What is the difference between direct air capture (DAC) and point-source CCS?

• A. Direct air capture removes CO2 from ambient air, while point-source CCS captures CO2 from a single emission source such as a power plant.
• B. Direct air capture captures CO2 from a single source; point-source CCS captures CO2 from ambient air.
• C. DAC captures CO2 from water; CCS captures CO2 from biomass.
• D. DAC and CCS are the same process with different names.

Answer: (A)

Where CO2 is removed drives the difference between the two. Direct air capture pulls CO2 directly from ambient air, where the gas is very dilute, so it requires processing large volumes of air and energy to collect a useful amount of CO2. The captured CO2 is then concentrated and stored or utilized. Point-source CCS captures CO2 from a single emission source, such as a power plant or industrial facility, where the CO2 concentration in the exhaust is much higher. This makes the capture process more efficient and easier to integrate with existing emissions streams, with the CO2 then compressed, transported, and stored geologically. So the key distinction is ambient air capture versus capture from a specific, concentrated emission source.