t have a waste removal service. And humans are waking up to say, we don’t want to live in a society where we don’t produce garbage, but we do want to live in a society where there’s no waste on the street, and we’re willing to pay, or we’re willing to vote in governments that will take care of this waste on our behalf. And- Nori is getting things going by saying, look, there are volunteers out there who want to get the carbon removal industry of the future going.
Let’s go. And let’s prove that it’s wildly profitable. I think we try to appeal to certain... I think greed is a powerful motivator. If you know that you can get paid $200 a ton, $500 a ton, even $50 a ton, maybe you might start trying to figure out how to do that in the most efficient way. So I’m with you. I got a little depressed, didn’t get too depressed. Once I got through my depression, I committed my career to working on climate solutions.
Dr. Jen Wilcox: That’s exactly right.
Christophe Jospe: Perfect. I guess maybe, Jen, we should pass it back to you for one more question, which is any words of wisdom for people who are thinking about the carbon removal space but aren’t quite sure how to dip their toes into it?
Dr. Jen Wilcox: Well, that’s a great question. So it’s almost as if it was planted, but it wasn’t. So there’s a group of us, about 30 authors, mostly from Europe and also North America, U. S. and Canada. And we are developing a first-of-a-kind primer on negative emissions. And it should be done ready for prime time this fall. It’s in an internal review process at this point. It’s really about that. It’s really about like trying to figure out like if you’re coming in with this kind of background, but you want to have an impact, it’s about helping you to kind of carve out that path of where are the gaps?
You know, first off, it’s like to get everybody who’s interested in this space on the same page of all of these definitions and all of these different approaches and, you know, the difference between The technology of planting a tree, for instance, versus the technology of using chemicals to capture CO2 out of the air. They’re both doing it, but in very different ways. They’re both important. We need them both. And about kind of identifying what all of the different approaches are and even the policy levers, the creative policies that could be put into place to deploy these on an interesting scale.
And then finally, to think about oftentimes what drives these decisions is costs in economics. And we try to turn that on its head a little bit and say, forget about costs, forget about economics. Maybe let’s start with environmental equality, right? Let’s find out, let’s start with jobs. Let’s start with Like these other societal impacts and what we maybe see as co-benefits now, but maybe primary benefits with kind of a new vision on this. And that maybe we can think about policies being creative such that these are the things that we stress and that we motivate and get excited about.
And the co-benefit is that we’re removing carbon on an interesting scale at the same time. So we’re like stimulating jobs and stimulating the economy, you know, and anyway, so it’s a document, it’s about 250 pages at this point. And again, like actually 30 to 35 authors from all over the place who are thought leaders in this space. And I’m happy to share a kind of a beta version with you guys. And you can kind of see the journey that we’ve taken. It’s taken us three years to develop this. And super excited about launching it this fall and hoping to answer exactly that question of many excited people who are interested in this space.
Ross Kenyon: Great. Looking forward to taking a look at that. And then I imagine you probably want to steer people to your personal Twitter, your website.
Dr. Jen Wilcox: Yep. I do not have that many followers. I’m pretty new to Twitter. But I enjoy it. So it’s good.
Ross Kenyon: Well, thanks for being with us, Jen.
Dr. Jen Wilcox: Thanks for having me. Super fun. And it’s great to meet you guys.
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