Towards climate-neutral and circular industrial systems - approaches for integrated modelling, assessment and planning at regional level

Abdelshafy, Ali Ezzat Abdelhamid; Walther, Grit (Thesis advisor); Barbosa-Póvoa, Ana Paula (Thesis advisor)

Aachen : RWTH Aachen University (2023)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2023


The transformation towards carbon-neutral and circular economies and industrial systems is of utmost importance facing climate change and scarcity of resources. To tackle the resulting enormous planning and implementation tasks, there exist on the one hand very detailed bottom-up process models and roadmaps for specific technologies and companies, and on the other hand highly aggregated top-down approaches and scenarios for climate-neutral trajectories at global, EU and national scale. However, only few approaches so far specifically address the regional application level, which is of high importance for the implementation of car-bon-neutral and circular industrial systems because of the many intersectoral relations between companies and manifold links between material and energy flows within a region. This holds especially for the regional interrelations of energy and material intensive industries like steel, cement, or chemistry. Additionally, regional characteristics will have a strong impact on the design of new pipeline infrastructures for the transportation of hydrogen or CO2. Therefore, regional analyses and integrated approaches for modelling and assessment are required to overcome these gaps methods and applications. Against this background, the aim of this dissertation is to develop integrated modelling, evaluation and planning approaches for the transformation towards carbon-neutral and circular industrial systems and infrastructures with specific emphasis on solutions for the regional level. The dissertation serves to provide transparency on the development of material and energy flows over time, supports technology choice decisions based on techno-economic and environmental evaluations, and supports policy and management decisions on infrastructure and technology investments. The developed approaches have to regard for many requirements and challenges, i.e., approaches need to applicable at regional level, regard for the nexus between carbon neutrality and circular economy, incorporate intersectoral interdependencies between companies and material flows, be interdisciplinary in that they are able to regard for technical, economic, environmental as well as social aspects, consider spatial relations and regional networks, and are dynamic in that they regard for the transformation over time. These requirements and challenges are analysed and integrated via different methodological approaches and system boundaries. The dissertation specifically addresses the transformation of the metals and cement & construction sectors in North Rhine-Westphalia (NRW), a region that accounts for one third of the German cement and chemical production and two fifths of the steel production in Germany. Being a crucial hub for the heavy industries in Eu-rope, the state is responsible for one quarter of the annual GHG emissions in Germany, half of these emissions comes from the energy sector and approximately one fifth is generated by the regional industries. As the state is currently witnessing fundamental structural changes in the industrial sector, it is a suitable region for investigating the transformation process and demonstrating the respective methods. Moreover, the state can also represent the main features of other industrial regions in Germany and Europe. The dissertation consists of five parts. Part I presents the background, structure and region of interest, and dis-cusses the adopted methods and derived approaches. The next three parts (II - IV) encompass the cumulative dissertation. Herein, it is composed of nine peer-reviewed publications that address the two mentioned sectors (i.e. metals and cement & construction) via using different methods and system boundaries. Part II on the metals sector comprises three papers. Paper 1 addresses the industrial transformation in the steel industry by means of developing a hybrid model that defines and quantifies the changes in the regional and energy material flows in North Rhine-Westphalia. Paper 2 determines the causes of CO2 emissions during the production process of cast iron and steel and the mitigation potentials. Paper 3 presents a techno-economic and environmental (TEE) assessment to study the impact of increasing the share of secondary inputs (i.e. steel scrap) from an interdisciplinary perspective. Part III on the cement and construction industry contains four publications. Paper 4 studies the role of CCUS in decarbonizing the cement industry and discusses its necessity as well as the associated challenges. The paper is based on an extensive literature review and analyses the supply chains, the various options that cement producers have to mitigate their emissions and their techno-economic requirements, advantages, drawbacks, boundaries and challenges. Paper 5 aims at promoting a circular economy in the construction sector via presenting a novel model that estimates the regional supply and demand of secondary materials over time. Paper 6 focuses on the spatial aspects of carbonation as a specific CCU technology, and realizes a relationship between the distance and CO2 sequestration capacity in NRW via locational material flow analysis and an optimization model. Paper 7 enhances this analysis by using more data inputs and classifying the available materials into different categories, which results in more detailed analyses and outcomes. Part IV on the intersectoral impacts and infrastructure planning consists of two papers. Paper 8 focuses on the relationship between carbon neutrality and circular economy via an intersectoral energy and material flow analysis in NRW. Herein, a broad system boundary has been defined in order to comprehensively include a wide range of industrial value chains. Paper 9 presents an extensive analysis on the configurations and costs of the prospective CO2 network in Germany. Part V on the Conclusions & Outlook presents the main outcomes of the dissertation, and recommendations for future research activities. Methodologically, the derived approaches and frameworks are based on three fundamental methods A) Mate-rial Flow Analysis (MFA), B) integrated TEE assessment, and C) planning of optimal networks and infrastructures. A) The basic MFA methodology has been extended by integrating dimensions such as time, location, and process modelling. As a result, extended approaches such as regional intersectoral MFA, prospective MFA, locational MFA, and dynamic-locational MFA are developed and applied to practical planning case studies. B) Integrated TEE assessment is applied as a comprehensive approach to merge the relationship between the technical, economic and environmental performance. The derived framework is used to investigate and optimize the three aspects simultaneously. C) Approaches for planning of optimal networks and infrastructure are used to design the prospective infrastructures, specifically the CO2 pipeline network in Germany. Herein, an optimization model has been developed based on an extensive number of datasets and a scenario analysis has been also carried out to illustrate the impacts of different conditions. Overall, this dissertation succeeded in providing innovative modelling extensions and integrations, which have been used to investigate ongoing serious themes and address real industrial questions. The quantitative and qualitative analyses have achieved the dissertation’s goals and fulfilled the identified requirements. The presented case studies on the different industries and materials have demonstrated the effectiveness of the derived frameworks, which can be also used to solve other problems. Therefore, the dissertation is an added value to the academia and of high interest for the industrial sector and policymakers. For researchers, the presented models provide a basis for further studies and research. For the industrial sector and policymakers, the comprehensive analyses and conclusions can be very helpful in deriving regional strategies and roadmaps.


  • Chair of Operations Management [813510]