This dissertation explores the dynamic and complex nature of energy markets, focusing on the impact of deregulation and market transitions in various geopolitical contexts. The first chapter examines the impact of partial deregulation on South Korea's electricity and natural gas markets, with a specific focus on the wholesale electricity market. In the early 2000s, reforms transitioned the vertically integrated market, previously dominated by KEPCO, into a competitive landscape. Concurrently, the natural gas market was liberalized, breaking KOGAS' monopoly and permitting private firms to import LNG. Utilizing a structural model, this study estimates hidden market variables, including the fuel costs for independent firms, and conducts counterfactual simulations based on extensive data from the power generation and gas markets. The findings indicate that partial deregulation resulted in a slight increase in wholesale electricity prices, contradicting the expected decrease commonly associated with market liberalization. This deregulation significantly enhanced the market share and profits of independent gas power plants, often at the expense of KEPCO and other entities. While there was a marginal overall increase in total market surplus, mainly benefiting independent firms, this was countered by a reduction in consumer surplus and an uneven distribution of benefits. These outcomes underscore the complexities of partial deregulation, suggesting that while it can promote competition and diversify LNG sources, its advantages and impacts are unevenly distributed across different market players. The study emphasizes the importance of nuanced policy approaches in the deregulation of energy markets, especially in scenarios where changes are partial or constrained.

The second chapter of this dissertation focuses on the repercussions of Russia's invasion of Ukraine on February 24, 2022, particularly its impact on the security of natural gas supply in Europe. The unfolding events of 2022 have put the continent on alert, preparing for a winter that could pose significant challenges in terms of high prices and uncertainty. Despite a less severe winter than anticipated, the situation remains complex and unresolved. The drastic reduction in Russian gas imports casts a shadow of uncertainty over the future supply of natural gas in Europe. Germany, as the European Union’s largest economy, serves as a pivotal example in understanding the broader dynamics of the European natural gas market and the looming challenges. The reliance of manufacturing on natural gas underscores the potential far-reaching impacts on the availability of gas and the overall economic performance of the EU. To analyze the potential scenarios for the natural gas market balances in Germany in the upcoming winter season and beyond, we developed three demand-oriented scenarios: 1) a cold winter in 2022-23, 2) a mild winter in 2022-23, and 3) an extreme case scenario. This chapter presents the critical findings and implications derived from these scenarios, offering insight into the evolving landscape of energy security and economic stability in Europe.

The third chapter of this dissertation delves into the burgeoning influence of renewable energy generation in Texas and its significant impact on the electricity market. This segment of the study investigates the effects of increased renewable energy penetration on the pricing strategies of firms in the wholesale electricity market. Leveraging data from the day-ahead market within Texas' wholesale electricity framework, the research examines the shift in market power across varying hours of the day. It is discovered that during peak hours, market power diminishes considerably in the wake of the planned expansion of solar generation. This finding highlights the transformative role of renewable energy sources in reshaping traditional market dynamics and influencing competitive behavior in the energy sector.