Revisiting carbon lock-in in energy systems: explaining the perpetuation of coal power in Japan

Carbon lock-in hampers the realisation of sustainable energy systems. It occurs when carbon-intensive technologies, markets and institutions co-evolve and become wedded to historical trajectories despite environmentally superior technologies being available. Multiple material and non-material causes are discussed in literature on socio-technical or energy transitions and carbon lock-in. However, these are yet to be synthesised into a comprehensive framework to guide the empirical identification of lock-in factors. Also, empirical understanding into how various causes of lock-in can interact is limited. To deepen understanding into the various types of socio-technical lock-in affecting energy transitions, we develop an encompassing analytical framework accounting for material, human, non-material and exogenous factors. In addition to carbon lock-in and path dependency, we synthesise diverse literature encompassing sustainability transitions, energy policy, innovation and firm management, economics and political economy. The resultant framework provides a finer-grained and more comprehensive understanding of lock-in than previous studies. Using Japan as a case study, we then apply this framework with two questions in mind: (i) What factors are contributing to the perpetuation of coal power in Japan? and ii) What opportunities emerge to overcome these? The empirical analysis is informed by triangulated data involving 46 semi-structured interviews and diverse documents. Our findings reveal a wide array of interacting factors that contribute to the perpetuation of coal-power in Japan and several emerging opportunities to tackle these. They also demonstrate our framework's utility as a heuristic that scholars could apply to other cases to increase empirical understanding into the multiple causes of socio-technical lock-in.