Hybrid green infrastructure for reducing demands on urban water and energy systems: a New York City hypothetical case study

Green infrastructure shows promise as a “best management practice” for controlling stormwater runoff, particularly in older cities with combined sewer systems. Green infrastructure systems have been used to both mitigate pollutant loading to adjacent waterways as well as to reduce burdens on municipal wastewater and stormwater collection and treatment systems during storm events. Although the electric and water/wastewater networks are closely linked, wastewater, water supply, and energy systems have been typically studied in isolation. Here, we present a hypothetical case study for applying a modular hybrid green infrastructure approach to manage stormwater in the Newtown Creek sewershed in New York City. We provide background information on current and projected stormwater flows to the Newtown Creek Wastewater Treatment Plant (WWTP) and evaluate how interception and storage rainwater in the Newtown Creek sewershed could offset inflows to the WWTP and how this offset of stormwater inflows might result in reduced electric grid burdens and cost savings for the city. Our assessment indicates that a 0.66 % conversion of impervious sewershed surface area to modular hybrid green infrastructure could reduce stormwater inflow volumes (i.e., for an annual median storm) to the Newtown Creek WWTP by 10 %. We estimate that this would result in a 14-MWh reduction in energy required for wastewater treatment per storm event. Collectively, our results suggest that implementation of modular hybrid green infrastructure can significantly reduce burdens on urban water and energy systems, thereby helping to mitigate water-energy nexus challenges associated with climate change and population growth.