Load shifting at wastewater treatment plants: A case study for participating as an energy demand resource

Energy load shifting can allow for increased renewable energy integration and reduced greenhouse gas intensity of the electricity grid. Recent research has demonstrated that wastewater treatment plants have considerable potential to shift energy loads and act as energy demand resources due to their energetic flexibility and energy production capacity. This paper investigates a wastewater treatment plant in Santa Rosa, California, participating as a demand resource on the wholesale energy market through the proxy demand resource program. Test demand response events showed that the facility was able to shift its energy load by modifying select operations without impacting wastewater effluent quality. A cost-benefit analysis based on projected program participation and the results from the test events, estimates that the Santa Rosa wastewater treatment plant could achieve up to 4.8% energy cost savings through the proxy demand resource program. Two main issues were identified from the test events: (1) the difficulty of correctly timing demand reduction periods and (2) the inaccuracy of using standard baseline methods to measure the energy load reduction. As a supplement to the case study, this paper also presents a roadmap outlining the technology necessary for wastewater treatment plants to participate in demand resource programs through energy load shifting. The roadmap identifies key instrumentation and automation infrastructure, and assets that can be utilized to provide energetic flexibility; it also recommends additional infrastructure that can stabilize energy loads and enhance controlled energy load shifting. (C) 2020 Elsevier Ltd. All rights reserved.