Quantitative assessment of energy conservation and emission reduction effects of nationwide industrial symbiosis in China.

Studies on quantifying the energy conservation and emission reduction (ECER) effects of industrial symbiosis are mostly confined to micro-level industrial parks or regions, and few are on national level. Focusing on the symbiosis system formed by the iron and steel industry, the thermal power industry, the cement industry, and the social sector in China, this article aims to clarify the contribution of this nationwide industrial symbiosis system to China's total industrial ECER potential and to identify optimal symbiotic technologies that should be emphasized on from 2020 to 2030. By combining traditional bottom-up model and lifecycle material metabolism theory, this article simulates the technology structure of this symbiosis system. By clarifying the ECER mechanisms of different types of symbiotic technologies, this article evaluates the ECER effect of each symbiotic technology as well as the performance of the overall symbiosis system. The results show that: (1) this nationwide industrial symbiosis system can save 35.7 million tons of coal equivalent, and reduce 189 kt of SO2 emissions, 139 kt of NOx emissions, and 64 kt of PM emissions. These ECER effects contribute to 18-43% of China's national industrial ECER targets, which are larger than the potential of promoting energy efficiency technologies and end-of-pipe technologies in each single industry; (2) reutilizing solid wastes from the thermal power industry and the social sector as cementitious materials, as well as recovering iron and zinc from metallurgical dust are key symbiotic fields between 2020 and 2030. Three types of differentiated technology promotion suggestions are put forward.