To combat the climate change and for reasons of the security of supply the European Union and its member states have adopted a strategy to increase the use of energy from renewable resources until 2020 and beyond. One long run sub-target of this strategy is to increase the proportion of renewable energy for fuelling purposes to 20 percent. It is hardly possible to reach this ambitious objective by using current technology of bio-fuel production. The paper discusses alternative forms of fuels from renewable energy sources. This discussion identifies biomass-to-liquid (BtL) fuels as the most promising way to accomplish the EU target. The evaluation of the future role of BtL is difficult due to complex and uncertain interdependencies between several factors of influence. The paper develops the basic structure of a SD-model to capture the numerous effects and their dynamic feedbacks.