Scientific knowledge is the base to evidence-based policy-making on all levels of governance. The need for an excellent evidence base and independent data provision holds true for all policy areas. The role of scientific advice is often to ask, also evidence-based, the right questions and to point at potential future risks and opportunities. Scientists think in policy cycles while policy-makers in legislative periods. Scientists do not necessarily need a concrete output of their work besides having promoted scientific knowledge, while policy-makers are evaluated based on their actual successes and achievements. Scientific knowledge is needed in all stages of the policy cycle to improve effectiveness, efficiency and equity of policy tools. In the specific case of the Commission for Safe Energy Supply the German chancellor explicitly asked scientists for their advice; the whole process took place under close political scrutiny and was accompanied by high media attention.