>>12096972>https://www.sciencedirect.com/science/article/pii/S1876610211003900?via%3DihubThe minimum work can be used to estimate the cost of air capture. The minimum work required for air capture is
calculated to be 20 kJ/mol CO2 (462 kWh/tC) [11]. This assumes the process is ideal with 100% thermodynamic and
thermal efficiencies. However, we know operating at the thermodynamic minimum requires infinite capital costs, so
we must assume some efficiency. Thermodynamic efficiency calculated in literature for air capture processes are in the
2-3% range [9, 12].
M. Ranjan, H.J. Herzog / Energy Procedia 4 (2011) 2869–2876 2871
4 Author name / Energy Procedia 00 (2010) 000–000
Air capture, to be feasible, requires a carbon free electricity source for capturing carbon. The use of any fossil fuel
generated electricity will only end up releasing more CO2 to the atmosphere than capture [12]. Here, we assume that the
cost of carbon-free electricity is 10¢/kWh (though there are many indications it may be much higher [13]). Assuming a
thermodynamic efficiency in the range of 1-5%, the energy cost for air capture can then be estimated as $900-$4600/tC
($250-$1200/tCO2). This is just the energy cost, without factoring even a single dollar for the capital cost. Adding in
the capital cost will increase this estimate significantly. This calculation shows that many of the total cost numbers
reported in the literature ($100-500/tC ($27-136/tCO2)) are not very believable.
