Phasing out coal: An impact analysis comparing five large-scale electricity market models

Climate target achievement has a crucial influence on the modelling and the decision processes in the energy sector. It has motivated the development of several policy instruments to mitigate greenhouse gas emissions, including administrative and market-based mechanisms for phasing out coal-fired generation technologies. In order to analyse such instruments, electricity market and energy system models are widely used. However, the results and the corresponding recommendations largely depend on the formulation of the respective model. This motivates a systematic comparison of five large-scale electricity market models which are applied to European scenarios with a focus of the analysis on Germany considering the period until 2030. A method for the identification of model differences is proposed to analyse the effects of two coal phase-out strategies. This contribution expands on earlier studies and provides some more general takeaways for both modellers and decision-makers. For instance, our analysis demonstrates the influence of the reference scenario on evaluating a policy instrument. Furthermore, the importance of technical aspects, such as the constraints for combined heat and power plants, are discussed, and implications regarding three dimensions (the generation adequacy, economic efficiency and environmental sustainability of power supply) are presented.