Modeling electricity generation systems: generation investment planning under uncertainty

Many electricity generation systems are undergoing drastic changes, through rapidly increasing shares of intermittent renewable energy sources (RES) like wind and solar photovoltaics. Models are often used to address the corresponding challenges (technical, economic, policy), by analyzing system operation and planning. In this PhD, we aim to strengthen the link between generation and grid planning. During the optimization of the grid design, capital costs and operational costs need to be taken into account on a time horizon of several decades which means that many uncertainties need to be taken into account, transforming the optimization into a large scale stochastic problem. The goal of this PhD is to develop a planning methodology focused on credible/robust scenarios, bridging generation and grid planning methodologies. In the context of expansion planning, there are currently two classes of tools being used. The first class of tools consist of mature energy system planning tools which have continuously been developed over the past decades. In these tools, the transmission grid has traditionally been neglected or represented in a very simplified way. There are two reasons for that. Firstly, in the past, transmission expansion was comparatively cheaper compared to generation investments. Secondly, the transmission expansion problem is nonlinear and non-convex in its nature and thus hard to solve. As such, it has been assumed that there will always be enough transmission capacity built to foster the generation investments or transmission expansion optimization has been limited to interconnection capacity. This assumption only holds in case overhead transmission lines can be used for grid expansion. In the last decade, we have seen in Europe that this assumption is no longer valid, as it is very hard to obtain permits for new overhead lines. In the next ten years, it is expected that the total length of underground cables in the European high voltage grid will be 5 times higher than today. In case of offshore transmission, e.g., to connect wind farms, no overhead lines can be built which makes the transmission investment cost comparable to the generation investment. The second class of tools are widely used by utilities and offer great detail in modeling the transmission grid also considering reliability aspects. Nevertheless, these tools only provide the possibility to compare different grid architectures rather than to determine the optimal grid layout. Thus, the grid planner needs to carry out the task based on experience. As such, only a small number of scenarios and expansion options can be considered in the planning process. In this context we want to develop a tool accommodating most features of both tool classes mentioned above. Such a tool would be useable for TSOs and policy makers, bridging the gap between generation and transmission planning and considering technical constraints in detail. Focus of this PhD will be on the generation planning part of this broader endeavor. Modeling contributions will be made in the SPINE framework (toolbox and model) in this regard. This PhD connects to the projects NEPTUNE (North-sea Energy Plan for Transition to sUstainable wiNd Energy; focus on scenario building under uncertainty) and SPINE (Open source toolbox for modelling integrated energy systems).