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As the most essential factors affecting sustainable regional development, energy and water resources are closely related. Based on the three-scale energy intensity database, this study calculates the whole life cycle performance of a 25,000 tons/day desalination project in Hebei Province, China by combining life cycle analysis with input-output analysis. Considering the embodied energy consumption in different time periods, the corresponding freshwater production per year is 9.13 million m3, and the total energy consumption covering the construction and operation stages is 39.46 PJ, with the energy consumption per year of 1.94 PJ. Considering the embodied energy consumption in different scales and components, the energy consumption at the national scale contributes the largest proportion (68.79%), and the evaporator is the main component in the construction stage (34.30%). For energy consumption in water production, the energy-water nexus index in the project is 18.02 kWh/m3, among which the thermal power could be replaced through the combination of seawater desalination and thermal power plants. Through the reasonable selection of key materials and components and location of seawater desalination projects, the balance between the supply and demand of energy consumption and water production could be optimized from the energy-water nexus perspective. Systems diagram of the seawater desalination project. Image 1 • The energy-water nexus is assessed on the seawater desalination project. • The energy consumption in operation stage is higher than in construction stage. • The evaporator is essential energy-consuming equipment in desalination process. • The energy consumption in operation stage is 1.94 PJ per year. • The energy-water intensity is 18.02 kWh/m3, slightly higher than other plants. [ABSTRACT FROM AUTHOR]

Coastal cities play significant roles in the strategy of regional economic development as well as national water resource supply. As a typical coastal city in Hebei Province, China, Qinhuangdao is the main water supplier in Hebei Province but also faces increasingly scary water shortages at the same time. Taking Qinhuangdao as a case, this work analyzes the water supply and demand of a coastal city by multi-scale input-output analysis and conducts a comprehensive assessment on the water resource balance from the perspectives of global, domestic, provincial and municipal scales. Overall, the water use efficiency of Qinhuangdao is lower than that of Beijing but higher than China's average. Notice that, Qinhuangdao's local water resources only account for about 39.18% of its final water demand, which cannot fully satisfy its own demands. However, Qinhuangdao as a net embodied water exporting economy, has a total net export volume of 1.52E+08 m3 of embodied water. Especially, the secondary industry of Qinhuangdao has a great contribution to the provincial embodied water exports, while the primary industry is more essential in the domestic and foreign embodied water exports. From the global, domestic and provincial perspectives, the multi-scale supply chains of water resources at Qinhuangdao could provide a solid foundation for water allocation balance at different scales, which is necessary for regional water utilization and water saving policies from an embodied perspective. Multi-scale water balance flows for the coastal city (unit: billion m3). Image 1 • Multi-scale water resources of a typical coastal city are analyzed. • Water uses of the coastal city from source to sink are analyzed. • Water demands of the coastal city are much less than the local utilization. • Trade imbalances and whole balances of the coastal city are identified. • Water use between coastal cities and inland cities are compared. [ABSTRACT FROM AUTHOR]