How market design shapes the spatial distribution of power plant curtailment costs

When multiple power plants are curtailed at the same time and in the same region, electricity system costs rise. If transmission lines are congested, these costs might be amplified and spatially more concentrated, because there are less spatial spill-overs. We study how such costs and their distribution depend on the market design (nodal pricing or uniform pricing). We extend the literature on curtailment by considering space and market design, and the literature on market design by considering curtailment. We expose a DC load-flow model for Germany to severe correlated curtailment scenarios. We find that additional costs are moderate. For the simulated week, curtailment of 9.3% non-renewable capacity reduces welfare by 2.7% (uniform pricing). With nodal pricing, welfare loss can be reduced by 1.5%. Distributional differences are multiple times larger. For nodal pricing, producer surplus rises more, and costs are spatially more concentrated at the curtailed power plants. Consumer surplus becomes lower. The difference is unlikely to justify changes of the current market design. If also wind or photovoltaic feed-in is unavailable, economic impacts can decrease or increase, but remain in the same order of magnitude. The spatial electricity system structure matters more than the volume of curtailment.