Nova: Welcome back to the show. Today we are diving into a topic that sits at the very center of the climate conversation — carbon capture and storage. And we are looking at it through the lens of a foundational text: "An Introduction to Carbon Capture and Storage" by Stefan Bachu. Now, before we get into the book itself, let me tell you something remarkable. The author of this book, Stefan Bachu, shares in the 2007 Nobel Peace Prize. He was a lead author on the IPCC Special Report on Carbon Dioxide Capture and Storage, and he is only the fifth researcher in the 88-year history of the Alberta Research Council to receive the distinguished scientist designation. That is the caliber of expertise we are working with here.

Nova: : That is incredible. So this is not just another academic textbook — this is someone who has literally helped define the field putting everything he knows into an introductory volume. But I have to ask: why does CCS need an introduction? Is it really that complex?

Nova: That is exactly the right question. CCS sounds simple on the surface — capture carbon dioxide, stick it underground, problem solved — but the reality is extraordinarily nuanced. Bachu's book walks readers through the entire chain: from capture technologies at power plants and industrial facilities, through transportation, to the geological storage that is his personal area of deep expertise. And here is why this matters: as of 2024, CCS was operational at 44 plants worldwide, collectively capturing about one-thousandth of global carbon dioxide emissions. That is a tiny fraction of what is needed.

Nova: : One-thousandth? That is sobering. So this book is essentially a roadmap for scaling a technology that is still in its infancy?

Nova: Precisely. And Bachu brings a unique perspective because his career has spanned the entire arc of modern CCS development — from the early 1990s, when he published one of the very first papers on aquifer disposal of CO2, to chairing international task forces on storage capacity estimation, to advising governments on regulatory frameworks. His book synthesizes decades of frontline research into something accessible. So today we are going to unpack the key ideas: how carbon capture actually works, where we store all that CO2, what makes a good storage site, and the real-world track record so far.

Nova: : I am ready. Let us get into it.

Nova: Let us start with the capture side. One of the most useful things Bachu's book does is clarify the different capture approaches, because the terminology can be confusing even for people who follow climate tech. There are essentially three major pathways: post-combustion, pre-combustion, and oxy-fuel combustion.

Nova: : Okay, break those down for me. I have heard these terms thrown around, but I have never really grasped the practical differences.

Nova: Picture a conventional coal or gas power plant. You burn fuel with air, and the exhaust — the flue gas — goes up the chimney. Post-combustion capture means you install equipment to scrub CO2 out of that exhaust after combustion has happened. It is a retrofit approach. The challenge is that flue gas is mostly nitrogen from the air, so the CO2 is diluted — typically only 4 to 15 percent of the stream.

Nova: : So you are trying to fish out a relatively small amount of CO2 from a huge volume of gas. That sounds inefficient.

Nova: Exactly. And that is why it is energy-intensive. But it is also the most widely applicable because you can bolt it onto existing facilities. The most mature technology here uses chemical solvents — liquid amines — that selectively bind to CO2, then release it when heated. Think of it like a sponge that soaks up CO2 and then gets wrung out.

Nova: : And pre-combustion? That one always confused me because the name makes it sound like you capture CO2 before you even burn anything.

Nova: Right — and the name is a bit misleading, which Bachu's book helps clarify. Pre-combustion capture actually involves converting the fuel — say coal or natural gas — into a mixture of hydrogen and CO2, called syngas, before combustion. You then separate the CO2 from that gas stream, which is much easier because the CO2 is at high pressure and high concentration. The hydrogen can then be burned cleanly to generate power, producing only water vapor.

Nova: : So it is more like you redesign the fuel rather than scrub the exhaust. What about oxy-fuel?

Nova: Oxy-fuel is the most elegant conceptually. Instead of burning fuel with air, which is mostly nitrogen, you burn it with pure oxygen. The exhaust is then almost entirely CO2 and water vapor. Condense out the water, and you have a nearly pure CO2 stream ready for storage. The catch is that producing pure oxygen is itself energy-intensive and expensive. Bachu notes that each capture method has different cost profiles, energy penalties, and stages of technological maturity. There is no one-size-fits-all solution.

Nova: : So choosing a capture technology depends on the specific facility — what fuel it uses, what it produces, whether it is new or existing.

Nova: That is exactly the kind of systems-thinking Bachu brings. And here is a fascinating detail from the broader data: most of the carbon capture capacity actually in operation today is not post-combustion at power plants. It comes from something called inherent process capture — where CO2 separation is already built into the industrial process. Think natural gas processing, where CO2 has to be removed from raw gas anyway to meet pipeline specifications, or ethanol fermentation, where CO2 is a natural byproduct at high concentration.

Nova: : So in those cases, carbon capture is almost a free rider on an existing industrial process. That makes a lot of economic sense.

Nova: It does, and it explains why the capture side of CCS has been slow to scale at power plants — the economics are fundamentally harder there. But that brings us to the other half of the equation, which is where Bachu's expertise truly shines.

Nova: Stefan Bachu is, at his core, a geologist and hydrogeologist. His real passion — and where this book goes deepest — is geological storage. Once you capture CO2, where do you put it so it stays put for thousands of years?

Nova: : I think this is where a lot of people get skeptical. Pumping gas underground sounds like something that could go wrong. What are the actual storage options?

Nova: Bachu outlines four main types of geological storage. First, depleted oil and gas reservoirs. These are formations that have already trapped hydrocarbons for millions of years, so we know the cap rock is sound. Second, deep saline aquifers — porous rock formations filled with salty water, typically one kilometer or more below the surface. These have the largest storage capacity globally. Third, unmineable coal seams, where CO2 actually adsorbs onto the coal surface. And fourth, salt caverns, though these are relatively small in capacity.

Nova: : Let me guess — the saline aquifers are the big prize?

Nova: They are. Bachu's own research, particularly his highly cited 2007 paper on CO2 storage capacity estimation, has been foundational in quantifying just how much CO2 deep saline aquifers could hold. These formations exist all over the world, they are deep enough that the CO2 remains in a supercritical state — dense like a liquid but with the viscosity of a gas — and the overlying cap rock provides a natural seal.

Nova: : What does supercritical mean in practical terms?

Nova: Below about 800 meters depth, the temperature and pressure conditions turn CO2 into a supercritical fluid. In this state, it occupies much less volume than it would as a gas at the surface — about 500 times less. That is what makes underground storage physically feasible at scale. Bachu explains that once injected, the CO2 gets trapped through multiple mechanisms: structural trapping under the cap rock, residual trapping where tiny bubbles get locked in pore spaces, solubility trapping where CO2 dissolves into the brine, and eventually mineral trapping where it reacts with the rock to form stable carbonate minerals.

Nova: : So it actually gets safer over time, not more dangerous.

Nova: That is the key insight. The risk profile of a storage site actually declines as the CO2 becomes progressively more immobilized. The book emphasizes that proper site selection and characterization are everything. You need the right geology: sufficient porosity and permeability to accept the CO2, an impermeable cap rock to seal it in, adequate depth, and an absence of leakage pathways like unmapped faults or abandoned wells.

Nova: : And this is where Bachu's work on methodology becomes so important — you cannot just guess whether a site can hold CO2.

Nova: Exactly. Bachu chaired the Carbon Sequestration Leadership Forum's task force on CO2 storage capacity estimation, and his methodology for assessing storage capacity in saline aquifers has been cited over 1,600 times. The framework moves from broad regional assessments down to site-specific modeling. He introduced a resource pyramid concept — at the top, you have theoretical capacity, the total physical limit. Then effective capacity, factoring in geological and engineering constraints. Then practical capacity, which accounts for economic and regulatory realities. And finally matched capacity, where you actually pair specific sources with specific sinks.

Nova: : A resource pyramid for underground space. That is a powerful mental model. But I want to talk about what happens when theory meets reality. How have actual projects performed?

Nova: This is where the story gets complicated. The first major CCS project was Sleipner, operated by Equinor in the Norwegian North Sea, which started injecting CO2 into a deep saline aquifer in 1996. It has stored over 20 million tonnes of CO2 — and it has done so successfully, with extensive monitoring showing no leakage.

Nova: : That is nearly 30 years of operation. That seems like a solid proof of concept.

Nova: It is. But Sleipner benefited from unique economics. Norway has a carbon tax that made it cheaper to capture and store CO2 from natural gas processing than to pay the tax. The project was not driven by climate altruism — it was a cold business calculation. And that economic alignment is not present everywhere.

Nova: : What about North America? Bachu is based in Alberta, which has been a hotbed for CCS.

Nova: Right. The Boundary Dam project in Saskatchewan was the world's first commercial-scale CCS project at a coal-fired power plant. It cost about 1.47 billion Canadian dollars. It separates roughly 90 percent of the CO2 from the flue gas it treats. But it has also faced significant operational challenges, including periods of downtime and underperformance relative to its design targets. And then there is Gorgon in Australia — the world's largest CCS installation — operated by Chevron. It cost over 3 billion Australian dollars and was designed to capture around 4 million tonnes of CO2 per year. In 2024, its capture rate was around 30 percent of capacity.

Nova: : Thirty percent? After more than 3 billion dollars? That is deeply concerning.

Nova: It highlights a central tension that Bachu's book does not shy away from: CCS is technically proven at the component level, but integrating capture, transport, and storage at commercial scale remains enormously challenging. As of 2024, the total global CCS capture capacity was about 64 million tonnes per year. Global CO2 emissions are roughly 37 billion tonnes. So CCS is capturing less than 0.2 percent of annual emissions.

Nova: : That puts the one-thousandth figure from earlier into even sharper perspective. So how does Bachu frame the path forward?

Nova: He emphasizes that CCS is not a silver bullet — it is one tool in a portfolio. But it is an essential tool for sectors where emissions are hard to abate by other means: cement production, where 60 percent of emissions come from the chemistry of limestone calcination, not fuel combustion. Steelmaking. Hydrogen production from natural gas. These industrial processes will not be decarbonized by renewable electricity alone.

Nova: : And Bachu has also been deeply involved in the regulatory side, right?

Nova: Yes. He co-chaired the expert panel that advised the Government of Alberta on its regulatory framework for CCS. His view — and it runs throughout the book — is that public confidence requires robust regulation. You need clear rules around site selection, injection operations, monitoring, long-term liability, and closure. Without that regulatory scaffolding, CCS projects will struggle to get financing and social license.

Nova: : So the technology is proven but the system — economics, regulation, public acceptance, infrastructure integration — is still under construction.

Nova: That is an excellent way to put it. And that brings us to the big question: where is all of this heading?

Nova: Let us talk about numbers for a moment. The global CCS market was valued at approximately 3.4 billion dollars in 2024 and is projected to reach roughly 9.6 billion dollars by 2029. The project pipeline has expanded to about 672 facilities worldwide. But the International Energy Agency's net-zero scenario requires CCS to capture something like 7.6 billion tonnes of CO2 annually by 2050.

Nova: : That is a jump from 64 million tonnes to over 7 billion — roughly a hundredfold increase — in 25 years. Is that even remotely plausible?

Nova: It is a staggering scale-up challenge. Bachu's book was written partly to equip engineers, policymakers, and students with the foundational knowledge needed to accelerate deployment. He identifies several critical enablers. First, standardized methodologies for storage capacity assessment — so investors and regulators can compare apples to apples. Second, the build-out of CO2 transport infrastructure — pipelines and possibly shipping networks that connect capture sites to storage hubs. Third, policy frameworks that put a meaningful price on carbon emissions.

Nova: : That third one seems like the linchpin. Without a carbon price, CCS is just an added cost.

Nova: Exactly. The cost of capturing CO2 ranges from about 15 dollars per tonne for high-purity industrial streams — like ethanol or natural gas processing — to 50 to 100 dollars per tonne for power plants and cement facilities, to potentially over 200 dollars per tonne for direct air capture. If emitting CO2 is free, nobody pays those costs voluntarily. The economics only work when there is either a carbon price, a tax credit like the 45Q in the United States, or a market for the CO2 itself through enhanced oil recovery.

Nova: : So enhanced oil recovery — where you inject CO2 to push out more oil — is that part of the CCS story?

Nova: It is a controversial part. Bachu addresses it pragmatically. CO2-enhanced oil recovery has been used for decades, primarily in the Permian Basin of West Texas. It can be a bridge: it creates a revenue stream that helps fund capture infrastructure, and it builds expertise in CO2 handling and injection. But from a climate perspective, the net benefit depends on whether the oil produced offsets the CO2 stored — and ideally, you want dedicated storage where the sole purpose is permanent sequestration.

Nova: : That distinction between using CO2 and storing CO2 seems critically important.

Nova: Bachu co-chaired a task force specifically on the transition from CO2-EOR to dedicated CO2 storage, so he has thought deeply about this. His view is that EOR can be a stepping stone — it helps build the infrastructure, the workforce, and the regulatory experience — but the end goal must be permanent geological storage at a scale that actually moves the needle on atmospheric CO2 concentrations.

Nova: : Let me ask a tough question. Some critics argue CCS is a distraction — a way for the fossil fuel industry to claim climate action while continuing to extract and burn hydrocarbons. How does Bachu's work speak to that?

Nova: He is a scientist, not a polemicist, but his research implicitly addresses this. The book makes clear that CCS is not a substitute for renewable energy, energy efficiency, or electrification. It is a complement — specifically for sectors that lack alternatives. Cement will still be needed. Steel will still be produced. Some industrial processes will always release CO2. The question is whether we capture and store those emissions or release them. Bachu frames CCS as an essential piece of the decarbonization puzzle, not the whole picture.

Nova: : That is a more nuanced position than either the techno-optimist view that CCS will save us or the absolutist view that it is inherently a fossil fuel industry ploy.

Nova: So where does Stefan Bachu's "An Introduction to Carbon Capture and Storage" leave us? I think the biggest takeaway is that CCS is a technology where the individual components are well understood, but the system integration remains the grand challenge. Capture technologies work. Geological storage works — Sleipner has proven that for nearly three decades. The methodologies for assessing storage capacity, pioneered by Bachu and adopted globally, are rigorous and reliable.

Nova: : But the gap between what is technically possible and what is actually being deployed is enormous. And bridging that gap requires more than engineering — it requires carbon pricing, regulatory frameworks, public acceptance, infrastructure investment, and political will.

Nova: Exactly. Bachu's book is, at its heart, an invitation to take CCS seriously — not as a magic solution, but as a necessary tool. He brings the credibility of someone who has spent 30 years at the forefront of the science, who has advised governments, who has shared in a Nobel Peace Prize, and who has published over 180 papers on this topic. When he says CCS is feasible and essential, it carries weight.

Nova: : What would you say to someone listening who is skeptical about CCS?

Nova: I would say: look at the sectors where there is no alternative. Cement production alone accounts for roughly 8 percent of global CO2 emissions. There is no way to produce cement at scale without releasing CO2 from limestone — it is baked into the chemistry. For those sectors, CCS is not optional. It is the only pathway to deep decarbonization. Bachu's work gives us the technical foundation. The question now is whether we have the collective will to build on it.

Nova: : And the book makes these concepts accessible — not just for engineers and geologists, but for anyone who needs to understand this critical piece of the climate puzzle.

Nova: If there is one number to sit with, it is this: global CCS captures about one-thousandth of annual emissions today, and the IEA net-zero pathway requires that to scale roughly a hundredfold by 2050. That is the magnitude of the task. And it is exactly why books like Bachu's — which equip the next generation of scientists, engineers, and policymakers with the fundamentals — are so important.

Nova: : A foundational text for a foundational technology. Thank you for taking us through it.

Nova: This is Aibrary. Congratulations on your growth!