Long-term (LT) energy planning models are widely used for policy analysis and determining pathways towards a low-carbon energy system. In decarbonizing the energy system, these models predict a large contribution of renewable energy sources (RES), especially in the electricity sector. However, these models typically have a low temporal resolution and operate at a technology level rather than at power plant level, thereby omitting technical restrictions of power plants. Both modeling limitations might render these models unsuitable to analyze scenarios with large shares of intermittent RES.
The main contribution of this work is to quantitatively assess and analyze the effects of these modeling limitations of long-term energy planning models in a setting of a rapidly increasing penetration of intermittent RES. The focus of the assessment lies on the feasibility and the economic optimality of model outcomes. The analysis exposes caveats to be considered when interpreting the results of LT planning models and allows prioritizing modeling issues to be addressed.