Direct Air Capture

Direct air capture (DAC) pulls CO2 directly from ambient air using chemical processes. It is the CDR technology with the clearest path to permanent, verifiable removal. It is also, at current costs, absurdly expensive: $400-1,000 per ton of CO2 captured, versus $50-100 for the social cost of carbon in most estimates. DAC works. The question is whether it can ever work cheaply enough to matter.

How it works. Air passes through contactors containing a chemical sorbent (solid or liquid) that binds CO2. The sorbent is then heated to release concentrated CO2 for storage. The energy requirement is the fundamental challenge: CO2 is only 420 ppm of the atmosphere, so DAC must process enormous volumes of air. Climeworks' Orca plant in Iceland captures 4,000 tons/year. Global emissions are 37 billion tons/year. The scale gap is roughly 10 million to one.

The cost trajectory. DAC proponents cite the solar analogy: solar fell from $76/watt in 1977 to $0.20/watt in 2024. The IRA's 45Q credit offers $180/ton for DAC with geological storage, closing roughly half the cost gap. The DOE's "DAC Hubs" program funded four regional hubs at $3.5 billion total, targeting 1 million tons/year each by 2030.

Can DAC follow the solar cost curve?

Unlikely at the same rate. Solar costs fell through mass manufacturing of identical modules. DAC plants are large chemical facilities, more analogous to refineries than to solar panels. Process engineering improves incrementally, not exponentially. Most projections estimate DAC reaching $100-200/ton by 2050, competitive with the social cost of carbon but not cheap enough for gigatonne-scale deployment without sustained policy support.

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