The Limits of Sequestration Potential of Concrete

Under a new partnership, Heirloom Carbon Technologies captures carbon dioxide from the air, then passes it to CarbonCure Technologies, which permanently sequesters it in concrete. In this episode, CEOs Shashank Samala of Heirloom and Robert Niven of CarbonCure give the lowdown on this pioneering carbon removal project.

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David Roberts

Last month saw the announcement of a pioneering project: a company called Heirloom Carbon Technologies will capture carbon dioxide from the ambient air and then hand it off to a company called CarbonCure Technologies, which will inject the CO2 into concrete made by a company called Central Concrete. It will mark the first time ever that carbon from the air is permanently sequestered in concrete.

Heirloom, with runs the US’s only operating direct air capture (DAC) facility, does not use the familiar capture technique that involves giant fans. Instead, it binds carbon to exposed rock and then cooks it out using electric kilns — and then binds more carbon to the rock, in a circular process. It claims the capture is cheaper and more efficient than previous methods.

CarbonCure injects the CO2 into a concrete mixer, where it mineralizes, becoming permanently captured even if the building using the concrete is demolished. In the process, it strengthens the mix, requiring less cement and cutting costs.

Direct air capture (DAC) has faced a great deal of skepticism, and concrete has the reputation as one of the worst carbon offenders, so this project — one of the first that can fairly be called carbon removal — could go a long way toward convincing investors that the former can help the latter change its ways, with a technology that is, at least some day, commercializable.

I talked with Heirloom CEO Shashank Samala and CarbonCure CEO Robert Niven about their respective processes, how they work together, and what the project says about the future of carbon removal.

All right, Shashank Samala, CEO of Heirloom Carbon Technologies, and Robert Niven, CEO of CarbonCure. Welcome to Volts. Thank you guys for coming.

Robert Niven

Thanks very much for having us.

David Roberts

This is really a nifty project you guys are working on together. It's two separate pieces that normally I would probably do a pod on each. So we're going to have to, or at least I'm going to have to be less wordy than normal to squeeze it all in in 1 hour. I want to talk about both halves of it. So let's start with Shashank. The first half of this process is Heirloom’s process of removing carbon from the air. Can you just explain quickly how that process works, what it looks like?

Shashank Samala

Sure. So, Heirloom, if you're not aware of who we are, our goal is to basically remove a billion tons of CO2 from the atmosphere annually by 2035. And our whole goal is to help reverse climate change. And the way we do that is through a process called limestone looping. Essentially what that means is we use a rock that is very abundant in nature, limestone, that has a natural propensity to pull carbon from the air. What we do is we basically give superpowers to limestone to pull a lot more carbon than it otherwise would naturally.

So how it works is we start with limestone, we put that into a kiln, we heat it up, and we pull out the CO2 that's already sequestered in the limestone, which makes the leftover lime highly thirsty for CO2. So we take advantage of that natural property by laying it out on trays. Think about baking trays. I lay them out on trays, and then we vertically stack those trays, very tall, and the air brings in the CO2. And the the lime sitting on the tray acts as a sponge, pulls up the CO2 molecules. From there, it becomes limestone again after it pulls it up. And we do that in about three days.

Naturally, it would take many months to pull carbon from the air. We did that in three days using our well treated algorithms and technology.

David Roberts

So in three days means the lime is full, absorbed as much CO2 as it can.

Shashank Samala

Exactly. We don't go all the way up to 100%. We go up to about 85%, which is sort of the optimal point, we realized. And then, yeah, it becomes limestone again, which is great, because that's what you started with. So we can recycle limestone by putting it back into the kiln, pull out the CO2 we captured, and then store it underground or store it into concrete, which you're doing with Carbon here.

David Roberts

Right. So one of the questions I had is you crush up this lime and spread it out on, well, calcium carbonate is limestone. Calcium carbonate ...

The chemical formula. Exactly right, the calcium carbonate.

And then after you bake it, take CO2 out. Then what is the chemical remainder?

Shashank Samala

Calcium oxide.

David Roberts

Calcium oxide. Right. So you have calcium oxide laid out on trays, becoming calcium carbonate. Then you take the calcium carbonate, cook it, get the CO2 out of it, and then do the whole thing over again.

Shashank Samala

Exactly. We just keep doing that. It's a super simple chemical process to pull carbon from the air.

David Roberts

You have this calcium oxide, and it's absorbing CO2 from the air. That just sounds like an ambient chemical process. How can it be accelerated? What does it even mean to accelerate that?

Shashank Samala

So, technically, calcium oxide, we hydrate it, it becomes calcium hydroxide. Basically, there's a water molecule binding onto the calcium oxide. But essentially what we realized is that there's a specific parameter space where particle size, particle size distribution, thickness of the bed, humidity, temperature, airflow, there's all these different variables that dictate how fast calcium hydroxide likes to bind on to CO2 molecules. So it just so happens that in nature, there's a specific parameter space where this happens, and in nature, it doesn't see that parameter space as often. What we do is essentially make it see that all the time.

And how we specifically do that is really the IP. But we've collected millions and millions of data points over the last few years, doing lots of small experiments, adjusting thickness, adjusting particle size, surface area, all of these things. And we found that parameter space. And as the weather changes throughout the day, we have to change that parameter space. So essentially, we babysit these trays. If you look at, essentially, what this technology looks like is you have these tall stacks of trays, and in the middle, you have a little robot that goes up and down, and every few hours, it's babysitting these trays so that they can be carbonating as fast as they possibly could.

David Roberts

So is this all in a big climate controlled facility of some kind? I mean, presumably, you have to control the climate because you need specific conditions.

Shashank Samala

Yeah. So, fortunately, we were able to not have it be fully climate controlled. So if you actually if you come to Brisbane, our headquarters, where we have this pilot facility, this is actually sitting outside in ambient conditions. Yes. So this robot is actually creating a microclimate for each tray every few hours. So because what we're trying to do is try to symbiotically work with nature to pull carbon, right. And nature gives you humidity and temperature and airflow. Right. We don't want to put forced airflow, these large fans, pushing air through. We want to leverage wind. We want to leverage humidity.

And then when it doesn't get enough from nature, we complement it. We accelerate it with a few things.

David Roberts

And so when you have this calcium carbonate that's absorbed all the CO2 and you put it in the kiln, what does that kiln look like? How's it powered? And how hot does it have to get?

Shashank Samala

So the kiln is actually super simple. It's like your toaster oven. Effectively, it's electric. It can be run by renewable energy. Essentially, it's a metal tube, and you have an electric heating element, and just like your toaster oven, that sort of surrounds it. And then you have insulation ceramic that keeps the heat inside. And then that's it. You essentially send calcium carbonate through that metal tube. It stays in there for the order of minutes.

David Roberts

And how hot is the inside?

Shashank Samala

It's about 850 to 900 degrees C.

David Roberts

Oh, wow. Really hot.

Shashank Samala

It's hot. Electric kilns can actually go way higher than that. That's one of the questions we get. It's like, oh, you're using electricity. Why are you not? You would think that you would use natural gas or some other form of combustion to get that temperature. It's like no, the electric arc furnaces for steel actually go up to, like, 14,000, 15,000 degrees C. So, yeah, we need about 850, 900 C. And then, you know, it's only there for seconds to minutes.

David Roberts

Oh, really? So the CO2 comes out pretty easily.

Shashank Samala

Yeah, exactly. So there's only two things that come out. It's CO2 and calcium oxide. The CO2, it's pure. We capture that gas and compress it. And then the calcium oxide, we reuse it again.

David Roberts

And what's the sort of energy balance here? It just strikes me that it must take a lot of you're saving energy by letting natural conditions do the air circulation and humidifying and all that, but you're using a lot of energy in the kiln. I'm just sort of curious how energy intensive this is per sort of captured ton of CO2. I guess there's not a big comparison base of other carbon capture technologies to compare it against, but well, the lens.

Shashank Samala

We when we first started looking for which approach to use to pull carbon from the air, two things were important to us. One was use abundant, abundant minerals, abundant processes.

David Roberts

Did you start with the idea of mineralization, or did you just come to this with just a blank sheet of paper and say, what's the best way to capture carbon?

Shashank Samala

So I actually came in from the mineralization perspective. So I was looking at rocks. I was talking to lots of scientists working on using rocks to pull carbon because it's just like an abundant mineral to start. And if you want to pull gigatons of CO2. You need to have abundant minerals that are also trillions of tons of rock in the Earth's crust. And then we realized, actually, just using rocks won't get you the economics and the land. We wanted to use as little land as possible. We want to use as little water and energy as possible.

So we needed to engineer it a little bit to ensure that we use as little energy as possible.

David Roberts

In terms of materials, how much is lost in the full cycle of sort of you're mining the limestone to begin with, I guess, right? There are limestone mines around already. Limestones abundant. So you're mining the limestone to begin with. Once the limestone goes through, one of these whole cycles gets cooked, replaced, absorbed, absorbed again, cooked again. How much material is lost in those cycles?

Shashank Samala

So, so far we found very small material losses. Essentially, that's one of our main metrics over the last couple of years as we were scaling it up to actually putting this outside. And one of the things we get, it's like, hey, if you put these rocks out there, doesn't the wind blow everything off? Essentially what happens is when this is hydrated, it actually turns into a crust. It's like a cake. So, yeah, we've seen very small material losses, and we will continue to tweak the entire process to reduce it even further.

David Roberts

But your materials are pretty cheap. They're not the big cost center.

Shashank Samala

It's not. I mean, the material itself is like less than half a percent of the entire CapEx. Limestone is, You can buy it for $20 or $30 a ton. It's the second most mine material on the planet. You have way more than you need.

David Roberts

One additional question I wanted to ask about the process is you make a big deal about modularity. And this is a subject close to the heart of Volts listeners. We just did a pod a few weeks ago about sort of what kinds of technologies get on learning curves and what kinds don't and sort of what features of a technology lend it to rapid learning. And one of those features is of course modularity is it have easily reproducible bits. So just say a little bit about how you sort of had that in mind as you designed the process.

Shashank Samala

It was absolutely number one for me. I come from a manufacturing background. Before this I had an electronics manufacturing company where we basically built lots of circuit boards in a factory. One of the things that humanity really understands and knows is how to build things in mass volumes with a very steep learning curve. Right? And we saw that with solar panels, lithiumion batteries, cars. Tell the team here it's like you're trying to build cars, not airports. Right? Airports are on site custom construction and the folks who are working on one airport are not going to the next airport.

The learnings don't don't translate.

David Roberts

When people think about a big direct air capture facility. I think probably what comes to mind is something like an airport, a big bespoke one time thing, but you are trying to avoid that.

Shashank Samala

Yeah. So there's a difference between modularity and the plants, right? So the plants themselves need to have modules that are mass produceable or built in a factory so they can just be brought to the site, bolt them to the ground, ready to go, instead of having to build up from the ground up on the site. So essentially you're trying to minimize on site construction. So there's always like solar panels, right? They need to be bolted down to the ground. There is some concrete slabs involved and wiring and plumbing, et cetera. But you want to minimize that as much as possible and that's the fundamental idea behind Heirloom.

Like our tray is basically the smallest module and we make lots and lots of trays.

David Roberts

One doesn't think of trays as something that have a lot of room for innovation. Is there anything special about the trays?

Shashank Samala

There's a few things that are custom and it so happens that the world, we needed such large trays that we went to the vendor that makes the largest trays in the world and they just would not make the trays that we needed. So we actually make custom trays. Yeah, they're large, so we make the world's largest trays. They use traditional manufacturing processes, extrusion, thermal, formula, et. They're not complicated and that's one of the principles behind Heirloom too. We don't want to come up with a new manufacturing process. The world has immense just lots and lots of experience building all sorts of things and we just want to leverage them and scale them to the max because that's how you get 2 billion tons of CO2 remove it as fast as possible.

David Roberts

So the trays a module, the trays stack.

Shashank Samala

Are also and the next level of module.

David Roberts

Is a module. And presumably the kilns are pretty standard issue. They don't have to be tweaked or whatever for individual.

Shashank Samala

Yeah, traditionally, if you go to a cement factory, kilns are actually these massive onsite built kilns. But we use an electric kiln technology that we're actually going to be releasing a few weeks here that is modular. So you essentially stack a couple of cylinders on top of each other.

David Roberts

Oh, interesting. So you did a little design work of kilns of your own?

Shashank Samala

Yeah, we did some here. We were working with a technology partner to do that too.

David Roberts

This whole process, presumably, if you sat down to try to figure out what's the best process for capturing air carbon, you looked at the traditional. I think when most people think of direct air capture, if they think of it at all these days, the few people who think about it at all think about the big machines out in the desert with the fans sort of pulling air over a sorbent. Is your process more efficient than that in terms of sort of energy and material input versus CO2 output?

Shashank Samala

Yes. At the end of the day, what we're trying to do is use abundant materials that are incredibly cheap and use as little energy. That is thermodynamically possible. Really, all of our energy is in that back end where we are regenerating the sponge, which is common across all directory capture technologies. That's sort of second law of thermodynamics. You have to put in some energy to regenerate the sorbent. And for us, we want to essentially lower that regeneration energy as much as possible and then not use energy when we can leverage nature and other things.

David Roberts

It strikes me then that the cost of energy is going to be one of your big top line items. How big is the cost of energy in your overall picture?

Shashank Samala

At scale, it's more than half. And that's exactly where you want to be, right? Because laws of physics tells us that you have to put in energy to do gas separation, especially gas separation that is as hard as 400 parts per million. So if you design a system and you look at the long term economics, you want to make sure that, you know, at long term, almost all of all of that is energy, because that's something you cannot beat. Like energy creates your cost floor.

David Roberts

Right.

Shashank Samala

If your CapEx ends up being a much bigger proportion, well, you haven't really designed or engineered it. Well, that's what I tell the team. It's like you want your cost floor to determine by physics and not engineering. So that's why we use very simple trays. We're just putting a bunch of rocks and a bunch of trays and using a metal tube, on the other hand, and putting some insulation around it. So you want to keep that as low as possible so that your your $100 a ton. That's really our cost target. You've probably heard of the cost target.

$100 per ton. That's really the cost point where it's affordable for humanity to do this at a billion ton scale and actually make a meaningful impact.

David Roberts

And of course, it's like renewable electricity is galloping down the aforementioned cost curve. So insofar as you can hit your ride to it, it's going to tear you down the cost curve too.

Shashank Samala

Yeah, exactly. The nice thing about renewable energy for us is you can pull carbon from the air anywhere, right? It can be in the Gulf Coast. It can be New Zealand, it can be South Africa, India, Indonesia. Wherever you go, the concentration of CO2 in the air is exactly the same. And that's what our technology works with. So we will go to places where renewable energy supply is high, but the demand is low, so we don't take away the supply that could have been used for food production or putting our buildings.

David Roberts

So ideally then, these facilities would be colocated with some big renewable energy just to minimize ...

Exactly.

Transmission costs and all that. Two final questions. One is, you mentioned the $100 cost per ton target. Can you give us a sense of where you are on the road to that? Is there a number?

Shashank Samala

Yeah, so we're in the sort of high hundreds of dollars per ton right now and essentially we are at the demonstration scale, right? We are building this by hand, engineers are building them. We built a couple of Formula One cars effectively, and we need to get to a stage where we can mass produce Toyotas off of the factory line. What is Formula One cars cost these days? Like millions of dollars versus $20,000 Toyota. So at the end of the day, the material inputs are so cheap, limestone and trays and metal tubes, that at scale, we should be able to hit that cost.

And for us, it's all about how do you get there as fast as possible.

David Roberts

Yeah. And if you're chosen super cheap material and renewable energy, which is super cheap, and if those are your only two inputs, logic says you're going to get cheap eventually as you approach the cost of the materials. So the final question is this. At the end of this process, you have CO2, which you can do anything with. Are you deliberately staying out of the business of doing something with it? I mean, is the model always to just hand off the CO2 to someone else who's going to do something with it?

Shashank Samala

Yeah, there's a lot of things you can do with CO2, but for us, there's only two things you can do so far. One we are looking at is concrete, working with folks like CarbonCure and putting it underground. And both are permanent. And an incredibly important principle is permanence because CO2 stays in the air for 1000 years. So you don't want to pull carbon from the air only for that gas to go back in the air ten years later, 100 years later, we're just pushing the buck into the future. So for us, it's incredibly important that we permanently sequester it into something so it doesn't come back out.

And the only two things we've found so far with that type of over 1000 year durability is concrete, where essentially you're binding CO2 into a rock, it mineralizes and then putting it underground. And that is something that humanity has over five decades of experience putting CO2 underground. And it's permanent and we know it's safe.

David Roberts

But are you planning at all to get into the permanent storage business? Or is the idea that you produce the carbon and some other entity is running the storage facility, how does that work?

Shashank Samala

Some other entity is running the storage facility. We're going to be focused on really building an incredibly efficient, cost-effective capture system. And we will work with a whole set of partners to put a billion tons of CO2 stored somewhere permanently.

David Roberts

I've heard you say this in other interviews, too. But just to be clear, the vast bulk of it, especially once we get scaling up towards whatever, billions and billions of tons, the vast bulk of that is going to be stored in underground caverns. The amount that can be used in a way that permanently sequesters it is a relatively small fraction of the total amount that's going to be produced.

Shashank Samala

Yeah, I mean, as much as possible, every ton of concrete we can put CO2 into, we will do that. That is our first priority. Right? Because essentially you're creating a stronger building material. It's a value added product and it's permanent. You're checking all the boxes and that's better than putting the waste underground. So every ton of concrete, we can do that. We will absolutely want to do that. And when we can't, we will put that underground. And most likely at a gigaton scale, most of that will likely be underground, but it's hard to predict the future, right?

David Roberts

Right.

Rob, let's talk to you then, because here is where we get to the part of the relay race where Shashank hands you the baton, or rather hands you a bunch of tanks of CO2. So describe for us then the CarbonCure process, which starts with a source of CO2. You get the CO2 from Heirloom and then what?

Robert Niven

Sure, I'd be happy to jump into that just to help the audience understand, is we're both carbon removal companies, but coming at it from both ends of the process.

Shashank on the capture ourselves on the relay race, receiving that CO2 and doing something with it. CarbonCure has been in business for about ten years. We're a Canadian company and we have about 700 plus customers worldwide that every day are using CO2 to mineralize it in concrete. To make a better, stronger concrete that provides some cost efficiencies by cement efficiency. By making stronger concrete, you need less cement which provides that economic incentive.

And low carbon concrete is in great demand in the market, not only private sector, but we're seeing a lot of policy incentives as well.

David Roberts

So you're in the business, you're sequestering carbon, you're doing it today, you're getting CO2 from someone and sequestering it in concrete. Do you have any what's the current scale so we can get our heads around kind of what's involved there?

Robert Niven

We have everything connected through the cloud and you can actually pull up our our home page and you can see the numbers go up every second about how many metric tons and it's just about 250,000 metric tons to date. So the key difference here is that most of our CO2 to date is received from what's called post-industrial sources. So these are our large emitters and rather than diverting those emissions into the atmosphere, they're capturing it, compressing it. And companies that are industrial gas companies are taking that CO2 and selling it to a multitude of different industries.

And we're a relatively new user of that CO2.

David Roberts

The big one is beverages.

Robert Niven

Food and beverage is a big one. Yes, food and beverage. Also some CO2 is used in things like enhanced oil recovery which some other DAC companies are pursuing. So lots of different ways that you can use CO2. But the main point is there's a large existing commodity market for CO2. The key thing here and what's really special about our work with Heirloom is that this is direct air capture source of CO2, right? And by getting CO2 from the air it allows you to actually reverse the effects of climate change and pull down the parts per million of CO2 in the air rather than limiting and reducing the rate of emissions that go into the air, so there is a distinction.

David Roberts

Additionality is the term of art here. This is 100% additional CO2.

Robert Niven

Well, I would still say that it's also additional if you're using postindustrial CO2. The key difference here is like this actually enables you to get into removal, a pure removal kind of category.

David Roberts

Right.

Robert Niven

For ourselves, we've always seen this as we'll develop huge and a multitude thousands of storage centers, which is also called a concrete plant to most people. We'll run ahead as fast as we can and develop all of this demand for CO2. And then as DAC gets online is that we'll have the optionality to be able to use that CO2 when it's available.

David Roberts

Will there be degrees of greenness of concrete depending on the source of CO2? Have you thought about that? Sort of like different levels of concrete?

Robert Niven

I think so. We sell carbon credits as part of our business model and we definitely hear from our credit buyers is that they're willing to pay more if it's using atmospheric sources of CO2.

David Roberts

Interesting.

Robert Niven

Such as DAC or biogenic source or whatever it is, whatever can get CO2 out of the air. There is a demand for that. The other group that really matters are the people that purchase the concrete. So these would be architects, engineers, building owners. They're also really excited and probably not as sophisticated on the CO2 sourcing question, but I wouldn't be surprised if that starts to become higher in their consideration. The other point that was brought up by Shashak earlier was permanence. That is very, very important for everybody is we don't want to be going through all of this trouble to put away CO2 for it to just bubble out again in 30 days, like what's the point? So that's very important.

David Roberts

So when you say you inject CO2 into the concrete process, spell out a little bit what that means, what that looks like for people who are not that familiar.

Robert Niven

Most people, if they're familiar with CarbonCure are aware of our readymix technology. But CarbonCurever the last three years has expanded by creating technologies that use CO2 in the concrete value chain in different ways. But let's start off with the ready mix technology. So whenever concrete, if anyone's visited a concrete plant, there's about 125,000 of these locations worldwide, about 7000 of them in the US. They're basically all the same. They are mixing sites that take aggregates, rocks, cement, water and a few performance enhancing chemicals to mix those all up in a huge mixer. And then they pour that into a concrete truck, which you are all aware of and seen driving around the road.

And then that's delivered to the construction site so that if we go back and look at that mixer is all those ingredients are being added. And just like Shashank is like if we're really going to meet scale is we want to have a modular system that in our case retrofits these existing concrete plants very, very cheaply and very very quickly without disrupting their production. In fact, it takes us a day, we don't charge any CapEx and the system starts to use that is enabled to start using that CO2 and becomes a carbon removal factory. It starts mineralizing CO2 the next day and it has all these value added benefits without creating a price premium on the product.

David Roberts

Oh, interesting. So this is not some bespoke process that you have to build a concrete plant around. You're literally just going to an existing concrete plant, slapping something on that takes a day to add and then from the concrete plant owner's perspective, that's it. Nothing else changes. They don't have to do anything else operationally to accommodate this at all.

Robert Niven

We automate everything. That's the key. And it's the same design principles that Shashank has brought into his company. Of course, he's done it fully, separately is you want to make this as simple as possible to scale because the concrete industry just does not have the discretionary budget to start. Spending a lot of risk capital in these kinds of solutions. So we've done all that for them.

David Roberts

And they're very small C conservative too, for obvious reasons.

Robert Niven

Perhaps it comes in all different flavors of concrete producers, but they all want to work on this, but they have a lot of limitations. So what we've tried to do is make it as simple as possible, but also do it in a way that they receive the most rewards and that can be in the form of cost efficiencies and production, being able to tap into this rapidly growing demand in the market for low, so they can sell more. We always recommend to keep the price at parity and also participate in carbon markets. So we create the incentive structure and make it really simple to adopt and quick so that producers can start to mineralize CO2 as quick as possible.

So back to your question how the process looks like is we're actually adding CO2 into the mixer and please come to our website as well. We actually have footage and video of what's happening and then we also have some animation on what's happening at the chemical level. But essentially by adding CO2, it's a very similar type of reaction and thermodynamics as Heirloom. And that that CO2 is very quick to react in seconds with the concrete and it reforms a mineral, a calcium carbonate, if we go back to that again, but in a specific size called it's a nanomaterial, which provides all these performance benefits for concrete as it develops its strength, which then leads to some commercial benefits.

And then we also use CO2 to treat the main wastewater from the plant and that's called our reclaimed water technology. So it's a second way that we can mineralize a lot more CO2 on the concrete plant, but at a different site of the concrete plant where all their wastewater is being collected is we can actually treat that water to have it upcycled so it can be reused instead of version cement and water. And then finally we can make CO2 into aggregates, but all three of those can be bundled together to be able to drive down the carbon footprint of concrete.

David Roberts

Yeah, this was my question when I was looking at your website. If I'm a concrete plant owner, can I get all of those versions? Like, can I get CO2 in my wastewater and CO2 in my mixer and CO2 in my aggregate? And are they additive? Like, will that result in three times the carbon removal?

Robert Niven

Yeah. And that's how we're building this business, is to create multiple ways to mineralize CO2 in the concrete value chain and then surround that by doing all the enabling work. So we make it a very easy decision for concrete producers to do that. I will caveat that we don't have the aggregate technology commercialized, but the other two we do. In fact, we had the first pilot with Heirloom that was at the Central Concrete Facility, which is a division of Vulcan Materials in San Jose, California. That plant is the first in the United States to have the reclaimed water and the ready mixed technology.

So they're one of now two plants in the US. That are able to provide that combo, which is really exciting,

David Roberts

Interesting and do the strengthening benefits you're talking about, do you get double those too? When you do both the stages of adding carbon.

Robert Niven

The ready mix technology gives you that strength benefit and then on the reclaimed water, jury is still out on redefining the strength benefit. But what it definitely does is it allows you it's a substitution effect, is that you're actually able to recover the cement in that wastewater and then use that instead of virgin cement. So at the end of the day, it's the same effect using less virgin cement to make concrete.

David Roberts

Right.

Robert Niven

But you're achieving that by mineralization. What's cool about the reclaimed water technology is we actually won the Carbon Xprize for this technology, which was defined as the world's most scalable CO2 utilization technology.

David Roberts

Interesting. What happens to the water today? Is it just thrown out or what happens to the reclaimed water?

Robert Niven

Most of it just gets thrown out today. The traditional way of doing that is it would go into large settling ponds, they would scoop out the settled material, which by the way, is valuable cement and chemistry. That producer paid a lot of money for. And there was a lot of CO2 release to make that that would often just get landfilled and then the water would get sometimes treated for PH and then discharged. So we're able to turn all that process and eliminate it by reusing it in a circular manufacturing type of design.

David Roberts

Interesting, a question about the strength benefits, are the strength, by which we just mean the cement is a little stronger and so you have to use a little bit less cement in the concrete. So your savings that way, are those savings in terms of strength enough to pay for the thing? Or do you have to value the sequestration on some level to make this pencil out?

Robert Niven

We are able to provide the low carbon concrete to the market in combination through our carbon credit sales and through these manufacturing efficiencies of using less cement, we're able to provide that concrete at no price premium by using a blend of both contributions. And that's very important. Like a year ago, if you go onto your podcast catalog, Rebecca Dell was on the show talking about how green premium is really, really important. We need to find ways to eliminate that to unlock adoption in building materials. And green premium is really anything can inhibit mass adoption. That's what's really important is that we don't apply that green premium.

So that the market whether that be the government which is the largest buyer and we're seeing a lot of buy clean type legislation or private sector which have a lot of sustainability targets from corporate actors are able then to make these kinds of procurement decisions without compromising on price and certainly not compromising on quality, and working with the same suppliers that they've worked with for years prior.

David Roberts

Maybe this is a naive question, but if I'm a concrete manufacturer and I can have this done and installed in a day, it's not going to affect my operations. It's going to save me a little money on reducing cement, it's going to make me a little money on selling carbon credits. And otherwise I'm selling a more or less identical product at a more or less identical price. Why wouldn't I do that? What would stop someone from doing this?

Robert Niven

Yeah, I would say just education. But we're already, like I would say I don't know for sure, but probably the fastest growing technology in the concrete sector. Concrete sector is not known to be rapidly adopting new technologies, but I would say we are growing at a very rapid rate. And certainly there are different kinds of concrete producers which normally adopt technology faster than other types of producers profiles. And we're seeing that happen. And the rate of adoption is happening far faster when we see those market signals like the procurement policies or even requiring environmental product declarations in the procurement process.

So those kinds of things really accelerate this transition to the market. There's a reason why so much innovation is happening in San Francisco in the concrete sector, is because there's a lot of companies that operate there that are really walking the talk. And the concrete industry is enabled, empowered to bring their best forward. But if concrete producers are in markets where they're never hearing someone talk about decarbonisation, yeah, they have 20 other things that, that they can prioritize, that they need to work on.

David Roberts

Right? So you need some valuation of the carbon benefits to kind of push this up to the priority list.

Robert Niven

And it doesn't have to be a premium, right. When you say valuation, it just needs to be identified. Like an example would be of Microsoft. When they're building, they're asking all of their suppliers to say, I want to reduce our carbon target by X. And then they go around and they say, what can you do for me? What can you do for me? What can you do for me? When the concrete producer hears that loud and clear, and they may win that bid over a competitor if they have some ideas and they can bring something to the table.

David Roberts

I want to get a sense of scale before we move on from the process. Sort of if I'm producing concrete and I'm using your process to inject CO2, say I do both of the available options and I get CO2 injected into my wastewater and I get CO2 injected into my mixer, is the end product of that carbon negative or how close is it to carbon negative? Give a sense of scale, like how much of the carbon in the process is being offset by this?

Robert Niven

Yeah, it's one piece of the pie. To get to carbon negative or neutral concrete is we're going to need some substantial changes on the cement side as well. And there are some fellow companies within our investors portfolio. A great example would be like a Brimstone who are working on the cement side. We're working with whatever cement is coming down the line and we're adding if you sort of combine the reclaimed water and ready mix, you're getting another 10% to 15%. But that's 10% to 15% off of a global commodity with a huge volume and we can do it today with very little CapEx and it's permanent.

So if you think about a marginal abatement cost curve, it's like this is the furthest left on that curve. This is the thing that is easy to implement at scale. It has a significant percentage reduction, but off of a huge number, the volume of concrete is enormous. There's about 40 billion tons of concrete produced or 4.2 billion tons of cement.

David Roberts

And what's the number? I think it's 8% of global emissions, something like that.

Robert Niven

We use the word the number 7% and most of that's cement. And the reason it's so big is because so much concrete is being used, it's second only to drinking water in production. Yeah.

David Roberts

So you can take 10% to 15% of the CO2 basically out of the final product, but more than that is going to require deeper changes in the process.

Robert Niven

And that doesn't include our aggregate technology. So that will layer in a lot more. But we need to work together all the way along the value chain. The traditional cement sector are doing things like they're using supplementary cementitious materials instead of cement and that means using things like fly ash and slag. The problem is those materials are declining in availability, they're doing things like fuel switching, so using waste materials, energy efficiency, all those traditional things should be done. But then there's also some real deep tech stuff going on right now about fundamentally changing the cement process or chemistry.

But that's going to take a lot of money and we still have a lot of time ahead of us. So we need to get going today on those immediately deployable solutions.

David Roberts

Right, so you've got a solution here you can just slap on existing concrete, plant boom, you get your ten to 15, maybe a little bit more CO2 out.

Robert Niven

And we've shown that this is not only applicable in the United States, but we're operating in many many emerging markets and really only about 2% of cement is being produced in the US. It's the emerging markets. That's where we really impact climate.

David Roberts

Right. And that's where it's growing.

Robert Niven

That's where people is in concrete they haven't built out. There's a lot of population growth and we're already going into those markets now because we know that it takes a bit of incubation time and in some markets we're seeing that already entering into that scaling phase.

David Roberts

So you need CO2 as an input to your process. Is there any supply issue? CO2 easy to get and I'm also curious how much you pay for Heirlooms CO2 versus more traditionally acquired CO2? Is there a big price differential?

Robert Niven

So the first part of your question is, is there supply chain issues? Yes. Our industry, the concrete industry has been massively impacted over the last twelve months by cost and supply of cement and in our case cost and supply of CO2. Really? Believe it or not you can't buy CO2 in certain markets.

David Roberts

a shortage of CO2.

Robert Niven

And the price is skyrocketing because of it.

David Roberts

No kidding.

Robert Niven

It's a really perverse situation. So we need a lot more air loops and we need them to get them into market faster to start to diversify the supply of CO2 because some of the traditional emitters that you would have been collecting that CO2 are now changing their process so that that CO2 isn't becoming available anymore. Ethanol is the largest supplier of CO2 in the industrial gas market in the United States. So today if the price varies so much it's largely dependent on transportation. Very commonly we're paying well over $500 a ton for CO2. We haven't gotten to that stage with Heirloom where they have the volume, the capacity to have those discussions yet but we really encourage them to move along as fast as they can to get to that billion ton target because that gives us a lot more CO2 that we can work with.

So we're exploring all different options for CO2 supply because just from a supply constraint or supply chain disruptions we're very encouraged to solve for that problem now.

David Roberts

It's just something that sort of kind of confuses me. And maybe you both can take a swing at this answer, but I'm seeing a process here at your demonstration plant where we're digging a limestone up, doing a bunch of stuff that strips the CO2 out of it, and then injecting the CO2 back into the concrete process, where it then becomes limestone again. Why not just dig up the limestone and put it directly in the concrete? It seems like a lot of physical processes to sort of end up where you started. Maybe just sort of help me understand that kind of how is this not kind of running in place in sort of energetic and CO2 terms?

I'm sorry if that was a very vague question.

Shashank Samala

What we are trying to do is pull CO2 that is already in the air so you need a sponge to pull up that carbon and we find that calcium oxide which is derivative of calcium carbonate is highly alkaline. It's highly thirsty for that CO2 and then that's how you create the limestone and then you're essentially looping the limestone through the cycle.

David Roberts

The limestone you're finding that you're mining has already absorbed CO2, right? That's what it's been doing. It's what it's been doing. So in a sense, it's already absorbed it. Why not just put it directly into the concrete, do you know what I mean?

Robert Niven

Yeah, maybe my perspective solves that on that bit better. The way that I think about Heirloom is if you take a sponge and you put it into your kitchen sink and then you pick up collects water and then you squeeze it out, then you put it back in and squeeze it out. So it just happens to be calcium. But for our process, there may be some listeners who are from civil engineering and understand concrete a bit deeper, and they say, well, concrete already carbonates, right? So there is a natural process that's already happening, but that's limited to the exterior skin of concrete and it's not value added, it doesn't provide those performance benefits.

So some way of looking at that is like, yeah, if you left concrete exposed to the air for 1000 years, which not too many buildings are around for a thousand years, is you might get that full carbonation extent. But even if you did that, you wouldn't get all the benefits, the performance enhancing benefits that come from carbonating actively in a certain way that create this nanomaterials, which provides the cement savings. And it's also done in a very short time frame within seconds. And so that's a key difference here is the time. And the other thing is, if you let carbonation happen passively, that's called weathering carbonation is it actually has the opposite effects on performance.

David Roberts

Oh, really?

Robert Niven

Yeah, it'll actually cause the PH to drop and then it will make the steel corrode, which makes said structure made with that concrete to have durability issues and may fail. So engineers like myself are trained to limit carbonation because you don't want that carbonation layer to get to the steel, because then that causes that concrete to fail. So you take many, many steps to stop that from happening. The way that we're doing it is different in that we're actually deliberately carbonating to a certain extent. So you get all these performance enhancing benefits and that's a really important nuance.

David Roberts

One question is this sort of demonstration project of Heirloom on the one side, CarbonCure on the other side, pulling CO2 out of the air, putting it in concrete. I obviously see the benefits in terms of like educating the public, making carbon capture and sequestration more real and tangible to people, showing investors that things are happening here, all these effects. But looking down the roadways is the sort of direct capture to concrete pipeline. Is that going to be a real business? Is that going to scale up? Or is this mostly just for demonstration purposes?

Robert Niven

If they can provide CO2 for less than $500, we've already shown it scalable. Right. So for us, that's the marker. And we're more than happy to work with Shashank and Heirloom because if they can provide us cheaper CO2 on a reliable supply and the market would prefer atmospheric CO2, I'll do that all day, every day. But we're already showing today that using CO2 and concrete is immediately scalable and used in emerging markets, developed economies, what have you.

Shashank Samala

Yeah, the awesome thing about concrete is it's the most abundant commodity, the industrial commodity that we produce. It's like 12 billion tons of concrete that we make. So that's the awesome thing, right? That's why this demonstration, I think, is so powerful. This is not just a small test, that it is a signal for what's to come. And I tell Rob every time I see him, tell me what is the price where we can put CO2 in every ton of concrete that they're at and plants that they're not yet at? Right. To reduce that cost per ton on the concrete plant side, where it is just economical, no brainer for a concrete plan to add Heirloom CO2 into the CarbonCure process.

So, yeah, that's the thing that's exciting.

David Roberts

Has anyone done the math on the total sequestration potential of concrete globally? I mean, do we have a sense of scale here? The limits?

Robert Niven

Well, the theoretical limit is half the weight of cement could be carbonated.

David Roberts

Oh, wow.

Robert Niven

But I'm not saying you want to do that. I'm saying, theoretically, that Stoichiometry says that if there's 4.2 billion tons of cement, you could conceivably mineralize 2.1 billion tons. And that doesn't include all the aggregate. So you put all the aggregate on on top of that. And aggregate is the vast majority, about 85% 90% of the of the mass of of concrete. So you could really get to certainly hundreds of millions low billion tons of CO2 mineralization in the concrete value chain through carbonating, directly through concrete, like what we're doing, or by using CO2 to make aggregates.

There's a few companies that are doing that as well. So it does become sizable. But I really want to emphasize it's, the value added nature and the immediate nature of this, like the time value of carbon is important in climate change discussions.

David Roberts

Yeah.

Robert Niven

A lot of solutions are targeting to come online and start scaling in 2030-something. This is happening now, right? And we need to do as much that we can, especially if there's very little CapEx requirement and no price premium.

David Roberts

So I've kept you long enough, I guess I'd ask the same question to each of you to conclude it's the nature of carbon removal that it's not producing a product that is valuable enough in and of itself to pay for itself. There's going to have to be a market created for removed CO2. We're going to have to sort of generate a market around this if it's going to pay for itself. So I guess I just asked both of you, by way of concluding shashank you first, what sorts of policies can help you or would most directly help you scale up?

Shashank Samala

So two types of policies. One is a compliance market that essentially requires corporations to effectively price carbon as an externality and have a cap for carbon emitted so that carbon that is not abated or reduced needs to be offset and removed. And there's a price for that.

David Roberts

And this is something a few companies are doing kind of voluntarily, right? Like the stripe constellation of companies are basically sort of modeling what that would look like. But that's got to be made law at some point, right? You're not going to get enough voluntary companies to ...

Shashank Samala

No, according to APCC. We need to be removing five to 10 billion tons of carbon from the air by 2050. And if you want to see that type of scale, if you want to see that type of it's a trillion dollar market at $100 a ton. That's a trillion dollars of revenue every year that we need to get to. So it's amazing and we're so fortunate to work with folks like Frontier Stripe, Shopify, Microsoft, who are all early buyers of this technology, but we need thousands more and policy and compliance markets is what gets us there.

The second type of policy is what 45Q is doing today. You may have heard of it. It's a tax credit. It's a direct pay for direct recapture that is stored permanently. So, you know, we're fortunate and, and, you know, really we, we appreciate everyone who, who worked on the Inflation Reduction Act, having that passed last year, that is such an important element. It's at $180 per ton subsidy. It's it's stackable on top of what customers pay us that helps us bring down the cost of, of carbon removal so it is affordable to everyone. So, you know, that is something that, you know, not just the US.

But, you know, every other count ry, europe and Asia should adopt something similar. So compliance markets and subsidies like 45Q really help us come down the cost curve.

David Roberts

Is there a country doing more than the US for this or they are their models to look to where they're going more sort of gangbusters on on DAC?

Shashank Samala

Canada is actually pretty close. I don't think they've passed this yet, but there's a pretty large CapEx, I think it's called the Production Tax Credit that might be even more compelling than 45Q depending on how that's written. So, yeah, super fortunate that US and Canada, that is the type of competitive battle we want, right? This sort of geopolitical competition to see which country can help us decarbonize the planet. And in the past it was some countries in Europe that were sort of good hearted and have these policies like the subsidy for solar in the early 2000s.

But now you're seeing countries compete against each other to bring clean tech and climate tech into their country. So I think it's warring from a good hearted nature to a competition, which is exactly what the planet wants. So that's what we should all be up to, optimistic and excited about.

David Roberts

And how about you, Rob? What's your policy wish list? What's on top?

Robert Niven

I would echo what Shashank said, certainly. And about we need many more credit buyers of some of the same names, like the Shopifys and Stripes. That really the Microsoft's and Patches that drove the world of demand for these credits. 45Q, for sure. For us, though, the most important policy are these low carbon, concrete, or buy-clean type procurement policies.

David Roberts

Right.

Robert Niven

New Jersey just passed landmark policy just a couple of weeks ago. It was based upon similar work done in New York and Hawaii and California. We saw a lot of it in the Federal Infrastructure Act. That's what really drives us.

David Roberts

Are there federal procurement buy-clean elements in the Infrastructure Act?

Robert Niven

Yes. If I recall, it's about $4 billion in incremental spend on low carbon material purchases. That is very important for our business, and that's what will drive the storage piece within concrete especially. And then that in turn will drive the DAC side or the carbon capture side. So that was really important. And they're designed in a way that also requires a strong reporting element using LCA documents like environmental product declarations, and you need those to compare the different options in a third party verified way. So that procurement policy is very important based upon the kind of models like we're seeing in New Jersey with its LECCLA Bill.

David Roberts

Interesting. Well, thank you guys for coming on and walking us through. It's really interesting. I think if nothing else takes a very abstract discussion, what can often be a very abstract discussion about carbon and carbon removal and all this and just makes it very tangible. One of the things I love about this is that on both sides, this is not PhD chemistry or whatever. It's trays of rocks and squirting CO2 into a mixer. I love the there's a ruggedness, I guess, to simple processes that I really like. So it's been really fun to talk through.

Robert Niven

You're welcome. Although I will say we have a lot of PhDs working on our team as well, so I don't want to diminish the great work that they're doing to make it look this simple. You need to work extra hard.

Shashank Samala

Yeah, exactly. There's just a lot of engineering and science that goes into making things simple and scalable. So, yeah, you have lots of PhDs and great engineers on the team.

David Roberts

All right, Shashank Samala and Rob Niven, thank you so much for coming on and talking us through. This is super fascinating.

Shashank Samala

Thank you so much for having us.

David Roberts

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