@unpublished{GrimmGruebelSchmidtetal.2023, author = {Grimm, Veronika and Gr{\"u}bel, Julia and Schmidt, Martin and Schwartz, Alexandra and Wiertz, Ann-Kathrin and Z{\"o}ttl, Gregor}, title = {On a Tractable Single-Level Reformulation of a Multilevel Model of the European Entry-Exit Gas Market with Market Power}, pages = {26}, year = {2023}, abstract = {We propose a framework that allows to quantitatively analyze the interplay of the different agents involved in gas trade and transport in the context of the European entry-exit system. While previous contributions focus on the case of perfectly competitive buyers and sellers of gas, our novel framework considers the mathematically more challenging case of a strategic and monopolistic gas seller. We present a multilevel framework that is suitable to capture the sequential nature of the decisions taken. We then derive sufficient conditions that allow for reformulating the challenging four-level model as a computationally tractable single-level reformulation. We prove the correctness of this reformulation and use it for solving several test instances to illustrate the applicability of our approach.}, language = {en} } @techreport{OggioniSchwartzZoettletal.2022, type = {Working Paper}, author = {Oggioni, Giorgia and Schwartz, Alexandra and Z{\"o}ttl, Gregor and Wiertz, Ann-Kathrin}, title = {Dynamic Pricing and Strategic Retailers in the Energy Sector: A Multi-Leader-Follower Approach}, pages = {41}, year = {2022}, abstract = {We consider strategic retail pricing in markets, where retail companies buy commodities at fluctuating wholesale prices and resell them to final consumers by applying dynamic retail tariffs. This is of especially large relevance in the context of energy markets where substantial wholesale price fluctuations are observed. Policy makers currently foster the introduction of such dynamic tariff schemes. From a modelling point of view, we propose a multi-leader-follower problem to investigate the implications of strategic retail pricing and we compare the impacts of implementing dynamic tariffs on retailers and final consumers. Our analysis tackles different aspects: first, we formulate the model and provide theoretical results. Second, we develop algorithms, which solve the multi-leader-follower problem and allow us to characterize the resulting market equilibria. Third, we calibrate and solve our framework based on data of the German retail electricity market for the years 2020 and 2021. This allows us to quantitatively assess the impact of introducing real time prices on retailers' profits and customers' benefits. As our results show, dynamic real-time pricing on the one hand typically increases market efficiency, which confirms previous results obtained without the explicit consideration of strategic behavior. On the other hand, however, as a novel aspect, dynamic real-time pricing turns out to significantly reduce equilibrium profits in case of strategic firms. This effect is especially large in environments with strongly fluctuating wholesale prices.}, language = {en} }