Direct air capture (DAC)

“Capturing a dilute gas from air is possible. Doing it at climate-relevant scale is an energy and infrastructure challenge. ”

Direct air capture uses chemical sorbents or solvents to extract carbon dioxide from ambient air. The captured gas can then be compressed and stored underground or used in products and fuels. When paired with durable geological storage and powered with low-carbon energy, DAC can deliver carbon removal. The attraction is location flexibility and measurable capture.

Unlike land-based removals, DAC does not require photosynthesis and may use less land, although it still requires energy, water, materials and suitable storage infrastructure. Because atmospheric carbon dioxide is dilute, the process is energy-intensive and currently expensive. DAC is sometimes presented as a reason to continue emitting. That misreads both economics and climate pathways.

Scaling removal to compensate for avoidable emissions would require far greater energy, infrastructure and finance than reducing many sources directly. The mitigation hierarchy therefore remains essential. Climate benefit depends on the full system. If the plant uses carbon-intensive electricity or heat, upstream emissions can materially reduce net removal.

If captured carbon is used in short-lived fuels, it may soon return to the atmosphere. A utilisation route should not be described as permanent removal unless storage duration supports that claim. DAC projects also raise governance questions: who pays, who owns the stored carbon, how long monitoring continues and who carries liability after closure.

Public support may be justified to develop a necessary technology, but it should not obscure distributional choices or crowd out proven reductions.

For practitioners, DAC should be evaluated as a specific removal pathway, not as an abstract future solution. The relevant metric is net tonnes durably stored after life-cycle emissions—not gross tonnes captured at the equipment boundary.

Practical application

Require a full energy and life-cycle balance, storage evidence, monitoring plan and clear treatment of utilisation. Distinguish capture capacity from verified net removal and disclose public subsidies or contractual dependencies.

Why it matters

DAC may provide durable removal for hard-to-abate residual emissions. Its constraints make it a complement to reduction, not a substitute for it.

Common misconception

Every tonne captured by DAC is a tonne permanently removed. Net removal depends on upstream emissions and on whether the carbon is durably stored.

Connections

Carbon Removal defines the category. CCS provides transport and storage infrastructure. Residual Emissions determine the legitimate demand for neutralisation.

A question worth asking

Are you evaluating gross capture, net removal or merely announced future capacity?

Selected references

International Energy Agency, Direct Air Capture tracking and analysis. IPCC, Sixth Assessment Report, carbon dioxide removal. ISO 27914, geological storage of carbon dioxide.