# Analysis of Technologies for Carbon Dioxide Capture from the Air
## 4 Key Performance Indicators
In this analysis, the capital cost has the highest influence on the total cost, with a value of 1000 $/tonCO\({}_{2}\) for the solid sorbent process. However, a low value of about 14 $/tonCO\({}_{2}\) has also been obtained in this case. The capital cost for the liquid sorbent system is between 80 $/tonCO\({}_{2}\) and 150 $/tonCO\({}_{2}\). Lower values are given for the operating costs for both processes: a range of 40-80 $/tonCO\({}_{2}\) for the absorption plant, and a range of 4-48 $/tonCO\({}_{2}\) for the adsorption system. Overall, it is \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Company** & **Time Period** & **Total Cost (\$/tonCO\({}_{2}\))** & **Reference** \\ \hline Carbon Engineering & 2018 & 94–232 (levelized) & [34] \\ \hline \multirow{3}{*}{Climeworks} & 2018 & 600 & [113] \\  & 2025 & 200 & [3] \\  & 2030 & 100 & [3] \\ \hline \multirow{3}{*}{Global Thermostat} & 2017 & 50 & [141] \\  & future & 15–50 & [141] \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Costs of the main DAC companies. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Company** & **Thermal Energy (kWh\({}_{\text{th}}\)/tonCO\({}_{2}\))** & **Electrical Energy (kWh\({}_{\text{el}}\)/tonCO\({}_{2}\))** \\ \hline Carbon Engineering & 1458 (by natural gas) & 366 (air separation unit for oxy-fuel + compressor + fan) \\ Climeworks & 1500–2000 (by waste heat) & 200–450 (fans + control) \\ Global Thermostat & 1170–1410 (by steam) & 150–260 (fans + control) \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Energy consumption for the main DAC companies [129]. possible to underline that the wide range of costs is due to the emerging technology, the process boundaries considered and approaches to economic assessment. Another KPI is land use. To have an idea of this indicator, respective values for Carbon Engineering, Climeworks and Global Thermostat have been reported as follows: 0.2 km\({}^{2}\) for 1 MtCO\({}_{2}\)/year (plant in Texas), 0.1 km\({}^{2}\) for 1 MtCO\({}_{2}\)/year (plant in Switzerland), 0.0008 km\({}^{2}\) for 1 MtCO\({}_{2}\)/year (plant in Iceland) and 0.05-0.002 km\({}^{2}\) for 1 MtonCO\({}_{2}\)/year [40]. Data are reported in the literature for the land use for different combinations of DAC systems and energy sources, as reported in Table 7[143]. For the absorption process, land use ranges between 0.4 and 14 km\({}^{2}\) for 1 MtonCO\({}_{2}\)/year, while for the adsorption system, land use is between 0.5 and 66 km\({}^{2}\) for 1 MtonCO\({}_{2}\)/year. It is evident that, if renewable energy is used, a higher portion of land is needed. Figure 17: DAC cost breakdown and comparison: (**A**) liquid solvent SAC capital costs; (**B**) liquid solvent DAC operating costs; (**C**) solid sorbent DAC capital costs; (**D**) solid sorbent DAC operating costs. Reproduced with permission from [40]. It is interesting to underline the total area required to meet the global goal set in the international agreements that aims to remove 1000 GtonCO\({}_{2}\) by 2100. Supposing that 13,000 Carbon Engineering-type plants are needed, a total land area of about 6.6 times the size of New York city will be required [137]. Water can be lost in absorption processes capturing CO\({}_{2}\) from the air but can be produced in adsorption processes. [PERSON] et al. [43] reported that for an absorption process using an aqueous NaOH solution, water losses would be 20 mol H\({}_{2}\)O/mol CO\({}_{2}\). For [PERSON] et al. [33] water losses can be in a range between 0 and 50 tons per ton of captured CO\({}_{2}\). This loss depends on several factors, including the humidity and ambient air temperature and the solution concentration. For the Carbon Engineering company, 4.7 tons of water are lost per ton of captured CO\({}_{2}\)[129]. On the other hand, for Climewords, water is produced as a by-product in an amount of 0.8-2 tons per ton of captured CO\({}_{2}\)[129]. This water can be used to produce H\({}_{2}\) and fuels.