Yamaguchi Shingi, Amasawa Eri, Ebe Hiroji, Hirao Masahiko, Sugiyama Masakazu
Research Center for Advanced Science and Technology, The University of Tokyo, 4-6-1Komaba, Meguro, Tokyo, 153-8904, Japan.
ChemSusChem. 2025 Feb 1;18(3):e202401409. doi: 10.1002/cssc.202401409. Epub 2024 Oct 30.
To mitigate global warming to the most ambitious targets, it is necessary to remove CO from the atmosphere and reduce fossil fuels use. The electrochemical conversion of CO to ethylene (CH) as a basic chemical is a promising technology that meets both requirements; however, its life cycle CO emissions remain inconclusive because of varying assumptions in the performance indices. This study aimed to set benchmarks for the four most sensitive indices to achieve -0.5 t-CO/t-CH by calculating net greenhouse gas (GHG) emissions through a prospective life cycle assessment of a model system including CO capture, CO enrichment, electrochemical conversion, CO recycling, and cryogenic separation. As a result, the electrochemical conversion process was the hotspot of life cycle emissions, and representative benchmarks were determined as follows: cell voltage, 3.5 V; CH Faraday efficiency, 70 %; conversion rate, 20 %; and electrochemical CO recycling energy, 2.2 GJ/t-CO. The gaps between the benchmarks and current top data of cell voltage and Faraday efficiency were <10 %, and suppressing the performance degradation for up to one year was found to be a critical requirement. These results can direct research towards the development of a year-round stable system, rather than further improving the performance indices.
为了将全球变暖缓解至最具雄心的目标，有必要从大气中去除二氧化碳并减少化石燃料的使用。将二氧化碳电化学转化为乙烯（C₂H₄）作为一种基础化学品，是一项满足这两个要求的有前景的技术；然而，由于性能指标的假设不同，其生命周期二氧化碳排放量仍无定论。本研究旨在通过对一个包括二氧化碳捕获、二氧化碳富集、电化学转化、二氧化碳循环利用和低温分离的模型系统进行前瞻性生命周期评估，计算净温室气体（GHG）排放量，从而为四个最敏感的指标设定基准，以实现-0.5 t-CO₂/t-C₂H₄的目标。结果表明，电化学转化过程是生命周期排放的热点，确定的代表性基准如下：电池电压为3.5 V；C₂H₄法拉第效率为70%；转化率为20%；电化学二氧化碳循环利用能量为2.2 GJ/t-CO₂。基准与当前电池电压和法拉第效率的顶级数据之间的差距小于10%，并且发现抑制性能下降长达一年是一项关键要求。这些结果可以引导研究朝着开发全年稳定系统的方向发展，而不是进一步提高性能指标。
