Concern has increased about climate change caused by carbon dioxide (CO₂) emissions through human activities in recent years. The Intergovernmental Panel on Climate Change predicts a 1.9°C rise in temperature by the year 2100, and this means a reduction in CO₂ is vital for human beings and all other life on earth. Therefore, there is an urgent need for the development of CO₂ separation processes to mitigate this potential problem. Post-combustion power plants can employ various types of separation technology. Among them, chemical absorption using aqueous amine is more developed and more reliable. The conventional solvents used in the chemical absorption process together with the use of absorbents, ionic liquid, alkanolamines and their blended aqueous solutions are reviewed in this work. Different ionic liquid-based solvents for CO₂ absorption and the most effective parameters on mass transfer phenomena between CO₂ and solvent are reviewed. The major concerns for this technology, including the physiochemical properties of ionic liquid-based solvents, Henry’s constant and mass transfer coefficient and their correlations, and various factors for effective CO₂ absorption, are addressed.

Blue hydrogen is a promising low-carbon alternative to conventional fossil fuels. This technology has been garnering increasing attention with many technological advances in recent years, with a particular focus on the deployed materials and process configurations aimed at minimising the cost and CO₂ emissions intensity of the process as well as maximising efficiency. However, less attention is given to the practical aspects of large-scale deployment, with the cooling requirements often being overlooked, especially across multiple locations. In particular, the literature tends to focus on CO₂ emissions intensity of blue hydrogen production processes, with other environmental impacts such as water and electrical consumption mostly considered an afterthought. Notably, there is a gap to understand the impact of cooling methods on such environmental metrics, especially with technologies at a lower technology readiness level. Herein, two cooling methods (namely, air-cooling versus water-cooling) have been assessed and cross-compared in terms of their energy impact alongside techno-economics, considering deployment across two specific locations (United Kingdom and Saudi Arabia). A sorption-enhanced steam-methane reforming (SE-SMR) coupled with chemical-looping combustion (CLC) was used as the base process. Deployment of this process in the UK yielded a levelised cost of hydrogen (LCOH) of GBP 2.94/kg H₂ with no significant difference between the prices when using air-cooling and water-cooling, despite the air-cooling approach having a higher electricity consumption. In Saudi Arabia, this process achieved a LCOH of GBP 0.70 and GBP 0.72 /kg H₂ when using air- and water-cooling, respectively, highlighting that in particularly arid regions, air-cooling is a viable approach despite its increased electrical consumption. Furthermore, based on the economic and process performance of the SE-SMR-CLC process, the policy mechanisms and financial incentives that can be implemented have been discussed to further highlight what is required from key stakeholders to ensure effective deployment of blue hydrogen production.