Tools to accelerate the global energy transition: assessing and improving open energy system modelling frameworks

This dissertation covers the topic of energy system models and their usefulness as tools to accelerate the global low-carbon transition. To do so, it provides an overview over the general field of research, the current landscape of modelling tools, current research topics, and gives an outlook to future expansion possibilities. The thesis focuses on the Global Energy System Model (GENeSYS-MOD) in particular, which is an open-source energy system modelling framework that has been in development for the last nine years. Part I of the dissertation focuses on a comparison of different open source energy system models, analyzing the tools oemof, Balmorel, Genesys-2, GENeSYS-MOD, and urbs. The first of the two included chapters carries out an in-depth code-level and mathematical comparison of the five frameworks, looking into different design choices and core differences. The second chapter of Part I then looks into the behavior of the different models on the result side, using a harmonized test data set for Germany as a case study. The different models are then compared regarding their investment and dispatch choices, revealing how different design decisions impact the results for each of the modelling tools. Part II then focuses on GENeSYS-MOD as an exemplary open-source energy system model. The first chapter dives into the area of energy system design regarding the robustness towards inter-annual weather variability (e.g. how different weather years can influence the operational behavior of the system as a whole). Doing so, it develops a metric to assess the robustness of the energy system results by comparing 90 different system configurations across over 40 different weather years and validating their electricity supply via the use of an hourly dispatch model. The chapter then assesses the robustness of the different system designs and tries to formalize a method to quantify and possibly improve the robustness of energy system models. The final chapter then focuses on the newest version GENeSYS-MOD, version 4.0. The new model version introduces several improvements to the overall framework, including a Julia version of GENeSYS-MOD, updated documentation, testing routines, and a complete overhaul of the public repositories. By providing an overview of different energy system models, as well as the research area as a whole, the dissertation tries to provide relevant insights into the field of energy system modelling. The aim is to contribute both to the further development of GENeSYS-MOD and the general research area of open-source modelling, but also highlight possibilities for further research in the field.