Water-energy nexus and energy efficiency: A systematic analysis of urban water systems

Water-energy nexus plays a vital role to re-phase, plan and develop an urban region for the present and future demands. This phenomenon is complex because of many inter-connected variables of technical and non-technical contexts. This paper reviewed the scope, aims, and approaches from the perspective of water-energy nexus studies in urban water system. The aim is to provide insights to minimize water-energy consumption and achieve maximum efficiency in urban water system management. A systematic review methodology was used to study 94 research papers, selected from relevant literature through the lens of water-energy nexus and energy efficiency. This research focuses on methodologies, models and affecting factors of water-energy nexus in different urban water system. The finding shows that most of studies used different frameworks and optimization approaches to achieve maximum energy efficiency. Integral Theory Framework (ITF) was used to find the inter-connectivity among existent variables of water-energy nexus for future demands. The ITF covers all aspects of waterenergy nexus, not only for technological assessments, but also for other variables; technological, environmental, socio-economical, and geographical dimensions. It was concluded that water and energy management have a big gap between policy and implementation. A systematic understanding of relationship and interactions between water and energy was needed not only for researchers, but the managers as well. This study recommended that optimum water-energy efficiency is attainable only when almost all variables and integral sections of water-energy nexus are integrated according to the existent conditions, which are different from locality to locality and system to system.