# Special Issue on Carbon Capture and Utilization
## 2 Contributions to This Special Issue
Experiments showed that this unit is characterized by a low-pressure drop and contacting energy (0.7-1.5 G) per ton of CO\({}_{2}\)), uniform flow distribution, and short adsorption time (24-43 min); this is a viable solution for scaled-up applications. The Intergovernmental Panel on Climate Change (IPCC) published guidelines for national greenhouse gas inventories in 2006 which provide a procedure for calculating emissions. However, it does not consider the net CO\({}_{2}\) emissions to the atmosphere (released in clinker fabrication minus those due to concrete carbonation) by the Portland cement clinker. [PERSON] et al. [5] applied a quick and easy method to quantify net CO\({}_{2}\) emissions of the cement industry. This method considers CO\({}_{2}\) uptake with concrete and mortar carbonation (cement-based materials), and it was applied to calculate the Portuguese net emissions of cement produced from 2005 to 2015. The results showed that 8.7 million tons of CO\({}_{2}\) were taken up in carbonation processes in the analyzed period; 37.8 million tons were released due to the calcination process. Short carbonation periods delivered a low CO\({}_{2}\) uptake. This methodology may improve the developed IPCC climate models. [PERSON] et al. [6] applied a similar method to the Spanish cement industry, evaluating the CO\({}_{2}\) emissions which were avoided by the carbonation process. After CO\({}_{2}\) capture, the gaseous stream can be transported by pipeline or ship. The last option may be advantageous if the distance between the capture unit and the destination is large. In this case, the energy consumption for the stream liquefaction may be significant, being important to define an energy-efficient process. [PERSON] and [PERSON] [7] modelled several CO\({}_{2}\) liquefaction processes for a range of ambient temperatures, thus optimizing process operating parameters. Different scenarios were defined and modelled. The lowest energy consumption was achieved for the cooling temperature of 20 \({}^{\circ}\)C. A temperature change to 50 \({}^{\circ}\)C increased energy consumption by around 40%. CO\({}_{2}\) storage at high concentrations is not presently acceptable due to the risk of leakage and its associated impacts. Thus, the development of materials for CO\({}_{2}\) storage is important. [PERSON] et al. [8] synthesized and characterized (structure and physicochemical properties) three novel heteroatom-doped porous organic polymers (POPs) containing phosphate units. They have the following characteristics: (i) high surface area (S\({}_{\text{BET}}=82.7\)-213.5 m\({}^{2}\)/g); (ii) small pore-size distribution in terms of pore volume (0.11-0.32 cm\({}^{3}\)/g); (iii) small pore diameter (1.96-2.43 nm); and (iv) high CO\({}_{2}\)-storage capacity, in particular for high pressures (1.42 mmol/g (6.00 wt%) at 323 K and 40 bar). This high performance was mainly attributed to their geometry, since it provides a highly distorted and extended surface area network compared with other POPs. To evaluate the sustainability of a process, the life cycle assessment (LCA) method is commonly used. However, integrated sustainable analysis is not possible within this method, as LCA does not quantify the biophysical capacity of the ecosystems to supply ecosystem services. [PERSON] et al. [9] propose a methodology for connecting a process- or system-product flow demand from the technosphere and the feasibility of the ecosystem being able to supply ecosystem services based on sink capacity. The case study was a combined heat and power (CHP) plant with and without post-combustion carbon-capture technology in Mexico. Three scenarios were tested, and the CHP plant requires between 323.4 and 516 ha to supply the required oil as stock flow and 46-134 ha to supply the required freshwater. Concerning CO\({}_{2}\) sink, 52-5,096,511 ha is necessary to sequester the total emissions.