The ultimate mission of critical infrastructure industries is to ensure that critical infrastructure is always on and continues to provide essential services to other industries and society. Nevertheless, the critical infrastructure industries are on the brink of changes, which will be enabled by digital technologies, and therefore will embrace the path of digital transformation. Unlike other industries, the digital transformation of critical infrastructure companies will not focus on competition on the market, growth of profits or creation of new competitive products. Instead, they will focus on resilience, affordability and sustainability of the essential services, and ability to rapidly restore the services in case of incidents. This paper explores the transformative forces in the energy sector and introduces two initial frameworks: a generic energy sector-specific digital transformation framework and a framework for guiding digital transformation in electric power transmission system operator companies.