Measuring the Energy Efficiency of Water Utilities

Abstract

Water infrastructure systems worldwide use large amounts of energy to operate. Energy efficiency efforts are relevant because even relatively small gains in efficiency have the potential to bring significant benefits to these utilities in terms of financial savings and enhanced sustainability and resiliency. In order to achieve higher efficiency levels, energy usage must be measured and controlled.A common tool used to measure energy efficiency in water utilities and perform comparisons between utilities is metric benchmarking. Energy benchmarking scores are intended to measure how efficient water systems are among their peers, in a simple and accurate fashion. Although many different benchmarking methods are currently used, we chose to use the segregated benchmarking scores proposed by Carlson on his research report from (Carlson, 2007.The research objective is to improve these production energy use and treatment energy use benchmarking scores by analyzing the system's particular characteristics that might skew the results, such as topology, water loss and raw water quality. We propose that benchmarking metrics should be always used within a particular context for each specific utility being analyzed. A complementary score (Thermodynamic Score) was developed to provide context on how energy efficient is the utility not only compared with other utilities, but also compared with the potential maximum efficiency the utility can reach itself.We analyzed eight utilities from Virginia to obtain production and treatment energy use benchmarking scores and also thermodynamic scores using the minimum required energy approach. Benchmarking scores were skewed in 50% of the studied utilities. This means that benchmarking scores should never be used as a black box. The thermodynamic score proved to be useful for measurement of energy efficiency of a water utility on its production phase. In addition, some utilities can detect significant financial saving opportunities using the minimum required energy analysis for production operations.iii DEDICATIONTo my wife Beatriz for supporting me always, even through the most daring and unlikely enterprises with quiet patience and loving, forgiving, steady support. This project would not be possible without you.To my Dad Leon Gay Guerra, outstanding civil engineer and great human being, who showed me the path of science, knowledge and beauty of nature; and always a strong, patient leader in my life, and To my Mom Lila Alanis who inspired me to never, never give up fighting and searching for a better world for me and all those around me, in spite of all obstacles that may and will arise.iv ACKNOWLEDGEMENTS