A simulation-assessment-optimization approach towards energy self-sufficiency and carbon reduction in regional-scale sewage systems

Utilizing renewable energy is a practical pathway for realizing energy self-sufficiency and offsetting carbon emissions in wastewater treatment plants (WWTPs). The holistic optimization of hybrid renewable energy of multiple WWTPs overweighs individual WWTPs studies by providing global optimal solutions and cost-effective resources management schemes with expended spatial scales. Few studies have focused on the overall optimal utilization and management of hybrid renewable energy from WWTPs on a regional scale. This study aims to explore how to optimize the configuration of renewable energy facilities for multiple WWTPs to achieve the costeffective use of renewable energy for the overall system. Uncertainty associated with PV power generation and the size effects of WWTPs were considered in the general framework to enhance the reliability and cost effectiveness of the utilization of renewable energy. The developed approach was then applied to the hybrid renewable energy management of a city-scale WWTP system comprising 31 plants in Guangzhou, China. Results indicated that the energy self-sufficiency of sewage systems can be realized by recovering renewable energy. The levelized cost of energy generation in the overall system was approximately 0.19 CNY/kW center dot h, and the overall reduction in greenhouse gas (GHG) emissions was approximately 129.5 t CO2-eq/d. The overall optimization reduced the total cost by approximately 3% than did the traditional individual WWTP studies. The thermal energy recovered from wastewater could further reduce the operational costs of WWTPs through carbon credit trading. The developed approach can also be applied to other areas of the world to promote sustainable wastewater treatment and strengthen the utilization of renewable energy.

Automated summary

Utilizing renewable energy in wastewater treatment plants is a practical way to achieve energy self-sufficiency and reduce carbon emissions. This study focuses on the optimization of hybrid renewable energy in multiple plants, providing global optimal solutions and cost-effective resource management. The approach was applied to a city-scale wastewater treatment system in Guangzhou, China, showing that renewable energy can achieve energy self-sufficiency and reduce overall costs and greenhouse gas emissions.