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Category

Direct Air Capture DAC/DACCS

Direct air capture is a family of systems that pass atmospheric air over a sorbent or through a solvent, bind the CO2 chemically, and store the concentrated gas geologically. The durability evidence is strong and the deployed scale is the smallest of any durable pathway: 1,186 tonnes delivered cumulatively.

One of eight durable carbon removal pathways presented by CDR Türkiye, all intended to store carbon for centuries to millennia.

Overview

Open a heading to read the detail.

  1. What sets it apart Direct air capture is the only removal family that depends on neither biomass nor land.

    Its feedstock is the air itself, so a plant can be sited without regard to harvest cycles, land competition or residue supply chains. The price of that freedom is paid in physics: CO2 in ambient air is far more dilute than in a flue gas, which is what makes the separation work so heavy.

  2. One shared skeleton Every type shares the same skeleton.

    Air is brought to a contact surface, CO2 binds chemically, the binding material is regenerated with heat or electricity to release the gas, the released CO2 is purified and compressed, and it is injected into a geological formation. What separates the types is the binding chemistry, the energy that drives regeneration, and whether air reaches the contact surface through a fan or on its own; the storage step is common to almost all of them.

  3. Durability and cost Durability is the comfortable part of this story and cost is not.

    Observed prices run at $600–1,000+/t, while the widely quoted $100–300/t is a projection rather than a present-day price, a gap of roughly five times. The distance between design capacity and actual capture is wide too: Mammoth captured 105 tonnes in its first ten months against a design capacity of 36,000 tonnes a year.

  4. Türkiye: geothermal heat One structural fit is worth naming for Türkiye.

    Solid sorbents need regeneration heat in the 80–100°C band, heat is 75–80% of system energy demand, and Türkiye holds 1,797 MW of installed geothermal capacity, fourth in the world. That is a genuine fit but not an established advantage: no Turkish geothermal field has been assessed for DAC siting.

Ember IPCC AR6 WG3, Ch. 12 CDR.fyi DAC Snapshot IEA, Direct Air Capture ThinkGeoEnergy

Technologies and applications

Technology types The technical methods that capture, convert or store the carbon. Deployment routes The different routes by which the carbon reaches a durable store.

Technology types

The technical methods that capture, convert or store the carbon.

  • Technology type

    Solid sorbent

    A cyclic capture method in which CO2 adheres to the surface of a porous solid and is released again when that solid is heated.

    How it works
    1. Air intake

      Fans draw atmospheric air into the system.

    2. Sorbent contact

      Air passes over a solid sorbent that binds CO2 chemically.

    3. Saturation

      The sorbent fills with CO2 and the airflow is stopped.

    4. Heat applied

      The collector is sealed and the sorbent is heated to 80–100°C under vacuum, regenerating it and releasing the CO2.

    5. Concentration

      The released CO2 is purified and compressed.

    6. Injection

      Compressed CO2 is injected into a suitable geological formation.

    Durability
    Modelled

    >1,000 years

    Applies only once the CO2 is stored geologically.

    What it rests on
    Durability comes from geological storage rather than the capture chemistry, and every type in this category rests on that same step. What sets this type apart is energy: a peer-reviewed review puts the sorbent process at roughly 6 GJ of heat and 1.5 GJ of electricity per tonne of CO2, over 2,000 kWh in total. That sorbents needing less heat could halve the heat demand, to about 3 GJ per tonne, is an estimate, not an operating measurement.
    McQueen et al., Progress in Energy
    Türkiye context
    The 80–100°C regeneration band overlaps with Türkiye’s 1,797 MW of geothermal capacity; that overlap has never been tested at site level.
    ThinkGeoEnergy

  • Technology type

    Liquid solvent (KOH / calcium loop)

    A continuous-flow capture method in which an alkaline liquid binds CO2 from air and the carbonate is recovered at high temperature through a lime loop.

    How it works
    1. Contactor

      Fans draw air horizontally through plastic packing over which a potassium hydroxide solution trickles as a thin film.

    2. Carbonate formation

      CO2 binds in the solution and becomes dissolved carbonate.

    3. Pellet formation

      The carbonate is reacted with calcium and separated as a solid pellet.

    4. Kiln heating

      The pellets are heated to about 900°C in a kiln, releasing pure CO2.

    5. Compression and storage

      The released CO2 is compressed and injected into a geological formation.

    Durability
    Modelled

    >1,000 years

    Applies only once the CO2 is stored geologically.

    What it rests on
    The storage step is identical to solid sorbent, so the durability basis is identical too. The distinguishing loads sit elsewhere: the kiln runs far hotter than the heat a solid sorbent needs, and water use is an independent constraint in liquid-solvent systems.
    Alcalde et al., Nature Communications

  • Technology type

    Solid calcium looping

    A closed loop in which hydrated lime made from limestone carbonates passively in open air on trays, and the saturated carbonate returns to the kiln to be split again.

    How it works
    1. Kiln heating

      Limestone is split in a kiln: calcium oxide remains and the released CO2 is captured.

    2. Slaking

      The calcium oxide is reacted with water to become hydrated lime.

    3. Spreading on trays

      The hydrated lime is spread in thin layers across open-air trays.

    4. Passive carbonation

      No fan runs; the material binds CO2 from the air on its own and turns to calcium carbonate over a matter of days.

    5. Loop and storage

      The saturated carbonate returns to the kiln, and the CO2 released in the kiln is compressed and injected into a geological formation.

    Durability
    Early stage

    >1,000 years

    Applies only once the CO2 is stored; durability comes from storing the CO2 released in the kiln, not from the loop itself.

    What it rests on
    The distinguishing feature is that air contact is passive: no fan, and therefore no electrical load on the capture side. The energy is spent in the kiln, which needs high temperature, and the process only yields net removal where that heat is low-carbon. The cost is speed: in laboratory conditions it took 300 hours for 70% of the hydrated lime to turn into carbonate, so contact runs over days and scale grows with tray area. The loop itself is durable: conversion did not fall appreciably after the material went through the kiln and back five times.
    Erans et al., Journal of Cleaner Production

  • Technology type

    Electrochemical (electro-swing)

    A capture method in which CO2 is bound and released by switching an electrical voltage rather than by heat, so the input is electricity.

    How it works
    1. Charging

      A voltage is applied and the electrode surface gains affinity for CO2.

    2. Binding

      CO2 in the air passing through the cell is held at that surface.

    3. Polarity reversal

      The voltage is reversed and the surface loses its affinity for CO2.

    4. Release

      The held CO2 is freed into a closed volume and collected.

    5. Compression and storage

      Collected CO2 is compressed and injected into a geological formation.

    Durability
    Early stage

    Depends on the storage step

    The capture chemistry does not change durability; what decides it is where the CO2 is stored.

    What it rests on
    The appeal is that a heat requirement becomes an electricity requirement, which simplifies the energy accounting wherever low-carbon power is available. Today the work is at laboratory and pilot scale, with no commercially demonstrated plant, so no field-based cost or yield statement can be made.

  • Technology type

    Membrane separation

    A capture method that separates CO2 by passing air across a film that lets CO2 through faster than other gases, rather than binding it chemically.

    How it works
    1. Pressurised air

      A fan moves air along one face of the membrane at about atmospheric pressure while a vacuum pump lowers the pressure on the other side.

    2. Selective transport

      CO2 molecules cross the film faster than the other gases.

    3. Staging

      One pass cannot reach a usable concentration, so the stream runs through several stages.

    4. Collection

      The enriched stream is collected and purified.

    5. Compression and storage

      The purified CO2 is compressed and injected into a geological formation.

    Durability
    Early stage

    Depends on the storage step

    The separation method does not change durability; what decides it is where the CO2 is stored.

    What it rests on
    With no sorbent to regenerate there is no thermal load; in exchange, a separation that starts from atmospheric concentration cannot be done in one stage, and compression work grows with each stage added. For direct air capture this remains a research approach with no demonstrated scale.

  • Technology type

    Moisture-swing

    A capture method in which the binding material holds CO2 when dry and releases it when wetted, so the cycle is driven by humidity rather than heat.

    How it works
    1. Dry phase

      Dry resin binds CO2 from the passing air.

    2. Saturation

      The resin reaches capacity and the airflow is stopped.

    3. Wetting

      Water or humid air is supplied to the material.

    4. Release

      Moisture weakens the bond and CO2 is freed into a closed volume.

    5. Collection and storage

      The freed CO2 is collected, compressed and injected into a geological formation.

    Durability
    Early stage

    Depends on the storage step

    The cycle chemistry does not change durability; what decides it is where the CO2 is stored.

    What it rests on
    The appeal is that regeneration runs on humidity rather than heat, shifting most of the energy load from thermal supply to water management. In arid settings water supply becomes the constraint; in humid ones the swing itself does. The approach sits at research and pilot stage with no commercial demonstration.
Next tab Deployment routes

Deployment routes

The different routes by which the carbon reaches a durable store.

  • Deployment route

    Geothermal-heated DAC

    A solid-sorbent arrangement in which the low-temperature heat needed for regeneration is drawn from geothermal fluid.

    How it works
    1. Geothermal fluid

      Hot fluid is brought to surface from the well.

    2. Heat transfer

      A heat exchanger passes that heat to the sorbent bed.

    3. Capture cycle

      The sorbent binds CO2 from air and is regenerated with the same heat once saturated.

    4. Concentration

      The released CO2 is purified and compressed.

    5. On-site storage

      Where the site is basaltic, the CO2 can be injected into the same geology.

    Durability
    Modelled

    >1,000 years

    Applies only once the CO2 is stored; on a basaltic site mineralization runs far faster.

    What it rests on
    The heat requirement and the geothermal temperature band coincide: sorbents want 80–100°C, and heat is 75–80% of system energy demand. Because the arrangement is otherwise identical to solid sorbent, the durability basis is identical.
    IEA, Direct Air Capture
    Türkiye context
    Türkiye ranks fourth in the world with 1,797 MW of installed geothermal capacity. Those same fields emit 400–1,300 g of CO2 for every kWh of power, against a global geothermal benchmark of 121 g, which makes capturing the CO2 that comes up with the geothermal fluid a separate domestic opportunity. No Turkish field has been assessed for DAC siting.
    ESMAP / World Bank

Frequently asked questions

Is direct air capture the same as flue gas capture?

No. Flue gas capture separates a concentrated CO2 stream at the exit of an emitting facility and abates an emission; direct air capture separates dilute CO2 from the atmosphere and, once the gas is stored, produces a removal. The difference in concentration is what sets the energy cost of the separation.

How long does the CO2 stay underground?

Durability comes from the storage step rather than the capture step, and geological storage exceeds 1,000 years. The rigorous underlying finding is more cautious: a 50% probability that more than 98% remains trapped over 10,000 years under well-regulated conditions. That probability qualifier is routinely dropped when the figure is cited.

What does direct air capture cost today?

Observed prices are $600–1,000+/t: Climeworks Orca at roughly $1,000/t and Mammoth above $600/t, with DAC credits at €450–1,000+/t. The frequently quoted $100–300/t is an IPCC projection, not a price anyone pays today.

Who verifies a direct air capture removal claim?

Captured CO2 is metered at the plant and injected CO2 is metered at the wellhead, so measurement is not the weak link in this family. The weak link is the net calculation: where the energy is fossil, part of the gross capture only offsets the plant’s own emissions and the removal is whatever survives that subtraction. Independent verification therefore examines the energy supply and the life-cycle accounting rather than the capture meter.

Do Turkish geothermal plants have an emissions problem of their own?

They do. Turkish geothermal plants emit 400–1,300 g of CO2 for every kWh of power, against a global geothermal benchmark of 121 g, because fluid from carbonate reservoirs brings CO2 and other gases up with it. The same condition points to a genuine domestic opportunity in capturing that CO2.