---444395:Widescreen?$responsive$&qlt=90,0&resMode=sharp2&fmt=webp "Can we carbon-capture our way out of climate change?")
C&EN’s award-winning podcast Inflection Point leans on our 100-year archive to trace headline topics in science today back to their disparate and surprising roots. In each episode, we explore three lesser-known moments in science history that ultimately led us to current-day breakthroughs. With help from expert C&EN reporters, this show examines how discoveries from our past have shaped our present and will change our future.
In this episode, hosts David Anderson and Gina Vitale travel back in time to understand how we are capturing carbon at the source and removing existing CO2 from our atmosphere. They also bring in C&EN reporters Alex Scott and Fionna Samuels to explain how CO2-scrubbing technology from a 19th-century submarine is still basically used today and how making the ocean more basic might help us mitigate our emissions.
Subscribe to Inflection Point now on Apple Podcasts, Spotify, or wherever you get your podcasts.
The following is a transcript of the episode. Interviews have been edited for length and clarity.
Gina Vitale: So David.
David Anderson: Yes, Gina, what’s up?
Gina: What am I looking at right now?
David: Oh, you mean this, this kooky-looking machine?
Gina: Yeah.
David: Right in front of us?
Gina: It looks kind of like a telescope on top of a ruler on top of a pipe.
David: Yeah. Honestly, I don’t know what any of those parts are, but the machine itself is a bolometer.
Gina: Bolometer. That’s not a real machine.
David: Yeah. Well, it is—or it was. We use versions of it today. This is the very first one. We’re here in 1878, and a scientist named Samuel Langley has just invented it.
Gina: OK. But sorry to be a little dense here, but what does a bolometer do?
David: Well, Langley here was trying to measure the surface temperature of the moon.
Gina: Temperature of the moon. Why?
David: Gina, come on. You don’t want to know what the temperature is on the moon? You’ve never wondered what the temperature—
Gina: I don’t know if it’s top of mind for me.
David: OK.
Gina: Like, “Oh, wow. I wonder what the temperature’s like on the moon. What’s the humidity? What’s the dew point?”
David: Yeah, I get you. Maybe I think it’s because nowadays we have a different perspective of the moon. Back then, they thought it was made out of cheese.
Gina: Oh, well, that is not true.
David: And so—
Gina: They never at any point really thought it was made out of cheese.
David: —maybe he wanted to know if it had spoiled.
Gina: David, what are we doing here in 1878? Why have you dragged me back to the 19th century? Why does the moon-temperature machine matter?
David: All right. Yeah. Enough fooling around. I will tell you exactly what’s going on here. Armed with Langley’s observations about the moon temperature, another scientist, Svante Arrhenius, was able to calculate how increasing CO2 levels would affect our atmosphere.
Gina: OK. So we’re here in 1878 to learn about how carbon dioxide is driving climate change?
David: Yes, but more importantly, in this episode as a whole, we’re exploring the little-known moments in history that have helped us combat the increasing levels of CO2 in our atmosphere. For instance, we’re going to go back to 1858, where an inventor trying to make a self-sustaining submarine came up with a way to remove carbon dioxide from the air.
Gina: OK. And if we’re doing that, we should also explain some of the other ways we’ve learned to remove CO2 from the atmosphere.
David: Right.
Gina: And to use carbon capture technology to stop it from getting out there in the first place.
David: Sure. And then we’re going to go to Guatemala in 1988, to the birth of carbon-offset projects.
Gina: We’ll also take a look at how well all of this stuff is working. What technologies are still on the horizon? Can carbon capture and removal save us from the threats of a rapidly warming climate?
David: Well, I really hope so.
Gina: Me too.
David: What do you say, GV? Do you want to fire up the time machine and figure this whole thing out?
Gina: Let’s do it.
David: All righty. Let’s go back in time.
Gina: This is Inflection Point.
David: Spanning a century of reporting from C&EN, this new podcast traces discoveries from our past—
Gina: —to how they shape our present—
David: —and will change our future.
Gina: I’m Gina Vitale.
David: And I’m David Anderson.
Gina: OK. So we are here in 1878 because this guy’s moon-temperature-measuring machine.
David: The bolometer, yeah.
Gina: The bolometer, right. That eventually helps us calculate basically for the first time that rising levels of CO2 could seriously warm the atmosphere, right?
David: Right. The moon-measuring machine helped us understand how CO2 could warm our atmosphere. It’s kind of weird, but I will explain exactly what’s going on. You see, Langley uses his bolometer—
Gina: Counting on it.
David: —to measure the temperature of the moon. He wanted to know what effect our atmosphere had on the Earth’s temperature by contrasting it with the moon, which I’m sure you know, has no atmosphere at all.
Gina: How? How’s he doing this?
David: Yeah, I get it. It sounds kind of like a stretch.
Gina: It does.
David: But I’m going to explain everything. First, we need to revisit some principles from your middle school earth science class. How well do you remember that curriculum?
Gina: Not super well.
David: OK. Well, maybe with a visualization exercise, you’ll jog your memory here.
Gina: OK.
David: So just picture yourself back in your classroom.
Gina: OK.
David: What do you see?
Gina: Let’s see. I’m at my old desk. I’m seeing a lot of weird posters. There’s a picture of the solar system I think still has Pluto in it. Some weird motivational poster of a cat saying, “Hang in there.” OK, I’m in the mindset.
David: Right. You can see the back of my head. You’ve been throwing little wads of paper at it all day long.
Gina: Yes. Yeah. Have those been reaching you, by the way? Because you’re a little far, but I’ve—
David: Very much they have. Yes.
Gina: I’m really throwing my arm to try to get there.
David: A little distracting. Yeah. Oh, I feel it.
Gina: Good. OK.
David: Yeah. Yeah, yeah, yeah.
Gina: Good. Yeah.
David: Perfect.
Gina: I’m ready to learn.
David: I’ll step up to the blackboard here. The sun shines sunlight down to Earth, right?
Gina: Yeah.
David: And Earth absorbs that sunlight. Then the Earth reemits this energy as heat. It sends it back out into the atmosphere. And this goes on continuously as a cycle, the sun sending the sunlight down to us and we emit that heat back out from the surface of the Earth. Now, scientists knew even back then that the heat that Earth emits back out is what gets trapped by gases in the atmosphere.
Gina: OK. So let me get this straight.
David: Yeah.
Gina: The sunlight that’s coming into us on Earth in the first place, that doesn’t get trapped? It just gets trapped when we emit it as heat back out?
David: Right, after it’s hit the Earth. It’s kind of counterintuitive, but yeah, the sunlight kind of just breezes through our atmosphere on the way in. But then when we, you know, the Earth, try to send that energy back out as heat, it gets caught up in some of the molecules in our atmosphere like carbon dioxide. It’s those molecules that have come to be known as greenhouse gases. Those, I mean, as you can imagine, they trap the heat like glass in a greenhouse.
Gina: Got it. Greenhouse gas molecules are trapping heat. Makes sense.
David: Yeah.
Gina: Good metaphor. OK. So let me just sum this all up. So the Earth absorbs sunlight and reemits that energy in the form of heat. This is sort of like when a car gets really hot in the sun, and you can kind of put your hand over it, and it’s like radiating some heat out.
David: Yeah. You can just sense the heat radiating off of the hood of the car.
Gina: Yeah, right. Broad strokes.
David: Yeah.
Gina: Very similar. So when the Earth reemits that energy, that energy gets stuck in our atmosphere and warms it up.
David: Yeah. Right.
Gina: I’m following all this so far. I’m grateful for the seventh grade earth sciences lesson, but what does this all have to do with the moon and the moon-measuring machine?
David: Right. Arrhenius wants to figure out how changes in the chemicals in our atmosphere like increasing, for instance, amounts of CO2, how that will affect how hot the Earth is. He needs to start by calculating roughly how much heat the Earth is reemitting after absorbing it from the sun. OK.
Gina: Got it.
David: And then he realizes, “Wait, this guy, Samuel Langley, remember? With his bolometer. He measured the heat that the moon emits towards the Earth.” So he figures, “Well, maybe I can, OK, well, I got these moon calculations. Maybe I can use that to figure out what’s going on with the earth (PDF).”
Gina: Let me just make sure I’m following this. So to figure out how things like upping CO2 might warm up our atmosphere, Arrhenius needed to know how much heat the Earth reemits after it comes in from the sun?
David: Yeah.
Gina: But because he didn’t actually have that base measurement, he basically swapped in a similar measurement from the moon?
David: Yeah. I mean, Earth, moon, close enough.
Gina: Is it close enough? We could just say, ah, Earth, moon, same thing.
David: Right. Yeah. I mean, maybe we’re simplifying things a lot. I’m sure his calculations were much more in depth than the way that we’re describing them here. Can’t go into every detail, but this did actually work out for him. He was able to make some pretty accurate calculations. He was able to calculate.
Gina: Wow.
David: That doubling the carbon dioxide in the atmosphere would significantly increase the temperature of the Earth. And to be fair, his calculations, though they were a little off—he thought it would be warmer than how it turned out to be—but there were still a huge breakthrough. It led us to better understand how CO2 levels would affect the climate.
Gina: So without Langley’s bolometer, the moon-measuring machine, Arrhenius couldn’t have made his calculation, which was one of the early indications that rising CO2 levels might seriously contribute to global warming.
David: Right. And once we figured out that CO2 was a threat to our environment, we started to dream up things like carbon capture and removal to try and mediate the damage. Speaking of CO2 being a threat.
Gina: Oh, boy. Yeah?
David: Sorry, what’s the “oh, boy”? Are you sensing I might say something silly?
Gina: I’m fearful that you might say something ridiculous. Go on. Prove me wrong.
David: My question is, I know that the CO2, that we breathe in oxygen, we breathe out CO2, but Gina, it’s not just down to our breathing, is it?
Gina: Man, I hope not, because I just let out—
David: A big sigh.
Gina: Let out a lot of CO2 right there. Yeah, no. Human society is putting out big numbers of CO2 into the atmosphere. The breathing, that’s not really the big source here that we’re worried about. And couldn’t really change that. But the biggest way we emit carbon dioxide is by burning fossil fuels.
David: Fossil fuels, natural gas.
Gina: Oil, coal, right. And we burn these fossil fuels for energy. We’re burning fuels to generate electricity, to power our cars, to heat our homes. They’re a pretty integral part of our energy system.
David: Yeah. They seem very important.
Gina: Right.
David: But burning a fossil fuel, how does that create CO2 in the atmosphere? What’s the process there?
Gina: Sure. So we can think of ourselves as back in that science classroom, maybe.
David: Yeah.
Gina: Fossil fuels are hydrocarbons.
David: Ow. Just threw another paper ball on my head.
Gina: Oh yeah. Sorry. A little bit of a delay on that one. So fossil fuels are hydrocarbons. That means a bunch of hydrogens bonded to a bunch of carbons. And when we burn them, those hydrocarbon bonds break. The carbon can then react with oxygen in the atmosphere, and it becomes, you have probably guessed it, CO2.
David: Yeah. And why is it CO2 specifically compared to all the other stuff that we have out there that’s such a problem?
Gina: Well, as you mentioned in your first inflection point, CO2 is a greenhouse gas. It traps heat in our atmosphere. And while there are other greenhouse gases that we’re worried about and that are relevant to climate change, things like methane, CO2 is the one that we emit the most by far. And in terms of greenhouse gases, it is kind of a bad one. It does not break down easily, so it really tends to linger.
In a 2013 report, the Intergovernmental Panel on Climate Change, also known as the IPCC, charted out how long CO2 might stay in the atmosphere (PDF). And what they found is a little bit discouraging. They project that after a pulse of CO2 is emitted, about 40% of it will remain in the atmosphere for a hundred years, and about 20% will remain for a thousand years, and around 10% will stick around for 10,000 years.
David: Wow. That is some unwelcome party guest just lingering around.
Gina: Yeah.
David: Thousands of years.
Gina: You know, like, read the room, man.
David: Yeah. Unbelievable. I had no idea that it just stuck around in our atmosphere so long.
Gina: Right.
David: So all this time, it’s building up in our atmosphere and seemingly taking a long time to leave. It’s trapping all this heat and causing global warming.
Gina: Right. That’s why it is such a problem. You unfortunately have nailed it.
David: Well, I guess I’m starting to understand why we’re doing this episode.
Gina: Yeah. There is too much CO2 in the atmosphere. We are churning it out like soft serve, and we need technology to help us with that before the Earth gets too hot. That’s where carbon capture and carbon removal technology come in.
David: Right. And just to make sure I understand this, carbon capture and carbon removal, kind of sounds like those are two different things that you’re describing?
Gina: Yes.
David: OK.
Gina: They both have the same goal of mediating the levels of CO2 in our atmosphere, but they work a little differently. Carbon removal draws existing CO2 out of the atmosphere. Carbon capture prevents newly produced CO2 from getting into our atmosphere in the first place.
David: Right. Carbon capture is the one that I feel like I hear all the time.
Gina: Totally. It’s got a really snappy name, that alliteration.
David: Yeah.
Gina: It’s a big buzzword. So carbon capture is basically when we catch carbon dioxide at the source and stop it from getting out into the atmosphere. Think power plants or big industrial facilities, these are places that are producing a lot of CO2. Without carbon capture, that CO2 would be getting released into the atmosphere, but carbon capture technology traps it before it can get out.
David: OK, cool. So carbon removal, that’s kind of taking it directly out of the atmosphere where it already exists. Then carbon capture, I’m kind of picturing like a smokestack with maybe you put a little balloon over the top of it and it’s kind of filling up with CO2.
Gina: Yeah. I mean, it would be a big balloon.
David: OK.
Gina: This is a chonker balloon.
David: This is a huge balloon?
Gina: Mm-hmm.
David: What do they do after they’ve got this giant balloon or whatever filled with CO2?
Gina: Right. Balloon is probably not the technical term for it. But yeah, once they’ve got the CO2 that they’ve captured, it can be used for other stuff. So, for instance, people can make fuels with it or building materials, but otherwise it pretty much gets buried underground.
David: Interesting. Kind of sounds like they literally sweep it under the rug a little bit. They’re taking it and burying it underground. It seems a little spooky that it’s just kind of sitting down there. I mean, couldn’t someone just kind of dig it up?
Gina: Well, I mean, we are talking really far underground, like about a mile underground.
David: I’ve probably dug that far, I think.
Gina: You have not.
David: When I was a kid, I dug a really deep hole in the sand at the beach and it felt like a mile, so.
Gina: Yeah. And you hit the ocean again, right? You dug so far, you—
David: I mean, explain that? Water was coming up out of the bottom, so.
Gina: I can’t.
David: There you have it.
Gina: Right.
David: Being serious, carbon capture is when we stop carbon at the source from getting out into the atmosphere. Is that the same as direct air capture, another thing that I’ve heard about?
Gina: No.
David: Right.
Gina: The names are really similar, so it’s confusing, but direct air capture is slightly different from carbon capture. Instead of catching carbon as it’s coming out of, say, an industrial plant, direct air capture is focused on drawing existing CO2 out of the air. So it’s more of a removal strategy than a stopping emissions at the source strategy. The actual chemistry can be pretty similar for both carbon capture and direct air capture, but the difference lies in just where the CO2 is coming from.
David: OK. So direct air capture is actually a type of carbon-removal technology.
Gina: Yes.
David: OK. And so when we talk about direct air capture, that’s usually what? In the form of those giant stacks of fans you see in the middle of nowhere?
Gina: Sure. Yeah, that’s a good way to visualize them. Those are carbon-removal devices. They suck in air and they remove CO2 from it.
David: OK. I mean, that sounds really cool, but do you know how it actually works? How do we literally physically grab the carbon dioxide and only the carbon dioxide from the air?
Gina: That’s a great question. It’s probably like a big vacuum or—
David: No, I don’t think so. That’s ridiculous.
Gina: No.
David: I mean, the balloon thing that I was talking about, that makes perfect sense, but a vacuum? Get real.
Gina: So I’m taking to understand that you know how it works?
David: Yeah, if you must know.
Gina: OK.
David: It starts with a guy named Narcís Monturiol. Like all great underdog stories, he’s got a submarine and a dream.
Gina: I don’t think that’s a very common underdog story, actually. Hold on a second. Did you say—
David: No, no, no, usually.
Gina: Did you say “submarine”?
David: Yeah, submarine.
Gina: Wait. OK.
David: Let’s go back to 19. Let’s—
Gina: We’re not going on a submarine?
David: Let’s go back to 1850.
Gina: Right, David? Because we’ve talked about this, and my water—I don’t—
David: Let’s go. I’m struggling with this button here. It’s not quite—
Gina: David, I swear to God—
David: 1858. Here we go.
[Inflection point sound effect: digital blips and tape-rewinding whir]
Gina: Last season, when you mentioned—some might say you threatened—that you were planning—
David: Yes. Some would say.
Gina: —on taking me down to the ocean on a submarine, I thought you were just kind of fooling around.
David: That doesn’t sound like me. Not really one to joke. Kind of a serious, dreadfully serious person.
Gina: I have heard that about you, but I am curious about the integrity of this submarine. It appears to be made out of wood.
David: Yes. The submarine is made out of wood, and it is incredible. Narcís was a really cool and interesting guy. He was a staunch pacifist. He was a feminist. He started a paper called La Madre de Familia in which he promised to, quote, “defend women from the tyranny of men.”
Gina: And boy do we need it. Well, he sounds very cool. Quite a girl’s girl. Ahead of his time.
David: Yeah.
Gina: But how do you know all this about Narcís Monturiol, which is a very cool name.
David: Superinteresting guy. I’ve read a lot about him because there’s this really great book called Monturiol’s Dream by Matthew Stewart. I highly, highly recommend anyone check this book out. This guy was a real character.
Gina: Back to the submarine. So what does Narcís Monturiol and his amazing wooden submarine have to do with removing CO2 from the atmosphere?
David: As you can probably imagine, a big problem with enclosed spaces like this one actually isn’t necessarily running out of oxygen. That could become a problem eventually, but long before that happens, the most pressing concern is actually a buildup of CO2.
Gina: Sure. Yeah. I mean, that makes sense. Carbon dioxide can poison you long before you run out of oxygen to breathe. I remember this was one of the problems the astronauts on Apollo 13 had to deal with.
[Astronaut voice saying “OK, we’ve got a problem here.”]
Gina: It can be fatal. So that’s what this rickety little container is, with the pump attached to it?
David: Yeah.
Gina: This funny little homespun device here is keeping us alive?
David: Yeah. I mean, OK. I’m sensing a little bit of an attitude. You’re banging on the walls of the sub, you’re saying, “Oh—”
Gina: I’m skeptical. I’m wishing I brought some oxygen with me, because I’m—
David:“ —Oh, the CO2 scrubber.”
Gina: —I’m a little scared.
David: “I don’t know about this.”
Gina: Yeah.
David: But you should know that Monturiol was serious about safety. You see, the whole inspiration for this-sub of his came to him after he helped revive a drowning man on the Catalonia coast. The man was a coral harvester, and Monturiol became obsessed with making their profession safer.
Gina: Coral harvester.
David: Yes.
Gina: Sounds like a cool job, actually, right up there with time-traveling podcast hosts.
David: Yeah, it’s close. But believe it or not, back then there was this huge demand for coral for use in jewelry and other luxury goods. Harvesters, these diver guys, would dive down into the ocean and chip bits off of this razor-sharp coral to bring back up to the surface and sell. Monturiol thought this whole thing would be a lot safer if these harvesters could operate out of a submarine.
Gina: Interesting. But he didn’t want them to die in the submarine.
David: Right, of course not.
Gina: So he created this device that scrubs CO2 from the air, right?
David: Yeah.
Gina: But how did he do it? What’s it made of?
David: It’s pretty cool. It’s kind of full circle. He took inspiration from the very thing those people were harvesting, coral. Coral builds their structures by taking carbon dioxide from the seawater and combining it with calcium to make calcium carbonate, a hard white material.
Gina: Interesting. OK. So he tried to replicate this natural process somehow?
David: Yeah. So he started out with old seashells. He’s not going to use coral, because that’s valuable. He’s trying to sell that.
Gina: Right.
David: But they’re also, the seashells, are made out of the same stuff. They’re made out of the calcium carbonate. So he heats them up until all the carbon dioxide burns off of the ground-up seashells. And, all right, we’re going to go one more time. I’m protecting the back of my head. We’re going to go one more time back to the science class.
Gina: I’m going to get around it.
David: Only this time it’s kind of a high school chemistry class, so.
Gina: Oh, my favorite place.
David: So if we burn the CO2 from the calcium carbonate off, that leaves behind calcium oxide, right?
Gina: Calcium oxide, OK. Like lime, isn’t that lime?
David: Yes. So he takes the lime, he mixes it with water, and then that creates calcium hydroxide. OK?
Gina: Got it. And by the way, David, I’m loving the chemistry lesson. This is very my vibe, but OK, he’s got calcium hydroxide. Then what does he do with it? How does that remove CO2?
David: OK. I mean, I feel like you’re so close. You must know this.
Gina: OK. Yeah.
David: Think about it.
Gina: Just give me a little bit more.
David: When the air from the cabin is pumped through this calcium hydroxide, what do you think happens to the CO2 in that air when it passes through this calcium hydroxide?
Gina: I see. OK. So you’re saying the CO2 reacts with the calcium hydroxide and creates calcium carbonate all over again.
David: Yeah. Isn’t that cool? It just comes totally full circle.
Gina: That is cool. OK. So make sure I understand here. He is crushing up seashells, using them to make the calcium hydroxide base, and then reacting the base with the CO2 that needs removal to make calcium carbonate again. That’s how the CO2 scrubber works. Is that about right?
David: Yeah. To me, I think it’s incredible. I don’t know how he was able to come up with this 170 years ago.
Gina: Yeah. No, that’s really cool.
David: Yeah.
Gina: So with this invention, how long could they stay underwater?
David: OK. With his crew of three, including himself, they were able to double the time that they spent underwater. So they used to be able to spend 2 h down there. Now they could spend 4 h.
Gina: Whoa.
David: And keep in mind, the whole sub is human powered. They’re moving a propeller by hand to try and get around. So they are breathing in and out quite a lot.
Gina: So what happened with Monturiol and his submarine? Did he succeed in making coral harvesting safer?
David: He completed more than 50 dives in this submarine until eventually it broke apart.
Gina: Wait. Well, it broke apart? David, I thought you said this thing was safe.
David: It is safe. It’s safe. We’re safe. We’re fine.
Gina: Where’s the exit on this thing?
David: OK. Hold on. Before you get too nuts here, the only reason this sub was ever destroyed is because it was run into by a shipping vessel while it was docked, and no one was hurt.
Gina: Oh, well, that’s too bad.
David: Yeah. I’m disappointed. I’m sure Monturiol was disappointed.
Gina: Yeah. But he would probably be excited to find out that we still use something similar to his CO2 scrubber today.
David: We do?
Alex Scott: Yeah. So direct air capture in its modern form is actually quite similar to what happened in this submarine back in the 19th century.
Gina: That’s Alex Scott.
Alex: I am senior editor with Chemical & Engineering News. I cover a large range of subjects, from microplastics to looking at sustainability issues, carbon capture, and anything in between.
David: So Alex, you’re telling me that we still use a version of the technology that Monturiol tinkered away with all those years ago?
Alex: It’s very similar. With direct air capture, you are talking about an aqueous potassium hydroxide, and that is going to form a potassium carbonate, and in the same way that you would have a calcium carbonate precipitate out from the submarine process.
Gina: There’s also a form of direct air capture where, instead of reacting the CO2 with a base like potassium hydroxide, at least one company just compresses the CO2 into water.
David: Interesting, like a SodaStream.
Gina: Basically, yes. They are making a bunch of carbonated water, and then they bury that underground where it can react with the salt and form a mineral.
David: They’re not drinking it? I mean, it’s kind of free carbonated water. I would skim a little off the top.
Gina: Yeah, it’s a good point.
David: For myself.
Gina: Don’t think they’re drinking it, but there are actually a lot of different technologies that scientists are working on to remove carbon from the atmosphere, and some of them are really neat.
David: I’m all ears. What else you got?
Gina: OK. Well, there are some pretty logical, straightforward ways to go about it. One way is by generally trying to increase biomass.
David: Biomass. OK. So plants?
Gina: Exactly.
David: Got it.
Gina: Plants naturally absorb CO2. So there are efforts like reforestation, which involve trying to plant more trees, or efforts that involve planting seagrass, which sucks up carbon even faster than tropical rainforests do.
David: Wow. Interesting. I mean, that obviously makes a lot of sense. And Gina, I’m kind of doing my part. I have a lot of plants in my house. So.
Gina: You are an earth hero, David.
David: Thank you. And of course, you’re welcome.
Gina: Anyway, there are also some more-creative ways that scientists are going about this. One method basically involves grinding up certain types of rocks really small and then spreading that rock dust on the ground. Another method involves making the ocean less acidic.
David: All right. It’s my turn to play the skeptic here, Gina.
Gina: OK.
David: You’re talking about rock dust.
Gina: Yeah, love rock dust.
David: And fiddling with the pH of the ocean?
Gina: Mm-hmm.
David: What’s going on?
Gina: You’re not following this?
David: Are you kind of trying to throw a curveball my way? Are you making any of this up? You’re doing a David on me?
Gina: I am doing a Gina on you.
David: Oh, OK.
Gina: I’m talking about real hard science right now.
David: OK. And in your capacity as a Gina and doing the Gina on me, can you please—
Gina: Yeah, I’m Ginamaxxing.
David: —explain to me how does all this work? Tell me, how does grinding up rocks, how does the messing with the pH help with the CO2 in the atmosphere?
Gina: OK. I think it might actually be time to bring in somebody who knows a little bit more about this than I do. You want to take this one, Fionna?
Fionna Samuels: There’s a lot of ways to change alkalinity, and one way to do that is with minerals.
Gina: That’s Fionna Samuels, who covers chemistry, geochemistry, and cosmochemistry for C&EN.
Fionna: When you look at a big rock somewhere, right? You constantly have weathering happening on that big rock. So over the lifetime of that rock, as it goes from a big rock to a small rock to a grain of sand, it’s dissolving into its chemical components, which in some cases, depending on the rock, are alkaline.
And if it’s alkaline, it’s able to react with carbon dioxide and turn the carbon dioxide into a mineral that is no longer in the atmosphere. Right? The problem is that the surface area of that big rock is not as big as if we just crushed the big rock into a bunch of little rocks like teeny tiny sandy grains. And by increasing the surface area, we can basically up the rate of dissolution.
David: OK. So it’s enhanced because we’re crushing up a bunch of rocks and so that way they have more surface area to react with the CO2?
Gina: Exactly. And we can do it in the ocean too.
Fionna: That’s called ocean alkalinity enhancement if you’re doing it in the ocean. And it’s the same idea. You’re basically having these tiny particles, mineral particles, react with the carbon dioxide dissolved in the ocean and turn into bicarb and ultimately settle to the bottom of the ocean and stay there for millennia, which is great because we don’t want the carbon dioxide in our atmosphere.
David: This kind of sounds like we are giving the ocean a big Tums. Is that right? Do I have that right?
Gina: It’s honestly a great way to think about it. Tums are made of calcium carbonate, which is a basic substance that helps make your stomach less acidic. And some researchers are doing this ocean alkalinity work with calcium carbonate, literally the same compound that makes up Tums.
David: Wow. OK. So when we give the ocean this giant Tums.
Gina: Yeah. Big old Tums.
David: The gigantic Tums reacts with the CO2 dissolved in the water?
Gina: That’s right.
David: Wow. OK. So it’s kind of sounds very, very similar to Monturiol and his CO2 scrubber. Tell me, is it working? Are we making a difference?
Gina: Well, it’s early.
Fionna: So right now there’s a bunch of really small-scale outdoor experiments that are happening around the world, which is exciting, but also it’s not clear if this will work. The amount of carbon dioxide removed at a maximum, like the maximum amount removed, is way less than the amount that we’re emitting. So it doesn’t matter. If we were able to perfect every single one of these techniques, and we’re doing them in the real world, it wouldn’t matter—if we didn’t also decarbonize the rest of our lives.
David: OK. Hold on. Hold on.
Gina: Yeah, yeah, yeah, pump the brakes.
David: So we already have put so much CO2 in the atmosphere that removing it, you’re telling me what, it doesn’t matter?
Gina: It does matter. It just doesn’t matter on its own.
David: OK.
Gina: We need to stop putting out as much CO2 into the atmosphere as we’re currently putting in. Full stop.
David: Got it.
Gina: But even if-slash-when we manage to slow our output, we’re still going to need to remove a lot of the CO2 that we’ve put out.
David: OK. So essentially we need to stop the bleeding, and we also need to clean up the mess that we’ve already made?
Gina: Yeah.
Fionna: We can avoid the worst outcomes of a warming world by preventing more carbon dioxide being released and also incorporating some of these carbon dioxide–removal technologies.
Gina: Right. It kind of seems like we need a little bit of everything to slow the speed of climate change.
David: To me, it kind of seems like we need a lot of everything.
Gina: Well, yeah.
David: I mean, it’s cool that these people are taking on these projects, rock weathering and so forth, but none of this really screams profitability to me.
Gina: Right. Yeah. There’s probably not a lot of money to be made by throwing rock dust into the ocean, I assume.
David: Right. And I’m always, I’m kind of a finances guy. I’m always looking for the money angle.
Gina: You are such a budget guy.
David: So.
Gina: Yeah.
David: So Gina, I got to wonder who’s paying for all this stuff.
Gina: Right. Well, some of these projects are funded by this kind of sneaky little system called carbon offsets, which you might’ve heard of.
David: Yeah, sure. That sounds familiar.
Gina: So basically, companies that produce CO2 can kind of make up for their emissions by financially supporting efforts to reduce CO2 elsewhere.
David: Right. OK. For instance, let’s say, Gina, I am, I don’t know, a power plant.
Gina: I’ve always thought you’d be a good power plant.
David: Sure. And I of course appreciate whatever that means, but—
Gina: You’re welcome.
David: —let’s say I’m a coal-burning power plant, and I produce—
Gina: That sounds right.
David: And I produce on average, oh, I don’t know, 352,500 tons of CO2 per year.
Gina: Well, that’s a really specific number.
David: And I take my profits and I pay a bunch of money to a group that, well, let’s just say, I don’t know, spitballing here, they plant a bunch of trees.
Gina: Right.
David: If I give them enough money to plant enough trees to suck up that 300,000 or so tons of CO2 from the atmosphere, that means?
Gina: That you can now claim to be a carbon-neutral coal power plant.
David: And yet I’m still putting CO2 in the atmosphere.
Gina: Oh, yeah. You’re chugging it out.
David: Right.
Gina: But theoretically, you’re making it possible for CO2 to be drawn out somewhere else. It’s a confusing system, I know, but that’s basically how these technologies get implemented in a practical way. There’s a whole economy around mediating CO2 in the atmosphere.
David: Yeah. And Gina, just curious, do you know how that economy all got started?
Gina: Oh, boy. Do you know how that economy got started?
David: You got me. Yes, not only do I know.
Gina: Is that where we’re going here? OK.
David: I’ve already secretly kind of started. I’ve planted the seeds of the next inflection point right under your nose this whole time.
Gina: Yeah. Classic.
David: And it has to do with, of course, a power plant and whole mess of trees back in 1988.
[Inflection point sound effect: digital blips and tape-rewinding whir]
Gina: OK. I’m not absolutely hating this so far. It looks like we’re in some kind of clearing, seem to be in the tropics somewhere. I’m not mad about that.
David: I hear tropical birds out there in the trees.
Gina: I have been really wishing to take a vacation. I feel like we are just in the time machine.
David: Constantly.
Gina: A hundred hours a day. Time gets really weird in there.
David: Yeah. We’re in some hot and humid sub.
Gina: I’m in the desert. I’m in a submarine. I’m looking at a weird moon machine. It’s about time, is what I’m saying.
David: Yeah. Unfortunately, I didn’t bring the bug spray, so you’re on your own there.
Gina: Eaten alive already.
David: But yes, we are in Guatemala’s western highlands. It’s humid, but hey!
Gina: David, as much as I would love to just relax and enjoy this, what are we doing here?
David: I’ll get straight to this point. This exact spot is where the first-ever carbon-offset project is about to start.
Gina: Gotcha.
David: You see, in a few months, a bunch of people from AES CARE are going to show up and they’re going to—
Gina: Sorry. AE what?
David: Right. Sorry.
Gina: Is happening? AES CARE?
David: I’ll back up a little bit. AES is a big utility company. It stands for “Applied Energy Services.”
Gina: OK. Creative name.
David: And right now, in 1988, they’re about to create that big giant coal power plant that I was talking about. They’re creating it in Connecticut.
Gina: Gotcha.
David: And they’re feeling a little bit guilty about it.
Gina: OK. I mean, I guess that’s a little forward looking.
David: Sure.
Gina: They are making a big old coal power plant, but.
David: At least they’re trying something. They’re throwing some ideas at the wall.
Gina: Sure. Yeah.
David: And the other guys that I mentioned, CARE, they’re an international relief organization. So those two are kind of teaming up.
Gina: OK. So a utility company and an aid organization are heading here to the lovely rural Guatemala.
David: Yes.
Gina: Why?
David: So as I mentioned, AES, they’re concerned about the emissions that their new coal power plant would create, and they’re looking all around for solutions. An employee there, Sheryl Sturges, came across a paper that tried to calculate how many trees would need to be planted to offset all human carbon emissions.
Gina: So at this time, the idea of trees offsetting human CO2 pollution, that had already been kind of floating around?
David: Yeah, people were thinking about it. I mean, obviously they knew that trees suck up CO2 that turns into their, it turns into the tree.
Gina: Sure. Yeah.
David: But no one had actually done it intentionally. And so Sheryl thinks, “Well, obviously we’re not going to try and offset all human CO2 emissions like they propose in the paper.”
Gina: Yeah, that sounds like it would be really difficult. A lot, a lot of trees.
David: Yeah. I think it’d take them a tremendous amount of trees. But she says, “OK, what if we just focus on the emissions our one plant will create in, I don’t know, 40 years?”
Gina: Why 40 years?
David: That is the kind of projected lifespan of this specific plant. So they crunch some numbers, and they decide that they need to displace 14.1 million tons of CO2 over the next 40 years.
Gina: Got it. And they plan to do that by planting trees here?
David: Right. And protecting existing forests here, teaching sustainable farming practices to the people that live here, and other stuff like setting up a wildfire brigade to fight forest fires if they ever come up.
Gina: Sure. OK. So they’re going to come in here, plant a bunch of trees, set up sustainable forestry practices locally, and then what? Then they’re in the clear to pump a whole bunch of CO2 into the atmosphere?
David: That was their thinking, sure. It’s pretty easy to be cynical about it now. But at the time, think about it. This is a pretty novel idea. It wasn’t until nearly a decade later, in 1997, that the concept of the carbon-credit market really took off globally thanks to the Kyoto Protocol. But the idea really first took shape here, right here where we’re standing. I mean, that’s pretty cool.
Gina: Sure. So this project started here in 1988 and had a 40-year time frame, which if we go back to the present day, 2026, we’re only a couple years away from that.
David: Right.
Gina: So what’s the latest on it? Did they displace 14.1 million tons of CO2?
David: Right. Well, first of all, it’s very hard to calculate, but being realistic, probably not. They probably didn’t displace their goal.
Gina: Did not. OK.
David: The coal plant itself did close in 2011, and there’s also not really a lot of recent reporting on the forestry site. So the most recent hard data I could find is from 1999, but already by then, already at that point, it doesn’t sound like the project was on track to be very effective.
Gina: Wow. Oh boy. How close were they?
David: OK. So this paper that I found says the effort only achieved 1.8% of its 1999 offset target.
Gina: One point eight percent?
David: Yeah. That’s—
Gina: Dude, that is—
David: It’s like an F-minus for sure.
Gina: That’s so, so low. What happened?
David: So there were a lot of problems. I mean, obviously, what we know now is that these projects are really complicated. There’s a lot of moving parts.
Gina: Sure.
David: There were local political conflicts. Some of the trees they planted weren’t even the right type for the climate, so those died.
Gina: OK. It seems like you could have avoided that one.
David: Yeah.
Gina: So it turns out planting thousands of trees in another hemisphere, changing the way locals farm their land, and trying to prevent forest fires isn’t a walk in the park. Wow, who would’ve thought?
David: Well, I guess you. So tell me, Gina, what’s up with you and these offset projects? Why do you have such a carnivorous twinkle in your eye whenever you deride them so?
Gina: Well, I think they’re a little bit of a scam.
David: OK. I’m listening.
Gina: I mean, I don’t know. Just think about it. It’s, you’re a factory.
David: No, I’m thinking.
Gina: You’re turning all the CO2 out and you’re just like, “Oh, what if I plant some trees somewhere else?”
David: Yeah.
Gina: I don’t know. It just doesn’t—
David: Kind of summarizing the inflection point, it sounds like.
Gina: Yeah. I don’t know-
David: Where’s the scam part? I’d love to hear where the scam part is.
Gina: Details of it? Yeah.
David: Yeah.
Gina: OK.
David: Anything you could feed me there.
Gina: You know what? I need to make a call really quick.
David: Sure. What kind of a call?
Gina: Sorry, just give me one second. Yeah.
David: Sounds like a weird time to take a call, I would say.
Gina: I’m sorry. Could you just keep it down? I’m just trying to—
David: Sure. Yeah, you got it.
Alex: Hey, Gina, how’s it going?
Gina: Hey, Alex. Do you mind helping me out of a little bind here? Carbon credits, when we talk about carbon credits, how legit is that whole system?
Alex: Legit would not be the first word I would use to describe the feel of carbon offsets and credits. They’ve had a really bad reputation because so many things can go wrong with them, and the savings that they can make have been really overestimated by a factor of 5–10, or even more than that.
David: But there must be some projects carbon credits fund that are actually doing something, right?
Alex: The short answer is, it depends on the project, but they can be really hard to measure. They’re working in a limited way. So without them, we would be missing out on thousands of projects, such as renewable energy, methane capture, and clean technology projects around the world, especially in places where that money wouldn’t otherwise flow.
So they’re important, but they’re not a substitute for cutting emissions. And most of the bodies overseeing the sector now think that the offsets should only be used for residual emissions. So that’s the emissions that are hard to eliminate, such as emissions from airlines.
David: Got it. So the real utility of carbon credits ideally would be to make up for emissions that we otherwise just couldn’t possibly curtail?
Gina: Yeah. I mean, I guess that makes sense. I’m still a little skeptical about it, but.
David: Sure.
Gina: Maybe the system is not as scammy as I thought, but.
David: A healthy skepticism, I think.
Gina: A healthy skepticism, sure. So Alex, what’s next for carbon removal?
Alex: Yeah. For direct air capture, the focus is all about reducing that cost. At the moment, prices for capturing and storing a ton of CO2 are $600–$1,000. The companies hope they’re going to get that down to around $200–$300 in the next few years. And then in terms of the actual designs of the engineering of these direct-air-capture systems, they’re going to get more efficient. They’ve only been out of the lab for the last 3 years. So you would expect the engineering to drastically improve in the next few years.
David: All right. So Gina?
Gina: What’s up, David?
David: I understand now after we’ve done this episode that holding my breath for a long time probably wouldn’t help with the CO2 emissions problem.
Gina: Yeah. Oh, boy. You’re not going to hold your breath again, right? We’re not trying this again.
David: I’ve learned my lesson. No.
Gina: OK.
David: But for the record, I can hold it for a very long time. I can hold it for 10 min, I think. Maybe 20.
Gina: There’s no way that’s true. Absolutely not.
David: Yeah. I mean, I’ve dug a mile-deep hole.
Gina: You have not.
David: I can hold my breath for 10 min.
Gina: You can not.
David: I’d also be a great factory. You said it yourself.
Gina: Yes, I did say that. You’re a real Renaissance man, David.
David: But is there anything I can do on a personal level, besides all those great accomplishments I just listed, to decrease my carbon footprint?
Gina: Well, it’s important to say here that carbon emissions are a global problem, and we need changes on a massive scale. It’s not something that just individual action can solve, even such a great individual as yourself, David. But that said, there are definitely things you can do to help reduce your individual emissions.
David: All right. Lay it on me. What do we got?
Gina: Well, OK. If there are any gas-powered appliances that you could swap out for electric ones, that’s a great option. But if you want to start a little smaller, you could, I don’t know, weatherize your house. That involves things like sealing holes and cracks and making sure you have good insulation. That helps make your heating and cooling more efficient, which in turn uses less energy.
David: OK. I could start tinkering around with stuff in my house. That kind of sounds like a little Saturday project.
Gina: Sure. There are also more day-to-day things you can try to do. You could eat less meat, for instance. Estimates suggest that livestock is responsible for more than 10% of greenhouse gas emissions.
David: Wow.
Gina: You could also be really intentional about composting all your food waste instead of throwing it in the trash. Food waste in a landfill can produce a lot of methane, which like CO2, is a greenhouse gas. Emissions are much lower if that food waste is composted.
David: That’s interesting. The thing about livestock making up more than 10% of greenhouse gas emissions is pretty mind blowing.
Gina: Yeah. Isn’t it?
David: Yeah. But what if I maybe take it a step further? What if I go the Monturiol route, and I make a totally self-sustaining submarine?
Gina: That would be cool, but I’m not sure if we really need a self-sustaining submarine.
David: Well, think about it this way. We could use it to get around. We could paddle it ourselves. We wouldn’t need any fossil fuels.
Gina: Could we really use it to get around when we need to travel by sea, in that case?
David: Sure. And doesn’t that sound like a blast? I mean, where can’t you go by sea?
Gina: Gee, I don’t know. Just off the top of my head, my house.
David: Right.
Gina: Your house.
David: OK.
Gina: Our office.
David: Sure. Oh, OK.
Gina: Any of the good ice cream spots, really, those are mostly on land.
David: You are such a skeptic. Couldn’t we travel through the sewers in my submarine?
Gina: Oh, David, I really don’t want to travel by sewer. I think that’s where I draw on the line. Plus, I mean, don’t sewers only have a little trickle of water mostly? How are we going to take a submarine?
David: You’re not being very fun.
Gina: Oh, OK.
David: All right? Have some imagination.
Gina: Tell you what, how about after we record this episode, we can, maybe we can give the submarine a little test drive.
David: Sure.
Gina: But before we hop in the sub, we got to tell listeners what’s in the next episode.
David: OK. And what are we covering on the next episode?
Gina: David, you should know what we’re covering in the next—shouldn’t you know what’s in the next episode?
David: I’ve got a lot going on. I’m figuring out the sewer routes, ice cream, et cetera.
Gina: Whatever. I’ll handle it. So in the next episode, we’re going to be talking about fusion energy, which is a technology that promises nearly limitless energy without fossil fuels.
David: Right. Wow. Fusion. I take it for that we will definitely want to visit the Big Bang.
Gina: Big Band?
David: Where else? Where else should we go for fusion?
Gina: OK. Anyway-
David: Start with the Big Bang.
Gina: We’ll also talk about the different types of fusion reactors that are out there. We’ll explain how it works and why, even though we’ve been developing it for decades, it still only kind of works.
David: Right. And we’ll also go back to 1957 for a patent dispute over lasers that somehow involves a candy store.
Gina: Dispute over lasers. OK.
David: We’re going to visit the inventor of the mass spectrometer in 1919. I think that makes perfect sense.
Gina: Sure. Whatever you say.
David: It’s all right there.
Gina: You mentioned the Big Bang earlier.
David: Right.
Gina: That was a joke, right? We’re not going to the Big Bang for real?
David: We are going to the Big Bang. And you have a spacesuit guy, right? I mean, who’s your spacesuit guy?
Gina: Oh, David.
David: You will need a spacesuit.
Gina: You know I don’t have a spacesuit guy. Come on, man.
David: I’ll hook you up. Let’s get out of here. I’ll fire up the sub.
Gina: All right.
David: Here we go.
Gina: Inflection Point is a podcast project from Chemical & Engineering News.
David: Chemical & Engineering News is the official news outlet of the American Chemical Society.
Gina: Music by Kirk Ohnstad, Jeremy Barr, David Anderson, and Shutterstock.
David: Written, produced, and hosted by Gina Vitale and David Anderson.
Gina: Our audio producer is Jeremy Barr.
David: Our fact-checker is Michelle Boucher.
Gina: Email us at [email protected].
David: Thanks for listening.
