Toward the decarbonization of hard-to-abate sectors: a case study of the soda ash production

Abstract

Decarbonizing the so-called "hard-to-abate" sectors is considered more technically challenging than others such as energy or transportation because they entail emissions not only from heat and power generation but also from manufacturing and process industries. The opportunities for them are less obvious and the challenges are greater, so their shift or transition to zero emissions is still relatively unexplored. In this case study, we aim to analyze the environmental impact and the technoeconomic viability of the integration of a carbon capture and utilization (CCU) plant that produces CO2-based methanol (CO2-MeOH) by means of electrochemical reduction (ER) in the hard-to-abate sector of synthetic soda ash. With a rigorous emphasis on the goal of net zero CO2 emissions, life cycle assessment (LCA) and technoeconomic assessment (TEA) were used as tools in order to guide further research and development toward its potential final commercialization. LCA and TEA results have demonstrated that it is possible to reduce the carbon footprint (CF) of the synthetic soda ash production at a reasonable cost within proper medium/long-term developments. Several scenarios have been assessed considering the future innovation of the CCU-ER technology and the future evolution of the electricity and CO2 market prices because of the application of instruments such as Power Purchase Agreements (PPAs) and the European Union Emissions Trading System. The scenarios analyzed suggest that the complete electrification of the integrated plants of soda ash through electric heat (EH) is positive from the environmental perspective. This EH represents the direct conversion of renewable electricity to industrial heat. The results displayed a reduction in the CF of soda ash up to 74% as long as the entire integrated plant was run on renewable electricity and considering the commercialization of the ER side products such as H2 and O2. Not considering the selling of these two products leads to more modest reduction around 41%. However, this complete electrification has major implications on the economic profile under the current combination of electricity and CO2 market prices. Low-cost electricity, for example, using surpluses of renewable electricity and/or PPAs, and a higher CO2 price, which can be expected in the short/mid-term, are required to ensure economic feasibility. A 50% reduction of the current average wholesale electricity price that was used as a reference in the present study (43 €·MW h-1) will ensure economic feasibility under the proper ER technology development. The insights gained in this study may be of assistance in the sustainable implementation of CCU in energy-intensive manufacturing processes.