Researchers in the field of sustainable energy at Copernicus follow the adage the transition is our topic. We work from the understanding that the energy transition is at its core a technical transition at the system level, but that implementation also requires understanding of environmental, techno-economic and other societal factors. The defining strength of energy research at Copernicus is that collectively our expertise gives full coverage of the energy system, old and new, production and use. Our academic interest is driven by the desire of the researcher to help society address the energy challenge. As a consequence, the research profile adapts over time to tackle the most critical issues and knowledge gaps in the energy domain, increasingly incorporating also social sciences into our work program.