Summary: The closing of material loops is a critical challenge in industrial ecology. It relies mainly on the utilization of recovered materials/parts/products in the original and principal production system while their original function is retained at the highest level possible. In this study, advanced loop‐closing systems for the recycling of end‐of‐life vehicles and electric household appliances are first designed in “Hyogo Eco‐town.” Second, a methodology for evaluating the eco‐efficiency of these systems is developed. Finally, the eco‐efficiency of the designed advanced loop‐closing strategies for the two products is evaluated, based on the results of materials flow analysis and life‐cycle assessment. The results show that, compared with conventional recycling systems, when an industrial complex and an advanced loop‐closing system for end‐of‐life vehicles are established, the total economic value increases by 114% and the eco‐efficiency in terms of the amount of direct material input is improved by 57%. This system permits the utilization of the by‐products, wastes, and recovered materials that originate from other industrial sectors as input to production activities. In the case of end‐of‐life electric household appliances, an advanced loop‐closing strategy to lengthen the product life with parts reuse improves the eco‐efficiency in terms of carbon dioxide (CO ₂ ) emissions by 4% compared with the conventional replacement of the appliance with a new product along with the material recycling option.

In this study, we estimated the future emission inventory of primary air pollutants in Japan in 2050 after introducing low-carbon technology based on the results of the socio-economic model provided by the Japanese government. The results suggested that introducing net-zero carbon technology would contribute to a 50-60 % decrease in primary NO_x, SO₂, and CO emissions and a ~30 % decrease in primary emissions of volatile organic compounds (VOCs) and PM_2.5. The estimated emission inventory and future meteorological conditions in 2050 were applied as inputs to a chemical transport model. A scenario involving the application of future reduction strategies with relatively moderate global warming (RCP4.5) was evaluated. The results showed that the concentration of tropospheric ozone (O₃) was highly reduced compared with that in 2015 after applying net-zero carbon reduction strategies. On the other hand, the fine particulate matter (PM_2.5) concentration under the 2050 scenario was expected to be equal or higher because of the growth in secondary aerosol formation caused by the increase in short-wave radiation. Finally, the premature mortality change from 2015 to 2050 was analyzed, and the change in air quality contributed by net-zero carbon technology will contribute to a ~4000 decrease in premature deaths in Japan.