Energy, environmental, and economic (3E) analysis of water resource recovery facilities to participate in power system stability

Abstract

The integration of renewable energy sources is increasing the variability and unpredictability of power systems, compromising the stability of the grid frequency, essential for the reliable operation of electrical systems. To mitigate these frequency deviations, both the supply-side (generation) and demand-side (consumption) participants in the grid respond dynamically to changing conditions. Traditionally, this has been managed by adjusting the output of power plants, but as the proportion of renewables increases, there is a growing need to explore alternative methods. This paper investigates the feasibility of using water resource recovery facilities (WRRF) as active participants in frequency control services. By strategically turning aerators ON or OFF in response to grid frequency deviations, WRRFs could offer a novel and effective way to help stabilize grid frequency. This feasibility is examined from an energy, environmental, and economic point of view. A model of Kolding WRRF in Denmark is used. More than 1000 scenarios with different start and duration times were considered. The results show that the WRRF can provide upward reserves of about 1000 kW h in 2 h, but the emissions vary significantly depending on the timing and duration. Participating in frequency restoration reserves has negligible environmental impact in most cases, but participating in replacement reserves may cause emissions spikes, especially for biological oxygen demand. Additional ${\mathrm{CO}}_2$ emissions’ deviation from normal operation range from $-0.005{kg}_{{\mathrm{CO}}_{2,eq}}/kWh$ to $0.013{kg}_{{\mathrm{CO}}_{2,eq}}/kWh$ depending on grid mix. Overall, the analysis shows promise for the use of WRRFs for frequency regulation, but optimized control strategies are needed to limit emissions.