建立面向化学吸收法直接空气碳捕集(DAC)技术的火用-生命周期评价框架,从能源、资源和环境多维度对其评估.结果表明,在电网和天然气供能基准情景下,系统生命周期能耗为10.22GJ/t CO2,运行阶段捕集热耗、CO2压缩和空分制氧是主要耗能环节,占比分别为62.72%,13.41%和8.98%.系统生命周期累积火用耗和第二定律效率分别为9.19GJ/t CO2和10.34%,电能累积火用耗和热能累积火用耗分别占比39.98%和58.93%,材料火用占比为1.09%,可忽略不计.在环境效益方面,系统生命周期碳移除效率为47.50%,捕集热耗和电耗分别贡献53.18%和33.43%的碳排放.若采用生物质和风电供能,系统生命周期碳移除效率可提升至88.60%.此外,系统生命周期水耗和土地利用分别为80kg/t CO2和1465(m2×a)/t CO2,规模化部署时需进一步权衡.
Abstract
Direct air carbon capture (DAC) technology reached the stage of commercial deployment, yet its large-scale application still faced challenges of high energy consumption and resource-environmental impacts. An exergy-based life cycle assessment (ExLCA) framework for DAC systems was established, with their performance being evaluated across energy, resource, and environmental dimensions. It was shown that under grid-electricity and natural gas energy supply scenarios, the system’s life cycle energy consumption was 10.22GJ/tCO2, with thermal energy demand for capture, CO2 compression, and oxygen production through air separation being identifiedas the dominant energy-intensive processes, which accounted for 62.72%, 13.41%, and 8.98%, respectively. The cumulative exergy consumption over the life cycle was 9.19GJ/t CO2, with electricity and thermal energy contributing 39.98% and 58.93% to total exergy consumption, while material-related exergy was accounted for only 1.09%, which was negligible. In terms of environmental benefits, a life cycle carbon removal efficiency of 47.50% was achieved by the system, with thermal energy and electricity consumption contributing 53.18% and 33.43% to total carbon emissions. Carbon removal efficiency could be increased to 88.60% by transitioning to biomass and wind power as energy sources. Furthermore, 80kg of water and 1465(m2×a) per ton of CO2 removed were required by the system, highlighting the need for careful resource management in large-scale deployment.
关键词
直接空气碳捕集 /
负排放 /
热力学 /
火用分析 /
生命周期评价
Key words
direct air carbon capture /
negative emission /
thermodynamics /
exergy analysis /
life cycle assessment
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基金
国家自然科学基金青年基金(72104257);广东省自然科学基金面上项目(2024A1515012661,2023A1515240056)
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