Enabling the transition towards a more sustainable energy future represents a huge challenge requiring strategic scientific information. Scientific support of opinion formation and decision making on sustainable development has important different characteristics than the ones of 'traditional' science for policy. Sustainability’s normative character, inseparable connection with deep-rooted value patterns, long-term nature of most relevant developments, and necessary inclusion of societal actors, result in specific demands on science for sustainability. SEPIA addresses such needs in the field of long-term energy policy. Although part of the project results will be contingent on specifics of the Belgian context, the project is embedded in the wider context of European and global energy system governance debates.