Episode #64: Meet the Startup Revolutionizing Carbon Capture

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  Samantha Herrick:
  This is the Tech Optimist, a podcast brought to you by Alumni Ventures, a show where we tell you the stories of tomorrow.

  Cameron Halliday:
  The problem is essentially that carbon capture is expensive.

  Samantha Herrick:
  That’s Cameron Halliday, co-founder and CEO of Mantel.

  Cameron Halliday:
  If it were affordable, carbon capture would be a little bit of a no-brainer for hard-to-abate industries to meet their climate goals.

  Chris Sklarin:
  So given the environmental urgency, the speed to deployment—

  Samantha Herrick:
  And that’s Chris Sklarin, managing partner at Alumni Ventures.

  Chris Sklarin:
  …obviously is pretty important.

  Samantha Herrick:
  Carbon capture and storage is a technology designed to reduce carbon dioxide emissions, or CO2, from industrial processes and power generation to help combat climate change. That’s me. My name is Sam, and I am this show’s narrative writer.

  Let’s dive into Mantel a little bit—the startup that we are going to talk to today. I will preface this by saying that this conversation between Chris and Cameron is awesome. There is some really good insight here into their technology, how it works, how it works within our economy, and then I add a few things in there about how carbon capture works, what some good strategies are, and how to improve in the future.

  Let’s do a little dive into the company itself. Mantel was founded in 2022 as a spin-out from MIT’s Department of Chemical Engineering. The company is based in Cambridge, Massachusetts, and is co-founded by Cameron Halliday, our guest today and the CEO; Danielle Rapson, the COO; and Sean Robertson, the CTO.

  Now, the technology—Mantel is pioneering the use of molten salt-based carbon capture materials, specifically molten borates. The technology is designed to operate at high temperatures found inside industrial boilers, kilns, and furnaces to capture CO2 at the source of these emissions and to recover high-grade heat during CO2 absorption, offsetting energy costs for regeneration. This approach aims to significantly reduce carbon capture costs compared to conventional technologies available today.

  As far as their funding and growth, in September of this year, Mantel announced a $30 million Series A funding round co-led by Shell Ventures and Eni Next. This follows a $2 million seed round raised in 2022. The company is using the funding to scale up this technology, implement a demonstration project at an industrial site, and prepare for full-scale commercial deployment.

  Regarding progress and goals as a company, Mantel has already demonstrated carbon capture at lab scale, processing half a ton of CO2 per day. Their upcoming demo project aims to be about 10 times larger, capturing 1,800 tons of CO2 per year at an industrial site. The company’s ultimate goal is to provide a low-cost, energy-efficient carbon capture solution for hard-to-abate industrial sectors like cement, steel, and chemical production.

  Before we hop into the show, we’re going to take a quick second for an ad and then we’ll be right back.

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  Now, back to the show.

  Chris Sklarin:
  Hey, everyone, welcome and thank you for joining us. I’m Chris Sklarin, managing partner at Alumni Ventures, and I’m joined today by Cameron Halliday, who is CEO over at Mantel. Cameron, why don’t you do a quick intro and then we can get to some of the founder questions that we’re going to start with.

  Cameron Halliday:
  Hi, folks, and thanks for having me, Chris. It’s great to be here. As Chris said, I’m Cameron Halliday. I’m the co-founder and CEO of Mantel. We are a carbon capture company that is helping heavy industry decarbonize by capturing CO2 emissions and reducing emissions at the site. This technology—this idea of carbon capture—has been around for a long time, but it has proven to be very expensive, and what we are working on is solving that cost problem.

  Chris Sklarin:
  Yep. Yep. That’s great. That’s great. Well, let’s jump into some detailed questions on Mantel. Maybe jump in and describe the sort of core problem Mantel is solving and why it’s relevant in today’s market. I mean, everyone knows and they’ve heard about carbon capture, but it’s a pretty big set of words, and you can give us some more details at the layman’s level.

  Cameron Halliday:
  Yeah. Yeah. The problem is essentially that carbon capture is expensive. If it were affordable, carbon capture would be a little bit of a no-brainer for hard-to-abate industries to meet their climate goals. This is a very pragmatic solution to a very messy problem, but the problem is cost. Just going one level deeper, the reason carbon capture is expensive is because it’s very energy intensive, and that’s more of a technical problem—and that’s the technical problem that Mantel is solving.

  Chris Sklarin:
  Was there a particular moment that inspired you, probably while you were doing your PhD, to start Mantel?

  Cameron Halliday:
  Yeah. There was a moment during my PhD where we realized what we had solved. We began this journey in the 2018 timeframe, going after this problem, and there was a magic moment where we realized what we had done. Since then, it has been about proving it out, scaling it up, and dealing with all the challenges that happen along the way.

  Chris Sklarin:
  That perfectly leads into that next set of questions, which is what makes Mantel’s approach unique compared to the others in this space? Right—everyone’s trying to deal with this expense problem, but you’ve got some secret sauce. Actually, I’m going to say secret salts.

  Cameron Halliday:
  Secret salts. Carbon capture’s not new. People have been trying to do this for a very long time. This was developed a hundred years ago, and the approach that’s been taken has remained pretty similar over that time. The technology captures CO2 and then regenerates a pure stream of CO2 that can be used or sequestered. The challenge is that regeneration is very energy intensive. The insight that we had is that if regeneration is energy intensive, then that actually means capture is generating energy—so that capture step produces a lot of energy. The problem is all of that energy gets wasted when you do this with amines or other low-temperature processes. The insight here is if we do this at a high temperature, all of that energy is being generated as high-grade, high-quality heat—and that’s heat we can use. That is driving the energy penalty down. The net energy requirements of the system basically get eliminated, and that is the biggest chunk of cost, having a huge impact on the ability to do this in an affordable manner.

  Samantha Herrick:
  If you’re still a little confused about what carbon capture is and what carbon storage is—and you’re not a data scientist or a biological scientist or anything—then you have come to the right podcast because I’m going to tell you what it is and how it works very quickly and briefly. That way, when we get into the rest of the show, everyone’s on the same page and on the same wavelength about what we’re actually talking about here.

  Carbon capture and storage is a technology designed to reduce carbon dioxide emissions, or CO2, from industrial processes and power generation to help combat climate change. Here’s just a quick overview of how it works:

  Carbon capture storage is a three-step process. Step one: you capture CO2 emissions from large point sources like power plants, steel mills, cement factories—the list can go on. Step two: you transport that captured CO2. Step three: you store that CO2 permanently deep underground. The goal is to prevent CO2 from entering the atmosphere and contributing to the ever-growing crisis of global warming for our planet.

  How does it work? There’s post-combustion, where CO2 is separated from flue gases after fuel combustion using chemical solvents. There’s pre-combustion, where fuel is converted into a mixture of hydrogen and CO2 before burning, allowing easier CO2 separation. And there’s oxy-fuel combustion, where fuel is burned with pure oxygen to produce CO2 and steam for easier capture.

  Current technologies can capture around 90% of CO2 from these flue gases. For transporting, the CO2 is compressed into a liquid-like state and transported via pipelines, ships, or trucks. For storing, the captured CO2 is injected deep underground into geological formations like depleted oil and gas reserves, deep saline aquifers, and unmineable coal seams. These storage sites are typically at least one kilometer below the surface.

  Carbon capture has many applications and importance across various industries: power generation, cement production, steel manufacturing, chemical processing, and natural gas processing, to name a few. We’re going to get into that a bit more, so I’ll let Cameron take it over from here.

  Chris Sklarin:
  So what industries are showing the most interest in the solution, and who do you think the early adopters will be—or do you have some early adopters already signed up?

  Cameron Halliday:
  Yeah. Carbon capture is a solution for a lot of things—in fact, it’s a solution for essentially all emission sources. There are no silver bullets in this space, but carbon capture does get close. There are industries where this is harder and industries where this is easier, and there are also industries where your other options might be better or worse.

  Carbon capture is particularly attractive for these hard-to-abate sectors: cement, steel, hydrogen production, even power—especially in certain geographies. We end up very focused on geography over industry. Our technology actually looks quite similar regardless of the asset or site, but what matters is where is the geography? Where is the site? What are you doing with the CO2? Is there infrastructure around utilization or sequestration of that CO2? And are you in a jurisdiction that is supportive of this?

  That ranges from things like carbon pricing, the opportunity to drill wells and sequester CO2. There’s an ecosystem that needs to evolve to do this effectively, so we’re going after those spaces. Specifically, that means in North America: the Gulf Coast, Midwest, Alberta. A lot of this is being matured in the North Sea in Europe. Ultimately, this is everywhere—it’s just a matter of where the early adopters are, so that’s where we’re going.

  Chris Sklarin:
  You work at high temperature, really heavy industry—hard to do the carbon capture. How does this give you the advantage over competitors for efficiency and scalability?

  Cameron Halliday:
  Yeah. There’s a scale to think about here, where a lot of innovation comes out of labs and it’s what I’ll call delicate chemistry. It looks great at a bench scale, but then you have to scale up three, four, or five orders of magnitude, and you reach a concern. When we started this, we were very focused on that problem. We wanted to make sure we started with chemistry that was inherently simple and inherently scalable. That’s a huge advantage to what we’re doing, but the real driver is that energy efficiency piece I talked about—recovering all of this energy to drive the cost down.

  Chris Sklarin:
  Right. Right. Right. So often, as you’ve talked about, carbon capture is criticized for being so expensive. Now, when you’re doing things at high temperature, how does that help your client or customer? What do they see as the cost-efficiency breakthrough for you there?

  Cameron Halliday:
  Yeah. When people talk about cost, we have to be very clear about the cost of what and what’s included and excluded. There’s a sequence of things that need to happen—there’s a value chain. The CO2 needs to be captured, but it also needs to be compressed, transported, and either stored or utilized.

  We try to talk about the full value chain—the cost of all of those things—and typically what we see is we cut the cost in half compared to the state-of-the-art amine technologies. I like to use that halving in cost because it’s consistent across assumptions, geography, industries, and sectors. Specifically, that means we’re doing this in the range of $30 to $50 a ton, while amines are typically well over $80 and many are closer to $150 a ton.

  Chris Sklarin:
  So it sounds like there’s a replacement market for anybody already doing it, and maybe an adoption market for folks that aren’t doing it yet because of the better costs.

  Cameron Halliday:
  Yeah. We’re seeing a lot of sites looking at their roadmap toward net zero, making very significant investments—in the billions per site—to decarbonize. That decision is being contemplated now. It’s likely going to be made in the 2030s, and they’ll reach a final investment decision and start construction then. Really, what we’re about is a race against the clock to be a low-risk, mature technology when those decisions are being made.

  Chris Sklarin:
  Excellent. Excellent. So how do you integrate into the existing industrial processes, and why might it make adoption easier for places like cement or steel industries versus other solutions?

  Cameron Halliday:
  Yeah. A lot of other solutions essentially involve rebuilding the entire site, and that is something that scares the industry—that’s why you’re not seeing a lot of adoption. Not only is that a crazy expense and scrapping of stranded assets, it is also hugely risky. From a permitting and policy point of view, a lot of these sites were built a hundred years ago. They don’t really get built anymore anymore. They get rebuilt, fixed, and changed, and a lot of the electrification and hydrogen-firing pathways are pretty radical changes to how some of these processes work.

  The allure of carbon capture is that we leave that alone, but we still fix the problem. We fix the problem by capturing the CO2 coming out of the back end of the process, not interfering with the front end, and enabling that industry or site to continue largely as is, but with this additional unit that’s cleaning up the mess it’s creating.

  There’s a good analogy here because we’ve done this before, and this is what I find very intriguing. This was a problem in the ’70s for a different gas. SOx and NOx were causing acid rain, and we put systems on the back end of these facilities and reduced those emissions. Now, no one even thinks about that problem. It was solved, and I am optimistic that we can do the same thing for carbon.

  Chris Sklarin:
  I recall the scrubbers, right? You add scrubbers to the smokestack system.

  Cameron Halliday:
  It’s exactly the same process.

  Chris Sklarin:
  Just do it. Obviously, then, Mantel’s technology can be retrofitted. How does this compare to other emerging carbon capture systems? Literally, they want to rebuild your whole plant? Is that really the—

  Cameron Halliday:
  No. All of the carbon capture is a retrofit play. You’re adding something on the back end, so we look very similar to that. The advantage of what we’re doing, though, is that we don’t need to consume a huge amount of additional energy to run our system. That’s the key that makes this project economical, and making this economical is really the only way that we’re going to see wide-scale adoption.

  Chris Sklarin:
  Got it. Got it. Given the environmental urgency, the speed to deployment obviously is pretty important. How quickly can you scale across these industries and make you faster than all the competitors who are trying to do this?

  Cameron Halliday:
  This is a race against time, and as I said earlier, you’re scaling orders of magnitude—and that is very hard. The journey we’re on is difficult, but the impact that we can have is so huge that it’s worth the pain. The challenges here—we’re doing specific things. You can standardize designs, modularize. As I mentioned, much of what we look at appears quite similar across emission sources, so we can be quite standardized. But we have to build big systems, demonstrate the technology at each scale, and continue learning and improving to get to full scale.

  Chris Sklarin:
  Excellent. And then you obviously partner with various technologies or technology companies for the capture/sequestration side, right? So reliable storage—how do you approach that end-to-end solution? What collaborations or partnerships do you see being critical here?

  Cameron Halliday:
  Yeah. The way this ecosystem is evolving—it’s still a nascent market and space, so I would say everyone is still working out exactly what their role is. You have the emitter that is trying to decarbonize, you have the carbon capture technology provider, which is us and amine technologies, and there are lots of other solutions out there. Then you need to do something with the CO2, but all of it is done at the project level. We’re looking at projects and considering what you could use the CO2 for or where you could sequester it.

  Chris Sklarin:
  Got it.

  Samantha Herrick:
  Now, on their website, Mantel has a lot of research papers and peer-reviewed publications under their technology tab, and I want to share a bit from one of them. All of them are great reads—highly recommended for anyone interested. This one, which came out in August of this year, is titled What to Do with All This Captured CO2? I’m going to read a few bits from its executive summary. I won’t read the whole thing because we’d be here for hours—it’d be an interesting few hours, but for the purpose of the show, I’m just going to read a snippet because it ties into what the guys are going to talk about next—the governmental and federal aspect of all this.

  The world will need to capture over 6 billion tons of CO2 a year to meet net-zero goals. An important question is: what to do with all of it? Mantel is tackling emissions in the heavy industrial sector, and based on analysis of U.S. emissions today, we find there are ample prospects for managing current CO2 emissions, on top of opportunities to scale carbon management across the economy.

  We estimate that 95% of U.S. sites, representing 74% of heavy industrial emissions, have clear pathways to manage their current level of emissions with existing infrastructure through local storage (58%) or transport via truck (7%), rail (26%), ship (17%), or pipeline (8%) for CO2 storage or utilization.

  There are many possible markets for CO2, including synthetic fuels and chemicals, which could soon demand all captured CO2 globally. These markets would be unlocked through a high willingness to pay and low-cost clean energy. Even without utilization demand, existing incentives and infrastructure make projects profitable using Mantel’s exceedingly low-cost capture technology.

  In the U.S., assuming top-line revenue for decarbonizing at $85 per ton of CO2 and transport and storage costs near $15 per ton of CO2, the average margin for the capture step is $70 per ton of CO2. Mantel cuts capture costs by 50% to 75% relative to conventional carbon capture technologies, improving returns and making two-thirds of U.S. projects profitable. In the future, additional profitability can be unlocked through demand for CO2 utilization that provides added revenue, as well as infrastructure build-out that will drive down the cost of transport and storage.

  Cameron Halliday:
  And those are different partners. In many cases, they’re oil and gas players because they know this space. They know engineering very well. A lot of them have been doing this for a long time already, moving millions of tons of CO2 around for different purposes. The skill set is very similar.

  When we come into a project, we’re often looking at those projects and asking the emitter these questions. First, from a funding point of view, and second, what are we doing with the CO2 and how mature are we in that aspect of the project? It’s not something we bring to the table—it’s not our expertise. Often, we know the people, and we can bring them into the conversation, but it is an important part of this.

  Chris Sklarin:
  Got it. Got it. That’s great. How do you see the role of government policy here in scaling the business? Because certainly, it sounds like when you talk about geography, it wasn’t geography because you like the South or the North—it was more geography because you might like the municipality, state, or country.

  Cameron Halliday:
  Yeah. This is not just us. What the world needs to decarbonize is strong motivation, and that motivation needs to be financial—and that is, by and large, the role of policy. In North America, or in the U.S. specifically, 45Q is the tax credit motivating this. That’s currently $85 a ton, which means if you can capture, compress, transport, and store CO2 for less than $85 a ton, that project is in the money. That project is making money, and that is a good—

  Chris Sklarin:
  Got it.

  Cameron Halliday:
  Just as a side note, the reason why these technologies aren’t being deployed rapidly is there aren’t many projects doing this for less than $85, and that’s the step change we enable. That $85 is a tax credit in the U.S. In Canada, it’s a carbon tax—so it’s reversed; it’s a stick instead of a carrot—but it serves the same function. The EU is similar with its emissions trading scheme.

  We need to be doing this at a price point that makes sense, and then these projects become financially viable. So we’re targeting jurisdictions and geographies with strong carbon pricing. It’s not just the absolute value—it’s the certainty in that value and what it means over the lifetime of a 20–30-year project. It’s one thing to say it’s $100 a ton, but if that’s going to be stripped away in two years, no project investor is going to touch it.

  Chris Sklarin:
  Right. What challenges do you face in scaling Mantel? Have you gotten to that $85 magic number, or is that still something you’re working on with the pilot?

  Samantha Herrick:
  That’s the $85 per ton of CO2 that we just talked about.

  Chris Sklarin:
  Demonstration plan—

  Cameron Halliday:
  Yeah. Pilots are not cost-effective.

  Chris Sklarin:
  Right. Right. That’s—

  Cameron Halliday:
  The purpose of the—

  Chris Sklarin:
  … demonstration.

  Cameron Halliday:
  Yeah. The purpose of the demonstration project is to fully de-risk the technology end to end, which will give us confidence in the commercial-scale designs that hit that number. For us, it really comes down to scale. If you want to do something for tens of dollars a ton, you need to be moving millions of tons a year. That’s just economies of scale you have to hit. We have to build a pretty big system to hit those numbers, but even at moderate sizes—hundreds of thousands of tons a year—we are cost compelling.

  Chris Sklarin:
  That’s good. So cost compelling means really close to that $85 number.

  Cameron Halliday:
  Yeah. Less than $85 and trying to make a positive return for whoever is investing in that project—whether it’s the site, a project developer, a project financier, whatever that happens to look like.

  Samantha Herrick:
  Okay. You all know the drill. Time for one more ad and then we’ll be right back. Hang tight—don’t go anywhere.

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  Chris Sklarin:
  That’s awesome. So looking ahead to your next round of funding—I know you just closed the round that we helped join—but what would be your biggest priorities or milestones in deploying new capital? How do you plan to do that?

  Cameron Halliday:
  Yeah. We just closed the Series A, and now we start the next one.

  Chris Sklarin:
  Exactly.

  Cameron Halliday:
  There are really two big milestones for us through the Series A. The first one, as I mentioned, is the demonstration project. That project is about to start construction, and we’ll be in construction through next year. We’ll run our testing and commissioning plan toward the end of next year, and the goal is by 2026, we’ll have the data to raise the Series B with fully de-risked technology.

  In parallel, we’re doing a lot of work on commercial-scale units—specifically the design and setting up partners for those commercial-scale units. So while we’re de-risking the technology, we’re also positioning ourselves to hit the ground running and start building many commercial-scale units as soon as we have the demonstration data.

  Chris Sklarin:
  Right. I’ve got to imagine, once you have that data, you’ll also start signing up customers for the commercial-scale units. Right? So you can say to investors on the B side, “Here are all these customers we’ve signed up. If we just have money to build things, they will sign up and deploy.”

  Cameron Halliday:
  Exactly, Chris—and we’re signing those guys up now.

  Chris Sklarin:
  That’s great.

  Cameron Halliday:
  There’s a lot of excitement around what we’re doing, and the process for deploying these projects is time-consuming. You do design studies—often for many years—before you start building. So we’re engaged in a lot of those design studies now, building conviction around operability and cost. Through these design studies, you can get close to a definitive cost point—and that’s what’s investable. That’s what we’ll go and build the project against.

  Chris Sklarin:
  Got it. Got it. I guess, how do you plan to measure success here—the environmental impact, short and long term? How does Mantel declare success? Obviously, investors love commercial success, but there have to be a few other metrics too.

  Cameron Halliday:
  Yeah. Billions of tons of CO2 captured—that’s our North Star. How many billions? We’re just a fraction of that right now, but we have big ambitions.

  Chris Sklarin:
  On the collaboration side—more generally—if you had to pick another company or research institution to collaborate with, who would it be and why? You’re already at MIT, doing lots out of The Engine.

  Cameron Halliday:
  We have collaborators around the world already. We work with universities on various things, but much of our focus right now is commercial. A goal and a core culture of the company is that this is not meant to be a science experiment. We’ve done the science—the science is sound and secure. This is about scaling up and deploying.

  So the partners we’re looking for are the sites—the emitters committed to decarbonizing, not just window shopping. The partners that understand this space and what it takes. That includes the emitter, but also the offtaker, the financiers, and all the stakeholders involved.

  Chris Sklarin:
  Excellent. Well, I was just at the MIT Industrial Liaison Program meeting yesterday about digitization—a different world, not sustainability. But you’ll find lots of partners. I’m sure of it—very much looking forward to it.

  Cameron Halliday:
  And we’ve made a lot of great connections and have a lot of partners that have joined us on our journey. We’re always looking for more folks who think they can help us on our mission.

  Chris Sklarin:
  That’s excellent. Well, I guess to wrap up here, what’s something you’ve learned as a CEO that you didn’t expect going into it?

  Cameron Halliday:
  It’s a good question. I think when I started out, I was told this would be very hard, and I don’t think I internalized it. I think I’ve now internalized how difficult this journey is, but we remain very committed to it. We go from strength to strength as we scale up and prove out what we’re doing.

  What gives me a lot of enthusiasm and hope is when we engage with customers and see their excitement about what this could mean for their sites. That makes all of the challenges worth dealing with.

  Chris Sklarin:
  Yeah. You’ve hit a really strong pain point when they’re ecstatic that you’ve gotten them out of that pain, right? That’s—

  Cameron Halliday:
  Exactly. Exactly.

  Chris Sklarin:
  … super, super important.

  Cameron Halliday:
  That’s very rewarding.

  Chris Sklarin:
  Excellent. Well, for our listeners interested in supporting Mantel’s mission, what’s the most impactful way they can get involved or help you guys out?

  Cameron Halliday:
  Yeah. Depending on who you are—first, people. We’re always hiring and growing very quickly. Commercially, we’re looking for sites and industries that are committed to decarbonizing and want to find a pragmatic, low-cost way of doing so.

  As Chris mentioned, we’ve finished the Series A but we’re starting on the Series B now, so if you’re an investor, reach out. We like to build these relationships early, get to know the investors, their interests, their focus, and what they are looking for. However you might be interested, reach out, connect, and I’d love to get to know everyone.

  Chris Sklarin:
  That’s excellent. Well, thank you, Cameron. We’ll make sure your contact info is in the show notes, and thanks again for spending a half hour with us to chat about Mantel. It’s exciting.

  Cameron Halliday:
  Thank you so much, Chris.

  Chris Sklarin:
  Cheers.

  Cameron Halliday:
  Bye.

  Samantha Herrick:
  Thanks again for tuning in to the Tech Optimist. If you enjoyed this episode, we’d really appreciate it if you’d give us a rating on whichever podcast app you’re using, and remember to subscribe to keep up with each episode.

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