Capturing Carbon Dioxide From Air

The goal of carbon sequestration is to take CO2 that would otherwise accumulate in the atmosphere and put it in safe and permanent storage. Most proposed methods would capture CO2 from concentrated sources like power plants. Indeed, on-site capture is the most sensible approach for large sources and initially offers the most cost-effective avenue to sequestration. For distributed, mobile sources like cars, on-board capture at affordable cost would not be feasible. Yet, in order to stabilize atmospheric levels of CO2, these emissions, too, will need to be curtailed. This paper suggests that extraction of CO2 from air could provide a viable and cost-effective alternative to changing the transportation infrastructure to non-carbonaceous fuels. Ambient CO2 in the air could be removed from natural airflow passing over absorber surfaces. The CO2 captured would compensate for CO2 emission from power generation two orders of magnitude larger than the power, which could have instead been extracted from the same airflow by a windmill of similar size. We outline several approaches, and show that the major cost is in the sorbent recovery and not in the capture process. Air extraction is an appealing concept, because it separates the source from disposal. One could collect CO2 after the fact and from any source. Air extraction could reduce atmospheric CO2 levels without making the existing energy or transportation infrastructure obsolete. There would be no need for a network of pipelines shipping CO2 from its source to its disposal site. The atmosphere would act as a temporary storage and transport system. We will discuss the potential impact of such a technology on the climate change debate and outline how such an approach could actually be implemented.