Analysis of the water–energy–greenhouse gas nexus in a water supply system in the Northeast of Brazil

Abstract

In recent years, water utilities have been under pressure to increase the efficiency of their processes, mainly due to the decrease in water availability and the need to increase environmental sustainability in their processes. Leak reduction is clearly an important part of sustainable management in the water industry, and its impacts should be assessed with a broader environmental protection objective. This study aimed to present an environmental and energy assessment of the water supply system (WSS) in Caruaru City, northeast of Brazil, for different levels of water loss. This research is one of the first to assess the environmental impacts of a WSS in Latin America. Primary data adopted for preparing the inventory were provided by the water utility, and modeling and analysis were performed with the SimaPro 8.0® program. Cumulative energy demand (CED) was used to track the energy consumption of the system’s life cycle. Greenhouse gas (GHG) emissions were calculated through the IPCC GWP 100a method with emissions expressed as CO2-Eq. The data sets from life-cycle inventories were used from the Ecoinvent 3.1 database. Four scenarios with different levels of water loss were analyzed. Scenario S0 was represented with the real conditions of the system, whereas the others considered hypothetical indices. The percentages proposed for Scenarios S1, S2, and S3 were based on indices that indicate good loss rate in the distribution network for the Brazilian reality (25%), reduction by half of loss rates, and excellent loss rates for the water pipeline system (5%) and distribution network (10%). The analysis of the processes’ contributions showed that the electricity consumption  of the pumping systems of water mains represented the greatest environmental impact in all scenarios. The most efficient scenario would result in a 52% reduction in the emission of GHGs, demonstrating that the increase in the hydraulic efficiency of the distribution networks represents a significant opportunity to reduce the environmental impacts of the processes.