Capture separates CO₂ from a mixture. Absorption transfers CO₂ into a liquid; adsorption binds it on a solid; membranes exploit selective permeation; cryogenic approaches exploit phase behavior. Regeneration, purification and compression then determine whether the stream meets a downstream process specification. DOE CCUS technology overview
Compare the full delivery boundary
A capture-only cost excludes some combination of conditioning, compression, transport and storage. Direct air capture starts from a much more dilute stream than many industrial sources. Feed composition, contaminants, required purity, heat quality and plant integration all affect the appropriate separation route. IEA, Direct Air Capture
For each reported performance figure, record:
- Inlet composition and CO₂ concentration.
- Capture fraction and product purity as separate metrics.
- Heat and electricity use with units and boundary.
- Solvent or sorbent replacement and test duration.
- Delivered pressure, distance and available infrastructure.
Analyst reading rule: do not compare USD per tonne captured with USD per tonne delivered unless the missing steps are reconciled. A high capture fraction does not establish low cost or low lifecycle emissions.