Impact of demand uncertainties on the optimal design of the integrated energy system: determining no-regret infrastructure needs

The climate policy goals require a fundamental transformation of the energy system, including a shift from fossil fuels to re- newable energy sources. At the same time, the energy system must be able to reliably meet the future demand for various energy carriers. This raises the question of which infrastructures are needed to meet the future supply task in the energy system. Due to the required speed of the transformation, decisions regarding necessary infrastructures must be made already today. However, uncertainties concerning future developments make these decisions more difficult. Especially the future demand structure is highly uncertain. In this context, the paper investigates how uncertainties in the future demand structure affect the resulting needs for expanding generation and transport infrastructures in a sector-coupled energy system. To adequately reflect the un- certainties, a wide variety of scenarios for the future demand structure is examined. Furthermore, this paper presents a no-regret approach for incorporating uncertainties in the determination of infrastructure needs. This approach is then applied to an energy system optimization model in order to identify infrastructure technologies and capacities that will be needed regardless of the considered future developments. The investigations indicate that uncertainties in the demand structure have a major impact on the no-regret capacities of sector-coupling technologies, especially on electrolysis capacity. In contrast, uncertainties have less impact on the capacities of renewable energy plants, which results in higher no-regret capacities.