Interactions between the design of short-term electricity markets in the CWE region and power system flexibility

Short-term electricity markets are generally defined as markets that take place from the day-ahead stage until physical generation and consumption. These markets include day-ahead, intra-day, and real-time balancing markets. In Europe, the first two are managed by power exchanges, while the third consists of reserve procurement and imbalance settlement and is operated by the local transmission system operator. Short-term markets are important tools to deal with net demand variability in the system, in which the need for flexibility is expressed and its provision is valorized. Due to the ongoing integration of variable renewables in the generation mix, the system's variability is increasing as a result of the limited controllability and predictability of those resources. As such, these markets become increasingly important. The contribution of this article is a comprehensive up-to-date discussion of the key design parameters and functioning of all three short-term markets, and their impact on the demand for and supply of flexibility. An understanding of the design and its implications is useful to policy-makers who are considering changes to facilitate the integration, availability, or valorization of flexibility, while also contributing to the decision-making of flexibility investors and operators. The geographical scope is the Central Western European region, including the Belgian, French, German, and Dutch market zones.