Emergy analysis of seawater desalination system in coastal areas: a case study in Qingdao of China

Currently, seawater desalination technology, one of the important alternatives to address water shortage, has been applied more widely in coastal areas. However, the sustainability and environmental performance of the seawater desalination system are unclear. Scientific evaluation of resource input, environmental performance and sustainability of seawater desalination system can provide a reference for rational development and utilization of seawater desalination water. In this paper, emergy analysis, an effective ecological and economic evaluation method, was used to systematically evaluate the sustainability of a desalination plant in Qingdao of China. The results showed that the unit emergy value of the desalinated water was 4.13E+12 sej/m(3); the environmental loading ratio of the studied system was 5.46; the emergy sustainability index was 0.18. Compared to surface water and underground water treatment processes, the seawater desalination system has higher stress on the environment. Electricity for the operation of the seawater desalination system is the major emergy input. The optimization of the process and the research and development of energy-saving equipment are the keys to the application of seawater desalination. This study also illustrates that seawater desalination technology still faces many challenges. Therefore, it is important and necessary to strengthen the core technology and establish a sound law system in the application of desalination technology.