Water resource recovery facilities as potential energy generation units and their dynamic economic dispatch

The dynamic nature of wastewater treatment and the significant number of energy conversion and recovery technologies applicable to the process, require a modelling framework that can be used for optimization and planning. This paper introduces a dynamic energy dispatch optimization framework with a combination of energy recovery and reserve options for water resource recovery facilities (WRRFs). Energy potentials, including biogas, electricity, and heat, were assessed for 15 large-scale WRRFs, which serve approximately 80% of the Irish population. The framework was applied by simulation of the national electrical system on an hourly basis for 2030 using mixed-integer programming (MIP) for eight scenarios. The simulation enabled automatic operational command scheduling for the production, conversion, storage, and supply over a year at an hourly time resolution. Meanwhile, the significance of several energy resources was assessed, and the impact of dynamic energy dispatch examined. A total potential cost saving of €46.35 M was possible through implementation of dynamic economic dispatch optimization (54% from biogas cogeneration, 40 %from thermal energy recovery, and 6% from micro-hydropower electricity). In addition, reductions in carbon emissions (2%), fossil fuel consumption (3%), startup costs (18%) and outsourcing dependency (5%) were possible. Up to 0.5% of whole system power demand and 90% of considered heat demand at peak periods could be provided by the proposed framework through dynamic economic dispatch. Therefore, this study suggests that WRRFs can participate into energy system through the dynamic economic dispatch of recovered energy, and provide potential energy flexibility, as well as adding value to overall sustainability of energy system.