Extended water-energy nexus contribution to environmentally-related sustainable development goals

Challenges of high energy efficiency, water saving, low-carbon emissions, waste management and food saving have been considerable pressures on both regional and global sustainable development. This paper reviews the water-energy extended nexuses (e.g. food, greenhouse gases, waste, pollution, land and others) from the perspective of relationship and practicability in relieving the challenges towards environmentally-related sustainable development goals. A specific issue identified is that with the popularity of "nexus" and extension beyond resources nexus, the positioning and identity of nexuses become ambiguous. In most cases, nexus is a more attractively sounding term to replace specific expressions such as multi-criteria optimisation, trade-offs, correlation/relationship, input-output assessment, material flow analysis, and integrated design. The methodologies (e.g. input-output analysis and life cycle assessment) entail needing to be adequately integrated or expanded for diverse water-energy extended nexuses. It is crucial for evaluating resource flows in multiple regions and sectors and assessing the associated environment-economic impacts. A standardised understanding like establishing life cycle assessment and even more quantified footprints could ensure that the nexus would not fall as the group of a buzzword and contribute to sustainable development goals. This study serves as a stepping stone to establish quantified characteristics or components as eligibility to classify as nexus approaches and studies.