One tonne is a system boundary
The numerator is total cost. The denominator is net atmospheric CO₂-equivalent durably stored—not gas leaving a contactor.
A credible ledger includes plant construction, sorbent manufacture and replacement, electricity, heat, water, compression, transport, injection, monitoring, and eventual closure. A fossil-powered plant can still capture more than it emits, but its gross-to-net ratio worsens and clean-energy demand grows with every tonne.
The target has four simultaneous tests
Cost, net negativity, scale, and durability must coexist. Meeting any one alone does not produce the promised commodity.
The feedstock is everywhere and almost empty
At roughly 420 ppm, a cubic metre of air contains less than a gram of CO₂. The plant must expose an enormous air volume to chemistry without spending the product's value on pressure drop.
For an idealized separation at ambient temperature, the concentration term alone is on the order of 120 kWh of reversible work per tonne. That is a floor, not a machine specification: it excludes pressure drop, imperfect selectivity, heat transfer, sorbent regeneration, compression, and entropy created by real processes.
A contactor is a coupled chemical factory
A better sorbent can lower regeneration energy but bind more slowly, degrade faster, dislike humidity, or require a larger contactor. The optimum belongs to the whole plant.
Contact the air
Move or expose enough ambient air to a reactive surface while limiting fan pressure, land, fouling, and weather sensitivity.
- Layer
- Volume
- System metric
- Net tonnes durably stored per dollar and per year
Bind selectively
Capture CO₂ at roughly 420 parts per million while water, oxygen, and contaminants compete for sites and shorten sorbent life.
- Layer
- Material
- System metric
- Net tonnes durably stored per dollar and per year
Regenerate
Reverse the binding with heat, vacuum, humidity, electricity, or chemical work without destroying the capture medium.
- Layer
- Energy
- System metric
- Net tonnes durably stored per dollar and per year
Condition
Dry and compress a diffuse product into a specification that pipelines, ships, wells, or mineral processes can accept.
- Layer
- Compression
- System metric
- Net tonnes durably stored per dollar and per year
Transport and inject
Match a capture plant to pore space, wells, pressure management, permits, liability, and a route between them.
- Layer
- Infrastructure
- System metric
- Net tonnes durably stored per dollar and per year
Measure and verify
Prove net removal after lifecycle emissions and monitor storage strongly enough that a buyer can own a durable claim.
- Layer
- Product
- System metric
- Net tonnes durably stored per dollar and per year
Liquid-solvent systems can exploit large process equipment and high-temperature regeneration. Solid-sorbent systems can use lower-temperature heat and modular contactors. Electrochemical and moisture-swing routes rearrange the energy bill. None escapes the need to contact dilute air, release concentrated CO₂, and keep the capture medium productive across many cycles.
The capture plant ends where infrastructure begins
CO₂ is not removed when it leaves the regeneration vessel. It must reach a reservoir or durable mineral product with a chain of custody.
Compression is continuous load
Pipeline and injection specifications require conditioning and high pressure, adding equipment and electricity after capture.
Pore space is local
Capacity on a geological map is not a permitted, characterized well with pressure management and an operator.
Networks need anchor volume
A small capture plant cannot cheaply carry a dedicated pipeline, while shared hubs need coordinated schedules and liability.
MRV creates the commodity
Sampling, metering, lifecycle models, subsurface monitoring, and registries make a durable tonne distinguishable from a claim.
Utilization is not automatically storage. Fuel returns carbon quickly; some concrete and mineral routes retain it much longer. The accounting question is not whether CO₂ became a product but how much stayed out of the atmosphere, for how long, compared with the counterfactual.
$100 is a procurement specification
The target only matters if it means a net, durable, verified tonne at useful scale. Quoted capture cost, credit price, subsidy value, and full delivery cost are not interchangeable.
| Number | What it can prove | What it cannot |
|---|---|---|
| Modeled $/t | Design sensitivity and improvement priorities | Bankable delivered cost |
| Credit sale price | What one buyer accepted under one contract | Plant cost or broad demand |
| Nameplate t/y | Designed throughput | Uptime, net removal, or storage |
| Captured tonnes | Contactor output | Lifecycle emissions and durability |
| Verified net stored | The product the climate ledger needs | Whether it can scale cheaply |
The observable cost curve runs through contracts, not lab benchmarks. Early Frontier advanced-market commitments settled at $990/t for Heirloom and an average of $440/t for CarbonCapture, stepping from about $650/t toward $350/t by 2028 (Measured contract prices; the step is a Projected schedule). The largest Frontier and Stripe offtake of 2026 cleared at $315/t (Measured). Stratos, the 500 kt/yr 1PointFive plant, is estimated at $400–500/t with long-term credit pricing of $300–450/t, and Climeworks quotes $400–600/t credits (Projected). In short: $650 in early contracts, $440 on the CarbonCapture commitment average, $315 on the largest 2026 offtake, against an institutional floor of roughly $200–250/t by the early 2030s (Projected). The $100/t headline remains a Target that analyses call highly aspirational with current chemistries.
Peer-reviewed models of a 1 Gt/yr industry put liquid-solvent DAC at $341/t (range $226–544) and solid sorbent near $374/t (Derived/Projected). IPCC AR6 finds $100–300/t likely (Projected), and Global CCS Institute scenarios span $137–412/t at a 5% discount rate (Projected). Energy is the physical term beneath those models: first-of-a-kind designs consume 1.5–2.5 MWh/t against a thermodynamic minimum near 0.17 MWh/t—about a 10× engineering multiplier (Derived). Closing that multiplier, not a new chemistry alone, is what moves delivered cost toward the modelled range.
Contracted tonnes are not delivered tonnes
Climeworks reports capacity factors of 40–50% in upgraded Mammoth units and a 50% opex reduction after its September 2026 sorbent and mechanical upgrades, with more than double capture in the upgraded containers (Company-reported). Delivery, not contracting, is the curve that has to move: at 0.05%, the market has priced millions of tonnes it has not yet received.
An optimistic view, with conditions
The curve can move because today's gap is mostly engineering
Contactors, sorbents, heat integration, modular manufacturing, and shared storage can all improve far above the physical minimum. The proof is sustained net tonnes, not increasingly large announcements.
Measure the whole plant
Publish energy, sorbent loss, uptime, gross capture, lifecycle emissions, and injected mass on consistent boundaries.
Share infrastructure
Pair multiple capture approaches with characterized storage, compression, transport, and common MRV.
Buy net tonnes
Procurement should pay after verified delivery and make durability and reversal liability explicit.
Sources, method, and boundaries
The thermodynamic figure is a transparent ideal-gas concentration estimate, not observed plant consumption. Government goals and awarded capacity are labeled as targets and programmes, never operating performance.
