Future energy scenarios with renewables and flexibilities in distribution grids – National case study in France

Medium and low voltage distribution grids are at the core of the energy transition as they are expected to host a large share of renewables and flexible resources. Their modeling within decarbonization pathways is then of great importance in providing realistic future energy scenarios. This paper investigates different scenarios at the French national scale up to 2050 while varying the electricity demand, renewables installed in both transmission and distribution grids, and the considered flexibility technologies. The methodology relies on coupling a long-term energy model (POLES) and an open-source short-term optimization framework (Backbone). POLES produces long-term decarbonization scenarios, while Backbone enables the optimization of the power system. Technical and financial impacts are studied through ten scenarios regarding produced energy, installed capacities, and investment costs. The results highlight the importance of the load demand modeling assumptions, even raising the question of the feasibility of high-demand scenarios. Also, results show that demand-side flexibility can significantly reduce the requirements in conventional storage technologies (up to 98 %). Distributed flexibilities, such as electric vehicle smart charging, are especially effective. Considering multiple types of distribution grids allows, in the end, to show that installing renewable generation at the transmission or distribution level only moderately influences global costs, with a minor advantage for centralization to limit reverse flows on transformers. The paper concludes with a comparison with other scenarios (drawn from up-to-date literature) and a discussion of the environmental footprint of these scenarios, both in terms of mineral resource consumption (raw materials) and land footprint.