An Analysis of the Energy Intensity of Water in California: Providing a Basis for Quantification of Energy Savings from Water System Improvements

Robert Wilkinson, University of California Santa Barbara
Gary Wolff, Pacific Institute
William Kost, University of California, Santa Barbara
Rachael Shwom, Michigan State University

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Abstract

Energy use associated with water use in California is significant, with extraction / conveyance and urban end-uses accounting for major portions. Estimates by the California Energy Commission in 2005, developed as part of the Integrated Energy Policy Report, indicate that 19% of the state’s electricity use, and 33% of natural gas use (excluding power plants), is
devoted to water use. (CEC 2005) A characterization and initial assessment of statewide energy inputs into all elements of the water system is currently being undertaken by the authors with support from the California Energy Commission’s Public Interest Energy Research (PIER) program. The project is seeking to identify energy inputs to water systems in California, from the point where water is extracted from surface or groundwater sources, through conveyance, treatment, distribution, end-uses (thermal, further treatment, pressurization, etc.), wastewater collection, treatment at applicable discharge standards, and disposal. The sum of all of the energy inputs to water that is delivered to, used, and disposed of in a specific location constitutes its energy intensity. This energy intensity factor is in turn the best measure of the potential avoided energy derived from alternative management options, including end-use efficiency measures. Flow diagrams and models have been developed to characterize the energy inputs at each step of the process in order to facilitate consistent analysis of the energy intensity of water.