A water-energy nexus review from the perspective of urban metabolism

Urban water-energy (WE) nexus is regarded as highly important in managing resource shortage crisis in city. Integrating this nexus approach with metabolism framework can provide important insights for sustainable urban planning. In this paper, we present a comprehensive review on urban WE nexus from the perspective of urban metabolism. With the objective of less independence and impact on eco-environment, we make an inventory of alternative sources and associated optimized utilization pathways within urban water system context from resource management provision. Meanwhile, consumption patterns of water and energy in buildings, residential sectors and production sectors are also comprehensively reviewed from demand side management provision. In general, almost all the literatures on urban WE nexus have expressed their great ambitions to achieve integrative governance, which can be enhanced through a scientific management of the co-benefits and trade-offs with regard to development pathway planning, infrastructure spatial planning as well as corresponding auxiliary intervention. In addition, future prospects for urban WE nexus research are also proposed from the perspectives of conception development, methodology improvement and target region extension. The results show that: (1) The water-food-energy nexus is a further advance of WE nexus, while the adoption of Sustainable Development Goals (SDGs) can provide a renewed and more holistic paradigm for its conception development by incorporating other environmental, social and economic systems. (2) The conception improvement will also drive the urgent need for a more integrated scientific research tool. (3) Developing countries deserve a higher priority in urban WE nexus network, where both greater challenges and opportunities exist.