全球变化知识资源中心

Utilizing CO2 to produce value-added chemicals can save environmental and economic impacts. However, these savings are reduced by the cost of CO2 supply when CO2 has to be captured from dilute sources. To reduce the cost of CO2 supply, the combination of CO2 capture and utilization has been suggested in a single integrated CO2 capture and utilization (ICCU) process. Although integration is intuitively appealing, a rigorous assessment of the savings by integration is missing. In this work, we evaluate if integration indeed increases savings, by comparing a utilization process without integration to a novel ICCU process. In the novel ICCU process, methanol absorbs CO2 from raw natural gas, before the mixture of CO2 and methanol is hydrogenated to methyl formate. We show that the novel ICCU process saves up to 46% of the electricity demand, which results in savings of up to 8 and 7% in the cost and the greenhouse gas emissions of the utilities, respectively. However, these savings are only enabled when raw natural gas with 30 mol % CO2 is employed; with lower CO2 concentrations, integration can even increase the cost and emissions of CCU. From the obtained results, we derive an indicator to assess the savings potential of ICCU processes. Finally, life cycle assessment reveals that CO2-based methyl formate has the potential to reduce both the global warming impact and the depletion of fossil resources compared to methyl formate produced from fossil sources.