Life cycle assessment and comparison of energy supply system technical innovation: A case study

As the key sector of energy consumption in China, the industrial sector contributes the most to environmental pollution and CO2 emissions. With the goals of reaching the peak of CO2 emissions by 2030 and achieving carbon neutrality by 2060, optimizing the energy supply system of industrial enterprises is significant to achieve low-carbon development. In this study, the case of system upgrading concerning waste heat utilization in a manufacturing unit is applied. The total environmental impact of the energy supply system before and after transformation is quantified and compared based on life cycle assessment method, with "cradle to gate" as the system boundary and one year of system operation as the functional unit. It can be found that the environmental impact of the energy supply system is reduced from 4.54 to 4.14 through technical innovation. The key processes contributing to the environmental impact of the system are the refrigeration system, soft water system and boiler system. Electricity consumption of refrigeration system, NaCl of the soft water system and natural gas of the boiler system are identified as key substances. Sensitivity analysis reveals that the environmental benefits of reducing electricity consumption will be more effective than that of NaCl and natural gas. With the transformation of waste heat utilization and the increase of photovoltaic power generation, the environmental impact of the system is reduced obviously, which is significant for the low-carbon transformation of the manufacturing industry.