Planning and Optimizing the Water-Energy-Food Nexus in the Sahel: MAED-MESSAGE Diagnostic of Niger's Energy Mix, 2021–2050

Ibrahim ISSA SEIDI, Ibrahim HALIDOU

No prior study had coupled MAED demand and MESSAGE supply from the same in-house modeling over the full 2021–2050 horizon to quantify the WEF nexus investment effort for the Sahel, a gap this study addresses. Sahelian countries share a structural triple vulnerability: energy poverty, water stress, and dependence on traditional biomass. This study applies the IAEA's integrated MAED-MESSAGE modeling chain as a WEF nexus diagnostic protocol for Niger over 2021–2050, under three contrasted scenarios (S1-BAU, S2-SNAE+, S3- NDC+). The diagnostic reveals a non-monotonic electricity mix trajectory: a nexus performance peak in 2035 (100% sovereignty, low-carbon share renewables plus nuclear up to 91.5%) followed by a mechanical decline through 2050 (23.5–31.7%), due to the absence of a second planning wave beyond 2035. Water-food co-benefits, driven by biomass-to-electricity substitution, remain stable throughout. A composite nexus score confirms this asymmetry. Closing the post-2035 gap requires USD 13.3–21.7 billion depending on the scenario; the most ambitious scenario (NDC+) also shows the best capital intensity. This diagnostic constitutes a reproducible protocol transposable to other Sahelian countries.