Abstract:

The utilization of CO₂ coupled with renewable energy in electrolytic hydrogen production for synthesizing high-energy-density methanol products not only reduces CO₂ emissions but also enhances the on-site absorption capacity of intermittent and fluctuating renewable energy sources. In this study, a novel process called SOEC-CO₂tM, which couples solid oxide electrolysis cell (SOEC) with CO₂-to-methanol synthesis, is proposed. This process involves hydrogen production by SOEC, flue gas CO₂ capture, methanol synthesis, and refining units. Based on comprehensive process simulation data, heat integration design and optimization are carried out, and the technical and economic evaluation of the new process is carried out by using energy efficiency, investment, production cost, etc., and a comparative analysis is made with the traditional coal-to-methanol process and the green hydrogen coupled coal-to-methanol process. The results demonstrate that before energy integration, the process energy consumption is 420.05 MW, which is reduced to 254.88 MW after energy integration, resulting in a decrease of 39.32% in energy consumption. The energy utilization efficiency of the SOEC-CO₂tM process is 62.94%, comparable to that of the coal-based methanol synthesis coupled with green hydrogen, and 1.46 times higher than that of the traditional coal-based methanol synthesis. The total capital investment of unit methanol for the new process is 2964.68 CNY/t, with a production cost of 3742 CNY/t, where electricity cost constitutes 64.7% of the production cost. In the future, with the vigorous development of renewable energy, the economic performance of the new process will become more prominent. It has the potential to sequester 2 million tons of CO₂ annually and utilize 1245 MW of renewable electricity. The traditional coal-based methanol synthesis process has a CO₂ emission intensity of 2.66 t/t. Compared to the traditional coal-based methanol synthesis, the new process exhibits significant advantages in carbon reduction and on-site utilization of renewable energy.

Key words: solid oxide electrolysis cell, CO₂-to-methanol, energy integration, process systems, techno-economic analysis

摘要：

利用CO₂耦合可再生能源电解水制氢合成高能量密度甲醇产品，不仅可以降低CO₂的排放，而且可以提高间歇性和波动性的可再生能源的就地消纳能力。提出了一种耦合固体氧化物电解槽（SOEC）的CO₂制甲醇新工艺（SOEC-CO₂tM），该工艺包括SOEC制氢、烟气CO₂捕集和甲醇合成及精制单元。基于工艺全流程模拟数据，进行热集成设计与优化，采用能效、投资、生产成本等对新工艺进行技术经济评价，并与传统煤制甲醇工艺和绿氢耦合煤制甲醇工艺对比分析。结果表明：能量集成前，工艺能耗为420.05 MW，能量集成后，工艺能耗为254.88 MW，能耗降低了39.32%。SOEC-CO₂tM新工艺的能量利用效率为62.94%，与绿氢耦合煤制甲醇工艺能效相当，是传统煤制甲醇工艺的1.46倍。新工艺的单位甲醇总资本投资为2964.68 CNY/t，生产成本为3742 CNY/t，电价占生产成本的64.7%。未来随着可再生能源的大力发展，新工艺的经济性能将凸显优势。每年可以消纳200万吨CO₂，可再生电力1245 MW。传统煤制甲醇工艺单位产品二氧化碳排放量为2.66 t/t。相比传统煤制甲醇工艺，新工艺在碳减排和可再生能源就地消纳方面具有明显的优势。

关键词: 固体氧化物电解槽, CO₂制甲醇, 能量集成, 过程系统, 技术-经济分析