Comparative analysis of monoethanolamine, hot potassium carbonate, and co-electrolysis pathways for syncrude and methanol production from waste incineration

The energy-efficient removal of CO 2 from flue gas has become increasingly important for operators of CO 2 -emitting industrial facilities such as waste-to-energy plants and cement production sites. Conventional carbon capture processes have long been employed for acid gas removal (natural gas treatment) and are technologically mature. However, when applied for CO 2 capture from flue gases, these methods substantially decrease net energy production of the plants, and in many regions the regulatory framework for underground CO 2 storage remains uncertain. In recent years, a new process has been developed in which CO 2 capture and conversion are integrated into a single step through electrochemical solvent regeneration and conversion. The integration of regeneration and conversion promises a more straightforward process design and lower energy requirements for the production of carbon based products from diluted CO 2 sources. This work compares (1) interconnected state-of-the-art process chains—such as monoethanolamine (MEA) based CO 2 separation with subsequent reverse water-gas shift synthesis gas production, and Fischer-Tropsch (FT) or methanol (MeOH) synthesis, and (2) emerging electrochemical CO 2 conversion processes. Contrary to what current literature indicates, the findings in the carried out simulations show that conventional state-of-the-art processes require less energy to capture and convert CO 2 than the electrochemical pathway at its current stage of development. However, the difference in energy requirement is small especially with FT syncrude as an end product. The results show that the carbon capture and conversion effectiveness of the electrochemical pathways exceeds the carbon capture and conversion effectiveness of the MEA and hot potassium carbonate (HPC) pathways and leads to higher product outputs. Compared to conventional pathways, the electrochemical pathway has a 4.4 percentage points higher carbon capture and conversion effectiveness for MeOH production and a 15.5 percentage points higher carbon capture and conversion effectiveness for FT syncrude production, which highlights the large potential for electrochemical pathways. It is anticipated that the electrochemical pathway will become energy-competitive in the future, provided that development continues rapidly and the technology achieves parity with the advancement of water electrolysis.