The PhD study will be a part of the COMETS project (Co-Management of Energy and Transport Systems). The aim of COMETS is to develop a decision support system for reducing greenhouse gas emissions within the Danish transport sector, and ultimately moving towards a transportation sector free of fossil fuels. COMETS is a collaboration between DTU Management, DTU Transport, Roskilde University, and other Danish, Irish and Italian partners. It is financed by Det strategiske forskningsråd, now Innovationsfonden.