A U.S. National Level Study of Operational GHG Emissions Generated in the Water Sector

Abstract:

Nations are responding to global climate change with better accounting of greenhouse gas emissions (GHG) to develop strategies for reducing their carbon footprint. With energy demand being a major contributor to operational GHG emissions in the water sector, the United States (U.S.) struggles to track GHG emissions largely due to the absence of a centralized water database. The focus for tracking water sector GHG emissions largely remains on accounting primary emissions (i.e. emission created through: on-site electrical generation, anaerobic processes, treatment methods, etc). Accounting of energy-related GHG emissions in the water sector have largely been conducted at specific plants or cities and rarely at a regional or country scale. In this study, we assess the GHG footprints of energy use and detail patterns of variations in GHG intensity with different geographical boundaries. We analyze the GHG footprint of 77 wastewater utilities and 64 water utilities to determine broad patterns of water-related emissions across the U.S. This paper also investigates water-related GHG emissions at a sub-annual scale through three case cities to understand how GHG emissions change at the monthly scale. The research provides insights into operational GHG emissions of the water sector and advances the understanding of temporal variations in the life-cycle of energy use.