This roadmap aims to increase understanding among a range of stakeholders of the applications that electricity and thermal energy storage technologies can be used for at different locations in the energy system. Emphasis is placed on storage technologies that are connected to a larger energy system (e.g. electricity grid), while a smaller portion of the discussion focuses on off-grid storage applications. This focus is complemented by a discussion of the existing technology, policy, and economic barriers that hinder energy storage deployment. Specific actions that can be taken to remove these obstacles are identified for key energy system stakeholder groups.