Why capture CO2 from the Air?
Capture of dilute CO鈧� directly from the air at 450 parts per million requires more than three times the amount of energy than capture of concentrated CO鈧� from an industrial furnace or power plant. So how can it be justified?
Direct air capture can be practiced virtually anywhere, including geologic storage sites or facilities where CO鈧� is converted to fuels or chemicals. Pipelines to storage, use, or conversion facilities are not required. Geologic storage results in long-term negative emissions or a reduction in atmospheric CO鈧� concentrations, which is attractive to many stakeholders for managing our complex energy system.
CO鈧� purity is typically greater than that captured from fossil point source locations. If we use CO鈧� captured from the air with renewable energy to make a synthetic jet fuel, then combustion of the fuel during use results in a circular pathway: there are no new fossil CO鈧� emissions. One does not have to consider whether the CO鈧� used results in a displacement of fossil fuel use, in order to assess impact.
Direct air capture provides a pathway for offering options to consumers for purchasing products or credible offsets to reduce their greenhouse gas emissions, should they so choose.
Figure ET-25: Direct Air Capture of Carbon Dioxide [1]
Reference
Wilcox et al., World Resources Institute.