In cases of power outages the communication of organizations responsible for recovery work (emergency services, public administration, energy network operators) to the public poses several challenges, primarily the breakdowns of many communication infrastructures and therefore the limitations of the use of classical communication media. This paper surveys technical concepts to support crisis communication during blackouts. Therefore it first investigates the perception and information demands of citizens and communication infrastructures in different scenarios. Furthermore, it analyzes communication infrastructures and their availability in different scenarios. Finally it proposes ‘BlaCom', an ICT-based concept for blackout communication, which addresses the time span between the occurrence of the energy blackout and the possible overload of the mobile phone network. It combines general information with location-specific and setting-specific information, was implemented as a prototype smartphone application and evaluated with 12 potential end users.