Stephan Nagl

The Costs of Electricity Systems with a High Share of Fluctuating Renewables: A Stochastic Investment and Dispatch Optimization Model for Europe

Renewable energies are meant to produce a large share of the future electricity demand. However, the availability of wind and solar power depends on local weather conditions and therefore weather characteristics must be considered when optimizing the future electricity mix. In this article we analyze the impact of the stochastic availability of wind and solar energy on the cost-minimal power plant mix and the related total system costs. To determine optimal conventional, renewable and storage capacities for dierent shares of renewables, we apply a stochastic investment and dispatch optimization model to the European electricity market. The model considers stochastic feed-in structures and full load hours of wind and solar technologies and dierent correlations between regions and technologies. Key ndings include the overestimation of uctuating renewables and underestimation of total system costs compared to deterministic investment and dispatch models. Furthermore, solar technologies are - relative to wind turbines - underestimated when neglecting negative correlations between wind speeds and solar radiation.

German Nuclear Policy Reconsidered: Implications for the Electricity Market

In the aftermath of the nuclear catastrophe in Fukushima-Daiichi, German nuclear policy has been reconsidered. This paper demonstrates the economic effects of an accelerated nuclear phase-out in Germany on the European electricity market. An optimization model is used to analyze two scenarios with different lifetimes for nuclear plants in Germany (phase-out vs. prolongation). Based on political targets, both scenarios assume significant electricity demand reductions and a high share of renewable energy sources in Germany. We find that electricity costs and prices in the European system are higher in the phase-out scenario, especially in Germany, associated with welfare losses. Due to lifetime extensions of existing fossil-fired plants as well as moderate capacity additions, we conclude that the generation sector can generally cope with the phase-out under the given assumptions. Yet, we emphasize that this requires a substantial and costly transformation of the supply and the demand side.