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The Great Carbon Catch · The Climate Translation

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We've all been told that planting trees is a good answer to climate change, and while
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trees are amazing, they only grow so fast.
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But what if we could build mechanical trees that work thousands of times faster?
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Today we're looking at the world of carbon capture, from giant fans pulling carbon dioxide
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out of the sky to turning gas into solid stone to storing it underground.
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We are witnessing the birth of new industry.
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But as we'll see, technology isn't a get out of jail free card.
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It's a tool that only works if we use it correctly.
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Welcome to the podcast. I'm Dr. Mac, and this is the Climate Translation.
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Our first stop is direct air capture, or DAC.
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Imagine a giant wall of fans pulling in the same air you're breathing right now.
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Inside these machines are chemical filters.
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You can think of them like sponges, designed to grab on to carbon dioxide molecules while
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letting everything else pass through.
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Nitrogen goes through, oxygen goes through, carbon dioxide gets caught.
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Once those filters are full, the machine uses heat or pressure to squeeze the carbon
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dioxide back out.
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And what you're left with is a concentrated stream of carbon dioxide.
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No longer spread thinly through the atmosphere, but collected in one place where it can be
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stored or used for industrial purposes.
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At a basic level, the idea is that simple, and it works.
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But now the world's largest direct-air capture facility removes on the order of a few
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thousand tons of carbon dioxide per year.
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That's impressive engineering, but it also highlights a challenge, because humanity emits
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around 36 billion tons of carbon dioxide every year.
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So even the biggest DAC plant operating today is a very small piece of the puzzle.
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It exists because carbon dioxide mixes evenly through the atmosphere.
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Once it's released, it doesn't stay near the source.
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It spreads everywhere.
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Direct-air capture takes advantage of that fact.
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It doesn't make a difference where the carbon came from, a car, a plane, a power plant.
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DAC can pull it out of the air anywhere.
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That flexibility is a great strength, but it's also the reason DAC is hard.
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Carbon dioxide makes up only about 0.04% of the air.
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Pulling it out means moving enormous volumes of air.
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Moving air takes energy.
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Heating filters takes energy.
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Compressing and storing the gas takes energy.
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This is where most of the criticism of direct-air capture comes from, and fairly so.
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If a DAC system is powered by fossil fuels, it can end up removing far less carbon than
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it emits.
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In worst cases, it becomes an expensive way of just moving carbon around without actually
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helping at all.
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That's why recent breakthroughs matter.
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In 2025, researchers developed new materials and processes that cut the energy required
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for direct-air capture roughly in half compared to older systems.
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Now, that doesn't magically solve the scale problem, but it does move DAC from a laboratory
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curiosity towards something that could realistically work alongside things like renewable energy.
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Even so, the scale remains a hard limit.
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To make meaningful impacts, direct-air capture would require thousands, possibly tens of thousands,
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of large machines running continuously, powered cleanly, and connected to places where
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carbon could be stored safely for millennia.
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Now, that's not impossible, but it's not fast, and it's definitely not cheap.
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So the right way to think about direct-air capture is not as a silver bullet, it's more
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like a cleanup tool, especially useful for emissions that are hard to eliminate like aviation
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or shipping, or for removing carbon that's already in the atmosphere.
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And that leads naturally to the next question.
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If pulling carbon directly out of the air is this difficult, what happens when we try
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to capture it before it ever spreads to the atmosphere?
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Geological sequestration involves taking carbon dioxide gas, compressing it until it behaves
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like a dense, liquid-like fluid, and pumping it thousands of feet underground into specific
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rock formations.
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And no, we're not dumping it into giant underground caves.
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Instead we're injecting the carbon dioxide into tiny spaces within rock, the microscopic
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pores that once held oil, natural gas, or deep saltwater.
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Think less empty cavern and more sponge made of stone.
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The most important requirement is something geologists call integrity.
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That means the storage layer has to be capped by thick, solid rock that fluids can't pass
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through.
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Rock acts like a lid on the jar, keeping whatever's underneath from slowly leaking back out.
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As long as the lid stays intact, the carbon dioxide remains trapped.
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If the idea sounds familiar, it should.
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It's exactly how oil and natural gas stayed underground for millions of years.
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The earth already has a proven track record of storing fluids safely at depth long before
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humans ever drilled a well.
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In that sense, geological carbon storage isn't inventing a new system, it's using an
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old one in reverse.
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We're taking carbon that was locked underground for geologic time and putting it back into
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similar formations, essentially returning it to earth's long-term savings account.
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Of course, at this point, my students often ask me, what if the carbon leaks?
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What about earthquakes?
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Aren't we just delaying the problem instead of solving it?
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And they're fair concerns.
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The reality is that underground storage is not risk-free, but neither is leaving carbon
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dioxide in the atmosphere.
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The difference is that underground risks are local and monitorable, while atmospheric
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carbon affects the whole planet.
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Modern storage sites are carefully chosen, mapped and monitored, scientists track pressure,
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chemistry and movement over time.
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If carbon starts migrating where it shouldn't, operators can detect it early and respond.
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That level of control simply doesn't exist once carbon is released into the air, but
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geological sequestration does have limits.
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Storage sites are not evenly distributed across the globe.
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Transporting carbon dioxide requires pipelines or shipping infrastructure, and while underground
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storage can handle large volumes, it's not infinite.
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More importantly, the approach doesn't make the carbon disappear.
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A carbon is still carbon dioxide.
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It's just relocated, liquefied and trapped physically instead of chemically transformed.
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And that distinction matters because it sets up an important contrast.
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Geological storage relies on containment.
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It works as long as that rock lid holds.
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But there's another approach that doesn't rely on lids at all.
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Instead of trapping carbon dioxide as a fluid underground, it changes the carbon itself,
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turning it into solid rock that can't leak, migrate or escape.
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It's called mineralization.
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Instead of relying on pressure and containment, mineralization changes the carbon itself.
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In certain types of rock, especially basalt and minerals like olivine, carbon dioxide
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reacts chemically with the rock.
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When carbon dioxide comes in contact with these minerals, it doesn't just get trapped,
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it gets transformed.
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The carbon bonds with calcium, magnesium or iron in the rock and turns into solid carbonate
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minerals, the same kinds of minerals found in limestone and marble.
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Once that happens, the carbon is no longer a gas, it's stone.
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You can think of it like a volcano in reverse.
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Volcanoes bring carbon up from deep inside the earth and release it into the atmosphere.
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Mineralization does the opposite.
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It pulls carbon out of circulation and locks it back on the crust.
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The chemistry behind this is not new.
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Earth has been doing this naturally for millions of years through a process called weathering.
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Carbon water reacts with rock, carbon dioxide dissolves into that water, and over long
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periods of time, carbon ends up locked into minerals.
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The catch here is time.
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Naturally this process takes thousands to tens of thousands to millions of years to make
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a noticeable dent in atmosphere carbon, and that's where new research comes in.
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In early 2025, researchers at Stanford University demonstrated a process inspired by
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cement making that dramatically speeds the chemistry up.
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Instead of waiting centuries, their method allows common rocks to react with carbon dioxide
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and form stable minerals in weeks to months.
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The same basic chemistry just very different timescales.
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The breakthrough wasn't a single exotic material or rare element.
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It was finding the right conditions, the temperature, the pressure, the surface exposure.
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To let their reactions happen quickly and efficiently using absorbent rock.
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That's a big deal.
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It means mineralization could, in principle, be done almost anywhere their suitable rock,
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which is most of the planet.
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You wouldn't have to have a cap rock, no reliance on long-term containment.
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Once the carbon is mineralized, it's locked in place on geological timescales.
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From a risk perspective, that's about as permanent as carbon storage gets.
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But, and this is important, mineralization isn't a magic solution either.
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Turning gas into rock takes energy.
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Crushing and processing rock takes infrastructure.
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Moving carbon dioxide to mineralization sites takes planning and cost.
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And while the rocks themselves are abundant, scaling the process to billions of tons is
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an enormous challenge.
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It's also a trade-off.
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Mineralization is slower, a more resource-intensive than simply injecting carbon dioxide underground.
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But it offers something underground storage can't guarantee.
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Finality.
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Geological storage says, we'll keep it here safely.
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Mineralization says, there's no longer carbon dioxide anymore.
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That difference matters.
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So instead of thinking about the approaches as competitors, it helps to see them as tools
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designed for different jobs.
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Underground storage is about capacity and speed.
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Mineralization is about permanence.
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And together they point to something important.
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We're not short on ideas for dealing with carbon.
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We're short on our approaches that work quickly, cheaply, cleanly, and massive at scale.
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All at the same time.
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Understanding those trade-offs is the key to having an honest conversation about carbon
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capture.
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Now, at some point in this conversation, someone's going to ask some very reasonable questions.
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Maybe they say, why are we spending all this money on fans and rocks?
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Wouldn't it just be easier to stop burning fossil fuels?
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Of course, the retort is, well, if we're building machines to pull carbon out of the
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air, does that mean we don't have to stop using coal, oil, and natural gas?
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And this is where the conversation usually gets off the rails.
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So let's try to slow it down.
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Instead of talking about climate, let's start talking about the cleanup.
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Imagine you're renovating an old house.
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You discover some mold behind the walls, decades of it.
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Some of the mold is still growing.
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Some of it is old damage that's already there.
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Someone might say, why bother cleaning up the old mold just stop the leak?
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That sounds reasonable, but stopping the leak doesn't make the mold disappear.
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The damage that's there has to be dealt with.
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The other side is, why bother fixing the leak we've got great cleaning products?
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Well, that doesn't work either.
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If the leak keeps going, you're going to be cleaning forever.
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Climate change works the same way.
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We have ongoing emissions, the leak.
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And we have carbon already in the atmosphere, the damage that's built up.
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Carbon capture exists because stopping emissions alone doesn't instantly undo what's already
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there.
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The climate responds slowly, heat sticks around, carbon stays in circulation.
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But carbon capture only works if emissions are going down at the same time.
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Clean up only works if you stop making a mess.
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This is what people mean when they talk about net zero.
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And net zero does not mean zero emissions.
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It means emissions get as low as possible, and whatever we truly can't eliminate gets
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balanced by removals.
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Things like aviation, shipping, submit, and steel production are extremely hard to make
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completely carbon free.
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Even in a clean energy future, some emissions will likely remain.
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Carbon capture is meant to deal with the leftovers.
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It's not an excuse for businesses usual.
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And that's why the order matters.
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We have to cut emissions first.
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We have to cut them hard, and we have to switch to cleaner energy where we can.
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Only then do carbon capture and storage make sense, not as a get out of jail card, but
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as a mop after the leak is fixed.
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If someone tells you technology will fix it, you can agree partially, technology helps,
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but only paired with restraint.
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And if someone says nature will fix it, you can agree as well, partially.
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Nature fixes slowly, but we're moving too fast.
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So the real answer isn't either, or it's both, for different reasons, on different timelines,
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for different limits.
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Once people see that, hopefully the argument can soften.
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Because most of us already understand the logic, we just don't apply it to the climate.
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Carbon capture is a bridge to the future, but it isn't the destination.
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It's a set of tools that can help us clean up the mess we've already made, while we do
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the hard work of building an energy system that doesn't add to it.
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It only works when it's paired with real reductions in greenhouse gas emissions.
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Clean up without prevention, just means running in place.
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What this research and these technologies really show us is there's no single solution.
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The change isn't a problem you fix through just one breakthrough.
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It's something you manage with honesty, limits, and long-term thinking.
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Understanding the trade-off matters, knowing what the tools can do, and what they can't
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matters even more.
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I'm Dr. Mac and this has been the Climate Translation.
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If you have questions about the climate that you've been too afraid to ask, or you have
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a differing opinion, I want to hear from you.
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I can use your viewpoints and future episodes.
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You can reach me at the climate translation at gmail.com.
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I'll see you next time.