In order to support policy decisions, we have developed a modelling platform called AgentSpring, which facilitates the development of agent-based models in a modular and structured manner, using state-of-the-art IT development principles and tools. An attractive web-based interface allows for the interaction with policy makers. A model named d13n was developed on the topic of decarbonization of the power generation sector. For this model, relevant applications for policy makers – CO2 reduction, cross-border effects of policies, security of supply – have been identified. Each of those questions can be tackled by developing specific scenarios within the same modelling platform and with the same model core.