Direct Air Capture (DAC): How It Works and What It Costs
Most carbon capture starts with a concentrated stream: the exhaust of a power station or cement kiln, where CO₂ makes up a large share of the gas. Direct air capture takes on a far harder target, the open atmosphere, where carbon dioxide is about four molecules in every ten thousand. Pulling it out there is what makes the technology powerful, because it can remove CO₂ that was emitted anywhere, at any time, and also what makes it energy-hungry and expensive.
Direct air capture is a technology that chemically extracts CO₂ straight from ambient air. Capture alone is not removal: the CO₂ has to be durably stored.
Direct air capture (DAC) uses chemicals to pull CO₂ out of ordinary air. Stored underground (DACCS), that CO₂ counts as carbon removal. Studies put today’s cost at $400–2,500 a tonne, and DACCS removed only about 1,500 tonnes of CO₂ in 2025.
Definition — Pulling CO₂ Straight From the Air
Direct air capture is a group of technologies that separate carbon dioxide directly from the ambient atmosphere. Air is drawn across a chemical that selectively binds CO₂; the CO₂ is then released from that chemical in a concentrated, pure stream, and the sorbent is reused. The result is a supply of captured CO₂ that came out of the open air — not from a smokestack, and not from any single emitter.
That “from the open air” quality is what gives DAC its distinctive role. Because the carbon it captures was already in the atmosphere, DAC can address emissions regardless of where or when they were released — including the diffuse, historic, and hard-to-abate emissions that no point-source capture can reach. It is one of the engineered methods within carbon dioxide removal, and the one most often held up for its permanence and measurability.
Direct air capture is a capture technology, not by itself a removal. Capturing CO₂ from the air only becomes carbon removal once that CO₂ is stored durably. What happens to the captured carbon — permanent storage, or use and re-release — decides whether DAC removes anything at all.
DAC, DACCS, and DAC-U: Capture Is Not Removal
The most important distinction on this page is between capturing CO₂ and removing it. Direct air capture produces a stream of CO₂; its climate value depends entirely on where that stream goes.
| Term | What happens to the captured CO₂ | Is it carbon removal? |
|---|---|---|
| DAC (capture only) | CO₂ is captured; fate not yet specified | Not yet — capture alone removes nothing |
| DACCS (capture + storage) | Injected into geological formations for the long term | Yes — atmospheric source + durable storage |
| DAC-U (capture + utilisation) | Used to make fuels, chemicals, or carbonated drinks | Usually not — the CO₂ is soon re-released |
Only DACCS — direct air carbon capture and storage — is reliably a removal, because it satisfies both halves of the removal test: the carbon comes from the atmosphere and it stays out. DAC used to synthesise fuels can cut fossil use, but the CO₂ returns to the air when the fuel is burned, so it is not removal. When people call DAC a “negative emissions technology”, they mean DACCS.
How It Works: Liquid Solvent vs Solid Sorbent
Two engineering approaches dominate, distinguished by the chemical that grabs the CO₂ and the heat needed to release it again.
| Liquid solvent (l-DAC) | Solid sorbent (s-DAC) | |
|---|---|---|
| Capture medium | Aqueous alkaline (hydroxide) solution | Amine-functionalised solid filter |
| Release step | High-temperature calcination (~900°C) | Lower-temperature vacuum/temperature swing (~80–120°C) |
| Energy character | Large high-grade heat demand | Lower-grade heat, modular, batch cycles |
| Scale style | Large centralised plants | Many small stackable units |
| Maturity (2026) | Pilot scale (technology readiness level 6–7) | Commercially deployed (level 9) |
Solid-sorbent systems and mineral looping are commercially deployed; liquid-solvent systems are at pilot scale, and electrochemical approaches earlier still (readiness level 4–6), according to the State of CDR (2026). The lower-temperature heat of solid-sorbent systems can be met by heat pumps or waste heat; the high-temperature heat of liquid systems has historically been supplied by burning natural gas, which — unless that CO₂ is also captured — eats into the net removal. The choice of technology and, above all, the energy source drive both the cost and the real climate benefit.
Why DAC Is Energy-Hungry: the Dilution Problem
The central challenge of DAC is thermodynamic. Carbon dioxide is only about 0.04% of the air, against about 4% in a gas-turbine flue and 14% in a coal plant’s. Separating a dilute substance from a mixture takes intrinsically more energy than separating a concentrated one, so DAC needs a large energy input per tonne — commonly several gigajoules of heat plus electricity for every tonne of CO₂ captured.
Because DAC consumes so much energy, its climate value stands or falls on where that energy comes from. Powered by low-carbon heat and electricity, DACCS delivers a genuine net removal. Powered by unabated fossil energy, the emissions from running it can cancel out much — or in the worst case all — of the CO₂ it captures. This is why DAC plants are sited next to clean power and geological storage, and why any DAC figure must be assessed on a full lifecycle basis, not on the gross tonnes pulled from the air.
DAC in Numbers: Cost, Scale, Storage
| Measure | Figure | Source |
|---|---|---|
| Cost today, US$ per tonne CO₂ (levelised cost of gross removal) | 400–2,500 | van der Spek et al. (2025), in State of CDR 2026, p.242 |
| Cost once deployment reaches billions of tonnes | 100–600 | Same review |
| CO₂ removed by DACCS in 2025 | 0.0015 million tonnes (about 1,500 tonnes) | State of CDR 2026, p.172 |
| Largest plant: Climeworks Mammoth, Iceland (online 2024) | Nameplate up to 36,000 tonnes a year; net removal lower | Climeworks; State of CDR 2026 |
| Net removal as a share of CO₂ captured (Orca and Mammoth) | 23% to 90% | State of CDR 2026, Table 7.1 |
| How long the CO₂ stays stored | More than 10,000 years in rock | State of CDR 2026, Figure 1.3 |
| Modelled DACCS by 2050, most ambitious scenarios | Under 0.1 to 1.8 billion tonnes a year | State of CDR 2026, p.242 |
Two points stand out. First, the cost range is wide because studies model different technologies, energy assumptions and boundaries, and many leave out compressing, transporting and storing the CO₂. Second, real output is far below capacity: both Climeworks plants, Orca and the larger Mammoth, were still running below full capacity in 2025, though both increased their removal from 2024. The State of CDR revised its earlier DACCS figures down once registry data showed Orca had captured much less than its capacity.
Durability, Cost, and Footprint
DAC’s profile is almost the mirror image of nature-based removal, which is why it is discussed as a complement to — not a replacement for — forests and soils.
- Durability: very high. CO₂ stored geologically through DACCS stays put for more than ten thousand years and does not face the fire, drought, or land-use reversal risks of biological storage. This permanence is DAC’s headline advantage.
- Measurability: high. The captured tonnes are metered directly and the storage is monitored, making DACCS one of the easier removals to verify — an important quality signal for credits.
- Footprint: small land, large energy. DAC uses little land and does not compete with food or ecosystems, but it demands a great deal of low-carbon energy.
- Cost: high today. A 2025 review of published studies finds levelised costs of $400–2,500 a tonne of CO₂, falling to perhaps $100–600 once deployment reaches billions of tonnes (State of CDR, 2026).
- Scale: very small. The largest plant, Climeworks’ Mammoth in Iceland, has a nameplate capacity of up to 36,000 tonnes a year, and all DACCS removed about 1,500 tonnes in 2025, against the billions of tonnes of removal that mid-century pathways call for.
Gross vs Net Removal
DAC removals are counted in tonnes of CO₂, but the figure that matters is the net removal: the CO₂ durably stored minus the lifecycle emissions of capturing and storing it. Given how energy-intensive DAC is, that subtraction can be large, and it is dominated by the emissions of the energy supply.
Those lifecycle emissions include gases beyond CO₂ — methane leaking from a natural-gas heat supply, for instance, and nitrous oxide from upstream processes — so they are put on a common footing by global warming potential (methane at 29.8 [GreenCalculus gwp.CH4_fossil.ar6_100 · IPCC AR6 · v2026.284] and nitrous oxide at 273 [GreenCalculus gwp.N2O.ar6_100 · IPCC AR6 WGI Ch 7 Table 7.SM.7 (2021) — AR6 GWP-100] times CO₂ over 100 years) and expressed in CO₂e before being netted off. A credible DACCS removal figure is always net of this full lifecycle, which is exactly why the carbon intensity of the energy source is decisive.
Real plants show how much that matters. Only two DACCS plants had public lifecycle assessments when the State of CDR (2026) was written: Orca and Mammoth, both powered by nearby geothermal energy. Even with that low-carbon supply, reported lifecycle emissions cut net removal to 23% to 90% of the CO₂ captured, depending on equipment manufacture, capture, processing and transport into storage.
DAC Credits and EU Certification
DACCS removals are sold as carbon removal credits, one per tonne, and are among the easiest to verify because the captured CO₂ is metered and the storage is monitored:
- Isometric certifies a Direct Air Capture protocol (v1.3), approved by the Integrity Council for the Voluntary Carbon Market (ICVCM) in October 2025.
- Puro.earth credits DACCS under its Geologically Stored Carbon methodology, which it lists at 1,000+ years of durability.
- EU: The EU’s certification rules for permanent removals, Delegated Regulation (EU) 2026/285, were adopted on 3 February 2026, published on 17 April 2026 and entered into force on 7 May 2026. DACCS is one of its three methods, with BioCCS and biochar. An activity period can last up to 15 years, and monitoring continues until responsibility for the storage site passes to the national authority under the EU CO₂ storage directive (2009/31/EC).
DACCS credits are a small part of the market so far: about 850 were issued in 2025, against roughly 794,000 for biochar (State of CDR 2026, Table 4.2).
Where DAC Fits in Net Zero
DAC is one method inside the broader toolkit of carbon dioxide removal, and it plays the same bounded role removals play everywhere: neutralising the residual, hard-to-abate emissions that survive deep decarbonisation, and — later — drawing the atmospheric stock back down. Because its storage is so durable and so measurable, DACCS is often favoured for the portion of a net-zero claim that demands permanence, under frameworks such as the SBTi Corporate Net-Zero Standard.
DAC is not a reason to keep emitting. It is expensive, energy-hungry, and — today — operating at a tiny fraction of the scale required, so using it to justify avoidable emissions is both costly and counter-productive. Its value is in permanently removing the emissions that genuinely cannot be cut, and it counts as removal only when it is DACCS: captured from the air and durably stored, contrast this with avoided emissions, which take nothing out of the atmosphere at all.
Common Confusions
- Treating capture as removal. DAC on its own removes nothing; only DACCS — capture plus durable storage — is carbon removal.
- Confusing DAC with point-source capture. DAC works on 0.04% ambient air; power-plant capture works on a concentrated flue and is an emission reduction, not removal.
- Assuming DAC is always carbon-negative. On fossil energy, the emissions of running it can cancel much of what it captures. Net removal depends on low-carbon power.
- Counting DAC-U as removal. CO₂ used for fuels or drinks is soon re-released; utilisation is generally not removal.
- Quoting gross tonnes. Report the net, lifecycle removal, not the raw CO₂ captured.
- Assuming today’s cost is ~$100/t. Published studies put today’s cost at $400–2,500 a tonne; $100–600 is a projection for gigatonne scale.
Sources
- The State of Carbon Dioxide Removal, 3rd edition (June 2026; errata July 2026), Edwards, Geden, Gidden, Lamb, Minx, Nemet and Smith (eds.), stateofcdr.org, CC BY 4.0. Chapter 7, pp.172 and 175 (2025 DACCS removal, Orca and Mammoth, Table 7.1 net removal); Chapter 4, p.97 (Table 4.2, credits issued); Chapter 10, p.242 (readiness, potential, scenarios and the van der Spek et al. 2025 cost review); Figure 1.3, p.29 (storage time). Read 30 October 2026.
- Commission Delegated Regulation (EU) 2026/285 on certification methodologies for permanent carbon removals (DACCS, BioCCS and biochar), OJ L, 17 April 2026, EUR-Lex, Article 2 and Annex section 1.2.1; and the European Commission’s certification methodologies page. Read 30 October 2026.
- Registry methods: Isometric certified protocols (Isometric Standard v2.2); Puro.earth methodologies. Read 30 October 2026.
- Climeworks, Mammoth plant page (nameplate capacity up to 36,000 tonnes a year; net removal lower). Read 30 October 2026.
- Flue-gas CO₂ concentration: IPCC Third Assessment Report, Working Group III (2001), about 4% for gas turbines to 14% for pulverised-coal plants. Ambient CO₂: NOAA Global Monitoring Laboratory, Trends in atmospheric CO₂.
Cost, removal and scale figures marked from the State of CDR are served from the GreenCalculus MasterBrain (keys offsets.cdr.*), each with the report page it was read from. We re-check them when the State of CDR publishes a new edition, and the registry methods every quarter.
Frequently Asked Questions
Direct air capture is a technology that chemically separates carbon dioxide directly from ambient air. Air is passed over a chemical that binds CO₂; the CO₂ is then released as a concentrated, pure stream and the chemical is reused. Unlike capture on a power-station flue, DAC works on the open atmosphere, so it can address emissions released anywhere and at any time. On its own DAC is only capture — it becomes a carbon removal method (DACCS) when the captured CO₂ is stored durably underground.
DAC is the capture step — pulling CO₂ out of the air. DACCS (direct air carbon capture and storage) is DAC plus durable geological storage of that CO₂, and it is the version that counts as carbon removal, because the carbon both comes from the atmosphere and stays out of it. If the captured CO₂ is instead used to make fuels, chemicals, or carbonated drinks (DAC utilisation, or DAC-U), it is usually re-released and is not removal. So “DAC” describes the machine; “DACCS” describes the removal.
A 2025 review of published studies, assessed in the State of CDR (2026), finds levelised costs of about $400–2,500 per tonne of CO₂ removed, and possibly $100–600 once deployment reaches billions of tonnes. The range is wide because studies model different technologies and energy supplies, and many leave out compressing, transporting and storing the CO₂. These are cost estimates, not credit prices.
Very little. DACCS removed about 1,500 tonnes of CO₂ in 2025, according to the State of CDR (2026), mostly at Climeworks’ Orca and Mammoth plants in Iceland. Mammoth, the largest, has a nameplate capacity of up to 36,000 tonnes a year, and both plants were still running below capacity. For comparison, novel removal methods together removed about 2 million tonnes in 2025, led by biochar.
The difference is the concentration of the CO₂ and where the carbon came from. Capture at a power plant or factory treats a flue gas of about 4% to 14% CO₂ and stops fossil carbon from being emitted: an emission reduction. DAC treats ambient air at about 0.04% CO₂ and takes carbon out of the atmosphere: a removal, once stored. The dilution makes DAC far more energy-intensive and costly per tonne, but it can address emissions from any source, past or present.
Because CO₂ is very dilute in air, about 420 parts per million. Separating a dilute gas from a mixture takes more energy than separating a concentrated one, so DAC needs a lot of heat and electricity per tonne. The energy source therefore decides the climate benefit: even the two geothermal-powered plants with published lifecycle assessments, Orca and Mammoth, report net removal of 23% to 90% of the CO₂ they capture (State of CDR 2026, Table 7.1).
Only when it is DACCS run on low-carbon energy. The net removal is the CO₂ durably stored minus the lifecycle emissions of capturing and storing it, and because DAC is so energy-hungry, those emissions are dominated by the energy supply. Powered by clean heat and electricity, DACCS is carbon-negative; powered by unabated fossil energy, its own emissions can cancel much or all of what it captures. CO₂ used for fuels or drinks (DAC-U) is not carbon-negative at all, because it is soon released again.
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