Direct air capture (DAC) removes CO2 directly from the atmosphere and stores it underground or uses it in products. Currently expensive but scaling rapidly. This guide covers the technology, leading projects, and DAC role in net zero.
What DAC is
DAC uses large fans to move ambient air past a chemical solvent or solid sorbent that captures CO2. Captured CO2 is then either stored geologically or used in products (fuels, plastics, building materials). Unlike carbon capture at power plants or industrial sites, DAC captures CO2 already in the atmosphere.
Main technologies
| Approach | How it works |
|---|---|
| Solid sorbent | Amine or metal organic framework absorbs CO2 at ambient temperature, releases with heat |
| Liquid solvent | Aqueous hydroxide solution absorbs CO2, released via calciner |
| Electrochemical | Emerging technology using electrochemistry |
| Enhanced weathering | Related but different: accelerates natural rock weathering |
Leading DAC companies
| Company | Approach | Notable |
|---|---|---|
| Climeworks | Solid sorbent | Iceland Orca and Mammoth plants operating |
| Carbon Engineering (Oxy) | Liquid solvent | Occidental Petroleum acquisition; Texas STRATOS project |
| Global Thermostat | Solid sorbent | ExxonMobil partnership |
| Verdox | Electrochemical | Emerging technology |
| Heirloom | Mineralization | US pilots |
| 1PointFive (Oxy) | Liquid solvent | Multiple projects |
| Skytree | Modular solid sorbent | Netherlands, commercial partners |
Climeworks Mammoth
Iceland based Mammoth plant is the world largest operating DAC facility. 36,000 tonnes CO2 per year capacity. CO2 injected into basalt for permanent storage. Powered by geothermal energy. Cost currently very high (over USD 600 per tonne).
Occidental STRATOS Texas
Occidental Petroleum building 500,000 tonne per year DAC plant in Texas. Backed by USD 550 million from BlackRock partnership. Storage in Occidental oil field or use for enhanced oil recovery (contested for climate value).
DAC hubs
US DOE selected 4 initial DAC hubs receiving USD 1.2 billion in Bipartisan Infrastructure Law funding. Includes 1PointFive Texas, Battelle Louisiana, and others. Additional hubs planned.
Current scale
Cost trajectory
| Timeline | Cost per tonne CO2 |
|---|---|
| Early Climeworks (2017) | Over USD 1,000 |
| Current (2024 to 2025) | USD 400 to 700 |
| 2030 target | USD 200 to 300 |
| Long term target | USD 100 or below |
Policy support
| Programme | Value |
|---|---|
| US IRA 45Q | USD 180 per tonne for permanent storage |
| US DOE DAC Hubs | USD 1.2 billion first tranche |
| EU Innovation Fund | Grants for DAC projects |
| UK Direct Air Capture and Greenhouse Gas Removal | Multi hundred million pound funding |
| Voluntary carbon markets | Growing demand at high price |
Corporate offtake
Frontier (Stripe, Alphabet, Meta, Shopify, McKinsey) commits USD 1+ billion for advance market commitment. Microsoft has signed multi million tonne offtake agreements. Airlines increasingly buying DAC removals for corporate travel offset.
DAC role in net zero
CO2 storage
Captured CO2 stored geologically (deep saline aquifers, depleted oil and gas reservoirs, basalt formations). Permanent storage (thousands of years). US Class VI wells regulate injection. Some projects use CO2 for enhanced oil recovery which is more contested.
CO2 use in products
Captured CO2 can be used in synthetic fuels, plastics, concrete curing, greenhouse fertilisation, and other products. Products typically re release CO2 eventually but delay emissions. Less permanent than geological storage.
Alternative carbon removal
| Approach | Notes |
|---|---|
| Afforestation | Trees; cheap but reversible |
| Soil carbon | Agricultural practices; measurement challenges |
| BECCS | Bioenergy with CCS; scaling |
| Ocean fertilisation | Contested effectiveness |
| Enhanced weathering | Rock spread on land |
| Ocean alkalinity enhancement | Emerging |
Contemporary challenges
- High cost currently.
- Very energy intensive (2 to 3 MWh per tonne CO2).
- Land and water use.
- Storage capacity locally.
- Verification and permanence.
- Community acceptance.
- Balancing with emissions reduction priority.
Global DAC industry
US leads with IRA support. Iceland pioneers. UK, Norway, Canada, Germany all have projects. Growing Middle East interest tied to hydrogen ambitions. China DAC investment growing.
Where DAC is going
- US DAC hubs building through 2020s.
- STRATOS Texas 500,000 tonne facility 2025.
- Cost target 200 to 300 USD per tonne by 2030.
- Continued cost reduction with scale.
- Growing corporate procurement.
- Integration with hydrogen and synthetic fuels.
- Standards for verification and permanence.
Frequently asked questions
What is DAC?
Direct air capture. Removes CO2 from atmosphere.
How much does it cost?
USD 400 to 700 per tonne currently.
Is it real?
Yes. Multiple commercial plants operating.
Is DAC scaling?
Yes rapidly. Multiple mega projects in development.
Does DAC eliminate need for reduction?
No. Must reduce emissions primarily.
Who is leading DAC?
Climeworks, Carbon Engineering, and several startups.
Where is CO2 stored?
Deep saline formations or depleted reservoirs.
Is DAC clean?
Depends on power source. Renewable powered is clean.
What about enhanced oil recovery?
Contested for climate value.
Where can I read more?
Carbon180, DOE FECM, Frontier climate.
Summary
Direct air capture removes CO2 from atmosphere for geological storage or product use. Currently expensive but scaling rapidly. Climeworks Iceland and Occidental Texas projects lead. IPCC 2050 net zero scenarios require gigatonnes of DAC. Cost target USD 200 to 300 per tonne by 2030. Growing US federal support and corporate procurement. Essential net zero tool but not substitute for emissions reduction.
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