Modeling residential water and related energy, carbon footprint and costs in California

et al. 2020

Environ. Res. Commun.

Self Cite

Reducing energy consumption for urban water management may yield economic and environmental benefits. Few studies provide comprehensive assessments of energy needs for urban water sectors that include both utility operations and household use. Here, we evaluate the energy needs for urban water management in metropolitan Los Angeles (LA) County. Using planning scenarios that include both water conservation and alternative supply options, we estimate energy requirements of water imports, groundwater pumping, distribution in pipes, water and wastewater treatment, and residential water heating across more than one hundred regional water agencies covering over 9 million people. Results show that combining water conservation with alternative local supplies such as stormwater capture and water reuse (nonpotable or indirect potable) can reduce the energy consumption and intensity of water management in LA. Further advanced water treatment for direct potable reuse could increase energy needs. In aggregate, water heating represents a major source of regional energy consumption. The heating factor associated with grid-supplied electricity drives the relative contribution of energyfor-water by utilities and households. For most scenarios of grid operations, energy for household water heating significantly outweighs utility energy consumption. The study demonstrates how publicly available and detailed data for energy and water use supports sustainability planning. The method is applicable to cities everywhere.

Section: Introductionmentioning

confidence: 99%

Energy use for urban water management by utilities and households in Los Angeles

Porse

Mika

et al. 2020

Environ. Res. Commun.

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“…A system analysis is applied to households using a previous water-energy-CO 2 model [Escriva-Bou et al, 2015] for 10 cities in California following this procedure: (i) identifying potential long and short-term conservation actions; (ii) modeling water, energy and economic savings due to these technological and behavioral modifications and its costs accounting for water and energy variable prices; (iii) obtaining the composite of actions that minimize the annual water-energy cost for each household; and (iv) considering uncertainty through Monte Carlo simulation for a wide variety of household conditions (adapted from Alcubilla and Lund [2006] and Rosenberg et al [2007]). Finally one last run considering only water costs was done to obtain the increased willingness to adopt conservation actions from adding consideration of embedded energy.…”

Section: Introductionmentioning

confidence: 99%

Optimal residential water conservation strategies considering related energy in California

Water Resources Research

Lund

Pulido-Velázquez

2015

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Although most freshwater resources are used in agriculture, residential water use is a much more energy intensive user. Based on this, we analyze the increased willingness to adopt water conservation strategies if energy cost is included in the customers' utility function. Using a Water-Energy-CO 2 emissions model for household water end uses and probability distribution functions for parameters affecting water and water-related energy use in 10 different locations in California, this research introduces a probabilistic two-stage optimization model considering technical and behavioral decision variables to obtain the most economical strategies to minimize household water and water-related energy bills and costs given both water and energy price shocks. Results can provide an upper bound of household savings for customers with well-behaved preferences, and show greater adoption rates to reduce energy intensive appliances when energy is accounted, resulting in an overall 24% reduction in indoor water use that represents a 30% reduction in water-related energy use and a 53% reduction in household water-related CO 2 emissions. Previous use patterns and water and energy rate structures can affect greatly the potential benefits for customers and so their behavior. Given that water and energy are somewhat complementary goods for customers, we use results of the optimization to obtain own-price and cross-price elasticities of residential water use by simulating increases in water and energy prices. While the results are highly influenced by assumptions due to lack of empirical data, the method presented has no precedent in the literature and hopefully will stimulate the collection of additional relevant data.

“…In all cases we rely on energy intensity factors—amount of energy consumed per unit of water use—obtained from the literature. Residential water‐related energy is obtained from Escriva‐Bou et al () accounting for the different energy intensities of each residential water end use. Energy intensity of commercial and institutional uses were obtained from CEC ().…”

Section: Methodsmentioning

confidence: 99%

Saving Energy From Urban Water Demand Management

Water Resources Research

Lund²,

Pulido-Velázquez

2018

Water use directly causes a significant amount of energy use in cities. In this paper we assessed energy and carbon dioxide emissions related to each part of the urban water cycle and the consequences of some water demand management policies in terms of water, energy, and CO2 emissions in urban water users, water and energy utilities, and the environment. First, we developed an hourly model of urban water uses by customer category, including water‐related energy consumption. Next, using real data from the East Bay Municipal Utility District in California, we calibrated a model of the energy used in water supply, treatment, pumping, and wastewater treatment by the utility, obtaining also energy costs. Then, using data from the California Independent System Operator, we obtained hourly costs of energy generation and transport to the point of use for the energy utility. Finally, using average emission factors reported by energy utilities, we estimated greenhouse gas emissions for the entire urban water cycle. Results for East Bay Municipal Utility District show that water end uses account for almost 95% of all water‐related energy use; however, the remaining 5% of energy used by the utility still costs over USD12 million annually. The carbon footprint of the urban water cycle is 372 kg CO2/person/year, representing approximately 4% of the total per capita emissions in California. Several simulations analyze the consequences of different water demand management policies, resulting in significant economic impacts for water and energy utilities and environmental benefits by reducing CO2 emissions.