Report
Group D – D14.01
Wa t e r -Energy Calculator 2.0 Project Report
Submitted to
California Public Utility Commission
505 Van Ness Avenue
San Francisco, CA 94102
Submitted by
SBW Consulting, Inc.
2820 Northup Way, Suite 230
Bellevue, WA 98004
In association with
Pacific Institute
344 2
0th St
Oakland, CA
94612
F
ebruary 22, 2022
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Table of Contents
List of Figures .............................................................................................. v
Li s t o f Ta b le s .............................................................................................. vi
Executive Summary ..................................................................................... 1
Background ................................................................................................................. 1
Project Goals and Objectives ........................................................................................ 1
Ke y En hancements for the W-E Ca lcula tor 2.0 ............................................................... 2
Wa t e r -Energy Calculator 2.0 ........................................................................................ 2
Comparison of the W-E Calculator 1.0 and 2.0 .............................................................. 3
Recommendations ....................................................................................................... 4
1 Introduction ......................................................................................... 7
1.1 Wa t e r -Energy Nexus .......................................................................................... 7
1.2 Wa t e r -Energy Proceedings ................................................................................. 7
1.3 Project Goals and Objectives .............................................................................. 9
1.4 Structure of the Report ...................................................................................... 9
2 Ke y Enhancements for the W-E Ca lcu la t o r 2 . 0 ...................................... 10
2.1 Document Review ............................................................................................ 10
2.2 Interviews ....................................................................................................... 11
2.3 Summary of Findings ....................................................................................... 12
2.3.1 W-E Calculator 1.0 Errors ....................................................................................... 13
2.3.2 Calculator Functionality .......................................................................................... 14
2.3.3 CPUC Policies and Procedures ................................................................................. 14
2.3.4 Education and Outreach ......................................................................................... 15
3 Wa t e r -Energy Calculator 2.0 ................................................................ 16
3.1 General Approach ............................................................................................ 16
3.2 Relationship with Other CPUC Tools .................................................................. 17
3.3 Regional Analysis ............................................................................................. 19
3.4 Marginal Water Supply and Historical Water Supply Mix .................................... 20
3.4.1 Marginal Water Supply ........................................................................................... 20
3.4.2 Historical Water Supply Mix .................................................................................... 21
3.5 Resource Balance Year ..................................................................................... 23
3.6 Energy Intensity of Water-System Components ................................................ 23
3.6.1 Water Extraction and Conveyance .......................................................................... 24
3.6.2 Water Treatment ................................................................................................... 25
3.6.3 Water Distribution ................................................................................................. 27
3.6.4 Wa stewater Collection and Treatment .................................................................... 28
3.6.5 IOU Energy Intensity of Water-System Components ............................................... 28
3.7 Wa t e r -System Components by Sector ............................................................... 29
3.7.1 Urban Sector ......................................................................................................... 29
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3.7.2 Agricultural Sector ................................................................................................. 29
4 Comparison of the Water-Energy Calculator 1.0 and 2.0 ...................... 31
5 Recommendations .............................................................................. 34
6 References .......................................................................................... 37
Appendices ................................................................................................ 38
A. Interview Questions ............................................................................ 39
A. 1 Interview Questions for Energy Utilities ............................................................ 39
A. 2 Interview Questions for Consultants and Researchers ....................................... 40
B. Short- and Long-term Solutions for Integrating Embedded Energy
S a v i n g s i n t o CEDARS ........................................................................... 42
C. User’s Manual ..................................................................................... 44
Glossary of Terms ...................................................................................... 72
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List of Figures
Figure 1: Conceptual Framework of the W-E Ca lcula tor 2.0 ........................................................... 3
Figure 2: Conceptual Framework of the W-E Ca lcula tor 2.0 ......................................................... 17
Figure 3: Short-term Relationship Between the W-E Calculator 2.0, eTRM, CEDARS, and CET ....... 18
Figure 4 : Lo n g -term Relationship Between the W-E Calculator 2.0, eTRM, CEDARS, and CET ........ 18
Figure 5: California’s Ten Hydrologic Regions .............................................................................. 19
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Li s t o f Ta b le s
Table 1: Summary of Key Enhancements for the W-E Ca lculat or 2.0 .............................................. 2
Ta b le 2: Comparison of IOU Embedded Energy Savings, in kWh, from the W-E Ca lcula t or
1.0 and 2.0. ................................................................................................................................. 4
Ta b le 3: Documents Reviewed for the W-E Calculator Updates .................................................... 10
Ta b le 4: List of Representatives and Organizations Interviewed .................................................. 11
Ta b le 5: Summary of Key Enhancements for the W-E Ca lcula t or 2.0 ............................................ 12
Ta b le 6: Description of Water Supplies Options in California ........................................................ 21
Ta b le 7: Water-Supply Mix, 2006-2015, by Hydrologic Region. .................................................... 22
Ta b le 8: Total Electric Energy Intensity of Extraction and Conveyance for Each Hydrologic
Region (kWh/AF) ........................................................................................................................ 24
Ta b le 9: Total Electric Energy Intensity of Water Treatment (kWh/AF).......................................... 26
Ta b le 10: Total Electric Energy Intensity of Water Distribution (kWh/AF) ...................................... 27
Ta b le 11: Total Electric Energy Intensity of Wastewater Collection and Treatment (kWh/AF). ........ 28
Ta b le 12: Fraction of Energy Provided by an IOU for Each Water-Supply Component and
Type .......................................................................................................................................... 29
Ta b le 13: Comparison of Embedded Energy Savings for a Water-Efficiency Measure
Targeting
Urban Outdoor
Water Use and Leaks in the Water-Distribution System
(kWh/10,000 gal) ........................................................................................................................ 31
Ta b le 14: Comparison of Embedded Energy Savings for a Water-Efficiency Measure
Targeting
Urban Indoor
Water Use (kWh/10,000 gallons) ......................................................... 32
Ta b le 15: Comparison of Embedded Energy Estimates for a Water-Efficiency Measure
Targeting
Agricultural Outdoor
Water Use (kWh/10,000 gallons) .............................................. 33
Ta b le 16: Embedded Water Energy Intensities ............................................................................ 43
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Executive Summary
Background
Extracting, moving, treating, and using water requires a substantial amount of energy, especially
in California where large amounts of water are moved over long distances and steep terrain. As
a result, saving water through water-efficiency measures also saves energy and can help
investor-owned energy utilities (IOUs) meet energy-efficiency and greenhouse-gas-reduction
goals.
Beginning in 2013, the California Public Utilities Commission (CPUC) engaged Navigant
Consulting, Inc. and GEI Consultants (the Navigant team) to develop a cost-effectiveness
framework for analyzing demand-side programs aimed at saving water and energy, along with a
set of models and calculators to estimate three water-related benefits:
the avoided embedded IOU energy in water,
the avoided capacity cost of water, and
the environmental benefits of reduced water use.
With Decision 15-09-023, the CPUC adopted two tools developed by the Navigant team to
quantify the benefits of water-saving programs: the Avoided Water Capacity Cost Model (also
referred to as the Water Tool) and the Water-Energy Calculator (hereafter referred to as W-E
Calculator 1.0). The Water Tool estimates the avoided capacity cost of water, which is an input
into the W-E Calculator 1.0. The W-E Calculator 1.0 estimates the embedded IOU energy
savings of water-conservation measures, as well as the IOU avoided embedded energy cost.
A year of using the W-E Calculator 1.0 yielded new insights about its utility and function, and
in Decision 16-12-047, the CPUC directed the four major investor-owned utilities (IOUs) to
create a Plan of Action to update the W-E Calculator 1.0. Decision 17-12-010 approved the
unopposed Plan of Action and closed Rulemaking 13-12-011.
Project Goals and Objectives
The CPUC tasked the Pacific Institute and SBW Consulting Team with developing a new,
simpler Water-Energy Calculator (hereafter referred to as W-E Calculator 2.0). In pursuit of this
goal, the Pacific Institute and SBW Consulting Team had three primary objectives:
Engage stakeholders to identify key issues and concerns to inform changes to the W-E
Calculator 1.0,
Update the W-E Calculator 1.0 to create the W-E Calculator 2.0, in accordance with
Decision 17-12-010, the Water Energy Joint Utility Plan of Action, and input received
through stakeholder engagement, and
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Develop readable and accessible documentation for the W-E Calculator 2.0 that can be
easily understood by a nontechnical audience and provide a help desk and recorded training
session.
Key Enhancements for the W-E Calculator 2.0
Key enhancements to the functionality and utility of the W-E Calculator 2.0 were identified
based on a detailed review of the W-E Calculator 1.0 and related documents and interviews
with stakeholders. These are summarized in Table 1.
Ta b le 1: Summary of Key Enhancements for the W-E Ca lculator 2.0
Simplify the calculator
Remove cost-effectiveness calculations
Determine whether to use avoided/marginal water supply when calculating embedded
energy savings
Enhance the calculator functionality
Allow user to easily modify the resource balance year
Allow user to specify terrain to determine distribution energy requirements
Allow user to modify default selections and values for extraction, conveyance, water
treatment, water distribution, and wastewater systems
Allow for inclusion of water efficiency measures for distribution system leaks
Allow user to select trucked water as a marginal water source (if appropriate)
Provide user a mechanism for identifying the hydrologic region associated with a measure
Review model default values and update as needed
Ensure integration with other CPUC tools
Ensure model inputs are consistent with DEER, eTRM, and work papers
Ensure model outputs are consistent with CEDARS report structure
Ensure model outputs are consistent with CET
Expand education and outreach
Develop easy-to-read user's manual
Provide a recorded training session
Conduct presentations to promote opportunities for water-energy partnerships
Wa t e r -Energy Calculator 2.0
The W-E Calculator 2.0 is specifically designed to estimate the investor-owned utility (IOU) and
non-IOU embedded energy savings that result from water-efficiency measures. The embedded
energy savings can be entered directly into the California Energy Data and Reporting System
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(CEDARS) to count those savings toward their energy-efficiency goals and for cost-effectiveness
evaluations using the Cost Effectiveness Tool (CET). We and the CPUC identified a short-term
and long-term solution to expeditiously integrate the embedded energy savings into CEDARS.
Figure 1 illustrates the underlying methodology used in the W-E Calculator 2.0 to estimate
embedded energy savings. Fundamentally, the W-E Calculator 2.0 estimates embedded energy
savings by multiplying the annual water savings of an efficiency measure by the energy intensity
of relevant water-system components. The energy intensities of the water-system components
depend on several factors, including the source of the water saved and its geographic location.
Defaults are provided throughout the model; however, the user can adjust these defaults as
appropriate for the measures evaluated.
This is a simplified version of the underlying conceptual framework for the W-E Calculator. Although not depicted here, the installation
year, measure life, and resource-balance year determine whether the marginal or historical water-supply mix are used to estimate
embedded energy savings. This is described in more detail in sections 3.4 and 3.4.
Figure 1: Conceptual Framework of the W-E Calcula tor 2.0
Comparison of the W-E Calculator 1.0 and 2.0
In this section, we compare the embedded energy savings for a water-efficiency measure, as
estimated using the two versions of the W-E Calculator. In this example, the measure is
installed in 2021 and saves 10,000 gallons of water annually. We used the default values for the
resource balance year (2016), marginal water supply (non-potable recycled water), and water-
system components.
Table 2 provides the IOU embedded energy savings averaged across the state’s ten hydrologic
regions. IOU embedded energy savings for all sectors and water use types are higher with the
W-E Calculator 2.0 than with the W-E Calculator 1.0. Compared to the W-E Calculator 1.0,
IOU embedded energy savings in the W-E Calculator 2.0 are 226% higher for an urban outdoor
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water efficiency measure, 142% higher for an urban indoor water efficiency measure, and 245%
higher for an agricultural outdoor water efficiency measure. Across the three water use types for
the urban and agricultural sectors, the IOU embedded energy savings are 183% higher in the W-
E Calculator 2.0. This is because the W-E Calculator 2.0 uses non-potable recycled water as the
marginal water supply for each hydrologic region, whereas the W-E Calculator 1.0 bases
embedded energy savings on the historical water supply mix for each hydrologic region. The
historical water supply mix is less energy intensive than the marginal water supply in all but the
South Coast region and less reliant on electricity from IOUs across the state.
Ta b le 2: Comparison of IOU Embedded Energy Savings, in kWh, from the W-E Ca lculator 1.0
and 2.0.
Sector Water Use Type
IOU Embedded Energy Savings
(kWh per 10,000 gallons)
Percent Difference
W-E Calculator 1.0 W-E Calculator 2.0
Urban Outdoor 10.06 32.82 226%
Urban Indoor 22.51 54.42 142%
Agriculture Outdoor 8.00 27.60 245%
Average 13.52 38.28 183%
Based on an efficiency measure installed in 2021 that saves 10,000 gallons annually and the default values for the
resource balance year (2016), marginal water supply (non-potable recycled water), and water-system components.
Recommendations
The following recommendations for further improvements to the W-E Calculator 2.0 and its
implementation can help the state to better estimate embedded energy savings and realize the
full potential of water-efficiency measures to reduce statewide energy use and greenhouse-gas
emissions.
Evaluate the default marginal water supply and revise as appropriate.
The W-E Calculator 2.0 follows D.15-09-23 in its use of the long-run marginal water supply to
estimate embedded energy savings. Like its predecessor, it uses non-potable recycled water as
the default marginal water supply for each of the California’s ten hydrologic regions and allows
the user to adjust this default assumption according to local circumstances. New regulations,
along with changing technologies and practices, suggest that reviewing the default marginal
water supply may be warranted. We recommend that the CPUC evaluate whether it is
appropriate to modify the default marginal water supply for each hydrologic region for urban
and agricultural water use.
Evaluate whether to use a resource balance year (RBY), and if so, select an appropriate
year.
Consistent with D.15-09-23, the W-E Calculator 2.0 uses 2016 as the RBY and allows the user
to easily alter this default value. Using 2016 as the RBY recognizes that traditional water
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sources across California are overallocated, and there is pressure to reduce water withdrawals
from these sources by developing new, mostly local, water supplies. As a result, water savings
from water-efficiency measures reduce the need to develop new sources of supply, suggesting
that we are “in marginal territory.” Moreover, there was no immediately available process by
which to revise the RBY, and no new analysis indicating that a different year should be selected.
We recommend that the CPUC evaluate whether to continue using a RBY, or to eliminate it, as
has been done for energy efficiency analyses. If use of a RBY is maintained, we recommend that
the CPUC conduct an evaluation to determine the appropriate year.
Consider updating the Water Tool to include as a non-energy benefit in Total System
Benefit (TSB) analyses and to evaluate whether to incorporate water-related
environmental benefits.
The W-E Calculator 2.0 does not include a cost-effectiveness analysis. Rather, such analyses are
done within the CET. The CET allows including non-energy benefits in TSB analyses, and thus
the avoided cost of adding water capacity could be added to those analyses. While it was
beyond the scope of this work to revise the Water Tool, we recommend that the CPUC consider
updating the Water Tool and its underlying assumptions. We also recommend evaluating
environmental benefits associated with reduce water usage and incorporating them as non-
energy benefits as appropriate.
Review calculator default assumptions every five years and update as needed, consistent
with the frequency of updates for key water-planning documents.
Regularly updating the W-E Calculator 2.0 will help ensure that the default assumptions reflect
current water policies and practices. Ultimately, this will improve the accuracy of assessments of
embedded energy savings. We recommend reviewing the default assumptions every five years
and updating them as needed. This is consistent with the frequency of updates for key water-
planning documents.
Implement the long-term solution identified for integrating embedded energy savings
into CET analyses.
The stakeholder interviews identified two key issues: (1) cost-effectiveness analyses did not
include embedded energy savings, and (2) IOUs were unable to claim credit for these savings
toward their energy efficiency goals. While revising the water-energy calculator, we worked
closely with CPUC to develop a short-term and long-term solution for integrating embedded
energy savings into CET analyses. The short-term solution will be available immediately to
PAs. However, the long-term solution will require changes to the structure and calculations
within the CET, as identified in Appendix B. We recommend that the CPUC implement the
long-term solution for integrating embedded energy savings into CET analyses as soon as is
practicable so that PAs and CPUC can better determine the role of embedded energy savings in
meeting energy-efficiency goals and promote greater investment in cost-effective water-
efficiency measures that save energy.
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Expand partnerships between energy PAs and water utilities to realize greater water and
energy savings and help the state to meet its water, energy, and greenhouse-gas goals.
Spang et al. (2018) found that water efficiency can achieve significant electricity and
greenhouse-gas (GHG) savings at costs competitive with existing energy-efficiency programs.
This suggests that partnerships between energy PAs and water utilities could benefit ratepayers
and also help the state realize water, energy, and greenhouse-gas goals. This is especially
important as the state faces another severe drought and climate impacts are intensifying. We
recommend that the CPUC proactively expand partnerships between energy PAs and water
utilities across California. Additionally, we recommend that the CPUC facilitate partnerships
explicitly between water and energy IOUs, both of which are regulated by the CPUC.
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1 Introduction
1.1 Wa t e r -Energy Nexus
Extracting, moving, treating, and using water requires a substantial amount of energy, especially
in California where large amounts of water are moved over long distances and steep terrain. In a
landmark 2005 study, the California Energy Commission (CEC) found that water accounted for
nearly 20% of California’s electricity consumption and one-third of its non-power-plant natural-
gas consumption.
1
Water-related energy is often divided into two categories:
Direct energy, sometimes referred to as end-use energy, is the energy used on the customer
side of the meter by, for example, reducing on-site pumping and hot-water usage.
Embedded energy is the energy used to extract, convey, treat, and distribute water to end
users, and energy used to collect and transport wastewater for treatment prior to safe
discharge of the effluent in accordance with regulations.
As a result, water-efficiency measures also save energy and can help investor-owned energy
utilities (IOUs) meet energy-efficiency and greenhouse-gas-reduction goals. Energy utilities in
California often refer to water-efficiency measures as Water-Energy Nexus (WEN) measures.
These measures can be implemented in residential, commercial, industrial, and agricultural
settings and include, for example, low-flow showerheads, efficient clothes washers, high-
efficiency toilets, weather-based irrigation controllers, turf removal, drip irrigation, and dry-
vacuum pumps.
As with energy use, water-related energy savings that occur on the customer side of the meter
are referred to as “direct energy savings,” and those energy savings that occur upstream and
downstream of the customer are referred to as “embedded energy savings.”
1.2 Wa t e r -Energy Proceedings
Water-related energy use in California has been of interest to the California Public Utilities
Commission (CPUC) since the mid-2000s. In 2005 and again in 2010, the CPUC’s Water
Action Plan emphasized the importance of water and energy efficiency. In Decision 07-12-050,
the CPUC authorized three “embedded energy in water studies” and numerous pilot projects to
study the savings potential of programs targeting embedded energy in water.
With Decision 12-05-015, the CPUC directed staff to develop a robust record of strategies to
overcome barriers to the adoption and deployment of programs aimed at improving water-
energy-nexus efficiency, including methods for calculating the energy savings and cost-
1
California Energy Commission, November 2005, “California’s Water-Energy Relationship,” Final Staff Report
CEC700-2005-011-SF.
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effectiveness of water-efficiency measures, issues associated with the joint funding and
implementation of water-energy programs, and the development of an updated water-energy
cost-effectiveness calculator. In response to this directive, staff created a workplan to address
water-energy-nexus issues. They also presented a proposed cost-effectiveness framework that
would help evaluate water-energy-efficiency projects and programs. Finally, staff formed a
Project Coordination Group for Water Energy Cost-Effectiveness (PCG) to allow industry
stakeholders to provide input and assistance on a framework to analyze water-energy programs.
A petition from the Division of Ratepayer Advocates prompted the CPUC to open Rulemaking
13-12-011. The purpose of this rulemaking was to explore how best to “develop more robust
methodologies for measuring the embedded energy savings from energy efficiency and
conservation measures in the water sector, and for determining the cost-effectiveness of these
projects.”
2
This would inform whether and how such programs should be cofunded by the
energy IOUs and the water sector—both privately owned water utilities regulated by the CPUC
and public water and wastewater agencies—as well as how program costs should be allocated.
Beginning in 2013, the CPUC engaged Navigant Consulting, Inc. and GEI Consultants (the
Navigant team) to develop a cost-effectiveness framework for analyzing demand-side programs
aimed at saving water and energy. Through this effort, the Navigant team developed a set of
models and calculators for estimating three water-related benefits:
the avoided embedded IOU energy in water,
the avoided capacity cost of water, and
the environmental benefits of reduced water use.
With Decision 15-09-023, the CPUC adopted two tools to quantify the benefits of water-saving
programs: the Avoided Water Capacity Cost Model (also referred to as the Water Tool) and the
Water-Energy Calculator (hereafter referred to as W-E Calculator 1.0). The Water Tool
estimates the avoided capacity cost of water, which is an input into the W-E Calculator 1.0. The
W-E Calculator 1.0 estimates the embedded IOU energy savings of water-conservation
measures, as well as the IOU avoided embedded energy cost.
A year of using the W-E Calculator 1.0 yielded new insights about its utility and function, and
in Decision 16-12-047, the CPUC directed the four major investor-owned utilities (IOUs)—
Southern California Edison Company (SCE), San Diego Gas & Electric Company (SDG&E),
Southern California Gas Company (SoCal Gas), and Pacific Gas and Electric Company
(PG&E) (collectively referred to as the Joint IOUs)—to create a Plan of Action to update the
W-E Calculator 1.0 and to file it with the CPUC. Specifically, the Plan of Action was to address
how best to:
“(a) create, and incorporate into the Water-Energy Calculator, a greenhouse gas emissions
reductions value for water-energy nexus energy efficiency measures; (b) connect the Water-
Energy Calculator with the commonly-used E3 energy efficiency program calculator and the
2
D.13-12-11 at 2.
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Database for Energy Efficient Resources; (c) within 6 months of the completion of Southern
California Gas Company’s natural gas study, incorporate into the Water-Energy Calculator
a value representing the natural gas embedded in the water system.”
3
The Plan of Action submitted by the Joint IOUs in August 2017 described the options for
addressing each issue identified in Decision 16-12-047, as well as next steps required to
implement the recommended changes. The CPUC’s Energy Division previously met with
representatives of the Joint IOUs in January 2017 to discuss the Energy Division’s
“Recommendations for Water Energy Calculator Update,” and these recommendations were
incorporated into the Plan of Action. Decision 17-12-010 approved the unopposed Plan of
Action and closed Rulemaking 13-12-011.
1.3 Project Goals and Objectives
The Pacific Institute and SBW Consulting Team was asked to develop a new, simpler Water-
Energy Calculator (hereafter referred to as W-E Calculator 2.0). In pursuit of this goal, we had
three primary objectives:
Engage stakeholders to identify key issues and concerns to inform changes to the W-E
Calculator 1.0,
Update the W-E Calculator 1.0 to create the W-E Calculator 2.0, in accordance with
Decision 17-12-010, the Water Energy Joint Utility Plan of Action, and input received
through stakeholder engagement, and
Develop readable and accessible documentation for the W-E Calculator 2.0 that can be
easily understood by a nontechnical audience and provide a help desk and recorded training
session.
1.4 Structure of the Report
The remainder of this report describes the methodology and supporting documentation for the
W-E Calculator 2.0. Section 2 summarizes the key enhancements identified by reviewing the
W-E Calculator 1.0 and related documents and interviewing stakeholder. Section 3 describes the
underlying methodology for the W-E Calculator 2.0, as well as basic elements of that
methodology. Section 4 compares the outputs of the W-E Calculator 2.0 with those of its
predecessor. Section 5 offers recommendations for next steps. The Appendices provide
stakeholder interview questions, the short- and long-term solutions for integrating embedded
energy savings into the California Energy Data and Reporting System (CEDARS), and the W-E
Calculator 2.0 user manual.
3
D.16-12-047 at 50.
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2 Key Enhancements for the W-E Ca lcula tor 2.0
This section summarizes the key enhancements identified to improve the functionality and
utility of the W-E Calculator 2.0 based on a detailed review of the W-E Calculator 1.0 and
related documents prepared by and/or submitted to the CPUC and interviews with
stakeholders.
2.1 Document Review
We compiled a list of documents to review related to the development and use of the W-E
Calculator 1.0 and submitted this list to CPUC Energy Division staff for review for additional
suggestions. Table 3 lists all the documents reviewed to identify opportunities to improve the
utility and functionality of the calculator.
Ta b le 3: Documents Reviewed for the W-E Calculator Updates
Author(s) (Organization) Da t e Tit le
CPUC 2013 Rulemaking R.13-12-011
Morgenstern &
Younghein (CPUC)
3/21/2013 Energy Division Staff Proposal for a Water/Energy Cost-Effectiveness
Framework
McDonald et al.
(Navigant)
10/7/2014 Water/Energy Cost-Effectiveness Analysis, Final Report
Commissioner Sandoval
(CPUC)
4/27/2015 Order Instituting Rulemaking into Policies to Promote a Partnership
Framework between Energy Investor-Owned Utilities and Water Sector
to Promote Water-Energy Nexus Programs; Rulemaking 13-12-011,
Assigned commissioner's amended scoping memorandum and ruling
CPUC, Navigant, GEI
Consulting Engineers
and Scientists
9/1/2015 Avoided Water Capacity Cost Model, Draft V1.04
CPUC 9/25/2015 Decision 15-09-023 September 17, 2015, Before the Public Utilities
Commission of the State of California, Rulemaking 13-12-011
CPUC 2/1/2016 Water-Energy Calculator Draft: Version 1.05
Jill Kjellsson (PG&E) 4/6/2016 W-E Calculator 2.0 Workshop: Experience Implementing the W-E
Calculator
Athena Besa (SDG&E)
and Carlo Gavina (SCG)
4/6/2016 Water Energy Nexus Calculator 2.0 Workshop
Elise Torres (TURN) 4/6/2016 R. 13-12-011: Track 3 Water Energy Nexus Calculator 2.0 Workshop
Water Energy
Innovations, Inc. and
RMS Energy Consulting,
LLC
4/17/2017 Implementation of the California Public Utilities Commission's Water-
Energy Calculator: Issues and Opportunities
RMS Energy Consulting,
LLC
4/18/2017 WEN Calculator Usage Reconsideration
San Diego Gas &
Electric
4/21/2017 Work Paper WPSDGEWEN001 Revision 0, Water Energy Nexus
Measures
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Author(s) (Organization) Da t e Tit le
Water Energy
Innovations, Inc.
7/5/17 Natural Gas Intensity of Water
CPUC 8/14/2017 Water Energy Nexus Cost Calculator Plan of Action
CPUC 12/14/2017 Decision 17-12-010
The Climate Registry 6/1/2019 Water-Energy GHG Metrics Guidance for Water Managers in Southern
California, V2.0
Documents are listed in chronological order.
2.2 Interviews
We interviewed 22 stakeholders, including representatives from energy IOUs, water-energy
experts, and CPUC staff and consultants between April and July 2020 (listed in Table 4). The
interviews focused on identifying issues with the W-E Calculator 1.0 and, more broadly, with
implementing water-energy-nexus measures. CPUC staff reviewed the interview questions,
which are provided in Appendix A. We altered some questions slightly based on the
stakeholder’s area of interest and expertise. We sent the questions to all interviewees in advance
of the call. We conducted the interviews by phone and videoconference, and each lasted
approximately one hour.
Ta b le 4: List of Representatives and Organizations Interviewed
Name Organization/Company
Amy Reardon California Public Utilities Commission
Peter Biermayer California Public Utilities Commission
Eric Merkt Consultant
Bob Ramirez DNV GL
Kerri-Ann Richard DNV GL (formerly Energy & Resource Solutions)
Amul Sathe Guidehouse (formerly Navigant Consulting, Inc.)
Kristin Landry Guidehouse (formerly Navigant Consulting, Inc.)
Scott Fable Pacific Gas and Electric
Mary Anderson Pacific Gas and Electric
Martin Vu RMS Energy Consulting, LLC
Angela Crowley RMS Energy Consulting, LLC
Athena Besa San Diego Gas and Electric
Sandra Williams San Diego Gas and Electric
Jennifer Scheuerell Sound Data Management, LLC
Ryan Bullard Southern California Edison
Brandon Sanders Southern California Edison
Erin Brooks Southern California Gas Company
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Name Organization/Company
Paul Deang Southern California Gas Company
Carlo Gavina Southern California Gas Company
Chelsea Hasenauer
The Climate Registry
Kendra Olmos UC Davis, Center for Water-Energy Efficiency
Laurie Park Water Energy Innovations, Inc.
2.3 Summary of Findings
The documents reviewed and the interviews provided key insights on implementing water-
energy programs and use of the W-E Calculator 1.0. We found that energy IOUs’ water-energy-
efficiency programs were primarily focused on hot-water savings. Energy IOUs were partnering
with water utilities for some of these programs, including those for hot-water measures and for
custom programs at the water utilities’ facilities. The programs selected were largely limited to
those measures described in work papers. Energy-efficiency programs were shifting toward
third-party implementation, and the impact of this shift on water-energy programs was not
known.
Further, we found that energy IOUs were using the W-E Calculator 1.0 to estimate the
embedded energy savings from their water-energy-nexus programs. Some were also using it to
evaluate potential savings from proposed standards and codes. While embedded energy savings
are reported to the CPUC for informational purposes, these savings are not currently being
credited toward IOU efficiency goals. Additionally, the embedded energy savings are not
integrated into evaluations of measure cost effectiveness because the Cost-Effectiveness Tool
(CET) is not currently designed to receive those inputs.
Finally, the documents reviewed and the interviews identified several opportunities for
improving the utility and function of the calculator. These are described in more detail in
sections 2.3.1 and 2.3.4. Table 5 summarizes the key enhancements for the W-E Calculator 2.0
based on the opportunities identified.
Ta b le 5: Summary of Key Enhancements for the W-E Ca lculator 2.0
Simplify the calculator
Remove cost-effectiveness calculations
Determine whether to use avoided/marginal water supply when calculating embedded
energy savings
Enhance the calculator functionality
Allow user to easily modify the resource balance year
Allow user to specify terrain to determine distribution energy requirements
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Allow user to modify default selections and values for extraction, conveyance, water
treatment, water distribution, and wastewater systems
Allow for inclusion of water efficiency measures for distribution system leaks
Allow user to select trucked water as a marginal water source (if appropriate)
Provide user a mechanism for identifying the hydrologic region associated with a measure
Review model default values and update as needed
Ensure integration with other CPUC tools
Ensure model inputs are consistent with DEER, eTRM, and work papers
Ensure model outputs are consistent with CEDARS report structure
Ensure model outputs are consistent with CET
Expand education and outreach
Develop easy-to-read user's manual
Provide a recorded training session
Conduct presentations to promote opportunities for water-energy partnerships
2.3.1 W-E Calcula tor 1.0 Errors
Both the interviews and literature review uncovered several errors in the W-E Calculator 1.0,
including a few issues with the default selections and values for various water-system
components. For example, while Decision 15-09-023 specified that users can change default
selections for various water-system components, the W-E Calculator 1.0 only allowed the user
to change the default selection for water supply but not for water treatment, distribution, or
wastewater collection and treatment. Likewise, the W-E Calculator 1.0 erroneously assumes
that the embedded energy requirements for the distribution of non-potable recycled water are
the same as those for potable water.
Other errors related to implementing key features. For example, while there was a placeholder
for entering natural-gas energy intensity of all water-system components, the calculator did not
use those values when calculating embedded energy savings or avoided embedded energy cost.
Likewise, the urban-runoff function of the model allowed the user to account for embedded
energy attributable to capturing and treating runoff from outdoor irrigation in combined sewers.
However, this function overestimated embedded energy savings because it assumed that all the
water saved (rather than some fraction of it) would have gone to the sewer system and been
treated to secondary standards. Finally, several issues related to the resource balance year,
suggesting that the calculator did not appropriately integrate marginal supply into calculations
of embedded energy savings.
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2.3.2 Calculator Functionality
The W-E Calculator 1.0 is an Excel-based tool that most users found easy to use. The most
common feedback from the interviews was that outputs should be consistent with inputs needed
for other CPUC tools, including the CET and CEDARS. Additionally, several components of
the W-E Calculator 1.0 could be removed to provide a more streamlined calculator. For
example, the Plan of Action and Decision 17-12-010 recommended that greenhouse-gas
emissions not be included because they are already integrated into other models. Likewise,
some interviewees suggested that avoided water and wastewater-utility cost and the water-
related environmental benefits could be removed because they do not use these components
regularly and do not need them for advancing water-energy-efficiency programs. Others,
however, suggested that avoided water-capacity cost and environmental benefits could be
captured as non-energy benefits in other CPUC tools.
The literature review and interviews identified several components that could be added or
improved to enhance the functionality of the calculator. The opinions of stakeholders varied on
the potential addition of default natural-gas values. While this feature would increase the model
functionality, it would not likely be used because natural-gas use by water and wastewater
systems is small and declining. Finally, interviewees identified several other features that could
improve the model functionality, such as:
providing simple menus for users to select water-system components, energy-intensity
values, resource balance year, and terrain,
providing an energy intensity value for trucked water,
adding a GIS overlay of IOU service territories and hydrologic regions, and
adding a water-use designation that captures water savings opportunities from reducing
leaks in the water distribution system.
2.3.3 CPUC Policies and Procedures
The interviews and literature review revealed where additional clarity and guidance are needed
on CPUC policies and procedures. For example, there was some confusion about whether
embedded energy savings can be credited toward energy-efficiency goals. Some were also
unclear whether and what type of justification was needed to depart from the default selections
(e.g., changing the marginal supply from non-potable recycled water to imported water) or from
the default values (e.g., changing the energy intensity for treatment of non-potable recycled
water from 607 to 800 kWh per acre-foot). Finally, there were several technical questions about
how to handle areas that fall into multiple hydrologic regions or how to select an appropriate
resource balance year.
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2.3.4 Education and Outreach
The interviews identified the need for a comprehensive user manual and additional user support
for the calculator. Because the calculator is designed for energy IOUs and their Program
Administrators (PAs), several stakeholders noted that the user manual should be written for an
audience that may not be familiar with water terminology. Though the tool was primarily
designed for energy IOUs and PAs, using it to further partnerships with water suppliers might
be possible.
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3 Wa t e r -Energy Calculator 2.0
The W-E Calculator 2.0 estimates the investor-owned utility (IOU) and non-IOU embedded
energy savings that result from water-efficiency measures. Compared to the previous version,
the W-E Calculator 2.0 is simpler and focuses on embedded energy savings—calculations of the
avoided embedded energy cost, the avoided water-capacity cost, and all cost-effectiveness
functionalities have been removed. The W-E Calculator 2.0 provides an estimate of the
embedded energy savings (in kWh), which can be entered directly into the California Energy
Data and Reporting System (CEDARS) for cost-effectiveness evaluations using the Cost
Effectiveness Tool (CET).
3.1 General Approach
Fundamentally, the W-E Calculator 2.0 estimates embedded energy savings by multiplying the
annual water savings of an efficiency measure by the energy intensity of relevant water-system
components. The energy intensities of the water-system components depend on several factors,
including the source of the water saved and its geographic location. The calculator provides
many default inputs, which the user can adjust as appropriate for the measures evaluated.
Figure 2 illustrates the underlying methodology used in the W-E Calculator 2.0. Calculating
embedded energy savings follows these four steps:
The user enters basic information about the measure(s) being evaluated. This includes the
installation year, annual water savings per device, number of devices installed, measure
application, measure life, and the zip code where the measure was installed. The zip code
determines the hydrologic region for the analysis.
Based on the hydrologic region, the calculator provides a default marginal water supply that
represents the source of the water saved,
4
which the user can adjust as needed. The water
supply selected, combined with the measure application,
5
determine the water-system
components
6
included in the analysis.
Based on the hydrologic region and marginal supply, the calculator provides default energy-
intensity values (in kilowatt-hours per acre-foot) for each water-system component included
in the analysis. The calculator also provides default values for the percent of the energy
provided by an IOU. The user can adjust default values as appropriate for the measures
included in the analysis. However, per D.15-09-023, when PAs use non-default values, they
must prove that those values are reasonable in all documents submitted to CPUC.
4
As described in section 3.4.1, a default marginal supply of non-potable recycled water, i.e., wastewater treated to
tertiary, unrestricted standards, is assumed for all hydrologic regions in California.
5
The measure application indicates whether the measure is applied in an urban or agricultural setting and whether it
reduces indoor water use, outdoor water use, or losses in the water distribution system.
6
Water-system components include water extraction and conveyance, water treatment, water distribution, wastewater
collection, and wastewater treatment.
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The calculator estimates the total embedded energy savings (including IOU and non-IOU
energy, in kWh) by multiplying annual water savings by the sum of the energy-intensity
values of the water-system components. It then estimates IOU embedded energy savings by
multiplying the annual water savings by the sum of the product of the water-system-
component energy-intensity value and the fraction of IOU energy for each component.
Subtracting IOU embedded energy savings from the total embedded energy savings yields
the non-IOU portion of embedded energy savings.
This is a simplified version of the underlying conceptual framework for the W-E Calculator. Although not depicted here, the installation
year, measure life, and resource-balance year determine whether the marginal or historical water-supply mix are used to estimate
embedded energy savings. This is described in more detail in sections 3.4 and 3.4.
Figure 2: Conceptual Framework of the W-E Ca lculator 2.0
3.2 Relationship with Other CPUC Tools
The W-E Calculator 2.0 allows PAs to estimate embedded energy savings associated with
water-efficiency measures. Integrating embedded energy savings into CEDARS allows the PAs
to count those savings toward their energy-efficiency goals and to incorporate them into cost-
effectiveness evaluations. Integrating the embedded energy savings expeditiously, however,
requires a short-term and a long-term solution, which we summarize here. Appendix B contains
additional detail on these approaches.
Figure 3 shows the short-term solution for integrating embedded energy savings into CEDARS.
Here, the W-E Calculator 2.0 was run using default assumptions to estimate embedded energy
intensities (in units of kWh per 1,000 gallons, or kWh/kgal). Dividing the number of gallons
saved by a measure by 1,000 (to put the water savings in kgal) and multiplying the result by the
embedded energy intensity yields the embedded energy savings. The eTRM automatically adds
the embedded energy savings to the direct energy savings of the measure (per D.17-12-010). By
entering the combined value, along with other site-specific savings values, into the CET, it can
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calculate the measure’s cost-effectiveness. PAs can also use the combined value when
submitting a claim for this measure. This approach is only suitable for measures that use the
default marginal water supply, i.e., recycled non-potable water. Only under the long-term
solution can PAs claim measures that use a non-default marginal supply, so they must wait until
that solution is implemented. Additionally, per D.15-09-023, where PAs depart from default
values, they must show that the departure is reasonable in all documents submitted to the
CPUC.
Figure 3: Short-term Relationship Between the W-E Ca lc u la t o r 2 . 0 , e TRM, CEDARS , a n d CET
Figure 4 shows the long-term solution for integrating embedded energy savings into CEDARS.
Here, PAs will use the new CET functionality to enter the direct energy savings and IOU
embedded energy savings separately into the CET through CEDARS. The direct energy savings
will be calculated using the measure-package methodology. The IOU embedded-water-energy
savings will be calculated following the same methodology as used in the short-term solution,
but this value will be stored independently within the eTRM and CEDARS to facilitate
reporting and cost-effectiveness calculations. The PA will still receive the same credit for both
the direct and embedded energy savings as they received using the short-term solution, but for
accounting purposes the two types of savings will be entered into the CET and claims
separately. Once finalized by the CPUC, this will replace the short-term solution.
Figure 4: Lo n g -term Relationship Between the W-E Ca lc u la t o r 2 . 0 , e TRM, CEDARS , a n d CET
For example, assume low-flow showerheads were installed in a hotel in San Francisco,
consistent with the deemed measure “Low-flow Showerhead – Commercial” (SWWH020). The
measure’s permutations in the eTRM indicate that the annual water savings are 2,979 gallons
per showerhead. The water savings, along with the measure life, can be entered into the W-E
Calculator 2.0. The default water supply and energy intensity for the SF Bay hydrologic region
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produce an estimated annual IOU embedded energy savings of 16.2 kWh per showerhead. The
embedded energy savings can then be entered into CEDARS alongside the claimed direct
energy savings to get the total water-related energy savings. CEDARS then interfaces with the
CET to determine the measure’s cost effectiveness.
Previously, PAs have been required to report water savings on CEDARS. As a policy matter,
PAs were also able to claim savings towards their energy efficiency goals on WEN measures
using W-E Calculator 1.0. However, there was confusion about whether and how to do this, as
the CPUC had not created a clear mechanism to serve that function.
3.3 Regional Analysis
The available water supplies and their associated energy intensities vary across California. To
account for this variability, the W-E Calculator 2.0 operates at a regional level, using the ten
hydrologic regions of the California Department of Water Resources (DWR). These ten
hydrologic regions (Figure 5) generally correspond to the state’s major water-drainage basins:
North Coast (NC), North Lahontan (NL), Sacramento River (SR), San Francisco Bay (SF),
Central Coast (CC), San Joaquin River (SJ), Tulare Lake (TL), South Coast (SC), South
Lahontan (SL), and Colorado River (CR). This is consistent with the approach taken in the
W-E Calculator 1.0, as well as CPUC Decision D.15-09-23.
7
Source: https://indicators.ucdavis.edu/water/regions
Figure 5: California’s Ten Hydrologic Regions
7
Decision (D.) 15-09-23, at 28.
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The W-E Calculator 2.0 uses zip code as the common locator, consistent with how energy-
efficiency measures are assigned to climate zones within cost-effectiveness evaluations. We
conducted an analysis in GIS to assign each zip code to a hydrologic region. Where a zip code
straddled two or more hydrologic regions, we followed a “majority rules” approach, assigning
the zip code to the hydrologic region that contained the largest area of the zip code. This
approach is consistent with how evaluators assign energy-efficiency measures to climate zones
and reduces the complexity within the eTRM for deemed measures. The W-E Calculator 2.0
automatically selects the hydrologic region based on the user-entered installation zip code.
3.4 Marginal Water Supply and Historical Water Supply
Mi x
3.4.1 Marginal Water Supply
The marginal water supply represents the next unit of water supply that would need to be
developed within a region to meet demand in the absence of water conservation and efficiency.
When developing the W-E Calculator 1.0, the Navigant team consulted publicly available
documents, including state and regional planning studies, and consulted with experts and
stakeholders to identify the long-run marginal supply in each of California’s ten hydrologic
regions. Based on this consultation, the Navigant team identified a proxy marginal supply of
non-potable recycled water, i.e., wastewater treated to tertiary, unrestricted standards, for all
hydrologic regions in California. According to McDonald et al. (2014):
“Using recycled wastewater as the default proxy marginal supply is reasonable for several
reasons. All regions currently are developing and have available recycled water supplies.
Although the predominant use of these supplies currently is irrigation, these supplies are
approved for numerous other uses. Many utilities include recycled wastewater as a key
element of their future supply portfolios. Recycled water is a more conservative supply
option than ocean water, which addresses concerns raised by some stakeholders who
question the availability of treated ocean supplies to more inland coastal agencies. Lastly,
recycling of wastewater is consistent with the SWRCB goals, which encourage water
agencies to significantly increase development and use of these supplies.
When recycled water is used for non-potable end uses, it can displace potable or raw water
that was previously serving that end use. The displaced potable water can be used to increase
supply available to potable end uses; the displaced raw water could be treated further for
potable uses. Thus, developing a recycled water supply can still increase the amount of
supply available for potable end uses.”
CPUC D.15-09-23 supported use of the long-run marginal supply in the W-E Calculator 1.0.
The decision stated that “It is the margin—the next water resource we do not have to develop or
procure—that matters, and so the W-E calculator correctly considers costs for the marginal
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supply (e.g., recycled water) rather than average supply.”
8
D.15-09-23 further notes that while
users can override the default marginal supply to reflect local circumstances, they should
continue to use values for a marginal supply rather than for historical or existing supplies.
9
Additionally, D.15-09-023 supports the calculator’s use of the long-run marginal supply, rather
than the short-run marginal supply, for several reasons. “The first is that data on short-run
supplies remain hard to come by. The second is that imports continue to involve much energy
that is not from jurisdictional energy companies. A third is that short-run supply options can
vary enormously in cost from period to period, and from place to place.”
10
The W-E Calculator 2.0 follows D.15-09-23 in its use of the long-run marginal water supply to
estimate embedded energy savings. Like its predecessor, the W-E Calculator 2.0 uses non-
potable recycled water as the default marginal water supply for each of the ten hydrologic
regions and allows the user to adjust the default according to local circumstances. As described
in section 3.6.2 and 3.6.3, the energy intensities of water treatment and of distribution for non-
potable recycled water does not vary regionally and a single value is used for each of the state’s
ten hydrologic region.
3.4.2 His torical Water Supply Mix
To plan for and manage water supplies over time, water suppliers evaluate their available
supplies using a portfolio approach. The water-supply portfolio for the state varies across time
and space, and each hydrologic region has a unique mix of water supplies available, ranging
from imported water sources like the Colorado River to more local sources like groundwater.
While the type of water supplies available within a hydrologic region is subject to little
interannual availability, the
amount
of water available from each supply often changes from
year to year due to weather and other factors. Table 6 provides a short description of the various
water supply options in California.
Ta b le 6: Description of Water Supplies Options in California
Water Supply De scription
Brackish Water
Water with a salinity ranging from 0.5 to 30 parts per thousand
(ppt), which exceeds normally acceptable standards for municipal,
domestic, and irrigation uses but is less than that of ocean water.
Central Valley Project and
Other Federal Deliveries
The delivery of water to Central Valley Project contractors and to
other federal water projects.
Colorado River
Water diverted from the Colorado River by the Metropolitan
Water District of Southern California.
8
Decision (D.) 15-09-23, at 23.
9
Decision (D.) 15-09-23, at 24.
10
Decision (D.) 15-09-23, at 25.
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Water Supply De scription
Groundwater
Water beneath the Earth’s surface in soil pore space and in the
fractures of rock formations.
Local Surface Water
Water delivered by local water agencies and individuals. It includes
direct deliveries of water from stream flows, as well as local water
storage facilities.
Local Imported Water
Water transferred by local agencies from other regions of the state.
Recycled Water (Non-Potable)
Municipal wastewater that is treated to meet a non-potable
beneficial use.
Recycled Water (Potable)
Municipal wastewater that is treated to meet a potable beneficial
use.
Seawater
Water from the ocean, typically with a salinity between 33 and 37
parts per thousand (ppt)
State Water Project
A collection of canals, pipelines, reservoirs, and hydroelectric
power facilities that extends more than 700 miles and is managed
by the California Department of Water Resources.
As described in section 3.45, if a measure is installed before the resource balance year (RBY),
the W-E Calculator 2.0 uses the historical water-supply mix for each hydrologic region to
estimate the “historical” embedded energy savings. Table 7 shows the historical water-supply
mix for each hydrologic region based on water-balance data from the California Department of
Water Resources’ 2018 Water Plan Update for the ten-year period preceding the Resource
Balance Year of 2016, i.e., 2006 to 2015. The DWR data, however, does not differentiate
between potable and non-potable recycled water. We used data reported in the 2015 Urban
Water Management Plans to differentiate between these types of recycled water
Ta b le 7: Wa t e r -Supply Mix, 2006-2015, by Hydrologic Region.
Wa t e r -Supply Type NC SF CC SC SR SJ TL NL SL CR
Seawater 0.0% 0.1% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%
Brackish Water 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%
Recycled Water (Non-Potable) 0.0% 2.9% 0.47% 4.14% 0.0% 0.0% 0.0% 0.0% 0.1% 0.3%
Recycled Water (Potable) 0.0% 0.0% 0.03% 0.36% 0.0% 0.0% 0.0% 0.0% 0.0% 0.0%
Groundwater 2.1% 20.3% 88.5% 36.9% 21.6% 42.1% 62.8% 23.6% 70.6% 7.8%
Local Surface Water 96.4% 21.1% 2.2% 4.5% 54.3% 41.1% 16.9% 76.4% 15.9% 0.1%
Local Imported Water 0.1% 35.7% 0.0% 4.4% 0.3% 0.1% 0.0% 0.0% 0.0% 0.0%
Colorado River 0.0% 0.0% 0.0% 26.5% 0.0% 0.0% 0.0% 0.0% 0.0% 89.6%
Central Valley Project and
Other Federal Deliveries
1.4% 11.6% 7.0% 0.0% 23.6% 16.4% 12.9% 0.0% 0.0% 0.0%
State Water Project 0.0% 8.4% 1.8% 23.2% 0.2% 0.3% 7.4% 0.0% 13.4% 2.2%
Total 100% 100% 100% 100% 100% 100% 100% 100% 100% 100%
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Note: NC = North Coast, SF = San Francisco Bay, CC = Central Coast, SC = South Coast, SR = Sacramento River, SJ =
San Joaquin, TL = Tulare Lake, NL = North Lahontan, SL = South Lahontan, CR = Colorado River
Data Source: Based on data from DWR 2018 and Table 6.4 of DWR 2015.
3.5 Resource Balance Year
The RBY is the year in which new capacity will be required to meet water demand. Consistent
with both D.15-09-023 and the Water-Energy Calculator 1.0, the W-E Calculator 2.0 uses 2016
as the default RBY.
11
Using 2016 as the RBY recognizes that traditional surface water and
groundwater sources across California are overallocated, and there is no excess capacity within
these systems. Rather, there is tremendous pressure to reduce water withdrawals from existing
surface water and groundwater sources by developing new, mostly local, water supplies. As a
result, water savings from water-efficiency measures reduce the need to develop new sources of
supply, suggesting that we are “in marginal territory.” Moreover, there is currently no process to
revise the RBY, and no new analysis indicates that a different year should be selected.
According to D.15-09-23, however, the user can select a different RBY “to account for a
particular water supplier’s planning, resource, and other needs.”
12
Accordingly, the W-E
Calculator 2.0 lets the user override the default RBY and select a year up through 2050.
Within the W-E Calculator 2.0, the RBY determines whether the embedded energy savings are
based on the marginal water supply or the historical water-supply mix. Prior to the RBY, the
calculator uses the historical water-supply mix to calculate a “historical” embedded energy
savings. In the RBY and beyond, the calculator uses the marginal water supply to calculate a
“marginal” embedded energy savings. If some of the water savings from a water-efficiency
measure occur both before and after the RBY, the calculator uses the historical embedded
energy savings for the years preceding the RBY and the marginal embedded energy savings for
the RBY and subsequent years. Summing the annual embedded energy savings and dividing by
the measure life yields an annualized embedded energy savings.
3.6 Energy Intensity of Water-System Components
The W-E Calculator 2.0 estimates embedded energy savings and does
not
include direct energy
savings, which are accounted for in other CPUC tools. Within the calculator, embedded energy
is divided into five major water-system components:
Water extraction and conveyance
Water treatment
Water distribution
Wastewater collection
11
Decision (D.) 15-09-23, at 27.
12
Decision (D.) 15-09-23, at 27.
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Wastewater treatment
We developed energy intensity values for each water-system component after reviewing the
literature comprehensively. We identified 12 studies with energy intensity estimates relevant for
California water systems. If a study contained a single energy intensity value, we used that value
for the study. If a study contained more than one energy intensity value, we calculated an
average value for the study. If we found multiple studies for a water-system component, the
default energy intensity estimate was averaged across the studies. If sufficient data was available
and the energy intensity value varied by region, we provided default energy intensity values for
each hydrologic region. Otherwise, we provided a single statewide default energy intensity
value. We describe the major water-system component categories and data sources for the
default energy intensity values in more detail below.
3.6.1 Water Extraction and Conveyance
Water extraction and conveyance refer to the transport of untreated or partially treated water
from its source through aqueducts, canals, and pipelines to a water-treatment facility, or directly
to an end user that uses untreated water. The energy required to extract and convey depends on
the distance and net elevation it has to travel and the efficiency of the pumping system.
Table 8 provides the default energy intensity values for extraction and conveyance of each water
supply and hydrologic region. Based on Wilkinson (2007), we estimate that the energy required
to pump seawater from the ocean to the desalination facility is 197 kWh per acre-foot. The
energy intensity of extraction and conveyance for groundwater are based on values for each
hydrologic region reported in Klein (2005), GEI Consultants/Navigant (2010a and 2010b),
Plappally (2012), and Liu et al. (2017).
We provide default energy intensity values for the state’s major interbasin water transfers,
including the State Water Project, Central Valley Project, and Colorado River Aqueduct; local
imported water; and local surface water. For interbasin water transfers, we use the energy
intensity values for the furthest delivery point within a given hydrologic region. If there are
multiple branches of a project within the same region, we calculate a volume-weighted average
energy intensity across the delivery points in the region. In addition, we compute a net value of
energy required by subtracting the average hydropower generation per unit of water volume on
any conveyance project from the energy intensity. We drew the default energy intensity values
for interbasin water transfers, local imports, and local surface water from EPRI (2002), Klein
(2005), GEI Consultants/Navigant (2010a and 2010b), Cooley et al. (2012), Tarroja et al.
(2014), Liu et al. (2017), and Stokes-Draut et al. (2017).
Ta b le 8: Total Electric Energy Intensity of Extraction and Conveyance for Each Hydrologic
Region (kWh/AF)
Component NC SF CC SC SR SJ TL NL SL CR
Seawater Desalination Conveyance 197 197 197 197 197 197 197 197 197 197
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Component NC SF CC SC SR SJ TL NL SL CR
Brackish Desalination -Groundwater
Pumping
383 491 506 697 294 301 347 381 401 532
Brackish Desalination - Local Surface
Water
89 89 89 89 89 89 89 89 89 89
Groundwater Pumping 383 491 506 697 294 301 347 381 401 532
Central Valley Project Conveyance 225 478 696 225 120 327 241 N/A N/A N/A
Colorado River Conveyance N/A N/A N/A 2,111 N/A N/A N/A N/A N/A 116
State Water Project Conveyance NA 1,062 2,056 3,306 241 527 2,603 NA 3,600 4,000
Recycled Water (Non-Potable) Conveyance 107 107 107 107 107 107 107 107 107 107
Recycled Water (Potable) – Groundwater
Pumping
383 491 506 697 294 301 347 381 401 532
Recycled Water (Potable) – Local Surface
Water
89 89 89 89 89 89 89 89 89 89
Local Surface Water 89 89 89 89 89 89 89 89 89 89
Local Imported Water 89 112 N/A 33 N/A N/A N/A N/A N/A N/A
Note: NC = North Coast, SF = San Francisco Bay, CC = Central Coast, SC = South Coast, SR = Sacramento River, SJ =
San Joaquin, TL = Tulare Lake, NL = North Lahontan, SL = South Lahontan, CR = Colorado River.
Data Sources: EPRI 2002, Klein et al. 2005, Wilkinson 2007, GEI Consultants/Navigant Consulting 2010a, GEI
Consultants/Navigant Consulting 2010b, Cooley et al. 2012, Plappally 2012, Tarroja et al. 2014, Liu et al. 2017, and
Stokes-Draut et al. 2017
We assumed that that the energy intensity of extraction and conveyance for brackish
desalination is the same as for groundwater because most brackish water is drawn from
groundwater basins; however, the user can select “local surface water” if the brackish water is
drawn from a local surface water body.
The energy intensity of extraction and conveyance for non-potable recycled water is the energy
required to transport the partially-treated wastewater to the recycled-water treatment facility.
Based on estimates in Stokes-Draut et al. (2017), the default energy intensity of extraction and
conveyance for non-potable recycled water is 107 kWh per acre-foot.
Currently in California, recycled water for potable applications must be stored temporarily in
either a groundwater aquifer or a reservoir (surface-water augmentation), which serves as an
environmental buffer, before the water is conveyed to a conventional drinking-water treatment
plant and distributed to the end user. Currently, most potable recycled water in California is
temporarily stored in a groundwater aquifer. Therefore, the default energy intensity of
extraction and conveyance for potable recycled water is the same as for groundwater extraction
and conveyance; however, the user can select “local surface water” if the recycled water is
temporarily stored in a surface water reservoir rather than in a groundwater aquifer.
3.6.2 Water Treatment
Water treatment refers to processes and technologies that treat water before it is distributed to
the end user. The energy required depends on the quality of the source water, the level of
treatment appropriate for the end use, and the technology used to treat the water.
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Table 9 provides default energy intensity values of water treatment for each of the major water
sources and treatment technologies included in the calculator. Modern seawater-desalination
facilities typically rely on reverse osmosis to remove the salts, with an estimated default energy
intensity of 4,497 kWh per acre-foot based on Klein (2005), GEI Consultants/Navigant (2010a),
Cooley et al. (2012), Tarroja et al. (2014), Tidwell et al. (2014), Liu et al. (2017), and Stokes-
Draut et al. (2017). Brackish water is, by definition, less saline than seawater and thus requires
less energy to treat. Based on Klein (2005), GEI Consultants/Navigant (2010a and 2010b),
Cooley et al. (2012), Liu et al. (2017), and Stokes-Draut et al. (2017), the default energy
intensity for desalination of brackish water is 1,407 kWh per acre-foot. Geography does not
drive the energy requirements for water treatment, and as a result, the energy intensity of water
treatment does not vary by hydrologic region.
Ta b le 9: Total Electric Energy Intensity of Water Treatment (kWh/AF)
Treatment Technology Energy Intensity (kWh/AF)
Seawater Desalination 4,497
Brackish Desalination 1,407
Conventional Drinking Water Treatment 205
Chlorination 63
Recycled Water –
Urban Potable Treatment
1,272
Recycled Water – Ag Potable Treatment 1,066
Recycled Water - Non-Potable Treatment 607
Data Sources: EPRI 2002, Klein et al. 2005, GEI Consultants/Navigant Consulting 2010a, GEI Consultants/Navigant
Consulting 2010b, Cooley et al. 2012, Tarroja et al. 2014, Tidwell et al. 2014, Liu et al. 2017, and Stokes-Draut et al.
2017.
Treating conventional drinking water is a multistage process that includes physical filtration and
chemical disinfection. Based on EPRI (2002), Klein (2005), GEI Consultants/Navigant (2010b),
Cooley et al. (2012), Tarroja et al. (2014), Liu et al. (2017), and Stokes-Draut et al. (2017), the
default energy intensity for treating conventional drinking water is 205 kWh per acre-foot. In
some instances, such as for some groundwater, only chlorination is required, and the default
energy intensity is 63 kWh per acre-foot
The energy required to treat non-potable recycled water includes the incremental energy
required to bring treated wastewater to recycled-water standards appropriate for non-potable
uses. Based on Cooley et al. (2012), GEI Consultants/Navigant (2010b), and Stokes-Draut et al.
(2017), the energy intensity of non-potable reuse is 607 kWh per acre-foot.
For potable recycled water, partially treated wastewater is first subject to treatment (typically
membrane treatment) and then temporarily stored in a groundwater aquifer or surface reservoir
before use. In an urban setting, the water would be withdrawn from temporary storage and
conveyed to a water treatment plant, where it would be treated a second time to drinking water
standards before distribution to customers. While potable reuse is uncommon in an agricultural
setting, in theory, the water withdrawn from temporary storage would not be subject to
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additional treatment before use. Based on Cooley et al. (2012), GEI Consultants/Navigant
(2010a and 2010b), Tarroja et al. (2014), and Stokes-Draut et al. (2017), the default energy
intensity of membrane treatment is 1,066 kWh per acre-foot, and we use this value as the default
for potable reuse treatment in an agricultural setting. The default energy intensity for potable
recycled water in an urban setting is equal to the sum of the energy intensity of membrane
treatment (1,066 kWh per acre-foot) and conventional treatment (205 kWh per acre-foot), or
1,272 kWh per acre-foot.
3.6.3 Water Distribution
Water distribution is the transport of treated water, both potable and non-potable, to the end
user. Like water conveyance, the energy intensity depends on the distance and net elevation
traveled and pump efficiency.
Table 10 summarizes the default energy intensity values for distributing water in different
terrains and for different supply types. The default energy intensity of potable water distribution
in an urban water system with flat, moderate, and hilly terrain is 18, 163, and 318 kWh per acre-
foot, respectively (MacDonald et al.2014). In the W-E Calculator 2.0, we assigned a default
topography (flat, moderate, or hilly) to each hydrologic region based on GEI
Consultants/Navigant (2010b) and MacDonald et al. (2014). However, the user can override
these defaults to select a different topography, as needed. The default energy intensity for
distributing water in an agricultural setting varies by hydrologic region and is based on GEI
Consultants/Navigant (2010b).
The energy required to distribute non-potable recycled water may be higher than for potable
water. This is because the recycled-water facility is usually located at or near the wastewater-
treatment facilities, which are typically located at the lowest point of the service area. Based on
Klein (2005), GEI Consultants/Navigant (2010b), Cooley et al. (2012), and Tidwell et al. (2014)
and Liu et al. (2017), the default energy intensity for distributing non-potable recycled water is
416 kWh per acre-foot. This data was drawn from urban settings and was only applied to those
areas.
Ta b le 10: Total Electric Energy Intensity of Water Distribution (kWh/AF)
Component NC SF CC SC SR SJ TL NL SL CR
Urban Potable (Flat)
18 18 18 18
18
Urban Potable (Moderate) 163
163 163
163
Urban Potable (Hilly)
318
Recycled Water (Non-Potable) 416 416 416 416 416 416 416 416 416 416
Agriculture 144 144 144 488 19 19 389 144 389 488
Note: Distribution energy intensity for urban potable water was calculated by topography, i.e., flat, moderate, and hilly,
and a default topography was assigned to each hydrologic region.
Data Sources: Klein et al. 2005, GEI Consultants/Navigant Consulting 2010b, Cooley et al. 2012, McDonald et al. 2014,
Tidwell et al. 2014, and Liu et al. 2017.
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3.6.4 Wastewater Collection and Treatment
Wastewater collection is the movement of untreated wastewater from the end user to a
wastewater collection facility. The energy required depends on the distance, elevation, and
pump efficiency. Wastewater treatment is the treatment required to bring wastewater to
discharge standards. The energy required depends on the level of treatment, the technology
employed, and the efficiency of the pumps used to move wastewater throughout the treatment
facility.
Secondary treatment of wastewater involves primary treatment, which is largely a physical
filtration process, followed by biological disinfection. This is the most common level of
wastewater treatment in California (California State Water Resources Control Board 2021) and
is consequently the default wastewater treatment type in the W-E Calculator 2.0.
Table 11 summarizes default energy intensity values for collecting and treating wastewater.
Based on Klein et al. (2005), Cooley et al. (2012), and GEI Consultants/Navigant (2010b), the
default energy intensity for collecting wastewater is 72 kWh per acre-foot. Based on EPRI
(2002), Klein et al. (2005), GEI Consultants/Navigant (2010b), Cooley et al. (2012), Tarroja et
al. (2014), Tidwell et al. (2014), and Liu et al. (2017), the default energy intensity value for
secondary treatment is 654 kWh per acre-foot. Some wastewater is subject to tertiary treatment,
with a default energy intensity value of 999 kWh/AF based on Klein et al. (2005), GEI
Consultants/Navigant (2010b), and Cooley et al. (2012).
Ta b le 11: Total Electric Energy Intensity of Wastewater Collection and Treatment (kWh/AF).
Technology Energy Intensity (kWh/AF)
Wastewater Collection 72
Wastewater Secondary Treatment
654
Wastewater Tertiary Treatment 999
Data Sources: EPRI 2002, Klein et al. 2005, GEI Consultants/Navigant Consulting 2010b, Cooley et al. 2012, Tarroja
et al. 2014, Tidwell et al. 2014, and Liu et al. 2017.
3.6.5 IOU Energy Intensity of Water-System Components
Water systems may be powered by energy from an IOU or from another energy source.
Consequently, IOUs may not be able to claim credit for all embedded energy savings. In the
W-E Calculator 1.0, the Navigant team developed estimates of the statewide average fraction of
energy supplied by an IOU for each water-system component (MacDonald et al. 2014). These
estimates, shown in Table 12, were based on data derived from the Water Energy Load
Profiling Tool, as augmented by the Pacific Institute for use in the CPUC Water-Energy Pilot
Evaluations. Limited data was available, and it was not possible to develop more detailed
estimates, such as for each IOU. Additionally, no other data was readily available to update
them, so the W-E Calculator 2.0 also uses the values shown in Table 12.
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Ta b le 12: Fraction of Energy Provided by an IOU for Each Water-Supply Component and Type
Wa t e r -Supply Component Wa t e r -Supply Type Fraction of IOU Energy
Extraction and Conveyance Seawater 0.94
Brackish Water 0.94
Recycled Water (Non-Potable)
0.97
Recycled Water (Potable) 0.97
Groundwater 0.59
Local Surface Water 0.27
Local Imported Water 0.27
Colorado River 0
Central Valley Project 0
State Water Project 0
Water Treatment 0.94
Water Distribution 0.95
Wastewater Collection 0.97
Wastewater Treatment 0.97
Data Source: McDonald et al. 2014
3.7 Wa t e r -System Components by Sector
The W-E Calculator 2.0 requires the user to specify whether the measure applies to the urban or
agricultural sector. This determines which water-system components are included in the
analysis.
3.7.1 Urban Sector
In the urban sector, water for indoor use is subject to water extraction and conveyance, water
treatment, water distribution, wastewater collection, and wastewater treatment. So, when the
user selects “urban” for the measure-application sector and “indoor” for the water-use type, the
calculator provides default assumptions for each of those water-system components. By
contrast, water for outdoor uses and water losses during distribution are only subject to water
extraction and conveyance, water treatment, and water distribution, so default assumptions
apply only to those components.
3.7.2 Agricultural Sector
In most cases, water for agricultural applications is not subject to water treatment, i.e., raw
water, and the wastewater is not collected or treated prior to discharge. Thus, when the user
selects “agriculture” for the measure-application sector, default assumptions are only provided
for water extraction and conveyance, water treatment (when the marginal water supply is
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recycled water or desalination), and water distribution. Defaults are not provided for water
treatment (when the marginal supply is not recycled water or desalination), wastewater
collection, and wastewater treatment. However, the user can override this and provide energy-
intensity values for these water-system components if appropriate.
In some instances, especially in an agricultural or industrial setting, the end user may extract
water from a groundwater aquifer or nearby stream for their own use. In these instances, the
estimates of on-site direct energy savings may include embedded energy savings so be sure to
avoid double counting these savings.
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4 Comparison of the Wa t e r -Energy Calculator 1.0
and 2.0
This section compares the estimated embedded energy savings from the W-E Calculator 1.0 and
2.0. We analyze a water-efficiency measure installed in 2021 that saves 10,000 gallons of water
per year, using the default values for the RBY, the marginal water supply, and the water-system
components.
Table 13 compares the estimated embedded energy savings for a water-efficiency measure
targeting urban outdoor water use or leaks in the water distribution system. W-E Calculator 2.0
estimates that IOU and total embedded energy savings are 32.82 kWh and 34.68 kWh,
respectively, for each of the state’s ten hydrologic regions. IOU embedded energy savings are
lower in W-E Calculator 1.0 across all hydrologic regions. Total embedded energy savings are
lower in all but the South Coast hydrologic region. Across all hydrologic regions, IOU and total
embedded energy savings are 226% and 81%, respectively, higher in the W-E Calculator 2.0
than in the W-E Calculator 1.0 for this test case.
Ta b le 13: Comparison of Embedded Energy Savings for a Water-Efficiency Measure Targeting
Urban Outdoor
Water Use and Leaks in the Water-Distribution System (kWh/ 10,000 gal)
Hydrologic Region
W-E Calculator 1.0 W-E Calculator 2.0
IOU Embedded
Energy Savings
Total Embedded
Energy Savings
IOU Embedded
Energy Savings
Total Embedded
Energy Savings
San Francisco 14.68 21.26 32.82 34.68
Central Coast 13.30 20.77 32.82 34.68
South Coast 13.49 59.43 32.82 34.68
Sacramento River 6.77 7.83 32.82 34.68
San Joaquin 7.32 9.10 32.82 34.68
Tulare Lake 7.51 12.24 32.82 34.68
North Lahontan 8.23 9.30 32.82 34.68
South Lahontan 12.14 30.69 32.82 34.68
Colorado River 6.27 9.07 32.82 34.68
North Coast 10.86 12.20 32.82 34.68
Average 10.06 19.19 32.82 34.68
Table 14 compares embedded energy estimates for a water-efficiency measure targeting urban
indoor water use. W-E Calculator 2.0 estimates IOU and total embedded energy savings are
54.42 kWh and 56.95 kWh, respectively, for each of the state’s ten hydrologic regions. These
savings are higher than in Table 13 because they include the embedded energy savings from
reductions in wastewater collection and treatment. IOU embedded energy savings in the W-E
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Calculator 1.0 are lower across all hydrologic regions. Similarly, total embedded energy savings
are lower in all but the South Coast hydrologic region. Across all hydrologic regions, IOU and
total embedded energy savings for a water-efficiency measure targeting urban indoor water use
are 142% and 78%, respectively, higher in the W-E Calculator 2.0 than in the W-E Calculator
1.0.
The results shown in Table 13 and Table 14 are due to several factors. First, W-E Calculator 2.0
uses non-potable recycled water as the marginal water supply for each hydrologic region, and
the available data indicate that the energy intensity of non-potable recycled water does not vary
across the state. W-E Calculator 1.0, by contrast, bases the embedded energy savings on the
historical water-supply mix for each hydrologic region. The historical water-supply mix is less
energy intensive than the marginal water supply in all but the South Coast region and relies less
on electricity from IOUs across all hydrologic regions.
Ta b le 14: Comparison of Embedded Energy Savings for a Water-Efficiency Measure Targeting
Urban Indoor
Water Use (kWh/10,000 gallons)
Hydrologic Region
W-E Calculator 1.0 W-E Calculator 2.0
IOU Embedded
Energy Savings
Total Embedded
Energy Savings
IOU Embedded
Energy Savings
Total Embedded
Energy Savings
San Francisco 27.13 34.10 54.42 56.95
Central Coast 25.75 33.60 54.42 56.95
South Coast 25.94 72.26 54.42 56.95
Sacramento River 19.22 20.67 54.42 56.95
San Joaquin 19.77 21.93 54.42 56.95
Tulare Lake 19.96 25.07 54.42 56.95
North Lahontan 20.68 22.13 54.42 56.95
South Lahontan 24.59 43.52 54.42 56.95
Colorado River 18.72 21.91 54.42 56.95
North Coast 23.31 25.04 54.42 56.95
Average 22.51 32.02 54.42 56.95
Table 15 compares estimates of embedded energy savings for a water-efficiency measure
targeting agricultural water use. In the W-E Calculator 2.0, embedded energy savings are subject
to some regional variation due to differences in the energy intensity of distributing water to the
end user. IOU embedded energy savings across all hydrologic regions average 27.60 kWh,
ranging from a low of 21.26 kWh in the San Joaquin and Sacramento River regions to a high of
34.92 kWh in the South Coast and Colorado River regions. By comparison, IOU embedded
energy savings in the W-E Calculator 1.0 are lower, averaging 8.00 kWh across all regions.
Across all regions, IOU and total embedded energy savings for water-efficiency measures
targeting outdoor agricultural water use are 245% and 72%, respectively, higher in the W-E
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Calculator 2.0 than in the W-E Calculator 1.0. As with the urban analysis, these differences are
driven by use of the marginal water supply in the W-E Calculator 2.0 and the historical water
supply portfolio in the W-E Calculator 1.0.
Ta b le 15: Comparison of Embedded Energy Estimates for a Water-Efficiency Measure Targeting
Agricultural Outdoor
Water Use (kWh/10,000 gallons)
Hydrologic Region
W-E Calculator 1.0 W-E Calculator 2.0
I OU
Embedded
Energy
Savings
To t a l
Embedded
Energy
Savings
I OU
Embedded
Energy
Savings
To t a l
Embedded
Energy
Savings
San Francisco 11.44 17.82 24.89 26.33
Central Coast 12.70 20.13 24.89 26.33
South Coast 11.08 56.86 34.92 36.88
Sacramento River 4.26 5.16 21.26 22.50
San Joaquin 5.39 7.05 21.26 22.50
Tulare Lake 5.85 10.47 32.03 33.84
North Lahontan 6.38 7.33 24.89 26.33
South Lahontan 11.22 29.71 32.03 33.84
Colorado River 2.93 5.52 34.92 36.88
North Coast 8.73 9.94 24.89 26.33
Average 8.00 17.00 27.60 29.18
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5 Recommendations
The following recommendations for further improvements to the W-E Calculator 2.0 and its
implementation can help the state to better estimate embedded energy savings and realize the
full potential of water efficiency measures to reduce statewide energy use and greenhouse gas
emissions.
Evaluate the default marginal water supply and revise as appropriate.
The W-E Calculator 2.0 follows D.15-09-23 in its use of the long-run marginal water supply,
rather than the average water supply, to estimate embedded energy savings. Like its
predecessor, the W-E Calculator 2.0 uses non-potable recycled water as the default marginal
water supply for each of the California’s ten hydrologic regions and lets the user adjust this
default assumption according to local circumstances. This marginal water supply was
selected in 2014 after a review of planning documents and consultation with stakeholders
across the state.
New regulations, along with changing technologies and practices, suggest that reviewing the
default marginal water supply may be warranted. For example, the State Water Resources
Control Board is developing uniform water recycling criteria for direct potable reuse on or
before December 31, 2023; once adopted, these regulations are likely to generate greater
investment in this water-supply option among urban water suppliers in California and may
be the marginal water supply. Similarly, implementing the Sustainable Groundwater
Management Act (SGMA) will necessitate reducing groundwater pumping in some parts of
the state over the next several decades, especially among agricultural users in the San
Joaquin hydrologic region, suggesting that groundwater may be the marginal water supply
in these areas. We recommend that the CPUC evaluate whether it is appropriate to modify
the default marginal water supply for each hydrologic region for urban and agricultural
water uses.
Evaluate whether to use a resource balance year (RBY), and if so, select an appropriate
year.
In response to stakeholder comments, the Navigant team added a resource balance year to
the W-E Calculator 1.0. However, they did not determine the appropriate default resource
balance year. Rather, the calculator, which was developed in 2014, adopted the convention
used for energy-efficiency analyses at the time and used a default RBY that was two years in
the future—2016. D.15-09-23 supported using 2016 as the RBY and allowing the user to
change the RBY, as needed.
Consistent with D.15-09-23, the W-E Calculator 2.0 uses 2016 as the RBY and allows the
user to easily alter this default value. Using 2016 as the RBY recognizes that traditional
water sources across California are overallocated, and there is pressure to reduce water
withdrawals from these sources by developing new, mostly local, water supplies. As a result,
water savings from water-efficiency measures reduce the need to develop new sources of
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supply, suggesting that we are “in marginal territory.” Moreover, there was no immediately
available process by which to revise the RBY, and no new analysis indicating that a different
year should be selected. We recommend that the CPUC evaluate whether to continue using
a RBY, or to eliminate it, as has been done for energy efficiency analyses. If use of a RBY is
maintained, we recommend that the CPUC conduct an evaluation to determine the
appropriate year.
Consider updating the Water Tool to include as a non-energy benefit in TSB analyses and
to evaluate whether to incorporate water-related environmental benefits.
The W-E Calculator 1.0 included a cost-effectiveness analysis, and as part of that analysis,
the Navigant team also developed the Water Capacity Avoided Cost Tool (also referred to
as the Water Tool). The primary output of the Water Tool is the annual avoided cost of
capacity, which is the level annualized payment that would be required for an additional
unit of capacity.
The W-E Calculator 2.0 does not include a cost-effectiveness analysis. Rather, such analyses
are done within the CET. The CET allows including non-energy benefits in TSB analyses,
and thus the avoided cost of adding water capacity could be added to those analyses. While
it was beyond the scope of this work to revise the Water Tool, we recommend that the
CPUC consider updating the Water Tool. We also recommend evaluating environmental
benefits associated with reduced water usage and incorporating them as non-energy benefits.
Review calculator default assumptions every five years and update as needed, consistent
with the frequency of updates for key water-planning documents.
Regularly updating the W-E Calculator 2.0 will help ensure that the default assumptions
reflect current water policies and practices. Ultimately, this will improve the accuracy of
assessments of embedded energy savings. We recommend reviewing the default assumptions
every five years and updating them as needed. This is consistent with the frequency of
updates for key water planning documents. For example, water suppliers update Urban
Water Management Plans every five years, in years ending in 0 and 5. Additionally, the
State Water Plan is also updated every five years, in years ending in 3 and 8.
Implement the long-term solution identified for integrating embedded energy savings
into CET analyses.
The stakeholder interviews identified two key issues: (1) cost-effectiveness analyses did not
include embedded energy savings, and (2) IOUs were unable to claim credit for these
savings toward their energy efficiency goals. While revising the water-energy calculator, we
worked closely with CPUC to develop a short-term and long-term solution for integrating
embedded energy savings into CET analyses. The short-term solution will be available
immediately to PAs. However, the long-term solution will require changes to the structure
and calculations within the CET, as identified in Appendix B. We recommend that the
CPUC implement the long-term solution for integrating embedded energy savings into CET
analyses as soon as is practicable so that PAs and CPUC can better determine the role of
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embedded energy savings in meeting energy efficiency goals and promote greater investment
in cost-effective water-efficiency measures that save energy.
Expand partnerships between energy PAs and water utilities to realize greater water and
energy savings and help the state to meet its water, energy, and greenhouse-gas goals.
Spang et al. (2018) found that water efficiency can achieve significant electricity and GHG
savings at costs competitive with existing energy efficiency programs. This suggests that
partnerships between energy PAs and water utilities could benefit ratepayers and help the
state realize water, energy, and greenhouse-gas goals. This is especially important as the
state faces another severe drought and climate impacts are intensifying. We recommend that
the CPUC proactively expand partnerships between energy PAs and water utilities across
California, for example, through statewide organizations like the California Water-
Efficiency Partnership or regional organizations like the Metropolitan Water District of
Southern California or Bay Area Regional Energy Network (BayREN). Additionally, we
recommend that the CPUC facilitate partnerships explicitly between water and energy
IOUs, both of which are regulated by the CPUC.
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6 References
California Department of Water Resources (DWR). "California Water Plan Update 2018." 2018.
California Department of Water Resources (DWR). “2015 Urban Water Management Plan Data.” Water Use Efficiency
Data. Available at: https://wuedata.water.ca.gov/
California State Water Resources Control Board. “Volumetric Annual Report of Wastewater and Recycled Water -
California Open Data.” 2021. Available at:
https://data.ca.gov/dataset/volumetric-annual-report-of-wastewater-and-
recycled-water.
Cooley, H., Wilkinson, R. “Implications of Future Water Supply Sources on Energy Demands.” WateReuse Foundation,
Pacific Institute, UC Santa Barbara for California Energy Commission. July 2012. Available at:
https://pacinst.org/
publication/wesim/
EPRI. Water & Sustainability (Volume 4): U.S. Electricity Consumption for Water Supply & Treatment - The Next Half
Century. 1006787, 2002. Available at:
https://www.circleofblue.org/wp-content/uploads/2010/08/EPRI-Volume-
4.pdf
GEI Consultants/Navigant Consulting. “Embedded Energy in Water Studies Study 1: Statewide and Regional Water-
Energy Relationship.” Prepared for California Public Utilities Commission. August 2010a. Available at:
https://
waterenergyinnovations.com/wp-content/ uploads/2020/03/Embedded-Energy-in-Water-Studies-Study-1-
FINAL.pdf
GEI Consultants/Navigant Consulting. “Embedded Energy in Water Studies Study 2: Water Agency and Function
Component Study and Embedded Energy-Water Load Profiles.” Prepared for California Public Utilities Commission.
August 2010b. Available at:
https://waterenergyinnovations.com/wp-content/uploads/2020/03/Embedded-Energy-
in-Water-Studies-Study-2-FINAL.pdf
Klein, G., Krebs, M., Hall, V., O’Brien, T., Blevins, B.B. “California’s Water – Energy Relationship (No. CEC-700-2005-
011-SF).” California Energy Commission. November 2005. Available at:
http://large.stanford.edu/courses/2012/
ph240/spearrin1/docs/CEC-700-2005-011-SF.PDF
Liu, Qinqin, et al. Connecting the Dots between Water, Energy, Food, and Ecosystems Issues for Integrated Water
Management in a Changing Climate. Climate Change Program, California Department of Water Resources, Feb.
2017. Available at:
https://cawaterlibrary.net/wp-content/uploads/2017/10/QLf2017FinalWhitePaper_
jta_edits_fk_format_2.pdf
McDonald, Craig, et al. Water/Energy Cost-Effectiveness Analysis. Navigant Reference No.: 169145, Prepared for
California Public Utilities Commission, Oct. 2014. Available at:
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Appendices
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A. Interview Questions
We conducted interviews with energy utilities, consultants, and researchers, covering water-
energy savings and the W-E Calculator. We developed separate questions for energy utilities
and for consultants and researchers.
A. 1 Interview Questions for Energy Utilities
General Questions about Water-Energy Savings Estimates
Do you currently have any water measures in your energy efficiency programs?
If yes,
Which measures are included?
What were some of the challenges you encountered when integrating these measures
into your programs?
Is there anything that would help you to include more of these measures into your
programs?
If no,
Why not?
Is there anything that would help you to include more of these measures into your
programs?
Have you estimated the energy savings from water efficiency measures?
If no, why not?
If yes,
Did you evaluate the direct energy savings (aka hot water savings), the embedded
energy savings (e.g., the energy associated with treating and transporting
water/wastewater), or both?
For what purpose did you use these estimates, e.g., programmatic planning or site
estimates for specific projects?
Did you get credit for the embedded and/or direct energy savings toward meeting
your energy efficiency goals?
Did this evaluation change your investment decision?
What methods and tools did you use to estimate the embedded energy savings, e.g.,
the Water-Energy Calculator?
Specific Questions About the Water-Energy Calculator (W-E Calculator)
How familiar are you with the Water-Energy Calculator (W-E Calculator)?
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Did you participate in the development of the W-E Calculator, e.g., attending workshops or
providing comments? If so, how?
Have you used the W-E Calculator? (For reference, the calculator and user guide are
available here: https://www.cpuc.ca.gov/nexus_calculator/
)
If no,
Why not?
What tools would be useful for integrating energy benefits into efficiency
investments?
If yes,
Why did you use the W-E Calculator?
What was your general impression of the W-E Calculator?
Did you use the default values in the W-E Calculator?
Did you use the water and wastewater utility cost test? If so, for what purpose?
What outputs from the W-E Calculator were of greatest interest? Which were least of
interest?
Were you confident in the results provided by the W-E Calculator?
What changes to the W-E Calculator do you think are necessary? Of these, what is of
greatest importance? What would be of lesser importance?
How could the outputs from the W-E Calculator be better integrated into existing
CPUC calculation tools?
Is there anything else you think we should keep in mind when updating the W-E Calculator?
Who else should we talk to at your organization or elsewhere?
A. 2 Interview Questions for Consultants and
Researchers
General Questions Water-Energy Programs
Are you familiar with the energy efficiency program offerings? If yes,
What types of water efficiency measures are being integrated into these programs (e.g.,
cold water measures, hot water measures, or both)?
What are the challenges with integrating water efficiency measures into these programs?
What would help to integrate more measures into these programs?
Are there any policy issues that need to be addressed to better integrate water measures
into energy efficiency programs?
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Are you familiar with energy efficiency program evaluations? If yes,
to what extent are direct energy savings (aka hot water savings) being estimated?
embedded energy savings (e.g., the energy associated with treating and transporting
water/wastewater)?
Are they using the Water-Energy Calculator for these evaluations, or are they using other
methods?
For what purpose are these estimates used, e.g., programmatic planning or site estimates
for specific projects?
What are some of the barriers for estimating embedded energy savings?
Are the energy IOUs getting credit for the embedded and direct energy savings toward
meeting energy efficiency goals?
Specific questions about the Water-Energy Calculator (W-E Ca lcula tor )
Use of the W-E Calculator
For what purpose(s) have you used the W-E Calculator?
Did you integrate environmental benefits into your cost calculations?
Did you use the water and wastewater utility cost test? If so, for what purpose?
What changes to the W-E Calculator would improve its usability?
Model Defaults
What marginal supply and energy intensity estimates are the energy IOUs using? Default
values or other values?
What are the issues and concerns with the model defaults?
Outputs
What outputs are most important?
What outputs are of least interest or even unnecessary?
Were you confident in the results provided by the W-E Calculator? Why or why not?
How could the W-E Calculator outputs be better integrated into existing CPUC tools?
Can or should the W-E Calculator and its outputs be used for other purposes?
Other questions or concerns
Is there anything else you think we should keep in mind when updating the W-E Calculator?
Who else should we talk to?
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B. Short- and Long-term Solutions for Integrating
Embedded Energy Savings into CEDARS
On 20 December 2021, the California Public Utilities Commission (CPUC) published the final
version of the Water-Energy Calculator 2.0 (W-E Calculator 2.0). The W-E Calculator 2.0
replaces the first version of the Water-Energy Calculator, and Program Administrators (PAs)
will use its values going forward to calculate the embedded energy savings of Water-Energy
Nexus (WEN) measures. PAs can now use the embedded energy savings from these WEN
measures to claim incentives and they will count towards PAs’ energy-efficiency goals.
The two solutions described below detail how PAs will calculate the embedded energy savings
using the California electronic Technical Reference Manual (eTRM).
Short-term Solution
Until the CPUC implements the long-term solution, existing and new WEN-measure packages
will use the following method to calculate the embedded energy savings produced by a water-
efficiency measure and add it to the direct (site) energy savings generated by that measure.
The measure or measure update will add the energy-intensity values in Table 16 to eTRM. The
embedded energy savings for the measure will be the result of dividing the number of gallons
saved by the measure by 1000 and multiplying that result by the “Total IOU Embedded Water
Energy Intensity” value in Table 16, based on whether the measure is an indoor or outdoor
measure. For IOUs, the embedded-water-energy intensity is 5.44 kWh/kgal for indoor
measures, and 3.28 kWh/kgal for outdoor measures. Once the embedded energy savings have
been calculated, they will be automatically added in eTRM to the direct energy savings of the
measure (per D.17-12-010). That combined value, along with other site-specific savings values,
will then be input into the Cost-Effectiveness Tool (CET) through California Energy and Data
Reporting System (CEDARS) to calculate the measure’s cost effectiveness. Program
Administrators (PAs) will also use the combined value if they submit a claim for this measure.
As the embedded energy savings are present regardless of whether the measure uses hot or cold
water, the total annual water savings including both hot and cold water will be multiplied by the
appropriate “Total IOU Embedded Water Energy Intensity” value in Table 16. The calculation
of direct energy savings will be unchanged.
This approach is only suitable for measures that use the default marginal water supply—
recycled water (non-potable). PAs may claim measures that use a different marginal supply only
if they use the long-term solution, and thus must wait until that solution is implemented.
Additionally, per D.15-09-023, where PAs depart from default values, they must show that the
departure is reasonable in all documents submitted to CPUC.
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Ta b le 16: Embedded Water Energy Intensities
Cli m a t e
Zone
Sector
Water Use
Typ e
Marginal Supply
Total IOU Embedded
Water Energy
Intensity
( k Wh / k g al)
Total Non-I OU
Embedded Water
Energy Intensity
(kWh/kgal)
Any Urban Indoor
Recycled Water
(Non-Potable)
5.44 0.25
Any Urban Outdoor
Recycled Water
(Non-Potable)
3.28 0.19
Lo n g -term Solution
Once CPUC finalizes this solution, it will replace the short-term solution for the measure. When
the CPUC informs the relevant PAs of this transition, the PAs will create a Measure Log Entry
that includes a Measure Package Plan (MPP). The MPP will describe the administrative change
to the measure package that will incorporate the long-term solution used to calculate the total
energy savings as well as when the change will take effect. This administrative change will not
trigger a new version of the measure package since impacts (including savings, cost, and
measure life) have not changed. It is expected that total energy savings will be broken out in this
long-term approach so that direct energy savings can be distinguished from IOU embedded-
water-energy savings and stored separately in permutation data fields.
The measure or measure update will use the new CET functionality to accept the direct energy
savings and IOU embedded energy savings separately into the CET. The direct energy savings
will be calculated using the measure-package methodology. The IOU embedded-water-energy
savings will be calculated following the same methodology described in the short-term solution
but will be stored independently within the eTRM to facilitate reporting and cost-effectiveness
calculations. The PA will still receive the same credit for both the direct and embedded energy
savings as they received using the short-term solution, but for accounting purposes, the two
types of savings will be entered into the CET separately through CEDARS.
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C. Us e r ’s Manual
This appendix contains the User’s Guide for the Water-Energy Calculator 2.0
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Glossary of Terms
Te r m Definition
Acre-Foot
The volume of water that would cover one acre to a depth of one
foot (equivalent to 325,851 gallons).
Brackish Water
Water with a salinity ranging from 0.5 to 30 parts per thousand
(ppt), which exceeds normally acceptable standards for municipal,
domestic, and irrigation uses but is less than that of ocean water.
California Energy Data
and Reporting System
(CEDARS)
Data and reporting system that maintains California Energy
Efficiency Program data reported by Investor-Owned Utilities,
Regional Energy Networks, and certain Community Choice
Aggregators.
Central Valley Project
and Other Federal
Deliveries
The delivery of water to Central Valley Project contractors and to
other federal water projects.
Colorado River
Aqueduct
Water diverted from the Colorado River by the Metropolitan
Water District of Southern California.
Cost Effectiveness Tool
(CET)
An online tool designed for the California Public Utilities
Commission to determine the cost effectiveness and examine other
properties of energy efficiency programs and portfolios.
Desalination
Water treatment process for the removal of salt from water for
beneficial use. Source water can be brackish or ocean water.
Distribution
The transport of treated water (both potable and non-potable) to
the customer.
Electronic Technical
Reference Manual
(eTRM)
A statewide repository of California’s deemed measures, including
supporting values and documentation.
Embedded Energy
The energy used to extract, convey, treat, and distribute water to
end users, and energy used to collect and transport wastewater for
treatment prior to safe discharge of the effluent in accordance with
regulatory rules.
Embedded Energy
Savings
The energy saved due to reductions in the amount of water
extracted, conveyed, treated, and delivered as well as the
wastewater collected, treated, and discharged.
Entergy Intensity
The amount of energy used to extract, convey, treat, and distribute
water and to collect and treat wastewater on a per-unit basis, e.g.,
kilowatt-hours per acre-foot of water (kWh/AF) or kWh per 1,000
gallons (kWh/kgal)
Energy Load Profile
The hourly variation in energy use over the course of a day.
Extraction and
Conveyance
The transport of untreated or partially treated water from its source
through aqueducts, canals, and pipelines to a water treatment
facility, or directly to the end user if using untreated water.
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Te r m Definition
Groundwater
Water beneath the Earth’s surface in soil pore space and in the
fractures of rock formations.
Hydrologic Region
A geographical division of the state based on the local hydrological
basins. The Department of Water Resources divides California into
ten hydrologic regions, correspond to the state’s major water
drainage basins.
IOU Energy
Energy provided by an investor-owned utility.
Local Surface Water
Water delivered by local water agencies and individuals. It includes
direct deliveries of water from stream flows, as well as local water
storage facilities.
Local Imported Water
Water transferred by local agencies from other regions of the state.
Marginal Water Supply
The next increment or unit of water supply developed within a
region to meet demand in the absence of water conservation and
efficiency.
Measure Life
An estimate of the median number of years that the measure
installed will remain in place and operable.
Non-IOU Energy
Energy that is not provided by an investor-owned utility
Recycled Water (Non-
Potable)
Municipal wastewater that is treated to meet a non-potable
beneficial use.
Recycled Water
(Potable)
Municipal wastewater that is treated to meet a potable beneficial
use.
Resource Balance Year
(RBY)
The year in which new capacity will be required to meet water
demand.
State Water Project
A collection of canals, pipelines, reservoirs, and hydroelectric
power facilities that extends more than 700 miles and is managed
by the California Department of Water Resources.
Water Treatment
Processes and technologies that treat water prior to its distribution
to the end user.
Wastewater Collection
Movement of untreated wastewater from the end user to a
wastewater treatment facility.
Wastewater Treatment
Application of biological, physical, and/or chemical processes to
bring wastewater to discharge standards.
