Evaluating the impacts of priority dispatch in the European electricity market

This paper compares the impact of the Nodal Pricing and European Market Coupling organizations on different economic agents of the power system under two main wind policies. Under the "priority dispatch" policy, Transmission System Operators (TSOs) must accommodate all wind energy produced, which thus has the priority over energy produced by conventional plants; in the "no priority dispatch" policy, TSOs can decide not to inject all potential wind power in the grid in order to limit congestion problems. The effects of these two wind policies are measured by developing simple stochastic programming models that consider cases with different wind penetration levels, existing capacities and endogenous investments, as well as assumptions on the EU-ETS. Our computational experiments show that, when there is "priority dispatch", Nodal Pricing and Market Coupling evolve in a similar way as long as wind penetration is not too high. In contrast, a significant increase of wind penetration causes the collapse of the Market Coupling organization while Nodal Pricing continues to perform well. On the other hand, "no priority dispatch" removes most of the problems resulting from Market Coupling, which still exhibits a slightly lower efficiency than Nodal Pricing. These outcomes do not depend on the contextual assumptions (fixed capacities vs. investment; EU-ETS vs. non EU-ETS) that characterize the several cases analyzed. This suggested that our policy conclusions are robust. Furthermore, our models overestimate the flexibility of conventional plants, which means that these conclusions would likely be reinforced with a more detailed model.