Evaluation for the nexus of industrial water-energy-pollution: Performance indexes, scale effect, and policy implications

Abstract

The interaction of water and energy consumption and pollution emissions in the industrial system, defined as the Industrial Water-Energy-Pollution nexus (abbreviated as InWEP), has a prominent role in sustainable development. One of the great challenges is evaluating the systematic characteristics of InWEP to explain the index changes of nexus performances at different scales (i.e., enterprise, industrial park, county, and city) for more effective synergetic management. This study formulated two performance indexes of NPI (Nexus pressure index) and NCI (Nexus coupling index) to explain the scale effects for the InWEP. NPI is to explain the overall pollution pressure for InWEP, and NCI is to describe the interacted relations among InWEP. Structural Equation Model (SEM) was adopted to analyze influencing factors for the InWEP indexes. The results show that an increment of industrial output would lead to a decline of NPI and a rise of NCI. The average value of NPI decreases from 0.65 at the enterprise scale to 0.51 at the city scale. The average value of NCI shows a scale-up effect as it increases from 0.54 to 0.88. Efficiency factors have the most significant impacts on InWEP at all spatial scales, while the industrial structure and distribution only have impacts on counties and cities. The results implicate that synergetic and differentiated strategies should be conducted to optimize InWEP to support clean and sustainable development.