CO2 capture and storage (CCS) has been acknowledged as an essential part of a portfolio of technologies that are required to achieve cost-effective long-term CO2 mitigation. However, the development progress of CCS technologies is far behind the targets set by roadmaps, and engineering practices do not lead to commercial deployment. One of the crucial reasons for this delay lies in the unaffordable penalty caused by CO2 capture, even though the technology has been commonly recognized as achievable. From the aspects of separation and capture technology innovation, the potential and promising direction for solving this problem were analyzed, and correspondingly, the possible path for deployment of CCS in China was discussed. Under the carbon neutral target recently proposed by the Chinese government, the role of CCS and the key milestones for deployment were indicated.
Alkali carbonate-based sorbents (ACSs), including Na2CO3- and K2CO3-based sorbents, are promising for CO2 capture. However, the complex sorbent components and operation conditions lead to the versatile kinetics of CO2 sorption on these sorbents. This paper proposed that operando modeling and measurements are powerful tools to understand the mechanism of sorbents in real operating conditions, facilitating the sorbent development, reactor design, and operation parameter optimization. It reviewed the theoretical simulation achievements during the development of ACSs. It elucidated the findings obtained by utilizing density functional theory (DFT) calculations, ab initio molecular dynamics (AIMD) simulations, and classical molecular dynamics (CMD) simulations as well. The hygroscopicity of sorbent and the humidity of gas flow are crucial to shifting the carbonation reaction from the gas−solid mode to the gas−liquid mode, boosting the kinetics. Moreover, it briefly introduced a machine learning (ML) approach as a promising method to aid sorbent design. Furthermore, it demonstrated a conceptual compact operando measurement system in order to understand the behavior of ACSs in the real operation process. The proposed measurement system includes a micro fluidized-bed (MFB) reactor for kinetic analysis, a multi-camera sub-system for 3D particle movement tracking, and a combined Raman and IR sub-system for solid/gas components and temperature monitoring. It is believed that this system is useful to evaluate the real-time sorbent performance, validating the theoretical prediction and promoting the industrial scale-up of ACSs for CO2 capture.
The coal-to-liquid coupled with carbon capture, utilization, and storage technology has the potential to reduce CO2 emissions, but its carbon footprint and cost assessment are still insufficient. In this paper, coal mining to oil production is taken as a life cycle to evaluate the carbon footprint and levelized costs of direct-coal-to-liquid and indirect-coal-to-liquid coupled with the carbon capture utilization and storage technology under three scenarios: non capture, process capture, process and public capture throughout the life cycle. The results show that, first, the coupling carbon capture utilization and storage technology can reduce CO2 footprint by 28%–57% from 5.91 t CO2/t·oil of direct-coal-to-liquid and 24%–49% from 7.10 t CO2/t·oil of indirect-coal-to-liquid. Next, the levelized cost of direct-coal-to-liquid is 648–1027 $/t of oil, whereas that of indirect-coal-to-liquid is 653–1065 $/t of oil. When coupled with the carbon capture utilization and storage technology, the levelized cost of direct-coal-to-liquid is 285–1364 $/t of oil, compared to 1101–9793 $/t of oil for indirect-coal-to-liquid. Finally, sensitivity analysis shows that CO2 transportation distance has the greatest impact on carbon footprint, while coal price and initial investment cost significantly affect the levelized cost of coal-to-liquid.
In this work, using fractured shale cores, isothermal adsorption experiments and core flooding tests were conducted to investigate the performance of injecting different gases to enhance shale gas recovery and CO2 geological storage efficiency under real reservoir conditions. The adsorption process of shale to different gases was in agreement with the extended-Langmuir model, and the adsorption capacity of CO2 was the largest, followed by CH4, and that of N2 was the smallest of the three pure gases. In addition, when the CO2 concentration in the mixed gas exceeded 50%, the adsorption capacity of the mixed gas was greater than that of CH4, and had a strong competitive adsorption effect. For the core flooding tests, pure gas injection showed that the breakthrough time of CO2 was longer than that of N2, and the CH4 recovery factor at the breakthrough time () was also higher than that of N2. The of CO2 gas injection was approximately 44.09%, while the of N2 was only 31.63%. For CO2/N2 mixed gas injection, with the increase of CO2 concentration, the increased, and the for mixed gas CO2/N2 = 8:2 was close to that of pure CO2, about 40.24%. Moreover, the breakthrough time of N2 in mixed gas was not much different from that when pure N2 was injected, while the breakthrough time of CO2 was prolonged, which indicated that with the increase of N2 concentration in the mixed gas, the breakthrough time of CO2 could be extended. Furthermore, an abnormal surge of N2 concentration in the produced gas was observed after N2 breakthrough. In regards to CO2 storage efficiency (), as the CO2 concentration increased, also increased. The of the pure CO2 gas injection was about 35.96%, while for mixed gas CO2/N2 = 8:2, was about 32.28%.
Carbon capture, utilization, and storage (CCUS) is estimated to contribute substantial CO2 emission reduction to carbon neutrality in China. There is yet a large gap between such enormous demand and the current capacity, and thus a sound enabling environment with sufficient policy support is imperative for CCUS development. This study reviewed 59 CCUS-related policy documents issued by the Chinese government as of July 2022, and found that a supporting policy framework for CCUS is taking embryonic form in China. More than ten departments of the central government have involved CCUS in their policies, of which the State Council, the National Development and Reform Commission (NDRC), the Ministry of Science and Technology (MOST), and the Ministry of Ecological Environment (MEE) have given the greatest attention with different focuses. Specific policy terms are further analyzed following the method of content analysis and categorized into supply-, environment- and demand-type policies. The results indicate that supply-type policies are unbalanced in policy objectives, as policy terms on technology research and demonstration greatly outnumber those on other objectives, and the attention to weak links and industrial sectors is far from sufficient. Environment-type policies, especially legislations, standards, and incentives, are inadequate in pertinence and operability. Demand-type policies are absent in the current policy system but is essential to drive the demand for the CCUS technology in domestic and foreign markets. To meet the reduction demand of China’s carbon neutral goal, policies need to be tailored according to needs of each specific technology and implemented in an orderly manner with well-balanced use on multiple objectives.