The French prospective aims to influence the shaping of the future by exploring different scenarios and evolution, so that long-term challenges are considered in current decision-making. In practice realizing this linkage between modelers and policy makers is itself a process and comes with its own challenges. This chapter reflects on modelling to inform various energy policy assessments in France aligned with SDGs 7 (energy), 8 (economic growth), 9 (industry), 11 (cities) and 13 (climate), across several exercises around the reduction of greenhouse gas emissions, the nuclear phase-out, the implementation of a 100% renewable power system with its reliability issues and the assessment of carbon value. It is based on our practical experience at the Centre for Applied Mathematics (MINES Paris—Université PSL) where TIMES has been used as a bottom-up optimization approach to offer insights, within extended committees, to French policymakers. The model we developed is the TIMES-FR model where FR stands for France. Our experience reveals that policymakers do not fully harness the wealth of technical insights provided by researchers, as they often prioritize short or mid-term challenges. While policy perspective does not seem to need the precision and comprehensiveness of technical modelling, we show that the insights tend to penetrate at some point in the public debate and policy-making sphere, which emphasizes the relevance of using prospective and energy system models to address climate change.