Measuring Energy Efficiency in Urban Water Systems Using a Mechanistic Approach

Abstract

This paper presents an energy efficiency metric for the raw water extraction process at urban water systems. Raw water pumping is the second largest energy consumer at water treatment plants after finished water pumping. United States water utilities are using more benchmarking metrics to assess performance and to compare their energy efficiency with other utilities. This trend has become especially prevalent among water and wastewater utilities. This paper proposes a thermodynamic score to provide complementary information of a utility’s energy efficiency. The thermodynamic score arises from estimating the minimum energy required by the system in contrast to the benchmarking method in which the basis is an empirical approach. The thermodynamic score proved to be an effective additional tool for measuring energy efficiency in most cases may have significant limitations in others. However, the energy analysis developed for the thermodynamic score has further applications on proactive asset management of water utilities.