Green hydrogen and e-fuels are undoubtedly necessary for Germany’s course toward climate neutrality in 2045. Unlike renewable electricity from wind and sun, however, we have not yet made any practical use of these energy sources. In the debate, therefore, there are still very different estimates as to when which quantities of hydrogen will be available and at what prices. Even the five scenario analyses currently receiving the most attention show wide ranges for the use of hydrogen and e-fuels, at least in the long term. But what do we know for sure, where do uncertainties remain, and how can policymakers now quickly arrive at robust decisions? In a new paper published by the Kopernikus project Ariadne, which is funded by the German Federal Ministry of Education and Research (BMBF), experts from six institutes now present key points for an adaptable hydrogen strategy.