Nexus-e: A platform of interfaced high-resolution models for energy-economic assessments of future electricity systems

Energy systems are transitioning toward sustainable power generation largely due to new policies that are motivated by climate and renewable generation targets. This transition is felt throughout the entire economy and is affecting the long and short term operations of the energy system. In the last decade, the research community has made significant efforts to model the energy transition and its impacts. Typically, these models focus on a limited subset of the different components of the energy-economic system, including investments in centralized and distributed generation, electricity markets, electric power grids, security of supply, and macro-economic effects. However, there are research questions that require the analysis of how these different aspects are connected to each other and how they may interact. Therefore, the research community has stressed the need to leverage models across domains to enhance the capabilities and robustness of their results. Due partly to the high complexity of combining models developed in tangential domains, few attempts have been made to model in full the interactions among the interdependent components of the energy-economic system. The Nexus-e: interconnected energy systems modeling platform aims to show how this gap can be filled by demonstrating that an interdisciplinary set of models can be integrated in a model framework by linking them through structured interfaces. This platform combines four bottom-up models that capture different aspects of the electricity system and one top-down macro-economic model to represent a much broader scope of the energy-economic system as compared to traditional stand-alone modeling approaches. In this paper, we study the benefits and limitations of the interfaces established among the modules in Nexus-e with reference to the Swiss electricity system in a European context. We demonstrate that prominent changes in operational behavior could drive investments and should therefore be assessed in a framework that considers both transmission and distribution systems in a coordinated manner. We show that the bottom-up investments and operations (transmission and distribution) can have an impact on the overall economy, which in response can affect the demand for electricity. Moreover, we demonstrate that the changes in generation mix and operation behaviors may have a significant impact on system security. For policymakers, the approach can provide spatially detailed power system transformation options that enable decisions that are socially, politically, and technically acceptable.