Adding value with CLEWS – Modelling the energy system and its interdependencies for Mauritius

•Climate, Land-use, Energy and Water Systems (CLEWS) are strongly interlinked.•Related policy making is often informed by disconnected resource assessments.•The value of interlinking such assessments is demonstrated, focusing on energy.•The effects of water stress on the energy system were modelled more accurately.•The benefit of ethanol generation was largely overestimated without interlinkages. Climate, Energy, Water and Land-use Systems (CLEWS) are closely integrated. Yet, most related decision and policy making occurs in disparate institutional entities, informed by relatively disconnected assessments of the individual resource systems. This paper presents the added value of an integrated analytical assessment approach. In doing so, it explicitly values various interdependencies and interactions between CLEWS primarily from an energy sector perspective. The island state of Mauritius was identified as a useful case study given its diverse climate, its increasing water stresses, and its policy focus on reshaping agricultural land-use and reducing fossil fuel imports. Several scenarios to 2030 were defined and analysed to demonstrate the tensions around the CLEWS nexus. Results from an assessment of the energy system with no modelled interlinkages to land-use, energy and water systems are first presented. Then, these are compared to those from an integrated CLEWS assessment. This serves to highlight important dynamics that would have been overlooked without such a systems approach. As an example, the added value of this approach is clearly demonstrated when rainfall reductions are taken into account, and where future land-use changes might occur.