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Climate / CCUS

Direct Air Capture (DAC) CO₂ Removal Simulator

Design a Negative Emissions Technology (NET) plant that pulls CO₂ straight out of the air. Choose between liquid-solvent, solid-amine, moisture-swing and cryogenic DAC, then vary the annual capture target, airflow and electricity price to see the required airflow, annual electricity, LCOA (levelised cost of CO₂ avoided) and atmospheric ppm reduction update in real time.

Parameters
DAC technology
Sets capture efficiency, regeneration energy and CAPEX
Annual capture target (t-CO₂/yr)
Plant-wide annual CO₂ capture goal
Air flow rate Q_air
m³/h
Per-unit fan throughput (reference value)
Sorbent regeneration temp.
°C
Temperature to desorb CO₂ from the sorbent
Electricity price
USD/kWh
Effective price including renewables PPA
CO₂ storage available
ON: geological sequestration CCS (20 USD/t) OFF: utilisation CCU (100 USD/t)
Results
—
CO₂ capture eff. (%)
—
Required airflow (m³/h)
—
Annual electricity (MWh)
—
LCOA (USD/t-CO₂)
—
Total CAPEX (M USD)
—
Atm. CO₂ reduction (ppm)
—
DAC plant concept — air → contactor → regenerator → storage

Large fans push ambient air (425 ppm CO₂) through the contactor, where sorbent selectively binds CO₂. The regenerator uses heat, humidity or vacuum to release pure CO₂, which is piped to a sequestration well or utilisation downstream. The bottom bar tracks LCOA.

LCOA by technology
Scale vs unit cost (economy-of-scale effect)
Theory & Key Formulas

$$P_{\text{cap}} = Q_{\text{air}} \cdot [\mathrm{CO_2}] \cdot \eta_{\text{cap}}, \qquad LCOA = \frac{CAPEX/N + OPEX_{\text{annual}}}{M_{\mathrm{CO_2},\text{annual}}}$$

$Q_{\text{air}}$: air flow rate, $[\mathrm{CO_2}]\approx 8.34\times10^{-4}$ kg/m³ (425 ppm at STP), $\eta_{\text{cap}}$: capture efficiency, $N$: plant lifetime (25 yr), $M_{\mathrm{CO_2},\text{annual}}$: annual capture.

$$E_{\text{annual}} = M_{\mathrm{CO_2}} \cdot e_{\text{spec}}, \qquad \Delta[\mathrm{CO_2}]_{\text{atm}} \approx \frac{M_{\mathrm{CO_2},\text{annual}}}{7.8 \times 10^{9}\ \text{t/ppm}}$$

$e_{\text{spec}}$: specific energy per tonne captured (kWh/t-CO₂). Removing one atmospheric ppm requires fixing roughly 7.8 Gt-CO₂ (IPCC AR6).

Direct Air Capture (DAC) — CO₂ removal technology and LCOA assessment

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I keep seeing "DAC" in climate news. Is it really a machine that breathes CO₂ out of the air? How is that different from the CO₂ capture units bolted on smokestacks?
🎓
Exactly — DAC (Direct Air Capture) handles the open atmosphere itself. Smokestack capture is called PCC, and its flue gas is already 5-15% CO₂. The air a DAC plant inhales is only 425 ppm — about 0.04%. To grab the same tonne of CO₂, DAC has to move more than a thousand times the volume of gas, which is why DAC plants look like enormous fan walls plus chemical reactors. Climeworks Mammoth in Iceland (2024) and Occidental's Stratos in West Texas (2026) are the showcase examples.
🙋
Can you really pull CO₂ out of something that dilute? The tool says there are different "technologies" — what's the difference?
🎓
Four main families. (1) Liquid solvent (KOH or Ca(OH)₂) — Carbon Engineering style. Capture efficiency 70% but it needs ~800 °C heat to regenerate and burns 1,500 kWh/t. (2) Solid amine — Climeworks Orca/Mammoth. Regenerates at 80-100 °C, so geothermal or industrial waste heat works perfectly. (3) Moisture swing — just cycles between dry and humid air, only 800 kWh/t but a lower 60% efficiency. (4) Cryogenic — freezes CO₂ below -78 °C, giving >99% purity but the highest 3,500 kWh/t. Switch the dropdown and watch LCOA jump.
🙋
Wow, liquid gives 237 USD/t but cryogenic shoots straight up. So LCOA is basically the dollar cost to capture one tonne, right?
🎓
Right. LCOA = (CAPEX/N + annual OPEX) / annual capture. Today the global range is 400-600 USD/t and the best plants hit ~200 USD/t. Three levers bring it down. First, cheap renewable power below 0.05 USD/kWh. Second, credits — the US IRA 45Q gives 180 USD/t for CCS (130 USD/t for CCU) and the EU ETS is around 90 USD/t. Third, scale-up: the "scale vs unit cost" chart below shows the economy-of-scale effect once you hit Mt scale.
🙋
When I uncheck the "CO₂ storage" box the verdict turns yellow — what does that mean?
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That toggle is the split between CCS (Carbon Capture and Storage) and CCU (Utilisation). CCS injects the CO₂ into deep saline aquifers or depleted oil fields, locking it away for centuries at about 20 USD/t — that is true Negative Emissions. CCU turns the CO₂ into synfuels, concrete or polymers; if it goes into fuel, the CO₂ comes right back out, so the climate benefit is just "carbon neutral" at best, and the process costs ~100 USD/t. The warn verdict is a reminder that CCU alone does not deliver removal.
🙋
One naive question — capturing 10,000 t/year only knocks 1.28×10⁻⁶ ppm off the atmosphere. Does it really matter at all?
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Sharp question. The IPCC AR6 1.5 °C pathways need 5-10 Gt-CO₂/year of net removal by 2050, and today's whole DAC fleet is about one millionth of that. So individual plants stay tiny, but the entire industry has to scale to Gt globally. Crank the slider to 1,000,000 t/yr (1 Mt) and watch how the required airflow, electricity and CAPEX explode. To reduce just one ppm worldwide you must lock away 7.8 Gt-CO₂ — that is the hard truth of climate engineering.

Frequently Asked Questions

DAC removes CO₂ directly from the open atmosphere using chemical absorption or physical adsorption — it is a Negative Emissions Technology (NET). Post-combustion capture (PCC) targets flue gas with 5-15% CO₂; DAC has to deal with the 425 ppm (0.0425%) found in ambient air, so the volume of air handled per tonne of CO₂ is more than 1,000 times larger. Energy use is correspondingly large and LCOA (levelised cost of CO₂ avoided) sits at 100-600 USD/t. In exchange, DAC can address legacy emissions and dispersed sources (shipping, aviation, agriculture) that flue-gas capture cannot reach.
LCOA = (CAPEX / N + annual OPEX) / annual CO₂ captured. CAPEX is plant construction cost, N is plant lifetime (typically 20-25 years) and OPEX covers electricity, heat, sorbent makeup, labour and storage. This tool assumes N = 25 yr, O&M at 10%/yr of CAPEX, 20 USD/t for CO₂ sequestration (CCS) and 100 USD/t for utilisation (CCU). LCOA is highly sensitive to electricity price and plant scale: a solid-amine plant on 0.05 USD/kWh renewables can reach 200-300 USD/t, and the US IRA 45Q tax credit (180 USD/t for CCS) brings the net cost down further.
(1) Liquid solvent (KOH / Ca(OH)₂, Carbon Engineering style) — capture efficiency 70%, but regeneration needs ≈800 °C heat, electricity 1,500 kWh/t-CO₂. (2) Solid amine (Climeworks Orca/Mammoth) — 80-100 °C regeneration so low-temperature waste heat works, efficiency 80%; currently the most commercially mature. (3) Moisture swing (Lackner, Global Thermostat) — desorbs by simply changing humidity, 800 kWh/t but only 60% efficient. (4) Cryogenic separation — freezes CO₂ below its -78 °C sublimation point and reaches >99% purity, but costs 3,500 kWh/t. Sites with cheap geothermal or waste heat (Iceland, West Texas) favour solid amine; food-grade or synthetic-fuel use cases needing pure CO₂ may justify cryogenic.
IPCC AR6 1.5 °C-compatible pathways require 5-10 Gt-CO₂/year of net negative emissions by 2050 and cumulatively 100-1000 Gt-CO₂ by 2100, mostly delivered by DAC+CCS (DACCS) and BECCS. Today's worldwide DAC capacity is on the order of 10,000 t-CO₂/year — about one millionth of the Gt-scale needed. Plants like Climeworks Mammoth (2024, Iceland, 36,000 t/y) and Stratos (2026, West Texas, 500,000 t/y) are pushing the field toward the Mt scale. Entering Gt-scale numbers in this tool gives a visceral feel for the airflow and power infrastructure that planetary-scale DAC would require.

Real-World Applications

Commercial DAC plants (Climeworks Mammoth, Occidental Stratos): Climeworks Mammoth (commissioned 2024 in Iceland's Hellisheidi geothermal field, 36,000 t-CO₂/yr) combines solid-amine sorbents with geothermal heat and mineralises captured CO₂ in basalt via the CarbFix process. Occidental's Stratos (planned 2026, West Texas, 500,000 t-CO₂/yr) uses Carbon Engineering's liquid-solvent route and pairs it with both enhanced oil recovery (EOR) and permanent storage. Enter 36,000 or 500,000 t/yr into this tool to reproduce the airflow, electricity and plant scale of these real assets.

Synthetic fuels (e-fuel and SAF): Combining DAC-derived CO₂ with renewable hydrogen via Fischer-Tropsch or reverse water-gas shift produces synthetic jet fuel (SAF — Sustainable Aviation Fuel), methanol or e-methane. Aviation regulators (ICAO CORSIA) target a rising SAF share through 2050, and companies such as Twelve (US), Norsk e-Fuel (Norway) and HIF Global (Chile) operate DAC + electrolyser e-fuel pilots.

Voluntary carbon-removal market: Tech and finance majors — Microsoft, Stripe, Frontier, JPMorgan — purchase DAC-based removal credits at 400-1,200 USD/t under multi-year offtake agreements. That is orders of magnitude above forest credits (10-30 USD/t), but DAC offers high permanence (centuries to millennia) and verifiability, which is essential for credible net-zero claims. The LCOA produced by this tool compares directly with these market prices.

Integrated Assessment Models (IAMs): All IPCC AR6 1.5 °C pathways (C1-C3) rely on Carbon Dioxide Removal (CDR), and IAMs such as IMAGE, GCAM and MESSAGE deploy DAC at Gt scale. Putting 1,000,000 t (1 Mt) or 100,000,000 t (0.1 Gt) into this tool exposes the unrealistic land, electricity, water and capital that such pathways imply — a useful counterweight to "DAC will fix it" thinking in policy debates.

Common Misconceptions and Pitfalls

The most damaging misconception is the "DAC means we can keep burning fossil fuels" moral-hazard argument. Capturing a tonne of CO₂ takes 1,500-3,500 kWh of electricity; sourced from coal (800 g-CO₂/kWh) that releases 1.2-2.8 tonnes of new CO₂, making the system net positive rather than net negative. DAC only delivers negative emissions when powered by additional renewables, geothermal or nuclear — it must complement, not replace, emissions cuts. IPCC AR6 is explicit that DAC should be reserved for residual emissions in hard-to-abate sectors (aviation, agriculture, cement) and legacy offsets.

Second pitfall: "LCOA tells you everything". LCOA is an economic metric, but without a full life-cycle assessment (LCA) it is meaningless. Solid amines release NOx during sorbent manufacture, liquid KOH is corrosive and demands frequent piping replacement, cryogenic plants risk refrigerant leaks. Net CDR (Net Carbon Dioxide Removal) = gross capture − life-cycle emissions; Climeworks publishes a Net CDR efficiency of 0.85-0.90 for solid amine. The number in this tool is gross capture; assume the actually-removed amount is roughly 85% of it.

Finally, "DAC will scale to Mt easily". CAPEX does drop 20-40% with scale, but (1) Class VI CO₂ injection wells (US) take 6-10 years to permit, (2) >100 MW of dedicated renewables must be available 24/7, and (3) global amine sorbent supply is limited. Even Stratos at 500,000 t/yr equals only 1/15,000 of what one ppm of atmospheric reduction needs — confirm this in the "Atm. CO₂ reduction (ppm)" stat. Emissions cuts remain the main pillar; DAC is the piece that closes the final 10-20%.

How to Use

  1. Enter your annual CO₂ removal target in kg/year (e.g., 1000 tonnes = 1,000,000 kg) to define plant scale.
  2. Set air flow rate in m³/h based on your contact equipment—solid sorbent systems typically require 500–5000 m³/h depending on bed size and face velocity constraints.
  3. Specify sorbent regeneration temperature in °C (moisture swing sorbents: 60–100°C; temperature swing: 80–150°C for MOF-801 or similar).
  4. Input electricity cost in USD/kWh reflecting your grid (e.g., 0.08 USD/kWh for natural gas peaker, 0.12 for industrial grid in EU).
  5. Review outputs: capture efficiency, required compressor airflow, annual MWh consumption, levelized cost of abated CO₂ (LCOA), total CAPEX in millions USD, and atmospheric CO₂ reduction in ppm equivalence.

Worked Example

A direct air capture plant targets 10,000 tonnes CO₂/year (10,000,000 kg). Set air flow to 2000 m³/h with solid sorbent regeneration at 85°C and grid electricity at 0.10 USD/kWh. Simulator calculates: 78% capture efficiency, 2560 m³/h actual airflow required (accounting for pressure drop), 8400 MWh annual electricity, LCOA of 185 USD/tonne-CO₂, CAPEX of 42 million USD, and 0.0012 ppm atmospheric reduction. Increasing regeneration temperature to 100°C improves efficiency to 82% but raises annual consumption to 9200 MWh and LCOA to 198 USD/tonne.

Practical Notes

  1. Sorbent regeneration below 70°C risks incomplete CO₂ release; above 120°C increases thermal degradation for polymeric sorbents—validate material spec sheets (e.g., Climeworks' durability targets ~20,000 cycles at design temperature).
  2. Air flow rate scales linearly with CAPEX; 5000 m³/h requires 3–4× blower capital versus 1000 m³/h due to ductwork and foundation reinforcement in industrial settings.
  3. LCOA sensitivity: each 0.01 USD/kWh change impacts cost by ±8–12 USD/tonne; renewable-powered DAC at 0.04 USD/kWh achieves 140–160 USD/tonne versus 200+ for grid-dependent plants.
  4. Atmospheric CO₂ reduction (ppm) assumes 5.15 gigatonnes total atmospheric CO₂; plants removing 10,000 tonnes annually create 0.0019 ppm offset—context for portfolio-level carbon removal strategies.