Front-End Techno-Economic and Environmental Analysis on CCU Technologies

Abstract

Carbon capture and utilization (CCU) is an emerging technology for reducing the CO2 concentration in the atmosphere and to limit the negative effects on the global warming. Different from carbon capture and storage (CCS), in CCU the carbon captured from point sources or direct from air is processed to valuable carbon containing products. Several studies have been conducted on the technological and economic viability of CCU. However, no detailed process analyses with a system-level approach have been reported. Performance and challenges on pre-treatment and downstream processing of product streams have been ignored or generalized. This work aims to perform a detailed front-end techno-economic and environmental analysis on CCU pathways, focused on thermocatalysis (TC) and low- and high temperature electrolysis (LTE and HTE) of CO2. Identifying the most business critical pathways for valorization and utilization of CO2.

The scope of this study focuses on the identified single-step chemicals, that can directly be produced from CO2 without intermediates. KPI's selected for both conversion technologies are used to determine performance. A parametric analysis is carried out to evaluate the marginal costs of production per unit of weight for the selected chemicals. Based on costs, TRL and phase of product stream a selection of chemicals is made. Products identified as potential viable for industrial scale production and selected for further study are carbon monoxide (LTE, HTE and TC), formic acid (LTE and TC) and oxalic acid (LTE).

Conceptual process designs are made using reported system performance with all required units identified. A model is developed to simulate input- and product streams, scale size of units, calculate required utilities and costs of investment and operation. All processes are modulated according to generic battery limits, use cases and analysis methodology to provide an equal comparative study. It is found that state-of-the-art electrochemical processes are dominated by capital investment costs and are too immature for commercial application. For TC processes, production costs are primarily driven by H2 and CO2 costs. CO shows the most potential in this respect and is competitive with the market price. A sensitivity analysis is performed to gain understanding of the sensitivity of the parameters. Conversion pathways that could gain significant technical improvements are most sensitive to CAPEX varying and are less affected by variance in operating expenses. Main focus for investments on EC technologies should be current density. More mature technologies are most sensitive to varying the costs of feedstock and market parameters.

Opportunities for process improvements are evaluated by a performance analysis for current base-case versus the expected near-term and optimistic future scenarios. The parameters used for modulation vary according to the expected improvements in technical performance, economic performance and electricity price. Opportunities for EC processes lie within extensive R\&D on conversion technology. For TC process, and on the long term for EC, opportunities lie within further development of green H2 production and CO2 capture. EC CCU pathways demonstrate great potential for future performance with potential reduction up to 71\% for near-term future. To quantify the environmental impact of the pathways and their improvements compared to conventional processes, a gate-to-gate life cycle assessment is performed. Switching to a more renewable energy mix offers serious improvements to minimize global warming impact. The most emission reducing pathways are CO TC and OA LTE which utilize more CO2 than is emitted during the process, -0.16 and -0.26 kg CO2-eq per kg of product.