This book aims to assess multidimensional aspects of energy security in the electricity sector. There are few academic literature that assess regulation and governance, availability, technology development and efficiency, environmental sustainability, and affordability dimension comprehensively. This book demonstrates how these dimensions are interconnected. The publication of this book comes at a timely moment when the Indonesian government needs to provide electricity access to more than 60 million people, to speed up electrification ratio outside Java, to reduce electricity subsidy, and to promote green power system. Moving from "darkness to light", Indonesia needs to strengthen regulation and governance as a basis to elevate other dimensions to move forward.