Water-energy nexus embedded in coal supply chain of a coal-based city, China

Abstract

Shortage of water and energy, and uneven distribution of coal and water pose great challenges to the sustainable development of coal-based cities. Water and energy has nexus relationship through the coal supply chain and affect the sustainable development of the cities. While few studies consider water-energy nexus embedded in coal life-cycle for the coal-based cities. Here, we incorporated substance flow analysis (SFA) with life cycle assessment (LCA) and nexus theory to firstly construct a coupled layer model of water-energy nexus for coal resource cities. The coal life-cycle includes coal mining, coal processing, product utilization, and waste disposal. Both water consumption and energy consumption include direct consumption in the coal life-cycle layer, and indirect consumption in the water-energy layer. Then, we firstly applied the model to analyze water and energy consumptions in a typical coal-based city, Huainan City from 1990 to 2020. Our results show that both water and energy consumptions increased to 2.26*108 m3 and 2.14*1010 kgce in 2020. In the whole coal life-cycle, direct water use accounted for 84%–89% of the total water use, and direct energy use accounted for almost all of the total energy use. Among the four stages of the coal life-cycle, product utilization accounted for 80%–89% and 90%–95% of total water consumption and total energy consumption, respectively. In product utilization, mining and manufacturing sectors consumed most of the water and energy, while the consumption for services gradually increased. During coal mining and coal processing, all the consumptions of coal, water, and energy consumption firstly increased and then decreased after 2015. Then, we conducted sensitivity analysis and found that electricity generation and coal consumption coefficient of thermal power plant greatly influence the water consumption and energy use. Finally, we conducted scenario analysis and found that water consumption and energy consumption of Sustainability Scenario (SS) will be 6.3% and 9.4% lower than Baseline Scenario (BS), 12.0% and 17.5% lower than Crisis Scenario (CS), respectively. The study hopes to not only provide a research foundation for life cycle-based approaches and nexus theory, but also a demonstration for promoting sustainable development of other resource-based cities in China.