Attachment C - Community-Scale Greenhouse Gas Emissions Inventory
City of Phoenix — Community and Cultural Investment Subcommittee (2022-09-07)
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2020 Community-Scale
Greenhouse Gas
Emissions Inventory
A comprehensive report
prepared for
May 2022
sustainabilitysolutions.asu.edu
Attachment C
Acknowledgements
This report is a joint effort by:
City of Phoenix
•
Nancy Allen, Environmental Programs Manager
•
Rosanne Albright, Environmental Programs Coordinator
•
Dr. Matthew Potzler, Environmental Air Quality and Climate Specialist
And
•
William Campbell, Portfolio Manager
•
Lizzy Bruns, Graduate Student
And
•
Dr. Richard Rushforth, Assistant Research Professor
We wish to acknowledge the numerous city departments’ staff for supplying the data
needed to produce the City of Phoenix 2020 Community Greenhouse Gas Emissions
Inventory.
Finally, we would like to thank City of Phoenix employees, residents, and business
owners, who are on the ground supporting the city’s efforts and who are working toward
reducing their own greenhouse gas emissions.
Note: The data and calculations presented in this report may not be exact due to rounding errors within
the GHG emissions template.
3
Table of Contents
List of Tables ...................................................................................................................... 5
List of Figures ..................................................................................................................... 6
Acronym List ....................................................................................................................... 6
Executive Summary............................................................................................................ 8
Introduction ....................................................................................................................... 13
1. Stationary Energy Sector ............................................................................................. 16
1.1 Scope 1 Stationary Energy ..................................................................................... 17
1.2 Scope 2 Stationary Energy ..................................................................................... 18
1.3 Scope 3 Stationary Energy ..................................................................................... 20
2. Transportation Sector ................................................................................................... 21
2.1 Scope 1 Transportation GHG Emissions ............................................................... 22
2.2 Scope 2 Transportation GHG Emissions ............................................................... 23
2.3 Scope 3 Transportation GHG Emissions ............................................................... 23
3. Waste Sector ................................................................................................................ 24
Appendix A. Detailed GHG Emissions Summary ............................................................ 26
Appendix B. DRAFT GHG Emissions from Agriculture, Forestry, and Land Use
(AFOLU) and Food Systems ............................................................................................ 33
B.1 Livestock ................................................................................................................. 34
B.2 Land Use & Land Use Change .............................................................................. 37
B.3 Aggregate Sources And Non-CO2 Emissions Sources On Land ......................... 39
B.4 Food System GHG Emissions ............................................................................... 39
Appendix C. Stationary Energy – Natural Gas Documentation ...................................... 42
C.1 Natural Gas Data Collection .................................................................................. 42
C.2 Natural Gas Data Processing ................................................................................ 42
C.3 Changes between inventory years ........................................................................ 43
Appendix D. Stationary Energy – Electricity Documentation .......................................... 44
D.1 Electricity Data Collection ...................................................................................... 44
D.2 Electricity Data Processing .................................................................................... 45
D.2.1 APS Electricity Data Processing ..................................................................... 45
D.2.2 SRP Data Processing ..................................................................................... 46
D.2.3 Total GHG Emissions from Electricity Consumption ...................................... 47
D.3 Transmission and Distribution Loss (T&D Loss) ................................................... 47
4
D.4 Changes between inventory years ........................................................................ 47
Appendix E. Transportation Sector Documentation ........................................................ 49
E.1 Transportation Sector Data Processing................................................................. 49
E.2 On-Road Transport ................................................................................................ 49
E.2.1 Gasoline and Diesel ........................................................................................ 49
E.2.2 Alternative Fuel Vehicles – B20 Biodiesel, E85 Ethanol, CNG, LNG ............ 50
E.2.3 Electric Vehicles .............................................................................................. 50
E.3 Railways ................................................................................................................. 50
E.3.1 Valley Metro Light Rail .................................................................................... 50
E.3.1 Freight Rail ...................................................................................................... 51
E.4 Aviation ................................................................................................................... 51
E.4.1 Commercial Aviation ....................................................................................... 51
E.4.2 Civil Aviation .................................................................................................... 51
E.5 Off-Road Transportation ........................................................................................ 51
E.5.1 Nonroad Diesel ................................................................................................ 51
E.5.2 Other Nonroad GHG Emissions ...................................................................... 53
Appendix F. Waste Sector Documentation ...................................................................... 54
F.1 Solid Waste ............................................................................................................. 54
F.2 Wastewater Treatment ........................................................................................... 56
F.3 Compost Processing .............................................................................................. 56
F.4 GAC Hauling and Regeneration ............................................................................ 56
5
List of Tables
Table ES-1. Phoenix GHG emissions by Sector (MT CO2e) ............................................ 9
Table ES-2. Subsector Stationary Energy GHG Emissions (MT CO2e) ......................... 10
Table ES-3. Subsector Transportation GHG Emissions (MT CO2e) .............................. 11
Table ES-4. Subsector Waste Sector GHG Emissions (MT CO2e) ................................ 12
Table 1. Community- Level GHG Emissions by Sector for 2012, 2016, and 2018 ........ 13
Table 2. 2018 Community-Level GHG Emissions by Sector and Scope ....................... 14
Table 3. Summary of Scope 1 Stationary Energy GHG Emissions ................................ 17
Table 4. Summary of Scope 2 Stationary Energy GHG Emissions ................................ 19
Table 5. Summary of Scope 3 Stationary Energy GHG Emissions ................................ 20
Table 6. Summary of Scope 1 Transportation GHG Emissions (MT CO2e) ................... 22
Table 7. Scope 1 Transportation Activity Data and GHG Emissions by Fuel ................ 22
Table 8. Summary of Scope 2 Transportation GHG Emissions ..................................... 23
Table 9. Summary of Scope 3 Transportation GHG Emissions ..................................... 23
Table 10. Summary of Waste Sector GHG Emissions .................................................... 24
Table 11. Summary of Scope 1 Waste GHG Emissions ................................................. 24
Table 12. Summary of Scope 3 Waste GHG Emissions ................................................. 25
Table A1. Year-to-Year Comparison of Stationary Energy GHG Emissions .................. 27
Table A2. Year-to-Year Comparison of Transportation GHG Emissions ....................... 29
Table A3. Year-to-Year Comparison of Waste GHG Emissions ..................................... 31
Table C1. Changes to Natural Gas GHG Emissions Due to Updated Scaling Methods 43
Table D1. Changes to Scaling Methodologies for Electricity Data ................................. 48
Table E1. Changes to Non-Road Diesel Consumption and GHG Emissions ................ 53
Table F1. Data and Method Documentation for City-Owned Landfills ........................... 54
Table F2. Data Documentation for Privately-Owned Landfills ........................................ 55
Table F3. Data Documentation for Wastewater Treatment Plants ................................. 56
6
List of Figures
Figure ES-1. GHG emissions by emissions sector for 2012, 2016, 2018, and 2020. ...... 9
Figure ES-2. Stationary Energy GHG emissions for 2012, 2016, 2018, and 2020. ....... 10
Figure ES-3.Transportation GHG emissions for 2012, 2016, and 2018. ........................ 11
Figure 1. Total GHG Emissions and Per Capita GHG Emissions Since 2012 ............... 14
Figure 3. Stationary Energy GHG Emissions by Scope Since 2012 .............................. 16
Figure 4. Scope 1 Stationary GHG Emissions Since 2012 ............................................. 18
Figure 5. Scope 2 Stationary GHG Emissions Since 2012 ............................................. 20
Figure 6. Summary of Transportation Sector GHG Emissions by Fuel Type ................. 21
7
Acronym List
AFFA
Agriculture, Forestry, and Fishing Activities
AFOLU
Agriculture, Forestry, and Land Use
APS
Arizona Public Service
AR
IPCC Assessment Report (Numbered 2 through 5)
ASU
Arizona State University
AZNM
Arizona and New Mexico eGRID Subregion
B20 Biodiesel
Contains up to 20% biodiesel
BEV
Battery Electric Vehicle
BPEV
Batter Plugin Electric Vehicle
CH4
Methane
CNG
Compressed Natural Gas
CO2
Carbon Dioxide
CO2e
Carbon Dioxide Equivalent Emissions
E54
Fuel containing 54% ethanol
E85
Fuel containing 85% ethanol
eGRID
EPA’s Emissions and General Resource Integrated Database
EIA
U.S. Energy Information Administration
EPA
U.S. Environmental Protection Agency
EV
Electric Vehicle
FCEV
Fuel Cell Electric Vehicle
FERC
Federal Energy Regulatory Commission
FTE
Full-time equivalent
GGE
Gasoline Gallon Equivalent
GHG
Greenhouse Gas
GPC
Global Protocol for Community-Scale GHG Emission Inventories
GWP
Global Warming Potential
ICLEI
International Council for Local Environmental Initiatives,
IE
Included Elsewhere
IPPU
Industrial Processes and Product Use
LNG
Liquefied Natural Gas
LPG
Liquefied Petroleum Gas
MPST
Mining, Processing, Storage, and Transport of Coal
MT
Metric Tons
MWh
megawatt-hour
NAU
Northern Arizona University
NE
Not Estimated
NERC
North American Electric Reliability Corporation
NO
Not Occurring
N2O
Nitrous Oxide
ONGS
Oil and Natural Gas Systems
PNM
Public Service Company of New Mexico
SRP
Salt River Project
T&D
Transmission & Distribution
TRP
Trip Reduction Program
WECC
Western Electricity Coordinating Council
WWT
Wastewater Treatment
WWTP
Wastewater Treatment Plant
8
Executive Summary
The city of Phoenix (City) has completed a community-scale greenhouse gas (GHG)
emissions inventory for calendar year 2020 using the Global Protocol for Community-
Scale GHG Emission Inventories (GPC). The GPC is a worldwide standard for
inventorying city-induced GHG emissions developed by the World Resources Institute,
C40 Cities Climate Leadership Group, and ICLEI.1 The GPC is also the standard
supported by the Global Covenant of Mayors for Climate and Energy. The City of
Phoenix is a member of both the C40 Cities Climate Leadership Group and Global
Covenant of Mayors for Climate and Energy.
The GPC categorizes direct and indirect GHG emissions into three sectors: Stationary
Energy, Transportation and Waste. Direct GHG emissions occur within City boundaries,
while indirect GHG emissions are induced by activity within the City boundary.
• The Stationary Energy Sector includes GHG emissions that occur from energy
utilized in residential buildings, commercial buildings and facilities, manufacturing
industries, agriculture, forestry and fishing energy use, and electricity
transmission and distribution energy losses.
• The Transportation Sector includes GHG emissions from commercial and civil
aviation, on-road transportation, non-road vehicle use, freight and light rail.
• The Waste Sector includes GHG emissions from solid waste disposal, the
biological treatment of waste (composting), and wastewater treatment.
The 2020 community-scale GHG inventory is the fourth completed by the City following
the 2012, 2016, and 2018 community-scale GHG inventories. While each of the
community-scale GHG inventories completed by the City have followed the GPC, during
each inventory process the previous year(s) GHG inventory have been recalculated to
reflect updates to source data, data collection and processing methods, GHG global
warming potentials, and GHG emissions estimation methods. Changes to GHG
emissions totals for the 2012, 2016, and 2018 calendar years are reported along with
the 2020 GHG emissions totals.
Key Findings
•
In 2020, community-scale GHG emissions were 15,156,347 metric tons of
carbon dioxide equivalents (MT CO2e).
•
2020 community-scale GHG emissions were 14.0% lower than the 2012 levels of
17,622,666 MT CO2e (Figure ES-1).
• Stationary Energy Sector GHG emissions totaled 7,406,849 MT CO2e.
• Transportation Sector GHG emissions totaled 7,461,649 MT CO2e.
• Waste Sector GHG emissions totaled 287,850 MT CO2e.
• GHG emissions decreased 14% during a period when the City’s population grew
12.1% and the metro area economy grew 41.6%.
1 Greenhouse Gas Protocol. (n.d.). GHG Protocol for Cities | Greenhouse Gas Protocol. Retrieved from
http://www.ghgprotocol.org/greenhouse-gas-protocol-accounting-reporting-standard-cities
9
• GHG emissions per capita fell 23.3% from the 2012 baseline of 11.75 MT CO2e
to 9.02 MT CO2e in 2020.
Figure ES-1. GHG emissions by emissions sector for 2012, 2016, 2018, and 2020.
The distribution of GHG emissions between Stationary Energy, Transportation, and
Waste Sectors for four community GHG inventories is detailed in Table ES-1.
Table ES-1. Phoenix GHG emissions by Sector (MT CO2e)
Sector
2012
2016
2018
2020
% Change
2012 -2020
Stationary Energy
9,431,639
8,810,561
8,552,674
7,406,849
-21.5%
Transportation
7,823,097
8,255,732
8,464,774
7,461,649
-4.6%
Waste
367,931
316,170
304,066
287,850
-21.8%
Total
17,622,666 17,382,463 17,321,514 15,156,347
-14.0%
Stationary Energy
Stationary Energy is the second largest source of GHG emissions in Phoenix. These
GHG emissions occur from energy utilized in residential buildings; commercial buildings
and facilities; manufacturing industries; agriculture, forestry and fishing energy use; and
electricity transmission and distribution energy losses.
10
Figure ES-2. Stationary Energy GHG emissions for 2012, 2016, 2018, and 2020.
In 2020, Stationary Energy GHG emissions were 7,406,849 MT CO2e; a 21.5%
decrease below 2012 levels. Electricity-based GHG emissions decreased significantly
mainly due to the retirement of the Navajo Generating Station, which decreased the
carbon intensity of electricity consumed in Phoenix. Data to calculate Stationary Energy
GHG emissions were obtained from Arizona Public Service (electricity), Salt River
Project (electricity), Southwest Gas (natural gas), and the Energy Information
Administration (electricity transmission and distribution loss). Figure ES-2 shows the
distribution of GHG emissions between different sub-sectors in the Stationary Energy
Sector and Table ES-2 details the GHG emissions by subsector.
Table ES-2. Subsector Stationary Energy GHG Emissions (MT CO2e)
Stationary Energy
2012
2016
2018
2020
Residential Buildings
4,093,323 3,939,273 3,752,152 3,457,002
Commercial & Institutional Buildings
4,853,598 4,454,805 4,745,669 3,831,741
Manufacturing Industries & Construction
415,704
364,647
8,303
72,459
Agriculture, Forestry & Fishing Activities
68,954
51,758
46,477
45,523
Non-Specified Sources
60
78
74
123
Total
9,431,639 8,810,561 8,552,674 7,406,849
Transportation
In 2020, the Transportation Sector was the largest source of GHG emissions in
Phoenix. Transportation GHG emissions sources occur from commercial air travel, civil
aviation, on-road transportation, non-road vehicle use, light rail, and freight rail. GHG
emissions result from the combustion of fossil fuels (gasoline, diesel, CNG, LNG, LPG,
11
aviation gasoline, jet fuel A), blended alternative fuels (B20 biodiesel, E85 Ethanol, E54
Ethanol), or indirectly through the consumption of electricity to charge electric vehicles.
Transportation GHG emissions for 2020 were 7,461,649 MT CO2e, a 4.6% decrease in
GHG emissions from the 2012 level of 7,823,097 MTCO2e (Figure ES-3).
Figure ES-3.Transportation GHG emissions for 2012, 2016, and 2018.
Transportation emissions decreased in 2020 due to decreased commuting and travel,
including air travel, caused in part by the COVID-19 pandemic, while at the same time
there was a marked increase in heavy truck delivery services. Data were obtained from
the City of Phoenix, Arizona Department of Transportation, the Weights and Measures
Division of the Arizona Department of Agriculture, the Federal Aviation Administration,
and the Energy Information Administration. Table ES-3 details GHG emissions among
Transportation sub-sectors for the years 2012, 2016, 2018, and 2020.
Table ES-3. Subsector Transportation GHG Emissions (MT CO2e)
Transportation
2012
2016
2018
2020
On-road transport
5,855,958
6,446,392
6,595,753
6,050,418
Railways
29,113
29,300
31,541
28,792
Commercial Aviation
1,626,397
1,448,210
1,494,963
1,039,280
Civil Aviation (Aviation Gasoline)
13,392
11,708
16,164
16,801
Off-road transport
298,237
320,122
326,353
326,353
Total
7,823,097
8,255,732
8,464,774
7,461,649
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Waste
The Waste Sector includes emissions from the current and historic disposal of solid
waste generated and treated in Phoenix, the current disposal of solid waste generated
in Phoenix that is disposed outside the city, wastewater treated at the 91st Avenue and
23rd Avenue wastewater treatment plants in Phoenix, and the composting of waste
generated in Phoenix. The total GHG emissions from the Waste Sector was 287,850
MT CO2e in 2020 as compared to 367,931 MT CO2e reported in 2012 (Table ES-4).
Waste Sector GHG emission reductions were driven by multiple factors. First, while
Solid Waste GHG emissions will occur from the ongoing disposal of solid waste,
historic, closed landfills within the city of Phoenix would produce less GHG emissions
over time as the waste decays. Second, the capture and reuse of flared methane biogas
at the 91st Avenue Wastewater Treatment Plant led to a decrease in wastewater
treatment GHG emissions despite Phoenix’s population growing significantly between
2012 and 2020.
Table ES-4. Subsector Waste Sector GHG Emissions (MT CO2e)
Waste
2012
2016
2018
2020
Solid Waste Disposal
353,689 302,773 285,742 273,395
Wastewater Treatment & Discharge
8,440
9,428
10,199
8,094
Biological Waste Treatment (Composting)
5,802
3,968
8,125
6,360
Total
367,931 316,170 304,066 287,850
Conclusion
In 2020, citywide GHG emissions in Phoenix were 15,133,075 metric tons CO2e –
14.1% below the 2012 levels of 17,622,666 MT CO2e. Stationary Energy GHG
emissions decreased 2,051,816 MT CO2e below 2012 levels due to decarbonization of
the regional electricity grid. Transportation Sector GHG emissions decreased to 4.7%
below 2012 levels possibly due to the travel and commuting impacts of the COVID-19
pandemic. Waste Sector GHG emissions decreased by 21.8% between 2012 and 2020,
but are small compared to the Stationary Energy and Transportation sectors. While
Solid Waste GHG emissions will occur from the ongoing disposal of solid waste, closed
landfills within the City will produce less GHG emissions as the waste decays.
Despite falling below 2012 levels, the Transportation Sector was the largest source of
GHG emissions in Phoenix in 2020. The largest source of Transportation Sector GHG
emissions is gasoline and diesel use in private vehicles. The COVID-19 pandemic
greatly affected transportation behavior, causing a decrease in gasoline consumption
and an increase in diesel consumption between 2018 and 2020. The decrease in
Transportation Sector GHG emissions in 2020 will likely be temporary and measures to
reduce transportation-related GHG emissions will drive future community-scale GHG
emissions. An increased adoption of battery electric vehicles (BEVs), fuel cell electric
vehicles (FCEVs), plugin electric hybrid vehicles (PEHVs), or hydrogen vehicles can
reduce transportation-related GHG emissions. Another is higher adoption rate of mass
transit options.
13
Introduction
City of Phoenix community-scale GHG emissions were inventoried according to the
Greenhouse Gas Protocol for Cities (GPC). The GPC has five GHG emissions sectors –
Stationary Energy, Transportation, Waste, Industrial Processes and Product Use
(IPPU), and Agriculture, Forestry, and Land Use (AFOLU). The city of Phoenix
Community-scale GHG emissions inventory is a BASIC-level inventory. A BASIC-level
community GHG emissions inventory includes: all scope 1 emissions from Stationary
Energy sources (excluding energy production supplied to the grid, which shall be
reported in the scope 1 total); all scope 1 emissions from Transportation sources; all
scope 1 emissions from Waste sources (excluding emissions from imported waste,
which shall be reported in the scope 1 total); all scope 2 emissions from Stationary
Energy sources and transportation; scope 3 emissions from treatment of exported
waste. IPPU and AFOLU are not required to be inventoried for BASIC-level reporting
under the GPC.
In 2020, community-scale emissions totaled 15,160,180 MT CO2e, 14.0% decrease
below the baseline 2012 level of 17,622,666 MT CO2e (Table 1). Appendix A contains a
detailed breakdown of GPC sector and subsector GHG emissions for the 2012, 2016,
2018, and 2020 inventories. Stationary Energy and Transportation Sectors account for
approximately 99% of community-scale GHG emissions. On-road motor gasoline
combustion is the single largest source of GHG emissions, and comprises 71%
Transportation emissions and 35% of total emissions. The next largest source of GHG
emissions is commercial and industrial electricity consumption, which makes up 23% of
total emissions. Moreover, the top three emitting sources – on-road motor gasoline
consumption, commercial and industrial electricity consumption, and residential
electricity consumption – are 78.6% of total emissions. Since GHG emissions from
electricity consumption will likely decrease into the future due to the increased
decarbonization of the regional electricity grid, GHG emissions from on-road motor
gasoline consumption will likely remain the single largest source of GHG emissions for
the City. Policies to reduce gasoline consumption across Phoenix are critical to meeting
future GHG emissions targets and goals.
Table 1. Community- Level GHG Emissions by Sector for 2012, 2016, and 2018
Sector
GHG Emissions (MT CO₂e)
%
Change
2012-20
2012
2016
2018
2020
Stationary Energy
9,431,639
8,810,561
8,552,674
7,406,849
-21.5%
Transportation
7,823,097
8,255,732
8,464,774
7,461,649
-4.6%
Waste
367,931
316,170
304,066
287,850
-21.8%
Total
17,622,666
17,382,463
17,321,514
15,156,347
-14.0%
The observed decreases in community-scale GHG emissions were driven by the
regional electricity grid becoming less GHG-intensive. GHG emissions from electricity
production fell by 2,024,790 MT CO2e (21.5%) between 2012 and 2020. Transportation
14
Sector GHG emissions decreased by 357,614 MT CO2e (4.6%). Waste GHG emissions,
which are approximately 2% of community-scale GHG emissions, decreased by 80,081
MT CO2e (21.8%) between 2012 and 2020. Per capita GHG emissions fell by 23.3%
from 11.75 to 9.02 MT CO2e per resident between 2012 and 2020 (Figure 1).
Figure 1. Total GHG Emissions and Per Capita GHG Emissions Since 2012
GHG emissions are assigned to scopes based on where the emitting activity occurs.
Scope 1 GHG emissions occur directly within city boundaries from transportation
activities, natural gas combustion, and waste disposal. Scope 2 GHG emissions are
indirect GHG emissions through the purchase of grid-supplied energy, such as
electricity and do not necessarily occur within city boundaries. Scope 3 GHG emissions
are other indirect emissions from waste disposed of outside the city boundary. In 2020,
55% of GHG emissions occurred directly within the city boundary as Scope 1
emissions; 44% occurred indirectly as Scope 2 emissions through the purchase of
electricity; and approximately 1% occurred indirectly as Scope 3 emissions from waste
disposed of outside the city boundary (Table 2)
Table 2. 2018 Community-Level GHG Emissions by Sector and Scope
Sector
GHG Emissions (MT CO₂e)
Scope 1
Scope 2
Scope 3
Total
Stationary Energy
788,752
6,618,097
264,434
7,406,849
Transportation
7,448,545
13,104
548
7,461,649
Waste
139,649
0
148,200
287,850
Total
8,376,946
6,631,201
148,200
15,156,347
*Scope 3 Stationary Energy and Transportation GHG emissions do not count toward the BASIC-level
GHG emissions total.
15
In 2020, Stationary Energy activities – GHG emissions resulting from natural gas
combustion and electricity consumption – accounted for approximately 48.8% of
community-scale GHG emissions. Transportation activities comprise approximately
49.3%. Community-scale Transportation Sector GHG emissions have increased relative
to Stationary Energy Sector GHG emissions since 2012. Gasoline combustion produced
71% of Transportation GHG Sector emissions within city boundaries. The two largest
sources of GHG emissions produced 78.6% of total community-scale GHG emissions –
electricity consumption (43.6%) and gasoline combustion (35.0%). Community-level
GHG mitigation efforts should prioritize these two sources of GHG emissions to achieve
material GHG emissions reductions.
Recent plant closures and announcements by Arizona Public Service2 (APS), Salt River
Project3 (SRP) and the Public Service Company of New Mexico4 (PNM) to retire and
replace coal-fired power plants with generation sources that are less carbon intensive
will result in significant reductions to community-scale GHG emissions. The single
largest GHG emissions source in the regional electricity grid – the Navajo Generating
Station operated by SRP – closed in 2019. In fact, the measure of the carbon intensity
of the electricity grid – fell by 17.3% between 2018 and 2020.
Motor gasoline consumed for on-road transportation is the single largest GHG emitting
activity in Phoenix. These emissions grew between 2012 and 2018, but fell back to
2012 levels in 2020 largely due to the COVID-19 pandemic. GHG emissions from
gasoline consumption will likely rebound as activities return to pre-pandemic levels.
Therefore, the viability and cost effectiveness of strategies to reduce GHG emissions
from Transportation activities, specifically on-road motor gasoline consumption, will
drive future community-scale GHG emissions and the ability to meet GHG emissions
reductions goals.
2 Arizona Public Service (2020). Stakeholder Perspectives. URL: https://www.aps.com/en/About/Our-Company/Clean-
Energy/Stakeholder-Perspectives
3 Salt River Project (2019). Navajo Generating Station Permanently Shuts Down. URL: https://media.srpnet.com/navajo-generating-
station-permanently-shuts-down/
4 PNM (2020). Our Commitment. URL: https://www.pnm.com/our-commitment
16
1. Stationary Energy Sector
Stationary Energy GHG emissions are predominantly Scope 2 emissions, which occur
from electricity consumption (Figure 2). These emissions occur due to the combustion
of natural gas (Scope 1) and the consumption of purchased electricity (Scope 2).
Scope 2 Stationary Energy GHG emissions are the second largest of Phoenix’s GHG
emissions sources, comprising 48.9% of community-scale emissions in 2012; 46.1% in
2016; 44.9% in 2018; and 43.7% in 2020. However, because the carbon intensity of the
regional electricity grid decreased significantly, electricity-related GHG emissions
decreased 23% between 2012 and 2020 despite electricity consumption increasing
4.7%.
Figure 2. Stationary Energy GHG Emissions by Scope Since 2012
Electricity GHG emissions are calculated using electricity consumption data (activity
data) and GHG emissions factors published by the EPA in the eGRID.5 The Arizona-
New Mexico (AZNM) subregion GHG emissions factor is used to calculate electricity
GHG emissions. An eGRID subregion emissions factor is not utility-specific, and
characterizes the typical GHG profile of electricity generation in that area in CO2e
emissions per MWh of net generation. The AZNM subregion includes power plants in
Arizona, Western and Central New Mexico, Southern Nevada, and parts of
5 The eGRID database inventories plant-level environmental attributes of electric power generation and its effect on air emissions for
every power plant in the United States. Phoenix is in the Arizona and New Mexico (AZNM) subregion. The Emissions & Generation
Resource Integrated Database (eGRID), developed by the EPA in collaboration with the Energy Information Administration (EIA),
the North American Electric Reliability Corporation (NERC), and the Federal Energy Regulatory Commission (FERC), is a
comprehensive source of data on the environmental characteristics of almost all electric power generated in the United
States. Detailed information can be found at http://www.epa.gov/cleanenergy/energy-resources/egrid/index.html.
17
southwestern California. Since 2012, the AZNM subregion GHG emissions factor has
decreased 26.6% due to increased natural gas and renewable electricity generation,
and most importantly, a decrease in coal-fired electricity generation. The largest source
of GHG emissions in the AZNM subregion, SRP’s coal-fired Navajo Generating Station,
closed in 2019.6 Between 2018 and 2020, the AZNM subregion GHG emissions factor
dropped 17.3%, contributing to a substantial decrease in Phoenix’s GHG emissions.
Two factors were largely responsible for the observed decrease in the AZNM subregion
GHG emissions factor: (1) the closure of the Navajo Generating Station (NGS) coal-
fired plant and (2) new generation brought online between 2018 and 2020 were mostly
carbon-neutral electricity sources.7,8 Looking to the future, SRP has a long-term goal of
reducing the GHG-intensity of electricity production 65% below 2005 levels by 2035 and
90% by 20509; APS has stated it will cease using coal to generate electricity by 203110
and has a carbon neutrality goal for 205011; PNM plans to generate 100% carbon free
electricity by 2040.12 Utility plans to reduce the GHG-intensity of electricity generation
will significantly reduce Phoenix’s GHG emissions even further.
1.1 Scope 1 Stationary Energy
Scope 1 Stationary Energy GHG emissions occur, in part, from natural gas combustion
within the city boundary. In 2020, citywide natural gas consumption was 2.9% greater
than 2012 levels and 13.6% greater than 2018 levels (Table 3).
Table 3. Summary of Scope 1 Stationary Energy GHG Emissions
Scope 1 Activity Data (kilotherms)
2012
2016
2018
2020
Residential Buildings
58,796
58,946
53,241
60,479
Commercial & Industrial Buildings
63,802
69,036
83,367
65,688
Manufacturing Industries & Construction
16,289
13,850
1,562
13,632
Agriculture, Fishing, and Forestry
Activities
12,982
9,737
8,744
8,564
Non-specified
11
15
14
23
Total
151,881
151,584
146,927
148,386
Scope 1 GHG Emissions
(MT CO2e)
2012
2016
2018
2020
Residential Buildings
312,298
313,330
283,007
321,480
Commercial & Industrial Buildings
338,887
366,966
443,139
349,167
Manufacturing Industries & Construction
86,522
73,622
8,303
72,459
6 Salt River Project (2019). Navajo Generating Station Permanently Shuts Down. URL: https://media.srpnet.com/navajo-generating-
station-permanently-shuts-down/
7 Environmental Protection Agency (2020). eGRID2018 Unit, Generator, Plant, State, Balancing Authority Area, eGRID Subregion,
NERC Region, U.S., and Grid Gross Loss (%) Data Files.
8 Environmental Protection Agency (2022). eGRID2020 Unit, Generator, Plant, State, Balancing Authority Area, eGRID Subregion,
NERC Region, U.S., and Grid Gross Loss (%) Data Files
9 Salt River Project (2022). 2035 Sustainability Goals Delivering today, shaping tomorrow. URL:
https://www.srpnet.com/environment/sustainability/2035-goals.aspx. Accessed 10 March 2022.
10 Arizona Public Service (2020). Clean Energy. URL: https://www.aps.com/en/About/Our-Company/Clean-Energy
11 Arizona Public Service (2020). Stakeholder Perspectives. URL: https://www.aps.com/en/About/Our-Company/Clean-
Energy/Stakeholder-Perspectives
12 PNM (2020). Our Commitment. URL: https://www.pnm.com/our-commitment
18
Agriculture, Fishing, and Forestry
Activities
68,954
51,758
46,477
45,523
Non-specified
60
78
74
123
Total
806,722
805,753
781,000
788,752
Scope 1 Stationary Energy GHG emissions fell by 25,722 MT CO2e below 2012 levels
(Figure 3). Natural gas consumption at commercial and institutional buildings are the
largest source of Scope 1 Stationary Energy GHG emissions. In 2012, Scope 1
Stationary Energy GHG emissions from commercial and institutional buildings and
facilities subsector were only slightly higher than the residential buildings subsector,
42% and 39% respectively. In 2018, the commercial and institutional buildings and
facilities subsector comprised 57% of Scope 1 Stationary Energy GHG emissions.
Figure 3. Scope 1 Stationary GHG Emissions Since 2012
1.2 Scope 2 Stationary Energy
Scope 2 Stationary Energy GHG emissions occur from the consumption of electricity
purchased from APS and SRP within the city boundary. Between 2012 and 2020,
electricity increased 4.7% (809,198 MWh) and between 2018 and 2020, electricity
increased 2.9% (508,825 MWh) (Table 4). In 2020, Scope 2 Stationary Energy GHG
emissions were 6,618,097 MT CO2e, which was 23.3% below 2012 levels (Figure 4).
Stationary Energy GHG emissions decreased due to the regional electricity grid
becoming 35.4% less GHG-intensive between 2012 and 2020 from the retirement and
replacement of coal-fired power plants with natural gas and renewable (wind and solar)
19
electricity generation.13 Additionally, between 2012 and 2020, commercial and industrial
electricity consumption only grew 5.1% during a period in which GDP grew
approximately 41.6%. The decreased growth in electricity consumption relative to
economic growth could have occurred for numerous reasons, including energy
efficiency retrofits, energy efficient new construction, and commercial solar adoption.
Further work is recommended to explore the extent each of these factors contributed to
the decreased growth in electricity consumption.
Table 4. Summary of Scope 2 Stationary Energy GHG Emissions
Scope 2 Activity Data (GWh)
2012
2016
2018
2020
Residential Buildings
7,202
7,620
7,444
8,132
Commercial & Industrial Buildings
8,599
8,579
9,220
9,046
Manufacturing Industries & Construction
627
612
IE
IE
Total
16,428
16,815
16,671
17,199
Scope 2 GHG Emissions (MT CO2e)
2012
2016
2018
2020
Residential Buildings
3,781,025
3,625,943
3,469,145
3,135,523
Commercial & Industrial Buildings
4,514,711
4,087,840
4,302,529
3,482,574
Manufacturing Industries & Construction
329,182
291,025
IE
IE
Total
8,624,917
8,004,808
7,771,674
6,618,097
*In 2018, Manufacturing industries and construction were IE in Commercial and institutional buildings.
Scope 2 Stationary Energy GHG emissions from Energy Industries; AFFA; and Non-Specified Sources
were assumed to be included elsewhere (IE) and, therefore, not included in this table. Scope 2
Stationary Energy GHG emissions Fugitive Emissions from MPST; and Fugitive Emissions from ONGS
were NE and, therefore, not included in this table
13 The Emissions & Generation Resource Integrated Database (eGRID), developed by the EPA in collaboration with the Energy
Information Administration (EIA), the North American Electric Reliability Corporation (NERC), and the Federal Energy Regulatory
Commission (FERC), is a comprehensive source of data on the environmental characteristics of almost all electric power generated
in the United States. Detailed information can be found at http://www.epa.gov/cleanenergy/energy-resources/egrid/index.html. The
11.2% reduction in the GHG intensity of the regional electricity was calculated comparing the 2012 and 2018 emissions factor for
the Arizona-New Mexico subregion.
20
Figure 4. Scope 2 Stationary GHG Emissions Since 2012
1.3 Scope 3 Stationary Energy
Scope 3 Stationary Energy GHG emissions occur from transmission and distribution
loss in the state’s electricity grid and fluctuates from year-to-year (Table 5). Between
1990 and 2020, transmission and distribution (T&D) loss in the State of Arizona has
averaged 4.5% ± 0.7% of electricity consumption and has ranged between 3.4% in
2015 up to 5.7% in 1996.14 Scope 3 Stationary Energy GHG emissions are not within
the scope of GPC BASIC-level reporting. Nonetheless, these GHG emissions are
calculated to show the full extent of GHG emissions from electricity consumption.
Table 5. Summary of Scope 3 Stationary Energy GHG Emissions
Scope 3 Activity Data
2012
2016
2018
2020
Transmission & Distribution Loss (MWh)
613,573
631,792
666,138
685,863
Natural Gas Leakage (therms)
NE
NE
NE
NE
Total
613,573
631,792
666,138
685,863
Scope 3 GHG Emissions (MT CO2e)
2012
2016
2018
2020
Transmission & Distribution Loss (MWh)
322,125
300,632
310,345
264,434
Natural Gas Leakage (therms)
NE
NE
NE
NE
Total
322,125
300,632
310,345
264,434
*NE – Not Estimated
14 U.S. Energy Information Administration, Form EIA-923, Power Plant Operations Report and predecessor forms. U.S. Energy
Information Administration, Form EIA-860, Annual Electric Generator Report. U.S. Energy Information Administration, Form EIA-
861, Annual Electric Power Industry Report. Form EIA-111, Quarterly Imports and Exports Report.
21
2. Transportation Sector
Transportation Sector GHG emissions have Scope 1, 2, and 3 components. Scope 1
Transportation Sector GHG emissions occur due to the combustion of fossil fuels –
gasoline, diesel, CNG, LNG, LPG – and biofuel blends – B20 biodiesel and E85
ethanol. Scope 2 Transportation Sector GHG emissions occur from the consumption of
electricity to charge plug-in electric vehicles and power electric light rail; and Scope 3
emissions occur from the T&D loss associated with Scope 2 transportation. In 2020,
community-scale Transportation sector GHG emissions totaled 7,461,649 MT CO2e and
were 4.6% less than the 2012 levels of 7,823,097 MT CO2e.
Motor gasoline is the largest source of community-scale Transportation Sector GHG
emissions at 71.0% and 35% of all community-scale GHG emissions (Figure 5).
Community-level gasoline consumption encompasses all gasoline end uses. While
some end uses may not be for transportation purposes (e.g., gasoline lawnmowers),
emissions from these end uses were assumed to be insignificant compared to gasoline
consumption for motor vehicles.15 GHG emissions from Jet Fuel A (13.9%) and on-road
diesel fuel (8.8%) are the next largest sources of transportation GHG emissions. While
Transportation Sector GHG emissions showed a decrease between 2012 and 2020, this
may be a result of the COVID-19 pandemic. In previous inventories, GHG emissions
from gasoline combustion has grown with population. As growth occurs, viable solutions
to reduce gasoline consumption – from EVs and increased mass transit to creating
walkable communities – are critical for meeting GHG emissions reductions goals.
Figure 5. Summary of Transportation Sector GHG Emissions by Fuel Type
15 The U.S. Energy Information Administration estimates light-duty vehicles account for 92% of gasoline consumption in the United
States. Source: U.S. Energy Information Administration, 2019. Use of Gasoline. URL:
https://www.eia.gov/energyexplained/gasoline/use-of-gasoline.php
22
2.1 Scope 1 Transportation GHG Emissions
Scope 1 Transportation GHG emissions occur from the combustion of fossil fuels and
biofuel blends in on-road motor vehicles, commercial and civil aircrafts, freight rail, and
nonroad vehicles such as tractors and construction equipment (Table 6). Before 2020,
on-road transport GHG emissions growth (12.7%) had largely followed population
growth (12.7%). The second largest source of community-scale Transportation sector
GHG emissions comes from Commercial Aviation, which is almost primarily from the
Phoenix Sky Harbor International Airport. In 2020, Commercial Aviation GHG emissions
were revised upwards for all inventory years due to revised source data from the EIA.
Community-level GHG emissions from off-road transport, which is the third largest
source of community-scale Transportation sector GHG emissions, result from
construction equipment, agricultural equipment and mining equipment.
Table 6. Summary of Scope 1 Transportation GHG Emissions (MT CO2e)
Scope 1 Sources
2012
2016
2018
2020
On-road transport
5,855,292
6,441,344
6,586,630
6,042,566
Railways*
23,545
23,545
23,545
23,545
Commercial Aviation
1,626,397
1,448,210
1,494,963
1,039,280
Civil Aviation
13,392
11,708
16,164
16,801
Nonroad transport
298,237
320,122
326,353
326,353
Total
7,816,863
8,244,929
8,447,655
7,448,545
*Freight rail GHG emissions have not been re-estimated since the 2012 community inventory due to constraints with source data.
Gasoline consumption is the major driver of Scope 1 Transportation GHG Emissions
(Additionally, the further development and marketability and adoption of hydrogen
vehicles will further reduce on-road GHG emissions and should explored as a strategy
to displace fossil fuels.
Table 7). Between 2012 and 2020, fuel consumption increased across every fuel type
except LNG and B20 biodiesel. The city of Phoenix vehicle fleet – e.g., buses and
garbage and recycling trucks – is the primary consumer of LNG and B20 biodiesel.
Additionally, the further development and marketability and adoption of hydrogen
vehicles will further reduce on-road GHG emissions and should explored as a strategy
to displace fossil fuels.
Table 7. Scope 1 Transportation Activity Data and GHG Emissions by Fuel
Scope 1 GHG Emissions (MT CO2e)
2012
2016
2018
2020
Gasoline 1
5,250,540
5,797,934
5,917,671
5,299,647
On-Road Diesel1
529,242
591,063
617,575
660,148
B20 Biodiesel1
24,785
22,062
24,732
35,199
E85 Ethanol1
379
207
410
441
E54 Ethanol 1
0
441
0
0
CNG1 – therms
22,595
18,293
33,391
27,484
LNG1 – GGE
27,751
11,345
2,423
19,647
Jet Fuel A (Commercial Aviation)2
698,263
705,643
779,113
1,039,280
Aviation Gasoline (Civil Aviation)2
13,394
15,067
10,043
16,801
Railways**
23,545
23,545
23,545
23,545
Nonroad Diesel3
148,488
163,595
169,826
169,826
Nonroad LPG3
149,749
156,527
156,527
156,527
23
Total
6,888,732
7,505,722
7,735,257
7,448,545
*Activity Data are reported in gallons unless otherwise noted; NE – Not Estimated. Emissions estimated from EPA National
Emissions Inventory; Italicized entries denote Activity Data estimated from EPA National Emissions Inventory; **Emissions
estimated from the EPA National Emissions Inventory and not activity data; Transportation Sector: 1On-Road Sector; 2Aviation;
2Off-Road.
2.2 Scope 2 Transportation GHG Emissions
The 2020 levels of Scope 2 Transportation sector GHG emissions are 172% higher than
2012, but 1.1% lower 2018 levels (Table 8). The growth of Scope 2 Transportation
sector GHG emissions is primarily from the increased adoption of plug-in electric
vehicles. The estimated electricity consumption by EVs has increased 16-fold since
2012, but EVs are currently a small fraction of the on-road vehicle fleet. GHG emissions
related to the Valley Metro light rail system increased 33% due to the expansion of the
light rail system since 2012. GHG emissions from electric transport are a small
percentage of overall transportation-related GHG emissions (~0.2%). As the regional
electricity grid becomes less GHG-intensive over the coming decades, the use of
electric personal transport – plugin EVs and plugin hybrid EVs – and electric mass
transit – light rail and battery electric buses – will become GHG-saving alternatives to
traditional gasoline-powered personal vehicles. Increasing electric-powered transit will
require investment in electric mass transit, which is underway through T2050, battery
technology improvements, installing a regional charging station network, and consumer-
friendly market conditions.
Table 8. Summary of Scope 2 Transportation GHG Emissions
Scope 2 Activity Data (MWh)
2012
2016
2018
2020
On-road transport
1,269
10,608
19,576
20,368
Railways (Light Rail)
10,605
12,095
17,157
13,624
Total
11,874
22,703
36,733
33,991
Scope 2 GHG Emissions (MT CO2e)
2012
2016
2018
2020
On-road transport
666
5,048
9,123
9,490
Railways (Light Rail)
5,568
5,755
7,996
7,447
Total
6,234
10,803
17,119
16,937
2.3 Scope 3 Transportation GHG Emissions
Scope 3 Transportation GHG emissions occur from transmission and distribution loss in
the state’s electricity grid (Table 9). Scope 3 Transportation GHG emissions are not
within the scope of GPC BASIC-level reporting and presented for informational
purposes. Refer to the Scope 3 Stationary Energy section for a more detailed
discussion on T&D loss in the State of Arizona.
Table 9. Summary of Scope 3 Transportation GHG Emissions
Scope 3 Activity Data (MWh)
2012
2016
2018
2020
On-road transport
47
399
708
852
Railways (Light Rail)
396
454
620
570
Total
443
853
1,328
1,422
Scope 3 GHG Emissions (MT CO2e)
2012
2016
2018
2020
On-road transport
25
190
330
397
24
Railways (Light Rail)
208
216
289
266
Total
233
406
619
663
3. Waste Sector
Waste Sector GHG emissions have both Scope 1 and Scope 3 components (Table 11).
Unlike Scope 3 emissions in the Stationary Energy and Transportation sectors, Scope 3
Waste emissions are included within the GPC BASIC-level reporting. Overall, Waste
Sector GHG emissions decreased 21.8% (80,081 MT CO2e) between 2012 and 2020.
Table 10. Summary of Waste Sector GHG Emissions
Waste Sector GHG Emissions (MT CO2e)
2012
2016
2018
2020
Scope 1 Waste Emissions
250,130 156,167 150,118 139,649
Scope 3 Waste Emissions
117,800 160,003 153,948 148,200
Total
367,931 316,170 304,066 287,850
Scope 1 Waste Sector GHG emissions include emissions from municipal solid waste
and wastewater generated and treated within the city boundary in addition to waste
imported into the city and treated (Table 11). Scope 1 Waste Sector sources include the
following facilities:
• The 23rd Avenue and 91st Avenue wastewater treatment plants.
• Emissions from composting– the biological treatment of waste –at the 27th
Avenue Compost Facility. Prior to 2018, a different facility operated at the 27th
Avenue Landfill.
• Closed landfills within in the city of Phoenix boundary. Over time, these
emissions will decrease as the biological processes that generate methane
decrease. The last city-owned landfill to accept waste within the City boundary
closed in 2006 and the last privately-owned landfill to accept waste within the city
boundary – the Waste Management Lone Cactus Landfill – closed in 2019.
Table 11. Summary of Scope 1 Waste GHG Emissions
Scope 1 Sources Activity Data (MT CH4)
2012
2016
2018
2020
Disposal of Solid Waste Generated in the City
8,425
5,099
4,707
4,471
Biological Treatment of Waste Generated in the City
121
83
170
133
Wastewater Generated Inside the City
92
121
135
76
Total
8,638
5,303
5,011
4,680
Scope 1 Sources Activity Data (MT N2O)
2012
2016
2018
2020
Biological Treatment of Waste Generated in the City
9
6
13
10
Wastewater Generated Inside the City
22
23
24
23
Total
31
29
37
32
Scope 1 GHG Emissions (MT CO2e)
2012
2016
2018
2020
Disposal of Solid Waste Generated in the City
235,889 142,771 131,794 125,195
Biological Treatment of Waste Generated in the City
5,802
3,968
8,125
6,360
Wastewater Generated Inside the City
8,440
9,428
10,199
8,094
Total
250,130 156,167 150,118 139,649
25
Scope 3 Waste GHG emissions occur from the disposal of waste generated within the
city but disposed outside the city (Table 12). As GHG emissions are expected to
increase at the SR-85 landfill, methane capture and reuse programs may become a
viable way to reduce waste-related emissions, and offset Scope 1 Stationary Energy
GHG emissions from natural gas combustion. Organic waste diversion to the compost
facility at 27th Avenue is a viable way to reduce future Waste Sector GHG emissions.
Similarly, the capture of digester gas at the 91st Avenue Wastewater Treatment Plant
(WWTP) for processing and sale as renewable natural gas (RNG) by Ameresco, Inc.
will reduce Waste Sector GHG emissions from wastewater treatment.
Table 12. Summary of Scope 3 Waste GHG Emissions
Scope 3 Sources Activity Data (MT CH4
Emissions)
2012
2016
2018
2020
Disposal of Solid Waste Generated in the City
but Disposed Outside the City at SR-85
295
2,147
2,029
2,301
Disposal of Solid Waste Generated in the City
but Disposed Outside the City by Private Haulers
3,912
3,567
3,469
2,992
Total
4,207
5,714
5,498
5,293
Scope 3 GHG Emissions (MT CO2e)
2012
2016
2018
2020
Disposal of Solid Waste Generated in the City
but Disposed Outside the City at SR-85
8,260
60,116
56,820
64,416
Disposal of Solid Waste Generated in the City
but Disposed Outside the City by Private Haulers
109,540
99,887
97,128
83,784
Total
117,800 160,003 153,948 148,200
26
Appendix A. Detailed GHG Emissions
Summary
Appendix A contains tables detailing City of Phoenix community-scale GHG emissions
by each GPC sector and subsector.
27
Table A1. Year-to-Year Comparison of Stationary Energy GHG Emissions
GPC
ref No. Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas Emissions
(metric tons CO₂e)
2012
2016
2018
2020
I
Stationary Energy
I.1
Residential Buildings
I.1.1
1
Emissions from fuel combustion within the city boundary
312,298
313,330
283,007
321,480
I.1.2
2
Emissions from grid-supplied energy consumed within the city
boundary
3,781,025 3,625,943 3,469,145 3,135,523
I.1.3
3
Emissions from transmission and distribution losses from grid-
supplied energy consumption
141,216
136,245
138,614
125,284
I.2
Commercial and institutional buildings and facilities
I.2.1
1
Emissions from fuel combustion within the city boundary
338,887
366,966
443,139
349,167
I.2.2
2
Emissions from grid-supplied energy consumed within the city
boundary
4,514,711 4,087,840 4,302,529 3,482,574
I.2.3
3
Emissions from transmission and distribution losses from grid-
supplied energy consumption
168,618
153,600
171,913
139,151
I.3
Manufacturing industries and construction
I.1.1
1
Emissions from fuel combustion within the city boundary
86,522
73,622
8,303
72,459
I.1.2
2
Emissions from grid-supplied energy consumed within the city
boundary
329,182
291,025
IE
IE
I.2.3
3
Emissions from transmission and distribution losses from grid-
supplied energy consumption
12,294
10,935
IE
IE
I.4
Energy Industries
I.4.1
1
Emissions from energy used in power plant auxiliary operations
within the city boundary
NE
NE
NE
NE
I.4.2
2
Emissions from grid-supplied energy consumed in power plant
auxiliary operations within the city boundary
NE
NE
NE
NE
I.4.3
3
Emissions from transmissions and distribution losses from grid-
supplied energy consumption in power plant auxiliary operations
NE
NE
NE
NE
I.4.4
1
Emissions from energy generation supplied to the grid
986,289
1,200,633 1,391,552 1,659,111
I.5
Agriculture, forestry and fishing activities
I.5.1
1
Emissions from fuel combustion within the city boundary
68,954
51,758
46,477
45,523
I.5.2
2
Emissions from grid-supplied energy consumed within the city
boundary
IE
IE
IE
IE
28
GPC
ref No. Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas Emissions
(metric tons CO₂e)
2012
2016
2018
2020
I.5.3
3
Emissions from transmission and distribution losses from grid-
supplied energy consumption
IE
IE
IE
—
I.6
Non-specified sources
I.1.1
1
Emissions from fuel combustion within the city boundary
60
78
74
123
I.1.2
2
Emissions from grid-supplied energy consumed within the city
boundary
IE
IE
IE
IE
I.1.3
3
Emissions from transmission and distribution losses from grid-
supplied energy consumption
NO
NO
NO
NO
I.7
Fugitive emissions from mining, processing, storage, and
transportation of coal
I.7.1
1
Emissions from fugitive emissions within the city boundary
NO
NO
NO
NO
I.8
Fugitive emissions from oil and natural gas systems
I.8.1
1
Emissions from fugitive emissions within the city boundary
NE
NE
NE
NE
Notation Key
Definition
Explanation
Color Key
IE
Included
Elsewhere
GHG emissions for this activity are estimated and presented in another category of
the inventory. The category shall be noted in the explanation.
Sources required for
BASIC reporting
NE
Not Estimated Emissions occur but have not been estimated or reported; justification for exclusion
shall be noted in the explanation.
Sources required for
BASIC+ reporting
NO
Not Occurring An activity or process does not occur or exist within the city.
Sources included in Other
Scope 3
C
Confidential
GHG emissions which could lead to the disclosure of confidential information and
can therefore not be reported.
Sources required for
territorial reporting
Non-applicable emissions
Scope
Definition
Scope 1
GHG emissions from sources within the city boundary.
Scope 2
GHG emissions occurring as a consequence of the use of grid-supplied electricity, heat, steam
and/or cooling within the city boundary.
Scope 3
All other GHG emissions that occur outside the city boundary as a result of activities taking place
within the city boundary.
29
Table A2. Year-to-Year Comparison of Transportation GHG Emissions
GPC
ref
No.
Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas Emissions
(metric tons CO₂e)
2012
2016
2018
2020
II
Transportation
II.1
On-road Transportation
II.1.1
1
Emissions from fuel combustion for on-road transportation occurring
within the city boundary
5,855,292 6,441,344 6,586,630 6,042,566
II.1.2
2
Emissions from grid-supplied energy consumed within the city
boundary for on-road transportation
666
5,048
9,123
7,852
II.1.3
3
Emissions from portion of transboundary journeys occurring outside
the city boundary, and transmissions and distribution losses from
grid-supplied energy consumption
25
190
330
329
II.2
Railways
II.2.1
1
Emissions from fuel combustion for railway transportation occurring
within the city boundary
23,545
23,545
23,545
23,545
II.2.2
2
Emissions from grid-supplied energy consumed within the city
boundary for railways
5,568
5,755
7,996
5,253
II.2.3
3
Emissions from portion of transboundary journeys occurring outside
the city boundary, and transmissions and distribution losses from
grid-supplied energy consumption
208
216
289
220
II.3
Waterborne navigation
II.3.1
1
Emissions from fuel combustion for waterborne navigation occurring
within the city boundary
NO
NO
NO
NO
II.3.2
2
Emissions from grid-supplied energy consumed within the city
boundary for waterborne navigation
NO
NO
NO
NO
II.3.3
3
Emissions from portion of transboundary journeys occurring outside
the city boundary, and transmissions and distribution losses from
grid-supplied energy consumption
NO
NO
NO
NO
II.4
Aviation
II.4.1
1
Emissions from fuel combustion for aviation occurring within the city
boundary
1,639,788 1,459,918 1,511,127 1,056,081
II.4.2
2
Emissions from grid-supplied energy consumed within the city
boundary for aviation
NE
NE
NE
NE
30
GPC
ref
No.
Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas Emissions
(metric tons CO₂e)
2012
2016
2018
2020
II.4.3
3
Emissions from portion of transboundary journeys occurring outside
the city boundary, and transmissions and distribution losses from
grid-supplied energy consumption
NE
NE
NE
NE
II.5
Off-road transportation
II.5.1
1
Emissions from fuel combustion for off-road transportation occurring
within the city boundary
298,237
320,122
326,353
326,353
II.5.2
2
Emissions from grid-supplied energy consumed within the city
boundary for off-road transportation
IE
IE
IE
IE
Notation Key
Definition
Explanation
Color Key
IE
Included
Elsewhere
GHG emissions for this activity are estimated and presented in another category of
the inventory. The category shall be noted in the explanation.
Sources required for
BASIC reporting
NE
Not Estimated Emissions occur but have not been estimated or reported; justification for exclusion
shall be noted in the explanation.
Sources required for
BASIC+ reporting
NO
Not Occurring An activity or process does not occur or exist within the city.
Sources included in Other
Scope 3
C
Confidential
GHG emissions which could lead to the disclosure of confidential information and
can therefore not be reported.
Sources required for
territorial reporting
Non-applicable emissions
Scope
Definition
Scope 1
GHG emissions from sources within the city boundary.
Scope 2
GHG emissions occurring as a consequence of the use of grid-supplied electricity, heat, steam
and/or cooling within the city boundary.
Scope 3
All other GHG emissions that occur outside the city boundary as a result of activities taking place
within the city boundary.
31
Table A3. Year-to-Year Comparison of Waste GHG Emissions
GPC
ref
No.
Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas Emissions
(metric tons CO₂e)
2012
2016
2018
2020
III
Waste
III.1
Solid waste disposal
III.1.1
1
Emissions from solid waste generated within the city boundary and
disposed in landfills or open dumps within the city boundary
131,794 131,794 131,794 125,195
III.1.2
3
Emissions from solid waste generated within the city boundary and
disposed in landfills or open dumps outside the city boundary
117,800 160,003 153,948 148,200
III.1.3
1
Emissions from waste generated outside the city boundary and disposed in
landfills or open dumps within the city boundary
NO
NO
NO
NO
III.2
Biological treatment of waste
III.2.1
1
Emissions from solid waste generated within the city boundary that is
treated biologically within the city boundary
5,802
3,968
8,125
6,360
III.2.2
3
Emissions from solid waste generated within the city boundary but treated
biologically outside of the city boundary
NO
NO
NO
NO
III.2.3
1
Emissions from waste generated outside the city boundary but treated
biologically within the city boundary
NO
NO
NO
NO
III.3
Incineration and open burning
III.3.1
1
Emissions from solid waste generated treated within the city boundary
NO
NO
NO
NO
III.3.2
3
Emissions from solid waste generated within the city boundary but treated
outside of the city boundary
NO
NO
NO
NO
III.3.3
1
Emissions from waste generated outside the city boundary but treated
within the city boundary
NO
NO
NO
NO
III.4
Wastewater treatment and discharge
III.4.1
1
Emissions from wastewater generated and treated within the city boundary
8,440
9,428
10,199
8,094
III.4.2
3
Emissions from wastewater generated within the city boundary but treated
outside of the city boundary
NO
NO
NO
NO
III.4.3
1
Emissions from wastewater generated outside the city boundary but
treated within the city boundary
NO
NO
IE
IE
IV
Industrial Processes and Product Uses (IPPU)
IV.1
1
Emissions from industrial processes occurring within the city boundary
NE
NE
NE
NE
IV.2
1
Emissions from product use occurring within the city boundary
NE
NE
NE
NE
V
Agriculture, Forestry, and Other Land Use (AFOLU)
V.1
1
Emissions from livestock within the city boundary
NE
NE
NE
NE
32
GPC
ref
No.
Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas Emissions
(metric tons CO₂e)
2012
2016
2018
2020
V.2
1
Emissions from land within the city boundary
NE
NE
NE
NE
V.3
1
Emissions from aggregate sources and non-CO₂ emissions sources on
land within the city boundary
NE
NE
NE
NE
VI
Other Scope 3
VI.1
3
Other Scope 3
3,001
483
564
800
Notation Key
Definition
Explanation
Color Key
IE
Included
Elsewhere
GHG emissions for this activity are estimated and presented in another category of
the inventory. The category shall be noted in the explanation.
Sources required for
BASIC reporting
NE
Not Estimated Emissions occur but have not been estimated or reported; justification for exclusion
shall be noted in the explanation.
Sources required for
BASIC+ reporting
NO
Not Occurring An activity or process does not occur or exist within the city.
Sources included in Other
Scope 3
C
Confidential
GHG emissions which could lead to the disclosure of confidential information and
can therefore not be reported.
Sources required for
territorial reporting
Non-applicable emissions
Scope
Definition
Scope 1
GHG emissions from sources within the city boundary.
Scope 2
GHG emissions occurring as a consequence of the use of grid-supplied electricity, heat, steam
and/or cooling within the city boundary.
Scope 3
All other GHG emissions that occur outside the city boundary as a result of activities taking place
within the city boundary.
33
Appendix B. DRAFT GHG Emissions from
Agriculture, Forestry, and Land Use
(AFOLU) and Food Systems
The 2020 community GHG emissions inventory represents the first attempt at
cataloging GHG emissions for the AFOLU sector (Figure 1). AFOLU GHG emissions
are required for BASIC+ GHG inventory reporting, but optional for the current BASIC-
level GHG inventory reporting undertaken by the City of Phoenix and most cities.
However, as AFOLU emissions will be required for future GHG C40 reporting, these
initial efforts lay groundwork for comprehensive AFOLU emissions reporting for the
2022 community GHG emissions report and beyond.
Figure B6. Sources of AFOLU GHG Emissions16.
AFOLU emissions broadly fall into three categories: livestock; land; and aggregate
sources and non-CO2 emissions sources on land. As shown in Figure 1, some AFOLU
emissions are relevant to the City of Phoenix and some are not. For example, changes
in GHG emissions resulting from harvested wood products and rice cultivation are not
relevant to the City of Phoenix. Biomass burning, through the combustion residential
firewood; livestock emissions from enteric digestion and manure management; and CO2
and non-CO2 GHG emissions from agricultural soil management are relevant to the City
of Phoenix. Additionally, changes in carbon stocks from land types and land use change
are another highly relevant component of the City of Phoenix’s AFOLU sector. This
initial attempt at inventorying AFOLU GHG emissions will present estimation methods
and results for livestock GHG emissions and a framework for calculating GHG
16 Image Source: Greenhouse Gas Protocol. (n.d.). GHG Protocol for Cities | Greenhouse Gas Protocol. Retrieved from
http://www.ghgprotocol.org/greenhouse-gas-protocol-accounting-reporting-standard-cities
34
emissions from land and land use change and aggregate sources and non-CO2
emissions sources on land.
B.1 Livestock
Livestock GHG emissions fall into two categories: enteric fermentation and manure
management. Livestock populations drive the estimation of these GHG emissions.
Variations in livestock population estimation methods can create large ranges of
potential GHG emissions. Summary city-level livestock GHG emissions reflect the
uncertainty inherent to estimated livestock population levels. In 2020, total livestock
GHG emissions occurring in the City of Phoenix were estimated to be 3,368 to 94,702
MT CO2e. GHG Emissions from enteric fermentation were estimated to be 2,965 to
77,176 MT CO2e and the emissions from manure management estimated to be 674 to
17,526 MT CO2e.
Enteric fermentation by livestock – cattle, horses, sheep, swine, goats, American bison,
and the non-horse equines (mules and asses) – results in the emissions of methane
(CH4). While numerous animals contribute to livestock-related GHG emissions, cattle
are the primary source of livestock GHG emissions. In 2019 at the state-level, cattle
were responsible for the emission of 82,378 MT CH4 via enteric fermentation while all
other livestock types emitted 2,935 MT CH417. Similarly, cattle, and moreover dairy
cattle, were responsible for the vast majority of CH4 emissions from manure
management. In 2019 at the state-level, cattle were responsible for emitting 24,183 MT
CH4 of the state’s total 28,632 MT CH4 resulting from livestock manure management18.
Likewise, cattle were responsible for emitting 1,176 MT N2O the state’s total 1,218 MT
N2O resulting from livestock manure management19.
Estimates on the number of livestock head per livestock type – cattle, horses, sheep,
swine, goats, American bison, and the non-horse equines (mules and asses) – are
required to estimate livestock GHG emissions from the City of Phoenix. These data
were obtained from the United States Department of Agriculture’s Census of
Agriculture. However, the Census of Agriculture is published every 5-years for years
ending in 2 and 7, and not published yearly20. For this, reason the 2017 Census of
Agriculture was used to estimate livestock GHG emissions.
Census of Agriculture data on the number of livestock (head) are available at the state
and county geographic scales, but not at the city geographic scale. However, data on
the number and size of livestock operations are available at the zip code level. Using
these constraints, a scaling factor was developed for each livestock category; the ratio
of livestock operations in City of Phoenix zip codes to livestock operation in the county.
17 U.S. EPA. 2022. Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2020. Appendix 3, Part B. U.S.
Environmental Protection Agency, EPA 430-P-22-001. https://www.epa.gov/ghgemissions/draft-inventory-us-greenhouse-gas-
emissions-and-sinks-1990-2020.
18 Ibid.
19 Ibid.
20 United States Department of Agriculture. National Agricultural Statistics Service - Census of Agriculture. URL:
https://www.nass.usda.gov/AgCensus/.
35
This analysis found 151 cattle operations related with City of Phoenix zip codes and 610
cattle operations county-wide; 33 sheep operations related with City of Phoenix zip
codes and 96 county-wide; and 20 swine operations associated with City of Phoenix zip
codes and 104 hog operations county-wide21. It should be noted that these estimates
provide an upper bound on livestock estimates for the City of Phoenix because they
take into account the full zip code area, and zip codes located on the periphery of the
city boundary, which are more likely to contain livestock operations, may contain a
livestock operation though the livestock operation is not physically within the city
boundary. Additionally, this analysis revealed numerous livestock operations associated
with zip codes in the city center. Therefore, Census of Agriculture zip code level data
may be associated with the physical address of the company owning the livestock
operation, but not the physical location of the operation itself. Further, City of Phoenix
code specifies which animals are allowed to be owned within the city boundary and city
code currently forbids swine ownership within city limits except for certain types of pet
pigs. Taking these factors into account, zip codes on the periphery of the city with
livestock operations and city code, a more realistic upper bound estimated is 2-52 cattle
operations, 0-19 sheep operations, and 0 swine operations. It should be noted that a
satellite imagery evaluation of the Census of Agriculture data could only located two
dairy facilities physically within the City of Phoenix boundary, while most were located
adjacent to the city boundary in unincorporated county islands.
In the 2017 Census of Agriculture, Maricopa County had an estimated 210,980 cattle;
2,575 sheep and lamb; and 1,124 hogs and pigs22. Using the scaling factors described
in the previous paragraph, the estimated City of Phoenix cattle population was 692-
17,985 cattle; 0-510 sheep, and 0 swine. It should be noted that the horse population of
the City of Phoenix was not estimated as these data were not available in the Census of
Agriculture. Livestock emissions from enteric fermentation and manure management
are calculated by multiplying livestock population by animal type by animal type
emissions factors23. Animal type emissions factors were obtained and derived from the
U.S. EPA’s Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-202024.
Table B1 shows estimated GHG emissions from enteric termination.
Table B13. Estimated CH4 Emissions from Enteric Fermentation in the City of Phoenix
Livestock
Head
CH4 Emissions Factor
(kg CH4 per head per year)
CH4 Emissions
(MT CH4)
CH4 Emissions
(MT CO2e)
Cattle
692 – 17,985
153.00
106 – 2,752
2,965 – 77,048
Sheep and Lamb
0 – 510
9.00
0 – 459
0 – 128.43
Swine
0
1.50
0
0
Total
–
–
106 – 3,211
2,965 – 77,176
21 USDA National Agricultural Statistics Service. (2017). NASS - Quick Stats. USDA National Agricultural Statistics Service.
https://data.nal.usda.gov/dataset/nass-quick-stats. Accessed 2022-02-18.
22 Ibid.
23 Greenhouse Gas Protocol. (n.d.). GHG Protocol for Cities | Greenhouse Gas Protocol. Retrieved from
http://www.ghgprotocol.org/greenhouse-gas-protocol-accounting-reporting-standard-cities
24 EPA. 2022. Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2020. Appendix 3, Part B. U.S. Environmental
Protection Agency, EPA 430-P-22-001. https://www.epa.gov/ghgemissions/draft-inventory-us-greenhouse-gas-emissions-and-sinks-
1990-2020.
36
Table B2 shows estimated GHG emissions from manure management, which is several
times lower than the emissions from enteric fermentation.
Table B14. Estimated CH4 Emissions from Manure Management in the City of Phoenix
Livestock
Head
CH4 Emissions Factor
(kg CH4 per head per year)
CH4 Emissions
(MT CH4)
CH4 Emissions
(MT CO2e)
Cattle
692 – 17,985
23.82
16 – 428
462 – 11,995
Sheep and Lamb
0 – 510
0.21
0 – 0.11
0 – 3.00
Swine
0
416.73
0.00
0.00
Total
–
–
16 – 428.11
462 – 11,998
Table B3 shows estimated N2O emissions from manure management. This is the
smallest component of the GHG emissions emitted from the livestock sector.
Table B15. Estimated N2O Emissions from Manure Management in the City of Phoenix
Livestock
Head
N2O Emissions Factor
(kg N2O per head)
N2O Emissions
(MT N2O)
N2O Emissions
(MT CO2e)
Cattle
692-17,985
1.16
0.80-21
212-5,519
Sheep and Lamb
0-510
0.07
0-0.03
0-8.83
Swine
0
0.00
0.00
0.00
Total
–
–
0.80 – 21.03
215 – 5,271
Finally, Table B4 shows = total estimated GHG emissions by livestock type for both
enteric fermentation and manure management.
Table B16. Estimated GHG Emissions from Manure Management in the City of Phoenix
Livestock
Head
CH4
Emissions
(MT CO2e)
N2O
Emissions
(MT CO2e)
Total
Emissions
(MT CO2e)
Cattle
692 – 17,985 3,426 – 89,043
212 – 5,519
3,368 – 94,562
Sheep and Lamb
0 – 510
0 – 131
0 – 9
0 – 140
Swine
0
0
0
0
Total
–
3,426 - 89,174
212 – 5,528
3,368 - 94,702
37
B.2 Land Use & Land Use Change
Land sector GHG emissions fall into two broad categories: GHG emissions from the
changes in carbon stocks from land use and from changes in carbon stocks resulting
from land use change. Changes in carbon stock from both land use and land use
change requires in depth analysis on carbon stock by land use type in the City of
Phoenix. This section contains a reproducible method for creating the land use and land
use change data required for calculating the change in carbon stocks to calculate Land
Use GHG emissions.
There are multiple comprehensive land cover databases that are open source and free
to download. However, two provide a long history of comparable data for this analysis.
First, the USDA Cropland Data Layer (CDL), which dates to 2008, is a satellite imagery
data product that contains information on crop types under cultivation at 30-to-56-meter
resolution for the continental United States25. The Cropland Data Layer provides high
resolution of land cover type by crop, natural landcover, and type of urban settlement.
Second, is the National Land Cover Database (NLCD) produced by the United States
Geological Survey, provides land cover data on 16 land cover classes at a 30-meter
resolution26. Since NLCD data date to 2001 and have a consistent resolution over time,
these data were used to develop the method. However, CDL data could be used in the
future to provide greater resolution for crop-specific carbon stock and soil management
GHG emissions estimations.
A detailed summary of land use types by area, and changes between 2001 and 2019,
within current City of Phoenix boundaries is shown below in Table B5. Definitions of
these land use types can be found at the Multi-Resolution Land Characteristics
Consortium website.27
Table B17. Estimated Land Use by Type in the City of Phoenix Between 2001 and 2019
Land Cover (sq mi.)
Year
2001
2004
2006
2008
2011
2013
2016
2019
Change
2001-19
Open Water
1.1
1.1
1.1
1.2
1.4
1.4
1.1
1.1
-0.1
Developed,
Open Space
26.4
26.6
28.7
30.1
31.9
30.7
30.9
30.9
4.5
Developed,
Low Intensity
69.1
70.6
75.7
80.3
81.3
81.2
81.3
81.1
12.0
Developed,
Medium Intensity
128.5 130.4 137.6
144.0 145.7
147.4 148.9 151.8
23.3
Developed, High Intensity
46.5
47.9
50.7
53.3
54.1
55.4
56.2
58.3
11.8
Barren Land
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.3
0.0
Shrub, Scrub
224.3 222.5 211.8
199.3 194.6
193.3 191.5 186.6
-37.7
Grassland/Herbaceous
2.3
2.3
2.3
2.3
2.3
2.4
2.6
4.1
1.8
25 USDA National Agricultural Statistics Service Cropland Data Layer. 2019. Published crop-specific data layer [Online]. Available at
https://nassgeodata.gmu.edu/CropScape/ (accessed 14 February 2022; verified 18 February 2022). USDA-NASS, Washington, DC.
26 Dewitz, J., and U.S. Geological Survey, 2021, National Land Cover Database (NLCD) 2019 Products (ver. 2.0, June 2021): U.S.
Geological Survey data release, https://doi.org/10.5066/P9KZCM54
27 Multi-Resolution Land Characteristics Consortium (n.d.). National Land Cover Database Class Legend and Description [Online].
Available at: https://www.mrlc.gov/data/legends/national-land-cover-database-class-legend-and-description (accessed 22 March
2022; verified 22 March 2022). MRLC, Washington D.C.
38
Pasture/Hay
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.0
Cultivated Crops
30.9
27.7
21.2
18.6
17.9
17.4
16.8
15.3
-15.7
Woody Wetlands
1.0
1.0
0.8
0.8
0.8
0.8
0.8
0.8
-0.2
Emergent Herbaceous
Wetlands
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.0
Total
530.5 530.5 530.5
530.5 530.5
530.5 530.5 530.5
0.0
A simplified version of Table B5 is shown in Table B6. The Land Cover categories in
Table B5 have been condensed to four major categories: open water, developed land,
open space/desert, and cropland. Table B6 shows that the growth in developed area
has come about from the conversion of cropland and open space/desert land covers.
Table B18. Simplified Table of Land Use by Type in the City of Phoenix Between 2001
and 2019
Land Cover (sq mi.)
Year
2001
2004
2006
2008
2011
2013
2016
2019
Change
2001-19
Open Water
1.1
1.1
1.1
1.2
1.4
1.4
1.1
1.1
-0.1
Developed Land
270.4
275.5
292.7
307.8
313.0
314.8
317.3
322.2
51.7
Open Space/Desert
227.9
226.1
215.3
202.8
198.1
196.8
195.3
191.9
-36.0
Cropland
31.0
27.8
21.3
18.7
18.0
17.5
16.8
15.3
-15.7
Total
530.5
530.5
530.5
530.5
530.5
530.5
530.5
530.5
0.0
As shown in Tables B5 and B6, the growth of developed areas in the City of Phoenix
has resulted from the conversion of open space/desert and cropland. Calculating year-
over-year changes in carbon stocks from land use and land use types has two major
considerations. Land that remains in specified land use category and land that changes
between land use categories. Per GPC and IPCC guidance, land use changes that
occur within 20 years of the current inventory year need to be accounted for as land use
changes, and land use changes that occur more than 20 years before the inventory
year are not counted as land use changes. 28 For the 2022 inventory year, the NLCD will
provide 20+ year of land cover data to accurately account for this cutoff. However, the
fundamental challenge to calculating the change in carbon stocks from land use change
within Phoenix boundaries is that established methods do not explicitly consider desert
land use types. This first estimate was calculated assuming the grassland land use
type.29 Additional research studies are required to accurately tabulate the change in
carbon stocks from land use changes in the City of Phoenix as it is a desert climate.
28 Greenhouse Gas Protocol. (n.d.). GHG Protocol for Cities | Greenhouse Gas Protocol. Retrieved from
http://www.ghgprotocol.org/greenhouse-gas-protocol-accounting-reporting-standard-cities
29 U.S. EPA. 2022. Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2020. Appendix 3, Part B. U.S.
Environmental Protection Agency, EPA 430-P-22-001. https://www.epa.gov/ghgemissions/draft-inventory-us-greenhouse-gas-
emissions-and-sinks-1990-2020.
39
B.3 Aggregate Sources And Non-CO2 Emissions Sources On Land
GHG emission from aggregate sources and non-CO2 emissions sources on land were
not inventoried in 2022. However, estimates will be co-developed along with the
development of Land Use and Land Use Change GHG emissions.
B.4 Food System GHG Emissions
The Food System GHG emissions inventory captures GHG emissions from the
production, manufacturing, distribution, and consumption of food products at restaurants
and retail establishments. It is a full life cycle GHG emissions inventory of the food
consumption patterns of City of Phoenix residents. For 2020, food system GHG
emissions were estimated to be approximately 5,591,820 MT CO2e with a
minimum/maximum range of 4,080,490 to 8,511,300 MT CO2e. In 2020, overall food
system GHG emissions for the City of Phoenix resident population, across the lifecycle
of food from farm to table, are approximately 37% of total community-scale GHG
emissions and may range from 27%-56% of total community-scale GHG emissions.
Numerous methodologies exist to conduct a food system GHG emissions inventory,
including consumption-based emissions inventory methods and life cycle analysis (LCA)
based methods. The food system GHG emissions estimate for the City of Phoenix uses
published average per capita emissions numbers for the entire U.S. food supply chain30.
Mohareb et al. (2018) conducted a meta-analysis of food system LCAs to establish,
“representative carbon footprint values for a diversity of food commodities” for U.S. food
consumption that includes “processing, packaging, transportation, distribution, retail,
household preparation, and waste disposal31.” Per capita GHG emissions factors are
shown in Table B7.
Table B19. Per Capita Food System U.S. GHG Emissions Intensities for Food Supply
Chain Steps32
Food System GHG Category
Average
Min
Max
Production & Primary Processing
1935.8
1158
3366.1
Nuts
8.2
5.7
10.8
Fresh Fruit
33.2
13.7
68.5
Added Sugar and Sweeteners
39.5
39.5
39.5
Processed Fruit
40.4
32.8
54
Fish and Seafood
45.8
10
84.8
Fresh Vegetables
46.9
12.6
231.6
Eggs
47.4
20.4
100.7
Processed Vegetables
53.8
34.8
82.1
Grain Products
57.6
35.2
75.6
Fluid Milk
104.4
74.5
136.8
Added Fats and Oils
115.5
68.7
262
Other Dairy Products
246.6
202.7
301.6
Meat
1096.5
607.4
1918.1
30 Mohareb, E. A., Heller, M. C., & Guthrie, P. M. (2018). Cities’ role in mitigating United States food system greenhouse gas
emissions. Environmental science & technology, 52(10), 5545-5554.
31 Ibid.
32 Mohareb, E. A., Heller, M. C., & Guthrie, P. M. (2018). Cities’ role in mitigating United States food system greenhouse gas
emissions. Supporting Information. Environmental science & technology, 52(10), 5545-5554.
40
Secondary Processing
109.03
109.03
109.03
Packaging Materials
114.12
77.97
131.22
Distribution
238.5
214.55
264.5
Retail
390.6
370.79
410.41
Food Service
179.39
179.39
179.39
Grocery Trips
49.41
8.05
292.96
Household
309.65
309.65
309.65
Landfill - Food
445.04
164.71
745.12
Landfill - Sludge
26.32
18.24
36.72
Wastewater
59.16
59.16
59.16
Composting
3.24
0.2
4.4
Emissions
4.75
0.4
9.51
Fertilizer Offset from Composting
-0.66
-0.08
-1.72
Carbon Stored in Land Application
-0.85
-0.12
-3.39
Anaerobic Digesting
-0.09
0.05
-0.25
Emissions
0.15
0.11
0.22
Fertilizer Offset from Composting
-0.14
-0.03
-0.28
Carbon Stored in Land Application
-0.07
-0.03
-0.12
Offset from Electricity
-0.03
0
-0.07
Total Emissions (kg CO2e/cap)
3860.17
2669.79
5908.41
While Table B7 shows all GHG emissions factors developed by Mohareb et al. (2018),
the City of Phoenix government operations and community GHG emissions inventories,
contain GHG emissions totals from landfilling, composting, and wastewater. In order to
avoid double counting within the system, the food system GHG emissions inventory
only includes GHG emissions factors from production & primary processing to
household use categories (farm-to-table), yield an average per capita emissions total of
3,326 kg CO2e per capita, a minimum per capita emissions rate of 2,427 kg CO2e per
capita, and a maximum per capita emissions rate of 5,063 kg CO2e per capita.
However, it should be noted GHG emissions from local food production and processing
will occur by default.
Given these emissions factors, the estimated food system GHG emissions is 5,591,820
MT CO2e with range of 4,080,490-8,511,300 MT CO2e (Table B8). As these lifecycle
inventory emissions factors are on a per capita basis, they scale with population.
Table B20. Estimated Farm-to-Table GHG Emissions of the City of Phoenix Food
System
Inventory Boundary
2012
2016
2018
2020
Resident Population
1,499,274
1,612,199
1,654,675
1,680,992
Food System Minimum GHG Emissions (MT CO2e)
3,639,383
3,913,500
4,016,608
4,080,490
Food System Average GHG Emissions (MT CO2e)
4,987,335
5,362,980
5,504,276
5,591,820
Food System Maximum GHG Emissions (MT CO2e)
7,591,214
8,162,983
8,378,050
8,511,300
A detailed breakdown of 2020 food system GHG emissions by component is shown in
Table B9. As shown in numerous studies, meat production, processing, and
consumption is the single largest contributor to the City Phoenix’s farm-to-table food
system GHG emissions total.
41
Table B21. Estimated Farm-to-Table GHG Emissions of the City of Phoenix Food
System
Food System GHG Category
Average
Min
Max
Production & Primary Processing
3,254,064
1,946,589
5,658,387
Nuts
13,784
9,582
18,155
Fresh Fruit
55,809
23,030
115,148
Added Sugar and Sweeteners
66,399
66,399
66,399
Processed Fruit
67,912
55,137
90,774
Fish and Seafood
76,989
16,810
142,548
Fresh Vegetables
78,839
21,180
389,318
Eggs
79,679
34,292
169,276
Processed Vegetables
90,437
58,499
138,009
Grain Products
96,825
59,171
127,083
Fluid Milk
175,496
125,234
229,960
Added Fats and Oils
194,155
115,484
440,420
Other Dairy Products
414,533
340,737
506,987
Meat
1,843,208
1,021,035
3,224,311
Secondary Processing
183,279
183,279
183,279
Packaging Materials
191,835
131,067
220,580
Distribution
400,917
360,657
444,622
Retail
656,595
623,295
689,896
Food Service
301,553
301,553
301,553
Grocery Trips
83,058
13,532
492,463
Household
520,519
520,519
520,519
Total Emissions (MT CO2e)
5,591,820
4,080,490
8,511,300
42
Appendix C. Stationary Energy – Natural
Gas Documentation
Appendix C describes the data collection and data processing for obtaining natural gas
consumption data and calculating GHG emissions from natural gas combustion.
Appendix C also describes any changes to data sources and methodologies in the 2018
community-scale GHG emissions inventory.
C.1 Natural Gas Data Collection
Stationary Energy GHG emissions from the combustion of natural gas occur at
residential buildings, commercial and institutional buildings and facilities, manufacturing
industries and construction, energy industries, agriculture, forestry, and fishing activities,
non-specified sources, fugitive emissions from mining, processing, storage, and
transport of coal, and fugitive emissions from oil and natural gas systems. Natural gas
consumption data were obtained from the Southwest Gas Corporation (Southwest Gas),
which is the only natural gas utility that services the city. Natural gas data were obtained
for each GHG emissions inventory as the inventory was being compiled.
A similar data request process was followed for each of the GHG emissions inventory
years. For 2012 and 2016, Southwest Gas provided consumption data at the zip code
resolution for residential buildings, commercial and institutional buildings and facilities,
manufacturing industries and construction, energy industries, agriculture, forestry, and
fishing activities, and non-specified sources. For 2018 and 2020, Southwest Gas did not
provide zip code level data. Southwest Gas provided total annual consumption data for
residential buildings, commercial and institutional buildings and facilities, manufacturing
industries and construction, energy industries; agriculture, forestry, and fishing activities,
and non-specified sources.
C.2 Natural Gas Data Processing
For 2012 and 2016, zip code level data were scaled to the percentage of land area in a
zip code that was within the city. Natural gas consumption data were scaled only for zip
codes which contained a fraction of land within and outside the city boundary. Upon
follow up evaluation of the natural gas data previously provided by Southwest Gas; it
was found that this scaling of natural gas data by the percent area of a zip code with the
City of Phoenix was not necessary. Previously, zip code level natural gas consumption
was scaled by percent land area within the City boundary. However, a review of the
previous 2012 and 2016 datasets found that if a zip code was associated with more
than one Phoenix metropolitan area city the consumption was reported for each city
associated with that zip code. To avoid under-reporting natural gas consumption, the zip
code scaling factors which were used previously were no longer used. For this reason,
2012 and 2016 community-scale GHG emissions from natural gas combustion were
revised upwards (See Section Appendix A.3).
43
Using the data provided by Southwest Gas, the following equation was used to
calculate GHG emissions from Stationary Energy natural gas consumption.
𝐺𝐻𝐺𝑁𝐺,𝑖,𝑗,𝑦= 𝑁𝐺𝑖,𝑦 × 𝐶𝐹× 𝐸𝐹𝑁𝐺,𝑗
Where,
GHGNG,i,j,y = The GHG emissions in metric tons from natural gas (NG) consumption
from a Stationary Energy sector (i) for a GHG (j) for a GHG emissions
inventory year (y).
NGi,y = Natural gas (NG) consumption from a Stationary Energy sector (i) for a
GHG emissions inventory year (y) in therms.
CF = Conversion factor for converting data reported in therms to million British
thermal units (mmBTU).
𝐸𝐹𝑁𝐺,𝑗 = The natural gas consumption GHG emissions factor for CO2, CH4, N2O (j).
Finally, natural gas consumption GHG emissions were converted to metric tons of
carbon dioxide equivalent (MT CO2e) by multiplying 𝐺𝐻𝐺𝑁𝐺,𝑖,𝑗,𝑦 by global warming
potential 𝐺𝑊𝑃𝐴𝑅5,𝑗 and summed across GHGs (j).
C.3 Changes between inventory years
As mentioned in Section Appendix B.1, the natural gas consumption data for 2012 and
2016 in the 2018 GHG emissions inventory were not scaled unlike the previous 2012
and 2016 GHG emissions inventories. A comparison between the scaled (previously
reported) and unscaled natural gas consumption for 2012 and 2016 is shown below in
Table C1.
Table C1. Changes to Natural Gas GHG Emissions Due to Updated Scaling Methods
Year
Scaled
Natural Gas
Use
(kilotherms)
Scaled
GHG
Emissions
(MT CO2e)
Unscaled
Natural Gas
Use
(kilotherms)
Unscaled
GHG
Emissions
(MT CO2e)
∆GHG
Emissions
(MT CO2e)
%
Change
2012
122,983
650,267
151,881
806,722
156,455
24%
2016
128,256
678,147
151,584
805,753
127,606
19%
The result of using unscaled natural gas consumption data increases total Stationary
Energy GHG emissions by approximately 2% over reported 2012 and 2016 levels.
44
Appendix D. Stationary Energy – Electricity
Documentation
Appendix C describes the data collection and data processing for obtaining electricity
consumption data and calculating GHG emissions from electricity consumption. This
appendix also describes any changes to data sources and methodologies in the 2018
community-scale GHG emissions Inventory.
D.1 Electricity Data Collection
Stationary Energy GHG emissions from the consumption of purchased electricity can
occur at residential buildings, commercial and institutional buildings and facilities,
manufacturing industries and construction facilities, energy industry facilities,
agriculture, forestry, and fishing activities, and non-specified sources.
Electricity consumption data for the Community GHG Emissions Inventory were
obtained from Arizona Public Service (APS) and the Salt River Project (SRP). APS and
SRP are the only electric utilities that provide electricity to consumers within the city
boundary. Electricity data were obtained from APS and SRP for each GHG emissions
inventory as the inventory was being compiled – i.e., 2012 data were collected while
conducting the 2012 community-scale inventory, 2016 data were collected while
conducting the 2016 community-scale inventory, and 2018 data were collected while
conducting the 2018 community-scale inventory, and 2020 data were collected while
conducting the 2020 community-scale inventory.
Both APS and SRP have electricity generation facilities located within the Phoenix
metropolitan area, but only APS has an electricity generation facility within city
boundaries – the APS West Phoenix Power Plant. The APS West Phoenix Power Plant
is a 997 MW natural gas facility located in southwest Phoenix.33 The APS West Phoenix
Power Plant is included in the 2020 community-scale inventory as emissions from
energy generation supplied to the grid (eGRID). Emissions from the APS West Phoenix
Power Plant are included in this inventory as an information item (Appendix A, GPC ref.
no I.4.4), and are not tabulated as part of the community-scale inventory per GPC
guidelines. APS West Phoenix Power Plant emissions for 2012, 2016, 2018, and 2020
were obtained from the EPA Greenhouse Gas Reporting Program through the Facility
Level Information on GreenHouse gases Tool (FLIGHT).34
A similar data request process was followed for each of the GHG emissions inventory
years. For 2012 and 2020, APS provided consumption data at the zip code resolution
for residential, commercial, and industrial consumers. However, for 2016 and 2018,
APS only provided total consumption data for residential, commercial, and industrial
33 Pinnacle West Capital Corporation (2019). 2018 Annual Report. URL:
http://s22.q4cdn.com/464697698/files/doc_financials/annual/2018/Annual-Report_2018_Web.pdf
34 U.S. Environmental Protection Agency (2019). EPA Greenhouse Gas Reporting Program through the Facility Level Information on
GreenHouse gases Tool URL: https://ghgdata.epa.gov/ghgp/main.do
45
consumers for zip codes associated with the City of Phoenix. Unlike APS, SRP only
provided total consumption for residential and commercial consumers within the City of
Phoenix.
D.2 Electricity Data Processing
D.2.1 APS Electricity Data Processing
Using the data provided by APS, the following equation was used to calculate GHG
emissions from Stationary Energy electricity consumption in 2012 and 2020.
𝐺𝐻𝐺𝐴𝑃𝑆,𝑖,𝑗,𝑠𝑐𝑎𝑙𝑒𝑑,𝑦= ∑𝐸𝐶𝐴𝑃𝑆,𝑖,𝑧,𝑦 × 𝑆𝐹𝑖,𝑧,𝑦 × 𝐶𝐹× 𝐸𝐹𝐴𝑍𝑁𝑀,𝑗,𝑦
𝑧
Where,
GHGAPS,i,j,scaled,2012 = The scaled GHG emissions in metric tons from purchased electricity from
APS for a Stationary Energy subsector (i) for a GHG (j) for inventory year
(y) 2012 and 2020.
ECAPS,i,z,2012 = Purchased electricity from APS for a Stationary Energy subsector (i) in zip
code (z) for inventory year (y) 2012 and 2020.
SFi,z,y = Scaling factor for zip code (z) for inventory year (y) 2012 and 2020.. The
scaling factor the % of land area in z that is within the city boundary. SFi,z,y
ranges from near 0 to 1.
CF = Conversion factor to convert kWh to MWh. If data were reported in the MWh,
CF = 1. If data were reported in kWh than CF = 0.001.
EFAZNM,j,y = The eGRID35 emissions factor for the AZNM subregion for GHG emissions
factor for CO2, CH4, N2O (j) for eGRID reporting year (y).
Zip code level data from APS were not available for calendar years 2016 and 2018.
Therefore, the 2012 data (𝑆𝐹2012 ) were used to develop the scaling factors for 2016 and
2018:
𝑆𝐹𝐴𝑃𝑆,2012 = ∑
𝐸𝐶𝐴𝑃𝑆,𝑖,𝑧,2012 × 𝑆𝐹𝑖,𝑧,2012
𝑖,𝑧
∑
𝐸𝐶𝐴𝑃𝑆,𝑖,𝑧,2012
𝑖,𝑧
⁄
Where,
SFAPS,2012 = Is the overall scaling factor for APS data in calendar year 2012. It is the ratio
of the total purchased electricity from APS within the city scaled by zip code
specific scaling factors to the reported total unscaled purchased electricity
from APS within the city.
35 The eGRID database inventories plant-level environmental attributes of electric power generation and its effect on air emissions
for every power plant in the United States. Phoenix is in the Arizona and New Mexico (AZNM) subregion. The Emissions &
Generation Resource Integrated Database (eGRID), developed by the EPA in collaboration with the Energy Information
Administration (EIA), the North American Electric Reliability Corporation (NERC), and the Federal Energy Regulatory Commission
(FERC), is a comprehensive source of data on the environmental characteristics of almost all electric power generated in the United
States. Detailed information can be found at http://www.epa.gov/cleanenergy/energy-resources/egrid/index.html.
46
ECAPS,i,z,2012 = Purchased electricity from APS for a Stationary Energy subsector (i) in zip
code (z) for an inventory year 2012.
SFi,z,2012 = Scaling factor for zip code (z). The scaling factor the % of land area in z that
is within the city boundary. SFi,z,2012 ranges from near 0 to 1.
Therefore,
𝐺𝐻𝐺𝐴𝑃𝑆,𝑠𝑐𝑎𝑙𝑒𝑑,𝑖,𝑗,𝑦= ∑𝐸𝐶𝐴𝑃𝑆,𝑖,𝑧,𝑦 × 𝑆𝐹𝐴𝑃𝑆,2012 × 𝐸𝐹𝐴𝑍𝑁𝑀,𝑗,𝑦
𝑧
.
Where,
GHGAPS,scaled,i,j,y = The scaled GHG emissions in metric tons from purchased electricity from
APSY for a Stationary Energy subsector (i) for a GHG (j) for an inventory
year 2016 or 2018 (y).
SFAPS,2012 = Is the overall scaling factor for APS data in calendar year 2012. It is the ratio
of the total purchased electricity from APS within the city scaled by zip code
specific scaling factors to the reported total unscaled purchased electricity
from APS within the city.
EFAZNM,j,y = The eGRID emissions factor for the AZNM subregion for GHG emissions
factor for CO2, CH4, N2O (j) for eGRID reporting year (y).
Next, electricity consumption for the Lake Pleasant Water Treatment Plant (obtained
from the City of Phoenix Government Operations GHG Emissions Inventory) was added
to the APS electricity total to account its removal during the scaling process. Finally,
GHG emissions from APS electricity consumption were converted to metric tons of
carbon dioxide equivalent (MT CO2e) by multiplying 𝐺𝐻𝐺𝑖,𝑗 by the GHG-specific global
warming potential found in the IPCC AR5 report (𝐺𝑊𝑃𝐴𝑅5,𝑗).
D.2.2 SRP Data Processing
For each inventory, SRP provided total residential, commercial, and industrial electricity
consumption for accounts within the city boundary. As this data consisted of account
holders only within the city boundary, no scaling factor was applied to the data.
Using the data provided by SRP, the following equation was used to calculate GHG
emissions from Stationary Energy natural gas consumption.
𝐺𝐻𝐺𝑆𝑅𝑃𝑖,𝑗,𝑦= 𝐸𝐶𝑆𝑅𝑃,𝑖,𝑦 × 𝐶𝐹× 𝐸𝐹𝐴𝑍𝑁𝑀,𝑗,𝑦
Where,
GHGSRP,i,j,y = The GHG emissions in metric tons from purchased electricity from SRP for a
Stationary Energy subsector (i) for a GHG (j) for an inventory year (y).
ECSRP,i,y = Purchased electricity from SRP for a Stationary Energy subsector (i) for an
inventory year (y).
CF = Conversion factor to convert kWh to MWh. If data were reported in the MWh, CF
= 1. If data were reported in kWH than CF = 0.001.
47
EFAZNM,j,y = The eGRID emissions factor for the AZNM subregion for GHG emissions factor
for CO2, CH4, N2O (j) for eGRID reporting year (y)..
Finally, GHG emissions from SRP electricity consumption were converted to metric tons
of carbon dioxide equivalent (MT CO2e) by multiplying 𝐺𝐻𝐺𝑖,𝑗,𝑦 by the GHG-specific
global warming potential found in the IPCC AR5 report (𝐺𝑊𝑃𝐴𝑅5,𝑗).
D.2.3 Total GHG Emissions from Electricity Consumption
After the GHG emissions from electricity consumption (EC) in the SRP and APS service
territories were calculated, the following equation was summed across inventory sectors
(i) and GHGs (j) to calculate total GHG emissions from electricity consumption within
city boundaries.
𝐺𝐻𝐺𝐸𝐶,𝑖,𝑗,𝑦= 𝐺𝐻𝐺𝐴𝑃𝑆,𝑖,𝑗,𝑦+ 𝐺𝐻𝐺𝑆𝑅𝑃,𝑖,𝑗,𝑦
D.3 Transmission and Distribution Loss (T&D Loss)
GHG emissions from T&D loss were estimated using data obtained from the EIA on
Arizona’s supply and disposition of electricity from 1990 through 2020.36 For each
inventory year, T&D loss is calculated as the ratio between estimated electricity system
losses and the difference between total electricity disposition minus direct use of
electricity at power plants.
D.4 Changes between inventory years
For each of the inventory years – 2012, 2016, 2018, and 2020 – electricity consumption
has been provided by APS and SRP. SRP data has been provided as an overall total
electricity consumption for commercial and residential sectors within City boundaries.
For the 2012 community-scale inventory, APS provided zip code level consumption data
for commercial, industrial, and residential sectors for zip codes associated with the City.
An analysis of this data showed that some of the zip codes with highest reported
consumption only had minor portion of the zip code within the City. For example, in the
2012 data the zip code with the highest reported total consumption had less than 1%
land area within City boundaries and the zip code with highest reported residential
consumption had only 30% land area within City boundaries.
To account for this aspect of the data, a scaling factor was developed to scale reported
electricity consumption to City electricity consumption using land area as indicator of
electricity consumption. For 2012, a single scaling factor was used, which was a simple
ratio of the total area of the City compared to the total area of all zip code for which data
was provided. For the 2016 community-scale inventory, the same scaling factor
methodology was used because the reported electricity consumption was within 0.5% of
2012 levels. For 2018 community-scale inventory, the scaling methodology was
36 U.S. Energy Information Administration, Form EIA-923, Power Plant Operations Report and predecessor forms. U.S. Energy
Information Administration, Form EIA-860, Annual Electric Generator Report. U.S. Energy Information Administration, Form EIA-
861, Annual Electric Power Industry Report. Form EIA-111, Quarterly Imports and Exports Report.
48
updated for the 2012 data and then applied to 2016 and 2018 data. In the updated
method, consumption for each zip code is scaled by the percent land area within the
City; electricity consumption for some zip codes are scaled, others are not because
those zip codes are entirely within City boundaries. Use of this scaling factor assumes
that electricity consumption by customer-type within each zip code is constant through
the reporting time period from 2012 to 2018. This assumption and scaling approach
may need to be revisited in future community-scale GHG emissions inventories. After
data from each zip code are scaled, they are summed to arrive at electricity
consumption for the City. The result of this methodological change was to increase
GHG emissions from electricity consumption in 2012 and 2016 (Table D1). The 2020
inventory was able to follow the approach of the 2012 inventory because zip-code level
data were available.
Table D1. Changes to Scaling Methodologies for Electricity Data
Year
Old Scaling Method
New Scaling Method
∆GHG
Emissions
(MT CO2e)
%
Change
APS
Electricity
Consumption
GHG
Emissions
(MT CO2e)
APS
Electricity
Consumption
GHG
Emissions
(MT CO2e)
2012
(kWh)*
6,429,328,231
3,102,482
9,873,891,733
4,764,661
1,662,179
54%
2016
(MWh)
5,677,762
2,413,206
9,875,762
4,197,472
1,784,266
74%
*kWh data were provided in 2012; MWh data were provided in 2016 and 2018.
49
Appendix E. Transportation Sector
Documentation
Transportation Sector GHG emissions are generated by a number of different sources
and types of fuel. GHG emissions sources include on-road transport, railways,
commercial aviation, civil aviation, and off-road transport. Fuel types consumed
gasoline, diesel, B20 biodiesel, E85 ethanol, compressed natural gas (CNG), liquified
natural gas (LNG), propane (LPG), aviation gasoline, and jet fuel A. Transportation
sector GHG emissions also includes the consumption of purchased electricity to charge
electric vehicles and to power electric light rail. Appendix D describes data sources and
methods by fuel type.
E.1 Transportation Sector Data Processing
Transportation sector GHG emissions are calculated using a generalized formula.
𝐺𝐻𝐺𝑖,𝑗,𝑦= 𝐹𝐶𝑖,𝑦 × 𝐶𝐹× 𝐸𝐹𝑖,𝑗,𝑦
Where, GHGi,j,y =
The GHG emissions in metric tons from a transportation fuel (i) for a GHG (j) for
an inventory year (y).
ECSRP,i,y =
Fuel consumption of a transportation fuel (i) for an inventory year (y).
CF =
Conversion factor to convert fuel consumption data to the units of the emissions
factor. A CF is only used when necessary and is equal to 1 when not necessary.
EFi,j,y =
The GHG emissions factor in metric tons from a transportation fuel (i) for a GHG
(j) for an inventory year (y).
Finally, GHG emissions from transportation fuel consumption were converted to metric
tons of carbon dioxide equivalent (MT CO2e) by multiplying 𝐺𝐻𝐺𝑖,𝑗,𝑦 by the GHG-specific
global warming potential found in the IPCC AR5 report (𝐺𝑊𝑃𝐴𝑅5,𝑗).
E.2 On-Road Transport
E.2.1 Gasoline and Diesel
Gasoline and diesel consumption for Maricopa County were obtained from the Arizona
Department of Transportation (ADOT) via a public records request. Gasoline and diesel
gallonage data are reported to the ADOT in order to obtain funds through the Highway
User Revenue Fund (HURF). Historic HURF monthly distribution reports are available
through ADOT. ADOT HURF reports contain county-level monthly gasoline and use oil
(diesel) sales data.37 As these data were for the entirety of Maricopa County, gasoline
and diesel sales data were scaled using a ratio of City of Phoenix and Maricopa County
populations. Per GPC guidance, population is an acceptable scaling factor for
37 Arizona Department of Transportation. Archived Audits and Reports. Highway User Revenue Fund (HURF). URL:
https://azdot.gov/node/5069.
50
population-dependent activity data. A future study would be needed to determine if and
how driving behaviors differ by Phoenix metropolitan area city.
E.2.2 Alternative Fuel Vehicles – B20 Biodiesel, E85 Ethanol, CNG, LNG
The City of Phoenix 2018 GHG Emissions Inventory of Local Government Operations is
the primary source of data for alternative fuel consumption and the resulting GHG
emissions within the city boundary. It was assumed that local government operations
were the largest consumer of these fuels for transportation within the city boundary and
other alternative fuel uses were de minimis.
E.2.3 Electric Vehicles
GHG emissions from electric vehicles for 2012, 2016 and 2018 haven been added to
the community-scale inventory. National data were used to estimate electric vehicle
consumption as local data were not available for estimating these GHG emissions.
National-level statistics for annual gasoline consumption and electricity use for mobile
transportation were obtained from the EIA Annual Energy Outlook. The ratio between
electric energy for transportation and the energy in gasoline usage in the U.S. was used
as a proxy to estimate citywide residential electric vehicle usage. GHG emissions from
electricity consumption from electric vehicles were calculated according to the method
in Appendix C, Section C.2.2.
E.3 Railways
E.3.1 Valley Metro Light Rail
Valley Metro light rail electricity consumption data were obtained from two sources. The
National Transit Database38 used for inventory years 2012 and 2016. The National
Transit Database is published by the U.S. Department of Transportation and contains
various statistics about public transit systems across the United States, including fuel
usage. Electricity usage by Valley Metro is reported to the National Transit Database as
Valley Metro Rail, Inc. The National Transit Database had not been published for
calendar year 2018 during the time in which the 2018 inventory was compiled.
Therefore, 2018 electricity consumption by the Valley Metro light rail system was
obtained via a public records request of Valley Metro.
For each inventory year, total Valley Metro electricity usage for rail operations were
scaled based on ratio of the length of light rail track within the city compared to the
overall length of Valley Metro light rail track. GHG emissions from electricity
consumption from the Valley Metro light rail were calculated according to the method in
Appendix C, Section C.2.2.
38 U.S. Department of Transportation. The National Transit Database. URL: https://www.transit.dot.gov/ntd.
51
E.3.1 Freight Rail
The National Emissions Inventory (NEI)39 published by U.S. EPA was used to gather
data on GHG emissions from freight rail activity in Maricopa County. The 2011 NEI was
used as a proxy for 2012, 2016, 2018, and 2020. Please refer to the 2016 community-
scale GHG emissions inventory report for a summary of methods to estimate Freight
Rail GHG emissions.
E.4 Aviation
E.4.1 Commercial Aviation
The Energy Information Administration (EIA) State Energy Data System (SEDS) was
used to gather annual data on Jet Fuel A consumption in the State of Arizona. Next,
airport operations data were obtained from the Federal Aviation Administration’s (FAA)
Operations Network (OPSNET) database for the State of Arizona, Phoenix Sky Harbor
Airport, and the Phoenix Deer Valley. The FAA OPSNET data were used to calculate
the proportion of commercial airport operations that occurred at the Phoenix Sky Harbor
and Phoenix Deer Valley airports relative the State of Arizona. Once this annual scaling
factors were calculated, they were multiplied by the annual state-level Jet Fuel A
consumption to arrive at estimated Jet Fuel A consumption at the two Phoenix airports.
This number was then divided by two to only account for takeoffs. It should be noted
that EIA SEDS data are subject to revision from year-to-year.
E.4.2 Civil Aviation
The Energy Information Administration (EIA) State Energy Data System (SEDS) was
used to gather annual data on Aviation Gasoline consumption in the State of Arizona.
Next, airport operations data were obtained from the Federal Aviation Administration’s
(FAA) Operations Network (OPSNET) database for the State of Arizona, Phoenix Sky
Harbor Airport, and the Phoenix Deer Valley. The FAA OPSNET data were used to
calculate the proportion of non-commercial airport operations that occurred at the
Phoenix Sky Harbor and Phoenix Deer Valley airports relative the State of Arizona.
Once this annual scaling factors were calculated, they were multiplied by the annual
state-level Aviation Gasoline consumption to arrive at estimated Aviation Gasoline
consumption at the two Phoenix airports. This number was then divided by two to only
account for takeoffs. It should be noted that EIA SEDS data are subject to revision from
year-to-year.
E.5 Off-Road Transportation
E.5.1 Nonroad Diesel
Consumption data for nonroad diesel (dyed diesel) were obtained via a public records
request of the Arizona Department of Transportation for dyed diesel sales in Maricopa
County. Nonroad (dyed) diesel is only permitted for use in “vehicles and equipment
39 U.S. Environmental Protection Agency. National Emissions Inventory (NEI). URL: https://www.epa.gov/air-emissions-
inventories/national-emissions-inventory-nei.
52
used in agriculture (farming and ranching), mining and roadway construction”40 and
illegal for on-road transportation uses. Public records requests were submitted for two
different points in time. The public records request for nonroad diesel consumption for
calendar year 2016 was submitted in 2017 and data were obtained in 2017. These data
had contained origin-destination flows of dyed diesel sales – from the terminal to point
of sale – at the city level for Maricopa County. The second public records request for
dyed diesel sales in Maricopa County for 2012 and 2018 (submitted as one public
records request) yielded aggregate sales in Maricopa County for each calendar year
requested. Therefore, the ratio of dyed diesel sales in Phoenix compared to Maricopa
County was used as scaling factor for 2012 and 2018 data.
GHG emissions for dyed diesel were calculated using the following equation.
𝐺𝐻𝐺𝑁𝑜𝑛𝑅𝑜𝑎𝑑𝐷𝑖𝑒𝑠𝑒𝑙,𝑃ℎ𝑜𝑒𝑛𝑖𝑥,𝑗,𝑦= {𝐷𝑦𝑒𝑑𝐷𝑖𝑒𝑠𝑒𝑙𝐺𝑎𝑙𝑙𝑜𝑛𝑠,𝑃ℎ𝑜𝑒𝑛𝑖𝑥,𝑦 × 𝐸𝐹𝑑𝑖𝑒𝑠𝑒𝑙,𝑗 𝑖𝑓 𝑦= 2016
𝐷𝑦𝑒𝑑𝐷𝑖𝑒𝑠𝑒𝑙𝐺𝑎𝑙𝑙𝑜𝑛𝑠,𝑀𝑎𝑟𝑖𝑐𝑜𝑝𝑎𝐶𝑜𝑢𝑛𝑡𝑦,𝑦 × 𝑆𝐹𝑃ℎ𝑜𝑒𝑛𝑖𝑥,2016 × 𝐸𝐹𝑑𝑖𝑒𝑠𝑒𝑙,𝑗 𝑖𝑓 𝑦= 2012,2018
Where, GHGNonRoadDiesel,Phoenix,j,y =
the GHG emissions from red-dyed diesel sold within the city for
a GHG (j) and an inventory year (y).
DyedDieselGallons,Phoenix,y =
The gallons of red-dyed diesel sold at pumps located within the
city in an inventory year (y).
EFdiesel,j =
The diesel emissions factor (EF) for a GHG (j).
DyedDieselGallons,MaricopaCounty,y The gallons of red-dyed diesel sold at pumps located within the
Maricopa County in an inventory year (y).
SFPhoenix,2016 =
The ratio between total red-dyed diesel gallons sold at pumps
located in the city to the total red-dyed diesel gallons sold in
pumps located in Maricopa County for year 2016.
For 2012 and 2016, the 2011 and 2014 US EPA National Emissions Inventory (NEI)
were the sources of nonroad diesel GHG emissions, respectively. However, a follow up
analysis showed that the amount of CO2 emissions associated within nonroad diesel
use reported in the NEI was equivalent to the volume diesel sold in both 2012 and 2016
in Maricopa County as reported by ADOT. Therefore, it was concluded there was
double counting of diesel no. 2 sales for nonroad purposes included in the nonroad
diesel GHG emissions in the 2012 and 2016 community-scale GHG emissions
inventories (Table E1). To correct for this double-counting, red-dye diesel consumption
data for the City (2016) and Maricopa County (2012, 2018) were obtained from ADOT.
Red-dye diesel consumption was used as a proxy for nonroad diesel emissions
because it is illegal for purchase for on-road transportation. ADOT provided city-specific
data for Maricopa County for 2016 and county-level data for 2012 and 2018, so 2016
data was used to scale 2012 and 2018 county-level data to the city-level. Additionally,
2018 data was used as a proxy for 2020 data. With this updated method for estimating
40 Arizona Department of Transportation (2019). Red-Dyed Diesel Fuel in Arizona. URL: https://azdot.gov/motor-
vehicles/professional-services/fuel-tax-information/red-dyed-diesel-fuel-arizona.
53
non-road diesel consumption, on-road diesel GHG emissions may contain diesel
purchased for nonroad purposes, but nonroad diesel GHG emissions only contains
GHG emissions for nonroad purposes.
Table E1. Changes to Non-Road Diesel Consumption and GHG Emissions
Year
NEI Data Nonroad
Diesel
ADOT Dyed Diesel
Sales
∆GHG
Emissions
(MT CO2e)
% Change in
GHG
Emissions
GHG Emissions
(MT CO2e)
GHG Emissions
(MT CO2e)
2012
1,864,570
148,488
-1,716,082
-92%
2016
1,992,217
149,749
-1,842,468
-92%
E.5.2 Other Nonroad GHG Emissions
The NEI was used to gather data on GHG emissions from other nonroad fuel
consumption in Maricopa County. The 2011 NEI was used as a proxy for 2012 and the
2014 NEI was used as a proxy for 2016, 2018, and 2020. Other nonroad fuel
consumption data were scaled from Maricopa County to the city boundary. These data
primarily cover the combustion of propane for nonroad uses.
54
Appendix F. Waste Sector Documentation
Waste Sector GHG emissions occur from numerous sources: solid waste, wastewater
treatment, compost processing, and granulated activated carbon (GAC) hauling and
regeneration. Much of these GHG emissions occur due to city’s local government
operations and as such a description of the methods to calculate these GHG emissions
are found in the City of Phoenix 2018 GHG Emissions Inventory of Local Government
Operations.
F.1 Solid Waste
Solid Waste GHG emissions occur at landfills owned and operated by the city within city
boundary, a landfill owned and operated by the city outside city boundary, a privately-
owned landfill within the city boundary, and privately-owned landfills outside the city
boundary.
GHG emissions from landfills owned and operated by the city were obtained from the
City of Phoenix 2018 GHG Emissions Inventory of Local Government Operations. Of
the seven landfills owned and operated by the city, six are located within the city
boundaries – these landfills are closed and no longer accept waste – and the only open
landfill is located outside city boundaries. The names of these landfills, the data source,
method of GHG emissions calculation, and GPC subsector are described in Table F1.
Table F1. Data and Method Documentation for City-Owned Landfills
Landfill
Activity
Data
Source
Method
Active?
GPC Subsector
Skunk
Creek
CH4
Monitoring
City of
Phoenix
ICLEI
LGOP
No
Disposal of solid waste
generated in the city
27th
Avenue
CH4
Monitoring
City of
Phoenix
ICLEI
LGOP
No
Disposal of solid waste
generated in the city
Del Rio
CH4
Monitoring
City of
Phoenix
ICLEI
LGOP
No
Disposal of solid waste
generated in the city
Deer
Valley
CH4
Monitoring
City of
Phoenix
ICLEI
LGOP
No
Disposal of solid waste
generated in the city
19th
Avenue
CH4
Monitoring
City of
Phoenix
ICLEI
LGOP
No
Disposal of solid waste
generated in the city
Estes
EPA
LandGEM
Model
City of
Phoenix
First Oder
Decay
No
Disposal of solid waste
generated in the city
SR-85
CH4
Monitoring
City of
Phoenix
ICLEI
LGOP
Yes
Disposal of solid waste
generated in the city but
disposed outside the city
55
The City of Phoenix only collects municipal solid waste from single family residences
within city boundaries. Residents in the city that live in multi-family housing in addition to
commercial and industrial establishments are serviced by private haulers. There is one
landfill within the city boundary – the Lone Cactus Landfill – owned by a private waste
management company. GHG emissions from the Lone Cactus Landfill are reported by
Waste Management, Inc. to the EPA Greenhouse Gas Reporting Program. Therefore,
GHG emissions from the Lone Cactus Landfill were obtained from the EPA Facility-
Level Information on Greenhouse Gas Emissions Tool (Table F2).
Table F2. Data Documentation for Privately-Owned Landfills
Landfill
Activity Data
Owner
Active?
GPC Subsector
Lone
Cactus
EPA GHGRP
Waste
Management
Yes
Disposal of solid waste
generated in the city
Private
Haulers
EPA
GHGRP/Population
Multiple
Yes
Disposal of solid waste
generated in the city but
disposed outside the
city
Since solid waste is also collected by private haulers and disposed of in privately-owned
landfills outside of the city boundary, an additional estimation method was employed to
estimate GHG emissions from the landfills attributable to solid waste generated within
the City of Phoenix. First, a per capita GHG emissions from solid waste calculated for
Maricopa County. To do this, all landfill emissions data reported to the EPA GHGRP
within Maricopa County was pulled from EPA FLIGHT for 2012, 2016, and 2018 and
converted to a per capita metric using population data obtained from the U.S. Census
and City of Phoenix. Next, the number of residents living in multi-family housing in city
was estimated using data obtained from the U.S. Census American Housing Survey.
Finally, the population data were converted to GHG emissions using the per capita
GHG emissions rate, as shown in the equation below.
𝐺𝐻𝐺𝑃𝑟𝑖𝑣𝑎𝑡𝑒𝑀𝑆𝑊,𝑦=
∑𝐺𝐻𝐺
𝑙
𝑆𝑊,𝑙,𝑀𝑎𝑟𝑖𝑐𝑜𝑝𝑎,𝑦
𝑃𝑜𝑝𝑀𝑎𝑟𝑖𝑐𝑜𝑝𝑎,𝑦
× [(1 −
# 𝑆𝑖𝑛𝑔𝑙𝑒 𝐹𝑎𝑚𝑖𝑙𝑦 𝐷𝑒𝑡𝑎𝑐ℎ𝑒𝑑 𝐻𝑜𝑢𝑠𝑖𝑛𝑔
𝐴𝑙𝑙 𝐷𝑤𝑒𝑙𝑙𝑖𝑛𝑔𝑠
)
𝑃𝐻𝑋 𝑀𝑆𝐴,𝑦× 𝑃𝑜𝑝𝑃ℎ𝑜𝑒𝑛𝑖𝑥,𝑦]
Where,
GHGPivateMSW,y =
the GHG emissions from solid waste picked up by private haulers
(PrivateHaulers) in an inventory year (y).
Σl GHGSW,l,Maricopa,y = The total reported GHG emissions by all landfills in Maricopa County, Arizona.
PopMaricopa,y =
The population of Maricopa County, Arizona in an inventory year (y).
#
Single
Family
Detach Housing =
The number of single-family detached housing units in the Phoenix
metropolitan area in an inventory year (y).
# All Dwellings =
The number of housing units in the Phoenix metropolitan area in an inventory
year (y).
PopPhoenix,y =
the population of Phoenix, Arizona in an inventory year (y).
56
F.2 Wastewater Treatment
GHG emissions from wastewater treatment were obtained from the City of Phoenix
2018 GHG Emissions Inventory of Local Government Operations. Please refer to the
City of Phoenix 2018 GHG Emissions Inventory of Local Government Operations for
details about monitoring data and method. A summary table is presented below (Table
F3).
Table F3. Data Documentation for Wastewater Treatment Plants
Wastewater
Treatment
Plant
Service
Area
GHG
Emissions
Data
Source
GHG
Emissions
Methodology
GPC
Subsector
23rd Avenue
City of
Phoenix
CH4, N2O
City of
Phoenix
CH4 and
effluent
monitoring
data
ICLEI LGOP
Wastewater
generated in
the city
91st Avenue
All or
Portions of
Glendale,
Mesa,
Phoenix,
Scottsdale
and Tempe
CH4, N2O
City of
Phoenix
CH4 and
effluent
monitoring
data
ICLEI LGOP
Wastewater
generated in
the city
F.3 Compost Processing
GHG emissions from compost processing were obtained from the City of Phoenix 2018
GHG Emissions Inventory of Local Government Operations. The city provided data on
the total tons of green organic waste diverted to be processed as compost from FY
2005-2006 to FY 2018-19. Using these data, GHG emissions from composting were
calculated according to the methodology employed by the EPA to estimate national-
level emissions from composting in Section 7.3 of the Inventory of U.S. Greenhouse
Gas Emissions and Sinks: 1990-2017.41
F.4 GAC Hauling and Regeneration
GHG emissions from GAC hauling and regeneration were obtained from the City of
Phoenix 2018 GHG Emissions Inventory of Local Government Operations. The city
provided data on the vehicle miles driven to the GAC recharging facility and the amount
and type of energy used at the recharging facility. GHG emissions from GAC Hauling
and Regeneration are included as Other Scope 3 GHG emissions.
41 U.S. EPA. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2017. URL:
https://www.epa.gov/ghgemissions/inventory-us-greenhouse-gas-emissions-and-sinks-1990-2017