# Analysis of Technologies for Carbon Dioxide Capture from the Air
## 4 Key Performance Indicators  
The most important KPIs, such as thermal and electrical energy consumption, operating costs (OPEX) and capital costs (CAPEX) (or general total costs), land use, water demand, technology readiness level (TRL) and environmental impact, are analyzed in this section. These KPIs are important because they are related to the potential development and realization of these processes. Energy consumption, costs, land use, environmental impact and water demand are all important factors in the construction of a plant and its operation. Data about energy consumption in terms of thermal and electrical energies are provided in Table 5 for the main DAC companies described in Section 3. The Carbon Engineering company can achieve a thermal energy value of 366 kWhel\({}_{\text{el}}\)/tonCO\({}_{2}\). Figure 16: Global Thermostat plant [3]. Energy consumption in DAC processes investigated in the literature has been reported on in the work of [PERSON] et al. [49]. For the absorption process, thermal energy use is in the range of 1420-2450 kWh\({}_{\text{th}}\)/tonCO\({}_{2}\)[34; 41], while electrical energy use is in the range of 440-2790 kWh\({}_{\text{el}}\)/tonCO\({}_{2}\)[37; 139]. For the adsorption processes studied in the literature, on the other hand, thermal energy consumption is 165 kWh\({}_{\text{th}}\)/tonCO\({}_{2}\) in the work of [PERSON] and [PERSON] (2012), while 218 kWh\({}_{\text{el}}\)/tonCO\({}_{2}\) is the required electrical energy level. Higher values of electrical energy are needed for adsorption with metal organic frameworks, such as the value of 1420 kWh\({}_{\text{el}}\)/tonCO\({}_{2}\) reported in [PERSON] et al. (2017). Lower values of electrical energy are suggested in adsorption processes using ion-exchange resin: 316 kWh\({}_{\text{el}}\)/tonCO\({}_{2}\)[107], 423-631 kWh\({}_{\text{el}}\)/tonCO\({}_{2}\)[140] and 333 kWh\({}_{\text{el}}\)/tonCO\({}_{2}\)[141]. Cost estimation presents a more difficult problem. [PERSON] et al. [8] estimated a DAC cost of up to 1000 $/tonCO\({}_{2}\), this could decrease to 100-300 $/tonCO\({}_{2}\) in 2050, while [PERSON] et al. [29] suggested a range of 35-1000 $/tonCO\({}_{2}\). These costs are certainly higher than those of CO\({}_{2}\) capture from fine gas that are in the order of 30-100 $/tonCO\({}_{2}\)[18]. The high initial cost is due to the upfront expenses and the lack of experience with this technology. Table 6 shows the costs which are available for the main DAC companies, such as Carbon Engineering, Climeworks and Global Thermostat. The economic data for the first company (94-232 $/tonCO\({}_{2}\)) was obtained by a design in Aspen Plus [34; 113]. A different situation obtains for Climeworks, for which the first commercial plant has an actual cost of 600 $/tonCO\({}_{2}\), which is expected to be reduced in the future to 200 $/tonCO\({}_{2}\) and 100 $/tonCO\({}_{2}\), respectively, in 2025 and 2030 [113; 3]. Lower costs are given for Global Thermostat (50 $/tonCO\({}_{2}\)), which could be further reduced to 15-50 $/tonCO\({}_{2}\) depending on how long the amine surfaces last [142]. This small value can be obtained considering that the steam needed for the process comes from waste heat at low or even no cost. However, it is a very optimistic cost, without any transparency in the economic analysis and is presented in order to have a more competitive plant from an economic point of view operating in the market. In the literature, there are other cost analyses for CO\({}_{2}\) capture processes from the air, based on absorption and adsorption. A real comparison between these costs cannot be conducted due to the lack of transparency in economic analyses and due to different and undefined assumptions. A range of cost values have been reported, as shown in Figure 17, for adsorption and absorption processes.