Techno-Economic Evaluation of Different Scenarios for Carbon Capture and Utilization Concepts for Steel Mill Off-Gases

The focus of this study is to conduct a techno-economic evaluation of a chemical production plant that utilizes carbon-, nitrogen- and hydrogen-containing steel mill off-gases as a material feedstock. The chemical products analyzed are acetic acid, ammonia, methanol, and urea, all of which, except ammonia, are classified under the carbon capture and utilization (CCU) concept. In order to support the investment decision-making process, a superstructure optimization model is employed, which includes the main technical plants (e.g. reactors, storages and separators) and plant layout decisions (e.g. the choice between two reactors). To determine the impact of future developments, five scenarios are considered, focusing on environmental, technical, and economic key factors for the target operational year of 2040. The scenario-dependent optimization results represent the optimal CCU concept with the highest net present value (NPV) for a German steel plant in Duisburg in 2025. These results, including the chemical plant layout with selected chemicals and plants, demonstrate that different scenarios can lead to significant changes in the NPV and chemicals produced and subsequently exported. The results of this study can be utilized as a foundation for investment decisions.