A review of energy-for-water data in energy-water nexus publications

Published literature on the energy-water nexus continues to increase, yet much of the supporting data, particularly regarding energy-for-water, remains obscure or inaccessible. We perform a systematic review of literature that describes the primary energy and electricity demands for drinking water and wastewater systems in urban environments. This review provides an analysis of the underlying data and other properties of over 170 published studies by systematically creating metadata on each study. Over 45% of the evaluated studies utilized primary data sources (data collected directly from utilities), potentially enabling large-scale data sharing and a more comprehensive understanding of global water-related energy demand. The most prevalent geographic scale of the existing literature was at the individual city scale (39%), limiting comparisons between utilities. Additionally, energy-for-water studies span 34 different countries with 11 countries having at least 4 published studies. The analyzed literature often considered greenhouse gas emissions of energy demand as an important input for life cycle analysis, highlighting the broader impact of the energy-water nexus. As a result of the review, we identify several common practices for filling data gaps, discover that research and data are primarily concentrated in three countries (Australia, China, and the United States), and offer suggestions for the future of the energy-water nexus, specifically regarding energy-for-water.