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CO 2 capture, utilization, and storage (CCUS) are critical technical measures to effectively mitigate the global climate change problem. However, most of the existing research has focused on the capture end and lacks in-depth analysis of subsequent processes such as compression, leading to limitations in the improvement of system economics. Therefore, a novel CCS system for a 300 MW coal-fired power plant was proposed in this paper with two strategies: (1) a CCS system integrating CO 2 refrigeration cycle (CFPP-CCS-CRC); and (2) a CCS co-generation plant integrating CO 2 refrigeration cycle (CHP-CCS-CRC). The proposed systems' performance was comparatively evaluated by applying energy, exergy, and economic (3E) analyses. The results demonstrated that at different CO 2 capture percentages (13.1 %∼72.9 %), the CHP-CCS-CRC system has improved energy utilization efficiency by 1.2 %∼5.6 % and exergy efficiency by 7.7 %∼25.8 %, compared to the conventional CCUS system (CFPP-CCS). In particular, at a percentage of 13.1 %, the combined energy consumption of the CHP-CCS-CRC system was 0.39 GJ/tCO 2 , a 79 % reduction compared to 1.87 GJ/tCO 2 of the CFPP-CCS system, which resulted in a static payback period of less than 2 years. In general, the newly proposed system features more adequate energy utilization, lower operating costs, and higher economic efficiency. [Display omitted] • A novel CCUS system coupled with CO 2 refrigeration were proposed. • The performance of the proposed systems is comparatively evaluated by 3E analysis. • The energy consumption of the proposed CCUS systems is reduced by 29.24 %–79 %. • The exergy efficiency of the proposed CCUS systems is reduced by 7.7 %–25.8 %. • The static payback period for the proposed systems is reduced to less than 2 years. [ABSTRACT FROM AUTHOR]

• Ocean as a means of gigaton scale direct storage of atmospheric carbon. • Alkalinity transfer between deep and surface ocean for direct CO 2 capture. • Electrochemical ion selective electrodes to enhance surface ocean alkalinity. • Proof-of-concept enables a new family of scalable climate change solutions. The oceans play a major role in moderating atmospheric CO 2 levels. Enhanced CO 2 uptake into ocean waters can be achieved by the provision of appropriate cations to the surface ocean, an approach known as ocean alkalinity enhancement (OAE). Here, we present a calcium ion battery approach that enhances alkalinity via electrochemical manipulation of seawater calcium concentrations. We demonstrate the efficacy of this approach using a potassium barium iron cyanide [K 2 BaFe(CN) 6 ] (PBFC) electrode, a Prussian blue analogue, to move calcium ions from one reservoir of seawater to another. Using material and electrochemical characterization of the Ca2+ ion insertion and expulsion properties of PBFC in synthetic seawater, we determine the repeatability of Ca2+ ion insertion and expulsion from the PBFC electrode. Our analyses prove a 2.75 % increase in seawater alkalinity via the PBFC electrode, which yields 2.64 mg CO 2 (0.72 mg C) uptake per liter of seawater. This proof-of-concept method offers a unique, low-cost, energy efficient electrochemical approach for atmospheric carbon dioxide removal that can combine with marine-based renewable energy to enable a new family of effective, scalable climate change solutions. [Display omitted] [ABSTRACT FROM AUTHOR]