Systems Analysis and Cost Estimates for Large Scale Capture of Carbon Dioxide from Air

This paper explores the resource intensity and major cost elements of direct air capture of carbon dioxide. The levelized cost of carbon removal is calculated as the sum of costs resulting from interdependent capture devices, energy supplies, water supplies and sequestration resources. The analysis considers "generic" air capture technology characterized only by its energy use, capture footprint, and water use. Capital costs dominate the analysis, followed by energy efficiency. Four dedicated energy resources are considered: wind, enhanced geothermal, natural gas combined cycle (NGCC), and NGCC with 90% carbon capture. Nearly carbon-free energy is critical to keeping overall cost of carbon mitigation low. The analysis shows that high second law capture efficiencies (on the order of 10%) and relatively inexpensive capture devices (on the order $0.5M for an individual device capturing one tonne CO2/day) must be achieved if the cost of air capture is to approach $300/tonne-CO2. Reaching those goals is likely to require substantial research into the kinetics and thermodynamics of capture chemistry which, respectively, keep the capital and energy costs as low as possible. (C) 2011 Published by Elsevier Ltd.