The pressure to rapidly and comprehensively reduce global greenhouse gas emissions is constantly increasing - forest fires in many regions of the world, the increase in extreme weather events and melting glaciers provide us with clear evidence of this. The energy sector is responsible for a large part of greenhouse gas emissions. Therefore the conversion of the energy supply towards climate neutrality plays a decisive role. Using Germany as an example, the lecture shows various development pathways towards a climate-neutral energy supply, which are based on hourly simulation and optimization of the entire energy system and its transition. Social perspectives and behaviors are taken into account, because this transformation will only succeed if society follows the chosen pathway. The results of the investigation show that - depending on social behavior - the German energy transition relies on a more or less large amount of imported synthetic energy sources that are produced from renewable electricity in other regions in order to achieve the goal of a climate-neutral energy supply at reasonable costs. In addition important implications can be derived from the analysis with regard to necessary technology and system developments, which are valid far beyond the German example.