Attachment B - The 2018 Community-Scale GHG Emissions Inventory

City of Phoenix — Transportation, Infrastructure and Innovation Subcommittee (2020-11-04)

Extracted text (via pymupdf) 110164 characters

2018 Community-Scale
Greenhouse Gas
Emissions Inventory
A comprehensive report
prepared for
April 2020
sustainabilitysolutions.asu.edu
Attachment B

i
Acknowledgements

This report is a joint effort by the City of Phoenix:
Nancy Allen, Environmental Programs Manager
Rosanne Albright, Environmental Programs Coordinator
Dr. Matthew Potzler, Environmental Air Quality and Climate Specialist
Joe Gibbs, Environmental Air Quality Specialist

And

Arizona State University’s Walton Sustainability Solutions Initiatives:
Bill Campbell, Portfolio Manager
Mahindra Venkat, Graduate Student

And

Northern Arizona University’s School of Informatics, Computing, and Cyber Systems
Dr. Richard Rushforth, Assistant Research Professor

We would like to recognize the financial support from Aviation, Public Works, Water and
Transit Departments.

In addition, we wish to acknowledge the numerous city departments’ staff for supplying
the data needed to produce the City of Phoenix 2018 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.

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Table of Contents
List of Tables ...................................................................................................................iv
List of Figures .................................................................................................................. v
Acronym List ................................................................................................................... v
Executive Summary ........................................................................................................ 1
Introduction ..................................................................................................................... 7
1. Stationary Energy Sector .......................................................................................... 10
1.1 Scope 1 Stationary Energy .................................................................................. 12
1.2 Scope 2 Stationary Energy .................................................................................. 13
1.3 Scope 3 Stationary Energy .................................................................................. 14
2. Transportation Sector ................................................................................................ 16
2.1 Scope 1 Transportation GHG Emissions ............................................................. 17
2.2 Scope 2 Transportation GHG Emissions ............................................................. 19
2.3 Scope 3 Transportation GHG Emissions ............................................................. 20
3. Waste Sector ............................................................................................................. 21
Appendix A. Detailed GHG Emissions Summary .......................................................... 24
Appendix B. Stationary Energy – Natural Gas Documentation ..................................... 34
B.1 Natural Gas Data Collection ................................................................................ 34
B.2 Natural Gas Data Processing .............................................................................. 34
B.3 Changes between inventory years ...................................................................... 36
Appendix C. Stationary Energy – Electricity Documentation ......................................... 37
C.1 Electricity Data Collection ................................................................................... 37
C.2 Electricity Data Processing ................................................................................. 38
C.2.1 APS Electricity Data Processing ................................................................... 38
C.2.2 SRP Data Processing ................................................................................... 40
C.2.3 Total GHG Emissions from Electricity Consumption ..................................... 41
C.3 Transmission and Distribution Loss (T&D Loss) ................................................. 41
C.4 Changes between inventory years ...................................................................... 41
C.5 Impact of Electricity Emissions Factor on GHG Emissions ................................. 42
Appendix D. Transportation Sector Documentation ...................................................... 45
D.1 Transportation Sector Data Processing .............................................................. 45
D.2 On-Road Transport ............................................................................................. 45
D.2.1 Gasoline and Diesel ..................................................................................... 45
D.2.2 Alternative Fuel Vehicles – B20 Biodiesel, E85 Ethanol, CNG, LNG ............ 46
D.2.3 Electric Vehicles ........................................................................................... 46
D.3 Railways .............................................................................................................. 46
D.3.1 Valley Metro Light Rail .................................................................................. 46

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D.3.1 Freight Rail ................................................................................................... 47
D.4 Aviation ............................................................................................................... 47
D.4.1 Commercial Aviation ..................................................................................... 47
D.4.2 Civil Aviation ................................................................................................. 48
D.5 Off-Road Transportation ..................................................................................... 49
D.5.1 Nonroad Diesel ............................................................................................. 49
D.5.2 Other Nonroad GHG Emissions ................................................................... 50
Appendix E. Waste Sector Documentation ................................................................... 51
E.1 Solid Waste ......................................................................................................... 51
E.2 Wastewater Treatment ........................................................................................ 53
E.3 Compost Processing ........................................................................................... 54
E.4 GAC Hauling and Regeneration .......................................................................... 54

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List of Tables
Table ES-1. Phoenix GHG emissions by Sector (MT CO2e) ........................................... 3
Table ES-2. Subsector Stationary Energy GHG Emissions (MT CO2e) .......................... 4
Table ES-3. Subsector Transportation GHG Emissions (MT CO2e) ................................ 5
Table ES-4. Subsector Waste Sector GHG Emissions (MT CO2e) ................................. 6
Table 1. Community- Level GHG Emissions by Sector for 2012, 2016, and 2018 .......... 7
Table 2. 2018 Community-Level GHG Emissions by Sector and Scope ......................... 8
Table 3. Summary of Scope 1 Stationary Energy GHG Emissions ............................... 12
Table 4. Summary of Scope 2 Stationary Energy GHG Emissions ............................... 14
Table 5. Summary of Scope 3 Stationary Energy GHG Emissions ............................... 15
Table 6. Summary of Scope 1 Transportation GHG Emissions (MT CO2e) .................. 18
Table 7. Scope 1 Transportation Activity Data and GHG Emissions by Fuel ................ 18
Table 8. Summary of Scope 2 Transportation GHG Emissions .................................... 20
Table 9. Summary of Scope 3 Transportation GHG Emissions .................................... 20
Table 10. Summary of Scope 1 Waste GHG Emissions ............................................... 22
Table 11. Summary of Scope 3 Waste GHG Emissions ............................................... 23
Table A1. Year-to-Year Comparison of Stationary Energy GHG Emissions ................. 25
Table A2. Year-to-Year Comparison of Transportation GHG Emissions ....................... 28
Table A3. Year-to-Year Comparison of Waste GHG Emissions .................................... 30
Table B4. Changes to Natural Gas GHG Emissions Due to Updated Scaling Methods 36
Table A1. Year-to-Year Comparison of Stationary Energy GHG Emissions ................. 25
Table A2. Year-to-Year Comparison of Transportation GHG Emissions ....................... 28
Table A3. Year-to-Year Comparison of Waste GHG Emissions .................................... 30
Table B4. Changes to Natural Gas GHG Emissions Due to Updated Scaling Methods 36
Table C1. Changes to Scaling Methodologies for Electricity Data ................................ 42
Table C2. Electricity GHG EFs Derived from Multiple eGRID Decision Boundaries ..... 43
Table C3. Electricity GHG Emissions from Multiple eGRID Decision Boundaries ......... 44
Table D1. Changes to Non-Road Diesel Consumption and GHG Emissions ................ 50
Table E1. Data and Method Documentation for City-Owned Landfills .......................... 51
Table E2. Data Documentation for Privately-Owned Landfills ....................................... 52
Table E3. Data Documentation for Wastewater Treatment Plants ................................ 53

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List of Figures
Figure ES-1. GHG emissions by emissions sector for 2012, 2016, and 2018. ................ 2
Figure ES-2. Stationary Energy GHG emissions for 2012, 2016, and 2018. ................... 3
Figure ES-3.Transportation GHG emissions for 2012, 2016, and 2018. ......................... 5
Figure 1. Total GHG Emissions and Per Capita GHG Emissions Since 2012 ................. 8
Figure 2. Distribution of GHG Emissions by Sector for 2012, 2016, and 2018. ............... 9
Figure 3. Stationary Energy GHG Emissions by Scope Since 2012 ............................. 10
Figure 4. Scope 1 Stationary GHG Emissions Since 2012 ............................................ 13
Figure 5. Scope 2 Stationary GHG Emissions Since 2012 ............................................ 15
Figure 6. Summary of Transportation Sector GHG Emissions by Fuel Type ................ 17

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
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

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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

1
Executive Summary
The City of Phoenix (City) has completed a community-scale greenhouse gas (GHG)
emissions inventory for calendar year 2018. The 2018 community-scale GHG emissions
inventory was conducted 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 ICLEI1. The GPC is also the standard supported by the Global Covenant of
Mayors for Climate and Energy, of which the City is a member.
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 occurs 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 2018 community-scale GHG inventory is the third completed by the City following
the 2012 and 2016 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, GHG emissions estimation methods. Changes to GHG emissions
totals for the 2012 and 2016 calendar years are reported along with the 2018 GHG
emissions totals.

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

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Key Findings
•
In 2018, community-scale GHG emissions were 16,603,754 metric tons of
carbon dioxide equivalents (MT CO2e)
•
2018 community-scale GHG emissions were 0.5% lower than the 2012 levels of
16,692,626 MT CO2e (Figure ES-1).
• Stationary Energy Sector GHG emissions totaled 8,550,631 MT CO2e.
• Transportation Sector GHG emissions totaled 7,748,914 MT CO2e.
• Waste Sector GHG emissions totaled 304,209 MT CO2e.
• GHG emissions decreased during a period where the City’s population grew 12%
and the metro area economy grew 26%. Per capita emissions fell from the 2012
baseline of 11.33 MT CO2e to 10.00 MT CO2e in 2018.

Figure ES-1. GHG emissions by emissions sector for 2012, 2016, and 2018.
The distribution of GHG emissions between Stationary Energy, Transportation, and
Waste Sectors for 2012, 2016, and 2018 is detailed in Table ES-1.

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Table ES-1. Phoenix GHG emissions by Sector (MT CO2e)
Sector
2012
2016
2018
% Change
2012 -2018
Stationary Energy
9,431,574
8,806,621
8,550,631
-9.3%
Transportation
6,895,031
7,514,844
7,748,914
12.4%
Waste
366,021
312,881
304,209
-17.6%
Total
16,692,626 16,634,346 16,603,754
-0.5%
Stationary Energy
The Stationary Energy Sector is the largest source of GHG emissions in the City.
Stationary energy GHG emissions sources include energy utilized in residential
buildings; commercial buildings and facilities; manufacturing industries; agriculture,
forestry and fishing energy use; and electricity transmission and distribution energy
losses. GHG emissions from natural gas leakages were not included for any reporting
year due to a lack of data on leakage rates.

Figure ES-2. Stationary Energy GHG emissions for 2012, 2016, and 2018.
Stationary Energy GHG emissions for 2018 were 8,550,631 MT CO2e, which is a 9%
decrease in emissions from 2012. The driving force behind the large reduction in
Stationary Energy GHG emissions resulted from a regional increase in clean energy

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production, which decreased the carbon intensity of what Phoenix consumes, as
reflected in the EPA Emissions and General Resource Integrated Database (eGRID)
GHG emissions factor. Data to calculate Stationary Energy GHG emissions were
obtained from Arizona Public Service (electricity), the 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 Sectory for 2012 and
2018 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
% Change
2012-2018
Residential Buildings
4,093,258 3,940,954 3,755,614
-8%
Commercial & Institutional Buildings
4,853,598 4,449,184 4,740,164
-2%
Manufacturing Industries & Construction
415,704
364,647
8,303
-98%
Agriculture, Forestry & Fishing Activities
68,954
51,758
46,477
-33%
Non-Specified Sources
60
78
74
23%
Total
9,431,574 8,806,621 8,550,631
-9%
Transportation
The Transportation Sector is the second 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, 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 2018 were 7,748,914 MT CO2e, a 12% increase in
GHG emissions from the 2012 level of 6,895,031 MTCO2e (Figure ES-3).

Figure ES-3.Transportation GHG emissions for 2012, 2016, and 2018.
Increased on-road and off-road transportation activity was responsible for the increased
emissions. 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 Southwest Gas. Table ES-3 details
GHG emissions among Transporation sub-sectors for the years 2012, 2016, and 2018.

Table ES-3. Subsector Transportation GHG Emissions (MT CO2e)
Transportation
2012
2016
2018
% Change
2012-2018
On-road transport
5,856,023 6,444,711 6,601,864
13%
Railways
29,113
29,300
31,541
8%
Commercial Aviation
698,263
705,643
779,113
12%
Civil Aviation (Aviation Gasoline)
13,394
15,067
10,043
-25%
Off-road transport
298,237
320,122
326,353
9%
Transportation Sector Total
6,895,031 7,514,844 7,748,914
12%
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 biological treatment
(composting) of waste generated and treated in Phoenix. Between 2012 and 2018 there

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was a 17% decrease in Waste Sector GHG emissions. GHG emissions from solid waste
disposal decreased by approximately 19%, similar to the Waste Sector overall (Table
ES-4). GHG emissions from wastewater treatment increased by 21% and composting
increased 40%. The total GHG emissions from the Waste Sector were 304,209 MT
CO2e in 2018 as compared to 366,021 MT CO2e reported in the 2012. Waste Sector
reductions were driven by solid waste disposal, which is more than 90% of the sector
emissions. 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.

Table ES-4. Subsector Waste Sector GHG Emissions (MT CO2e)
Waste
2012
2016
2018
% Change
2012-2018
Solid Waste Disposal
351,780 299,484 285,885
-19%
Wastewater Treatment & Discharge
8,440
9,428
10,199
21%
Biological Waste Treatment (Composting)
5,802
3,968
8,125
40%
Waste Sector Total
366,021 312,881 304,209
-17%
Conclusion
In 2018, citywide GHG emissions in Phoenix was 16,603,754 metric tons CO2e – 0.5%
below the 2012 levels of 16,692,626 MT CO2e. Emissions increased in the
Transportation Sector by 853,883 MT CO2e, which was proportional to population
growth. Stationary Energy GHG emissions decreased 880,943 MT CO2e, driven by a
less GHG-intensive regional electricity grid. Waste Sector GHG emissions decreased by
17% between 2012 and 2018, 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 produce less GHG emissions as
the waste decays.

The Transportation Sector is the second largest source of GHG emissions in Phoenix
and grew by 853,883 MT CO2e between 2012 and 2018. On-road transportation, mainly
gasoline consumption, drove Transportation Sector GHG emissions increase. Measures
to reduce transportation-related GHG emissions will reduce community-scale GHG
emissions. Gasoline-powered motor vehicles used for on-road transportation is the
largest single source of transportation-related GHG emissions. An increased adoption of
battery electric vehicles (BEVs) or plugin electric hybrid vehicles (PEHVs) is one avenue
to reduce transportation-related GHG emissions. Another is higher adoption rate of
mass transit options.

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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, which only
requires an inventory of Stationary Energy, Transportation, Waste sectors. IPPU and
AFOLU are not required to be inventoried for BASIC-level reporting under the GPC.

In 2018, community-scale emissions totaled 16,603,754 MT CO2e, 0.5% decrease
below the baseline 2012 level of 16,692,626MT CO2e (Table 1). Appendix A contains a
detailed breakdown of GPC sector and subsector GHG emissions for 2012, 2016, and
2018. The Stationary Energy and Transportation Sectors account for 99% of the
community-scale emissions. The largest source of emissions is from on-road motor
gasoline combustion, which comprise 85% Transportation emissions and 36% of all
emissions. The next largest source is from electricity consumption from commercial,
industrial, and residential areas at 47%. Commercial aviation composed 5% of
emissions. Meeting any community-scale goal requires mitigating GHG emissions from
these sources.

Table 1. Community- Level GHG Emissions by Sector for 2012, 2016, and 2018
Sector
GHG Emissions (MT CO₂e)
% Change
2012 -2018
2012
2016
2018
Stationary Energy
9,431,574
8,806,621
8,550,631
-9.3%
Transportation
6,895,031
7,514,844
7,748,914
12.4%
Waste
366,021
312,881
304,209
-17.6%
Total
16,692,626 16,634,346 16,603,754
-0.5%

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 855,221 MT CO2e between 2012 and 2018. The Transportation sector
GHG emissions grew by 854,193 MT CO2e. Waste GHG emissions, which are 1% of
community-scale GHG emissions, fell by 61,813 MT CO2e. Per capita GHG emissions
fell by 11.8% from 11.33 to 10.00 MT CO2e per resident between 2012 and 2018
(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 2018,
52% of GHG emissions occurred directly within the city boundary as Scope 1
emissions; 47% occurred indirectly as Scope 2 emissions through the purchase of
electricity; and 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
781,000
7,769,631
310,445*
8,550,631
Transportation
7,735,257
13,657
546*
7,748,914
Waste
150,118
0
154,091
304,209
Total
8,666,375
7,783,288
154,091
16,603,754
*Scope 3 Stationary Energy and Transportation GHG emissions do not count toward the BASIC-level GHG emissions
total.

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In 2018, Stationary Energy activities – GHG emissions resulting from natural gas
combustion and electricity consumption – accounted for approximately 51% of
community-scale GHG emissions. Transportation activities comprise approximately
47%. Community-scale Transportation Sector GHG emissions have increased relative
to Stationary Energy Section GHG emissions since 2012 (Figure 2). Gasoline
combustion produced 76% of Transportation GHG emissions within city boundaries.
The two largest sources of GHG emissions produced 83% of total community-scale
GHG emissions – electricity consumption (47%) and gasoline combustion (36%).
Community-level GHG mitigation efforts should prioritize these two sources of GHG
emissions to achieve material GHG emissions reductions.

Figure 2. Distribution of GHG Emissions by Sector for 2012, 2016, and 2018.
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. This will reduce community-scale GHG
emissions significantly and should be measurable in all future inventories.

Motor gasoline consumed for on-road transportation is the single largest GHG emitting
activity. These emissions have grown in each GHG inventory. Between 2012 and 2018,
GHG emissions from gasoline consumption grew 667,130 MT CO2e (12.7%).The
viability and cost effectiveness of strategies to reduce GHG emissions from

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

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Transportation activities, specifically on-road motor gasoline consumption, will dictate
future community-scale GHG emissions and the ability of the City to meet GHG
emissions reductions goals.
1. Stationary Energy Sector
Stationary Energy sector GHG emissions occur due to the combustion of natural gas
(Scope 1) and the consumption of purchased electricity at residential, commercial, and
industrial buildings, in addition to other facilities (Scope 2).

Stationary Energy GHG emissions were predominantly Scope 2 emissions from
electricity consumption (Figure 3). Since 2012, the distribution of Stationary Energy
GHG emissions between Scope 1 and Scope 2 emissions have been 9% Scope 1
emissions and 91% Scope 2 emissions. Scope 2 Stationary Energy GHG emissions are
one of the largest sources of GHG emissions comprising 52% of total community-scale
emissions in 2012; 48% in 2016; and 47% in 2018. The decrease in electricity-related
GHG emissions has occurred during a period where electricity consumption has
increased by 1.5% from 16,428,313 MWh to 16,671,691 MWh. GHG emissions from
electricity fell despite consumption growing because of the significant decrease in the
carbon intensity of the regional electricity grid.

Figure 3. Stationary Energy GHG Emissions by Scope Since 2012

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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 emissions factor includes
all regional power plants in Arizona, Western and Central New Mexico, Southern
Nevada, and parts of southwestern California. Therefore, GHG emissions reduction
activities undertaken by regional utilities – APS, SRP, Tucson Electric Power, and the
Public Service Company of New Mexico (PNM) – and municipalities – such as the City-
owned solar facilities at the Lake Pleasant water treatment plant and Sky Harbor
International Airport – reduce the AZNM subregion GHG emissions factor.

Since 2012, the AZNM subregion GHG emissions factor has decreased 11.2%. This
reduction has occurred due to an increase in electricity generation from natural gas and
renewable sources, such as wind and solar energy, and, most importantly, a decrease
in coal electricity generation. According to eGRID data, the percentage of natural gas
production in the AZNM generation portfolio has increased 8%; wind and solar
generation has increased 5%; and coal has decreased 11%. Coal still made up 27% of
electricity production in the AZNM subregion.

The single largest source of GHG emissions in the AZNM subregion – the Navajo
Generating Station operated by SRP – closed in 20196. SRP has a long-term goal of
reducing the GHG-intensity of electricity production 62% below 2005 levels by 2035 and
90% by 2050. APS has a carbon neutrality goal for 20507; the utility plans to source
65% of electricity from renewable sources by 2030 and to stop coal-fired electricity
generation by 20318. PNM plans to have 100% carbon free electricity by 20409.
Therefore, based on how electricity emissions are calculated, the recent coal-fired
power plants closures and announcements by regional electric utilities to reduce the

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.
6 Salt River Project (2019). Navajo Generating Station Permanently Shuts Down. URL: https://media.srpnet.com/navajo-generating-
station-permanently-shuts-down/
7 Arizona Public Service (2020). Stakeholder Perspectives. URL: https://www.aps.com/en/About/Our-Company/Clean-
Energy/Stakeholder-Perspectives
8 Arizona Public Service (2020). Clean Energy. URL: https://www.aps.com/en/About/Our-Company/Clean-Energy
9 PNM (2020). Our Commitment. URL: https://www.pnm.com/our-commitment

12
GHG-intensity of electricity generation, or to go carbon neutral, will result in a significant
reduction in community-scale GHG emissions. The City of Phoenix recently pledged to
become carbon neutral by 2050 and similar efforts by Arizona Public Service (APS) and
Salt River Project (SRP) will help the City achieve its GHG reduction goals.

1.1 Scope 1 Stationary Energy
Scope 1 Stationary Energy GHG emissions occur from the combustion of natural gas
delivered by Southwest Gas within the city boundary. Citywide natural gas consumption
was 3% lower in 2018 than in 2012 (Table 3). Additionally, natural gas consumption in
the manufacturing industries and construction subsector has been reclassified to the
commercial and institutional buildings and facilities subsector, resulting in a relative
increase of natural gas consumption at commercial and institutional buildings and
facilities. Future community GHG emissions will consider retroactively combining these
two sectors.

Table 3. Summary of Scope 1 Stationary Energy GHG Emissions
Scope 1 Activity Data (kilotherms)
2012
2016
2018
Residential Buildings
58,796
58,946
53,241
Commercial & Industrial Buildings
63,802
69,036
83,367
Manufacturing Industries & Construction
16,289
13,850
1,562
Agriculture, Fishing, and Forestry Activities
12,982
9,737
8,744
Non-specified
11
15
14
Total
151,881
151,584
146,927

Scope 1 GHG Emissions (MT CO2e)
2012
2016
2018
Residential Buildings
312,298
313,330
283,007
Commercial & Industrial Buildings
338,887
366,966
443,139
Manufacturing Industries & Construction
86,522
73,622
8,303
Agriculture, Fishing, and Forestry Activities
68,954
51,758
46,477
Non-specified
60
78
74
Total
806,722
805,753
781,000

Scope 1 Stationary Energy GHG emissions fell by 25,722 MT CO2e below 2012 levels
(Figure 4). 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 4. 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 Arizona Public Service (APS) and Salt River Project (SRP) within the
city boundary. Between 2012 and 2018, GHG emissions from the consumption of
electricity purchased electricity fell by 9.92% (855,221 MT CO2e) despite consumption
levels increasing by 1.5% or 243,378 MWh (Table 4).

14
Table 4. Summary of Scope 2 Stationary Energy GHG Emissions
Scope 2 Activity Data (GWh)
2012
2016
2018
Residential Buildings
7,202
7,624
7,451
Commercial & Industrial Buildings
8,599
8,579
9,220
Manufacturing Industries & Construction
627
612
IE*
Total
16,428
16,815
16,671

Scope 2 GHG Emissions (MT CO2e)
2012
2016
2018
Residential Buildings
3,780,960
3,627,624
3,472,607
Commercial & Industrial Buildings
4,514,711
4,082,219
4,297,024
Manufacturing Industries & Construction
329,182
291,025
IE*
Total
8,624,852
8,000,868
7,769,631
*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 are were NE and, therefore, not included in this table.

In 2018, Scope 2 Stationary Energy GHG emissions were 7,769,631 MT CO2e, which
was 9.92 % below the 2012 levels of 8,624,852 MT CO2e (Figure 5). Stationary Energy
GHG emissions decreased due to the regional electricity grid becoming 11.2% less
GHG-intensive from the retirement and replacement of coal-fired power plants with
natural gas and renewable (wind and solar) electricity generation.10 Additionally,
residential electricity consumption only grew 3.5% during a period in which population
grew approximately 12.6%. The decreased growth in electricity consumption relative to
population growth could have occurred for numerous reasons, including energy
efficiency retrofits, energy efficient new construction, milder weather, cost, or resident
and commercial solar adoption. Further work must be conducted to determine the
extent each of these contributed to the decreased growth in electricity consumption.
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 2018, transmission and distribution (T&D) loss in the State of Arizona has

10 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.

15
averaged 4.6% ± 0.6% of electricity consumption and has ranged between 3.4% in
2015 up to 5.7% in 1996.11 Scope 3 Stationary Energy GHG emissions are not within
the scope of GPC BASIC-level reporting. They are being presented to show the full
extent of GHG emissions from electricity consumption. T&D loss underscores the fact
that that on-site renewable energy generation and energy efficiency avoids GHG
emissions from the electricity lost during T&D in the electricity grid.

Figure 5. Scope 2 Stationary GHG Emissions Since 2012

Table 5. Summary of Scope 3 Stationary Energy GHG Emissions
Scope 3 Activity Data
2012
2016
2018
Transmission & Distribution Loss (MWh)
613,573
631,792
666,138
Natural Gas Leakage (therms)
NE
NE
NE

Scope 3 GHG Emissions (MT CO2e)
2012
2016
2018
Transmission & Distribution Loss (MWh)
322,125
300,632
310,345
Natural Gas Leakage (therms)
NE
NE
NE
Total
322,125
300,632
310,345
*NE – Not Estimated

11 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.

16
2. Transportation Sector
Transportation Sector GHG emissions have both Scope 1 and Scope 2 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. In 2018,
community-scale Transportation sector GHG emissions totaled 7,748,912 MT CO2e and
were 12.7% greater (853,881 MT CO2e) than the 2012 levels of 6,895,031 MT CO2e.

Motor gasoline is the largest source of community-scale Transportation Sector GHG
emissions at 76.4% (Figure 6). 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.12 GHG emissions
from Jet Fuel A (10.1%) and on-road diesel fuel (8.0%) are the next largest sources of
transportation GHG emissions, and are much smaller sources than motor gasoline
consumption. On-road combustion of motor gasoline alone is responsible for 37% of all
community-scale GHG emissions.

Community-level GHG emissions reduction plans must address how to reduce the
single largest source of GHG emissions. Transportation Sector GHG emissions have
grown since 2012. GHG emissions from gasoline combustion grew on pace with
population growth. As growth occurs, viable solutions to reduce gasoline consumption –
from plug-in EVs and increased mass transit to creating walkable communities – are
critical for meeting GHG emissions reductions goals.

12 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

Figure 6. Summary of Transportation Sector GHG Emissions by Fuel Type

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). Growth in on-
road transport GHG emissions (12.7%) has 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. Community-level GHG emissions from off-road transport,
which is the third largest source community-scale Transportation sector GHG
emissions, result from construction equipment, agricultural equipment and mining
equipment.

18
Table 6. Summary of Scope 1 Transportation GHG Emissions (MT CO2e)
Scope 1 Sources
2012
2016
2018
On-road transport
5,855,292
6,441,344
6,596,202
Railways*
23,545
23,545
23,545
Commercial Aviation
698,263
705,643
779,113
Civil Aviation
13,394
15,067
10,043
Nonroad transport
298,237
320,122
326,353
Total
6,888,732
7,505,722
7,735,257
*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
(Table 7). Between 2012 and 2018, 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. With
the City of Phoenix phasing out LNG usage, emissions from this fuel type should reduce
to zero. LNG is being replaced by CNG in the City of Phoenix vehicle fleet.

Table 7. Scope 1 Transportation Activity Data and GHG Emissions by Fuel
Scope 1 Activity Data
2012
2016
2018
Gasoline 1
586,464
652,970
667,093
On-Road Diesel1
51,781
57,834
60,435
B20 Biodiesel1
3,034
2,701
3,028
E85 Ethanol1
287
157
311
E54 Ethanol 1
0
109
0
CNG1 – therms
4,304
3,484
6,356
LNG1 – GGE
6,222
2,544
543
Jet Fuel A (Commercial Aviation)2
71,038
71,788
79,263
Aviation Gasoline (Civil Aviation)2
1,569
1,765
1,176
Railways**
NE
NE
NE
Nonroad Diesel3
14,528
16,009
16,619
Nonroad LPG3
NE
NE
NE

19
Scope 1 GHG Emissions (MT CO2e)
2012
2016
2018
Gasoline 1
5,250,540 5,797,934 5,917,671
On-Road Diesel1
529,242
591,063
617,575
B20 Biodiesel1
24,785
22,062
24,732
E85 Ethanol1
379
207
410
E54 Ethanol 1
0
441
0
CNG1 – therms
22,595
18,293
33,391
LNG1 – GGE
27,751
11,345
2,423
Jet Fuel A (Commercial Aviation)2
698,263
705,643
779,113
Aviation Gasoline (Civil Aviation)2
13,394
15,067
10,043
Railways**
23,545
23,545
23,545
Nonroad Diesel3
148,488
163,595
169,826
Nonroad LPG3
149,749
156,527
156,527
Total
6,888,732 7,505,722 7,735,257
*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
Scope 2 Transportation sector GHG emissions, which includes the consumption of
purchased electricity to charge electric vehicles and to power electric light rail, have
increased 117% since 2012 (Table 8). The growth of Scope 2 Transportation sector
GHG emissions is primarily from the increased adoption of plug-in electric vehicles;
Scope 2 GHG emissions from on-road transport increased 674% since 2012. GHG
emissions related to the Valley Metro light rail system increased 2,428 MT CO2e (44%)
largely 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 already happening through T2050, battery technology improvements, installing a

20
regional charging station network, and market conditions to change so electric-powered
transport becomes more consumer-friendly.

Table 8. Summary of Scope 2 Transportation GHG Emissions
Scope 2 Activity Data (MWh)
2012
2016
2018
On-road transport
1,393
7,075
12,148
Railways (Light Rail)
10,605
12,095
17,157
Total
11,998
19,170
29,305

Scope 2 GHG Emissions (MT CO2e)
2012
2016
2018
On-road transport
731
3,367
5,661
Railways (Light Rail)
5,568
5,755
7,996
Total
6,299
9,122
13,657

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
On-road transport
52
266
485
Railways (Light Rail)
396
454
686
Total
448
720
1,171

Scope 3 GHG Emissions (MT CO2e)
2012
2016
2018
On-road transport
27
127
226
Railways (Light Rail)
208
216
319
Total
235
343
546

21
3. Waste Sector
The Waste Sector includes GHG emissions from the disposal of municipal solid waste
(MSW); wastewater treatment; and compost processing. It is the smallest GHG
emissions sector in the community-scale inventory, comprising only 1% of overall GHG
emissions.

Community-level emissions from MSW have both Scope 1 and Scope 3 components.
Unlike Scope 3 emissions in the Stationary Energy and Transportation sectors, Scope 3
Waste emissions are included within the scope of GPC BASIC-level reporting. Scope 1
MSW emissions include emissions from waste/wastewater generated and treated within
the city boundary in addition to waste imported into the city and treated. Wastewater
treatment GHG emissions sources include the 23rd Avenue and 91st Avenue wastewater
treatment plants. Compost emissions – the biological treatment of waste in – occur at
the 27th Avenue Compost Facility, but have historically also occurred at a compost
facility co-located at the 27th Avenue Landfill. Emissions from both wastewater treatment
and composting are Scope 1 emissions. Scope 3 MSW emissions cover the emissions
from all waste exported outside the city boundary. Currently, there are no open landfills
within city limits so all Scope 1 MSW emissions are from closed landfills. Over time,
these emissions will decrease as the biological processes that generate GHG emissions
cease. All solid waste is disposed at a city-owned landfill outside the city-boundary,
which is a Scope 3 emissions.

Scope 1 Waste GHG emissions occur from the disposal of solid waste generated within
the city. These GHG emissions will continue to decrease, as they have since 2012,
because there are no longer any open landfills within the City boundary, and each year
there is less waste available for the generation of methane emissions (Table 10). 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. However, as solid waste generated
within the City is now primarily disposed of outside the City boundary, Scope 3 Waste
GHG emissions will continue to increase in future GHG emissions inventories.

While wastewater treatment GHG emissions have increased since 2012, so too has the
population, and these emissions are largely population-dependent. Wastewater
treatment GHG emissions are a small fraction of overall community-scale GHG
emissions. Scope 1 GHG emissions from the biological treatment of waste generated
(compost processing) will likely increase over time with increased organic waste

22
diversion goals. These emissions will be offset by reducing future Scope 3 Waste GHG
emissions generated at the SR-85 landfill and Scope 1 Transportation GHG emissions
from hauling waste to the landfill.

Table 10. Summary of Scope 1 Waste GHG Emissions
Scope 1 Sources Activity Data (MT CH4 Emissions)
2012
2016
2018
Disposal of Solid Waste Generated in the City
8,425
5,099
4,707
Biological Treatment of Waste Generated in the City
121
83
170
Wastewater Generated Inside the City
92.00
121.39
134.68
Total
8,440
9,428
10,199

Scope 1 Sources Activity Data (MT N2O Emissions)
2012
2016
2018
Biological Treatment of Waste Generated in the City
9.09
6.22
12.73
Wastewater Generated Inside the City
22.13
22.75
24.26
Total
8,440
9,428
10,199

Scope 1 GHG Emissions (MT CO2e)
2012
2016
2018
Disposal of Solid Waste Generated in the City
235,889 142,770 131,794
Biological Treatment of Waste Generated in the City
5,802
3,968
8,125
Wastewater Generated Inside the City
8,440
9,428
10,199
Total
250,130 156,167 150,118

Scope 3 Waste GHG emissions from the disposal of waste generated within the city, but
disposed outside the city, will continue to increase (Table 11). This GHG emissions
trend will occur as 2018 was the last full GHG inventory year with an operating landfill
(Waste Management Lone Cactus Landfill) within the city boundary. As GHG emissions
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. The capture of digester gas at the 91st
Ave WWTP for processing and sale as renewable natural gas (RNG) by Ameresco, Inc.
will reduce Waste Sector GHG emissions from wastewater treatment. The diversion of
green-organic waste from waste streams is a viable way to reduce future Waste sector
GHG emissions.

23
Table 11. Summary of Scope 3 Waste GHG Emissions
Scope 3 Sources Activity Data (MT CH4 Emissions)
2012
2016
2018
Disposal of Solid Waste Generated in the City
but Disposed Outside the City at SR-85
295
2,147
2,029
Disposal of Solid Waste Generated in the City
but Disposed Outside the City by Private Haulers
3,844
3,450
3,474
Total
4,139
5,597
5,503

Scope 3 GHG Emissions (MT CO2e)
2012
2016
2018
Disposal of Solid Waste Generated in the City
but Disposed Outside the City at SR-85
8,260
60,116
56,820
Disposal of Solid Waste Generated in the City
but Disposed Outside the City by Private Haulers
107,631
96,598
97,271
Total
115,891 156,714 154,091

24
Appendix A. Detailed GHG Emissions
Summary
Appendix A contains tables detailing City of Phoenix community-scale GHG emissions
by each GPC sector and subsector.

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)
% Change
2012
2016
2018
2012 -
2018
2016 -
2018
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
-9%
-10%
I.1.2
2
Emissions from grid-supplied energy consumed within the city
boundary
3,780,960 3,627,624 3,472,607
-8%
-4%
I.1.3
3
Emissions from transmission and distribution losses from grid-
supplied energy consumption
141,213
136,308
138,752
-2%
2%
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
31%
21%
I.2.2
2
Emissions from grid-supplied energy consumed within the city
boundary
4,514,711 4,082,219 4,297,024
-5%
5%
I.2.3
3
Emissions from transmission and distribution losses from grid-
supplied energy consumption
168,618
153,389
171,693
2%
12%
I.3

Manufacturing industries and construction

I.1.1
1
Emissions from fuel combustion within the city boundary
312,298
313,330
283,007
-9%
-10%
I.1.2
2
Emissions from grid-supplied energy consumed within the city
boundary
3,780,960 3,627,624 3,472,607
-8%
-4%
I.2.3
3
Emissions from transmission and distribution losses from grid-
supplied energy consumption
168,618
153,389
171,693
2%
12%
I.4

Energy Industries

26
GPC
ref No. Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas Emissions
(metric tons CO₂e)
% Change
2012
2016
2018
2012 -
2018
2016 -
2018
I.4.1
1
Emissions from energy used in power plant auxiliary
operations within the city boundary
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
—
—
I.4.3
3
Emissions from transmissions and distribution losses from
grid-supplied energy consumption in power plant auxiliary
operations
NE
NE
NE
—
—
I.4.4
1
Emissions from energy generation supplied to the grid
986,289
1,200,633 1,391,552
41%
16%
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
-33%
-10%
I.5.2
2
Emissions from grid-supplied energy consumed within the city
boundary
IE
IE
IE
—
—
I.5.3
3
Emissions from transmission and distribution losses from grid-
supplied energy consumption
IE
IE
IE
—
—
I.6

Non-specified sources

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
—
—

27
GPC
ref No. Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas Emissions
(metric tons CO₂e)
% Change
2012
2016
2018
2012 -
2018
2016 -
2018
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
—
—

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.

28
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)
% Change
2012
2016
2018
2012-
2018
2012-
2018
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 6,596,202
13%
2%
II.1.2
2
Emissions from grid-supplied energy consumed within the city
boundary for on-road transportation
731
3,367
5,661
674%
68%
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
27
127
226
728%
79%
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
0%
0%
II.2.2
2
Emissions from grid-supplied energy consumed within the city
boundary for railways
5,568
5,755
7,996
44%
39%
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
319
54%
48%
II.3

Waterborne navigation

II.3.1
1
Emissions from fuel combustion for waterborne navigation
occurring within the city boundary
NO
NO
NO
—
—
II.3.2
2
Emissions from grid-supplied energy consumed within the city
boundary for waterborne navigation
NO
NO
NO
—
—

29
GPC
ref
No.
Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas Emissions
(metric tons CO₂e)
% Change
2012
2016
2018
2012-
2018
2012-
2018
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
—
—
II.4

Aviation

II.4.1
1
Emissions from fuel combustion for aviation occurring within the
city boundary
711,658
720,710
789,156
11%
9%
II.4.2
2
Emissions from grid-supplied energy consumed within the city
boundary for aviation
NE
NE
NE
—
—
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
—
—
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
9%
2%
II.5.2
2
Emissions from grid-supplied energy consumed within the city
boundary for off-road transportation
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

30
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.

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)
% Change
2012
2016
2018
2012-
2018
2016-
2018
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
235,889 142,770 131,794
-44%
-8%

31
GPC
ref
No.
Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas
Emissions
(metric tons CO₂e)
% Change
2012
2016
2018
2012-
2018
2016-
2018
III.1.2
3
Emissions from solid waste generated within the city boundary
and disposed in landfills or open dumps outside the city
boundary
115,891 156,714 154,091
33%
-2%
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
—
—
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
40%
105%
III.2.2
3
Emissions from solid waste generated within the city boundary
but treated biologically outside of the city boundary
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
—
—
III.3

Incineration and open burning

III.3.1
1
Emissions from solid waste generated treated within the city
boundary
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
—
—
III.3.3
1
Emissions from waste generated outside the city boundary but
treated within the city boundary
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
21%
8%

32
GPC
ref
No.
Scope GHG Emissions Source
(By Sector and Sub-sector)
Greenhouse Gas
Emissions
(metric tons CO₂e)
% Change
2012
2016
2018
2012-
2018
2016-
2018
III.4.2
3
Emissions from wastewater generated within the city boundary
but treated outside of the city boundary
NO
NO
NO
—
—
III.4.3
1
Emissions from wastewater generated outside the city boundary
but treated within the city boundary
NO
NO
IE
—
—
IV

Industrial Processes and Product Uses (IPPU)

IV.1
1
Emissions from industrial processes occurring within the city
boundary
NE
NE
NE
—
—
IV.2
1
Emissions from product use occurring within the city boundary
NE
NE
NE
—
—
V

Agriculture, Forestry, and Other Land Use (AFOLU)

V.1
1
Emissions from livestock within the city boundary
NE
NE
NE
—
—
V.2
1
Emissions from land within the city boundary
NE
NE
NE
—
—
V.3
1
Emissions from aggregate sources and non-CO₂ emissions
sources on land within the city boundary
NE
NE
NE
—
—
VI

Other Scope 3

VI.1
3
Other Scope 3
3,001
715
278
-91%
-61%

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

33
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.

34
Appendix B. Stationary Energy – Natural
Gas Documentation
Appendix B describes the data collection and data processing for obtaining natural gas
consumption data and calculating GHG emissions from natural gas combustion.
Appendix B also describes any changes to data sources and methodologies in the 2018
community-scale GHG emissions inventory.

B.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 – 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.

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, 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.

B.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

35
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).

Using the data provided by Southwest Gas, the following equation was used to
calculate GHG emissions from Stationary Energy natural gas consumption.

𝐺𝐺𝐺𝐺𝐺𝐺𝑁𝑁𝑁𝑁,𝑖𝑖,𝑗𝑗,𝑦𝑦= 𝑁𝑁𝑁𝑁𝑖𝑖,𝑦𝑦 × 𝐶𝐶𝐶𝐶× 𝐸𝐸𝐸𝐸𝑁𝑁𝑁𝑁,𝑗𝑗

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).

𝐸𝐸𝐸𝐸𝑁𝑁𝑁𝑁,𝑗𝑗 =
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 𝐺𝐺𝐺𝐺𝐺𝐺𝑁𝑁𝑁𝑁,𝑖𝑖,𝑗𝑗,𝑦𝑦 by global warming
potential 𝐺𝐺𝐺𝐺𝐺𝐺𝐴𝐴𝐴𝐴5,𝑗𝑗 and summed across GHGs (j).

36
B.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 B4.

Table B4. 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.

37
Appendix C. 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.

C.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.

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.13 The APS West Phoenix
Power Plant is included in the 2018 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, and 2018 were

13 Pinnacle West Capital Corporation (2019). 2018 Annual Report. URL:
http://s22.q4cdn.com/464697698/files/doc_financials/annual/2018/Annual-Report_2018_Web.pdf

38
obtained from the EPA Greenhouse Gas Reporting Program through the Facility Level
Information on GreenHouse gases Tool (FLIGHT).14

A similar data request process was followed for each of the GHG emissions inventory
years. For 2012, 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
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.

C.2 Electricity Data Processing
C.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.

𝐺𝐺𝐺𝐺𝐺𝐺𝐴𝐴𝐴𝐴𝐴𝐴,𝑖𝑖,𝑗𝑗,𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠,2012 = ෍𝐸𝐸𝐸𝐸𝐴𝐴𝐴𝐴𝐴𝐴,𝑖𝑖,𝑧𝑧,2012 × 𝑆𝑆𝑆𝑆𝑖𝑖,𝑧𝑧,2012 × 𝐶𝐶𝐶𝐶× 𝐸𝐸𝐸𝐸𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴,𝑗𝑗,2012
𝑧𝑧

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
2012.

ECAPS,i,z,2012 =
Purchased electricity from APS for a Stationary Energy subsector (i) in zip
code (z) for 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.

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 eGRID15 emissions factor for the AZNM subregion for GHG emissions
factor for CO2, CH4, N2O (j) for eGRID reporting year (y). y = 2012 (i.e.

14 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
15 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

39
electricity emissions from eGRID 2012) for calendar year 2012 data and y =
2016 (i.e. electricity emissions from eGRID 2016) for calendar year 2016
and 2018 data.

Zip code level data from APS were not available for calendar years 2016 and 2018.
Therefore, the 2012 data (𝑆𝑆𝑆𝑆2012 ) were used to develop the scaling factors for 2016 and
2018:

𝑆𝑆𝑆𝑆𝐴𝐴𝐴𝐴𝐴𝐴,2012 = ∑
𝐸𝐸𝐸𝐸𝐴𝐴𝐴𝐴𝐴𝐴,𝑖𝑖,𝑧𝑧,2012 × 𝑆𝑆𝑆𝑆𝑖𝑖,𝑧𝑧,2012
𝑖𝑖,𝑧𝑧
∑
𝐸𝐸𝐸𝐸𝐴𝐴𝐴𝐴𝐴𝐴,𝑖𝑖,𝑧𝑧,2012
𝑖𝑖,𝑧𝑧
൘

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.

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,

𝐺𝐺𝐺𝐺𝐺𝐺𝐴𝐴𝐴𝐴𝐴𝐴,𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠,𝑖𝑖,𝑗𝑗,𝑦𝑦= ෍𝐸𝐸𝐸𝐸𝐴𝐴𝐴𝐴𝐴𝐴,𝑖𝑖,𝑧𝑧,𝑦𝑦 × 𝑆𝑆𝑆𝑆𝐴𝐴𝐴𝐴𝐴𝐴,2012 × 𝐸𝐸𝐸𝐸𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴,𝑗𝑗,𝑦𝑦
𝑧𝑧

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). y = 2012 (i.e.
electricity emissions from eGRID 2012) for calendar year 2012 data and y =

(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.

40
2016 (i.e., electricity emissions from eGRID 2016) for calendar year 2016
and 2018 data.

Finally, GHG emissions from APS electricity consumption were converted to metric tons
of carbon dioxide equivalent (MT CO2e) by multiplying 𝐺𝐺𝐺𝐺𝐺𝐺𝑖𝑖,𝑗𝑗 by the GHG-specific
global warming potential found in the IPCC AR5 report (𝐺𝐺𝐺𝐺𝐺𝐺𝐴𝐴𝐴𝐴5,𝑗𝑗).

C.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.

𝐺𝐺𝐺𝐺𝐺𝐺𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆,𝑗𝑗,𝑦𝑦= 𝐸𝐸𝐸𝐸𝑆𝑆𝑆𝑆𝑆𝑆,𝑖𝑖,𝑦𝑦 × 𝐶𝐶𝐶𝐶× 𝐸𝐸𝐸𝐸𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴,𝑗𝑗,𝑦𝑦

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.

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). y = 2012 (i.e. electricity
emissions from eGRID 2012) for calendar year 2012 data and y = 2016 (i.e.
electricity emissions from eGRID 2016) for calendar year 2016 and 2018 data.

Finally, GHG emissions from SRP electricity consumption were converted to metric tons
of carbon dioxide equivalent (MT CO2e) by multiplying 𝐺𝐺𝐺𝐺𝐺𝐺𝑖𝑖,𝑗𝑗,𝑦𝑦 by the GHG-specific
global warming potential found in the IPCC AR5 report (𝐺𝐺𝐺𝐺𝐺𝐺𝐴𝐴𝐴𝐴5,𝑗𝑗).

41
C.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.

𝐺𝐺𝐺𝐺𝐺𝐺𝐸𝐸𝐸𝐸,𝑖𝑖,𝑗𝑗,𝑦𝑦= 𝐺𝐺𝐺𝐺𝐺𝐺𝐴𝐴𝐴𝐴𝐴𝐴,𝑖𝑖,𝑗𝑗,𝑦𝑦+ 𝐺𝐺𝐺𝐺𝐺𝐺𝑆𝑆𝑆𝑆𝑆𝑆,𝑖𝑖,𝑗𝑗,𝑦𝑦

C.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 2017.16 For each
inventory year, and using 2017 and proxy for 2018, 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.

C.4 Changes between inventory years
For each of the inventory years – 2012, 2016, and 2018 – 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

16 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.

42
2012 levels. For 2018 community-scale inventory, the scaling methodology was
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 C1).

Table C1. 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.

C.5 Impact of Electricity Emissions Factor on GHG Emissions
Community-level GHG emissions are highly sensitive to the emissions factor used to
calculate GHG emissions from electricity consumption. Previous GHG emissions
inventories – both government operations and community-scale inventories – have used
the electricity emissions factor for the Arizona-New Mexico subregion from EPA eGRID.
eGRID emissions factors available at multiple scales in addition to the eGRID
subregion. These scales include plant (finest resolution), plant operator (utility),
balancing authority, state, and NERC region to name a few. Arizona is in the Western
Electricity Coordinating Council (WECC) NERC region. The eGRID GHG emissions
factors at each of these scales provide a range of GHG emissions intensity for electricity
consumption within the city (Table C2).

43
Table C2. Electricity GHG EFs Derived from Multiple eGRID Decision Boundaries
Electricity EF Boundary
eGRID 2012
(MT CO2e/MWh)
eGRID 2016
(MT CO2e/MWh)
eGRID 2018
(MT CO2e/MWh)
SRP & APS
Plant Operator (Utility-Scale)
0.55
0.43
0.47
SRP & APS
Balancing Authority
0.53
0.43
0.46
State of Arizona
0.48
0.43
0.44
AZNM eGRID Subregion*
0.52
0.48
0.47
Western Electricity
Coordinating Council (WECC)
0.44
0.40
0.35

In the eGRID 2018 data, the plant operator GHG EF was greater than the AZNM GHG
EF; both were greater than the balancing authority and State of Arizona GHG EF. In the
eGRID 2012 database this is not the case: the AZNM subregion is less GHG-intensive
than SRP & APS plant operator and balancing authority scale, but more GHG-intensive
than electricity production in the State of Arizona. For all eGRID years, the local and
regional scales are all more GHG-intensive than the WECC as a whole. Using the
AZNM eGRID subregion EF for electricity increases emissions inventory by 657,133 MT
CO2e in 2012; 840,710 MT CO2e in 2016; and 418,274 MT CO2e in 2018 relative to the
State of Arizona GHG EF for electricity consumption (Table C3). Therefore, the
boundary used to calculate the EF for electricity consumption is extremely important as
minor changes can cause significant changes to GHG emissions totals. Therefore, per
existing EPA guidance, it is recommended to use the AZNM eGRID subregion EF until
new datasets are produced that provide more detailed information on the carbon-
intensity of a locality’s electricity supply.

44
Table C3. Electricity GHG Emissions from Multiple eGRID Decision Boundaries
Electricity EF Boundary
2012
(MT CO2e)
2016
(MT CO2e)
2018
(MT CO2e)
SRP & APS
Plant Operator (Utility-Scale)
9,035,572
(492,849)
7,230,104
(-840,710)
7,921,800
(152,169)
SRP & APS
Balancing Authority
8,707,006
(164,283)
7,230,104
(-840,710)
7,643,560
(-126,071)
State of Arizona
7,885,590
(-657,133)
7,230,104
(-840,710)
7,351,257
(-418,274)
AZNM eGRID Subregion*
8,542,723
—
8,070,814
—
7,769,631
—
Western Electricity
Coordinating Council
(WECC)
7,228,458
(-1,314,265)
6,725,678
(-1,345,136)
5,858,867
(-1,910,764)
*Note: Calculated GHG emissions are the top number in each cell. The change in emissions
relative to the AZNM eGRID Subregion EF is shown in parentheses in each cell. Positive
parenthetical values indicate an increase in GHG emissions relative to the AZNM eGRID
Subregion EF and negative parenthetical values indicate a decrease in GHG emissions.

Due to the interconnectedness of the gird, regional trends and projects to reduce the
GHG intensity of electricity production in the AZNM subregion will place downward
pressure on the subregion EF. For example, the closure of the Navajo Generating
Station in 2019, and additional closures and partial closures of coal-fired electricity
generating facilities by APS and PNM, will significantly reduce the AZNM subregion EF.
Additionally, further development of utility-scale solar power facilities will also reduce the
local and regional GHG EFs for electricity consumption, resulting in additional GHG
emissions reductions compared to the 2012 baseline.

45
Appendix D. 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.

D.1 Transportation Sector Data Processing
Transportation sector GHG emissions are calculated using a generalized formula.

𝐺𝐺𝐺𝐺𝐺𝐺𝑖𝑖,𝑗𝑗,𝑦𝑦= 𝐹𝐹𝐹𝐹𝑖𝑖,𝑦𝑦 × 𝐶𝐶𝐶𝐶× 𝐸𝐸𝐸𝐸𝑖𝑖,𝑗𝑗,𝑦𝑦

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 𝐺𝐺𝐺𝐺𝐺𝐺𝑖𝑖,𝑗𝑗,𝑦𝑦 by the GHG-specific
global warming potential found in the IPCC AR5 report (𝐺𝐺𝐺𝐺𝐺𝐺𝐴𝐴𝐴𝐴5,𝑗𝑗).

D.2 On-Road Transport
D.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

46
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.17 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
population-dependent activity data. A future study would be needed to determine if and
how driving behaviors differ by Phoenix metropolitan area city.

D.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.

D.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.

D.3 Railways
D.3.1 Valley Metro Light Rail
Valley Metro light rail electricity consumption data were obtained from two sources. The
National Transit Database18 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

17 Arizona Department of Transportation. Archived Audits and Reports. Highway User Revenue Fund (HURF). URL:
https://azdot.gov/node/5069.
18 U.S. Department of Transportation. The National Transit Database. URL: https://www.transit.dot.gov/ntd.

47
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.

D.3.1 Freight Rail
The National Emissions Inventory (NEI)19 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, and 2018. Please refer to the 2016 community-scale
GHG emissions inventory report for a summary of methods to estimate Freight Rail
GHG emissions.

D.4 Aviation
D.4.1 Commercial Aviation
The NEI was used to gather data on commercial aviation fuel consumption at Phoenix
Sky Harbor International Airport and Phoenix Deer Valley Airport. The 2011 NEI was
used as a proxy for 2012 and the 2017 NEI was used as a proxy for 2016 and 2018. Jet
Fuel A was assumed to be the primary fuel consumed by commercial aviation.

To estimate Jet Fuel A consumption the following procedure was followed, CO2
emissions Phoenix Sky Harbor International Airport and Phoenix Deer Valley Airport
data for ‘Aircraft /Air Taxi /Turbine’, ‘Aircraft /General Aviation /Turbine’, and
‘Aircraft/Commercial’ processes were obtained from the NEI. Next, the total emissions
of CO2 emissions were converted to gallons of Jet Fuel A using the CO2 EF for Jet Fuel
A. The estimated consumption of Jet Fuel A was then converted back into CO2
emissions in addition to CH4 and N2O emissions.

19 U.S. Environmental Protection Agency. National Emissions Inventory (NEI). URL: https://www.epa.gov/air-emissions-
inventories/national-emissions-inventory-nei.

48
As the NEI is published for 2011 and 2017, estimated Jet Fuel A consumption was
scaled to the 2012, 2016, and 2018 calendar years using landing and takeoff operations
(LTO) activity data obtained from the City of Phoenix.20 As Jet Fuel A consumption is
strongly tied to commercial aircraft LTO, it was used as an indicator to scale 2011 and
2017 activity data to the inventory calendar year.

D.4.2 Civil Aviation
The NEI was used to gather data on civil aviation fuel consumption at Phoenix Sky
Harbor International Airport and Phoenix Deer Valley Airport. The 2011 NEI was used
as a proxy for 2012 and the 2017 NEI was used as a proxy for 2016 and 2018. Aviation
gasoline was assumed to be the primary fuel consumed by commercial aviation. As
aviation gasoline contains lead (Pb), lead emissions reported at Phoenix Sky Harbor
International Airport and Phoenix Deer Valley Airport in the National Emissions
Inventory is used an indicator of aviation gasoline consumption.

Per EPA guidance documents, the lead emissions from piston-based aircraft is related
to aviation gasoline consumption through the following equation.21

𝑔𝑔 𝑃𝑃𝑃𝑃 =
𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺 × ൬
2.12 𝑔𝑔 𝑃𝑃𝑃𝑃
𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔𝑔 𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴𝐴 𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺 ൰ × 0.95
907,180 𝑔𝑔
𝑡𝑡𝑡𝑡𝑡𝑡

Lead emissions obtained from the NEI for Phoenix Sky Harbor International Airport and
Phoenix Deer Valley Airport were input to the equation above and used to solve for the
gallons of aviation gasoline consumed at each airport. As the NEI is published for 2011
and 2017, estimated aviation gasoline gallons is scaled to 2012, 2016, and 2018
calendar years using LTO activity data obtained from the City of Phoenix22. As lead
emissions are reported for LTO operations, which is 10% of an aircraft operation, the
estimated gallons of Aviation Gasoline are dived by 10%.

20 Phoenix Sky Harbor International Airport. Airport Statistics. URL: https://www.skyharbor.com/About/Information/AirportStatistics.
21 U.S. Environmental Protection Agency, 2013. Assessment and Standards Division Office of Transportation and Air Quality.
Calculating Piston-Engine Aircraft Airport Inventories for Lead for the 2011 National Emissions Inventory. Report EPA-420-B-13-
040.
22 Phoenix Sky Harbor International Airport. Airport Statistics. URL: https://www.skyharbor.com/About/Information/AirportStatistics.

49
D.5 Off-Road Transportation
D.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
used in agriculture (farming and ranching), mining and roadway construction”23 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.

𝐺𝐺𝐺𝐺𝐺𝐺𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁𝑁,𝑃𝑃ℎ𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜,𝑗𝑗,𝑦𝑦= ൜𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺,𝑃𝑃ℎ𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜,𝑦𝑦 × 𝐸𝐸𝐸𝐸𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑,𝑗𝑗 𝑖𝑖𝑖𝑖 𝑦𝑦= 2016
𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺𝐺,𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀,𝑦𝑦 × 𝑆𝑆𝑆𝑆𝑃𝑃ℎ𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜,2016 × 𝐸𝐸𝐸𝐸𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑𝑑,𝑗𝑗 𝑖𝑖𝑖𝑖 𝑦𝑦= 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.

23 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.

50
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 D1). 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. With this
updated method for estimating 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 D1. 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%

D.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 2017. 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.

51
Appendix E. 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.

E.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 E1.

Table E1. 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

52
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

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 E2).

Table E2. 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.

53
𝐺𝐺𝐺𝐺𝐺𝐺𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃,𝑦𝑦=
∑𝐺𝐺𝐺𝐺𝐺𝐺
𝑙𝑙
𝑆𝑆𝑆𝑆,𝑙𝑙,𝑀𝑀𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎𝑎,𝑦𝑦
𝑃𝑃𝑃𝑃𝑃𝑃𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀,𝑦𝑦
× ቈቀ1 −
# 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆 𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹𝐹 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷ℎ𝑒𝑒𝑒𝑒 𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻𝐻
𝐴𝐴𝐴𝐴𝐴𝐴 𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷𝐷
ቁ
𝑃𝑃𝑃𝑃𝑃𝑃 𝑀𝑀𝑀𝑀𝑀𝑀,𝑦𝑦
× 𝑃𝑃𝑃𝑃𝑃𝑃𝑃𝑃ℎ𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜𝑜,𝑦𝑦቉

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).

E.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
E3).

Table E3. 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

54
E.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: 1990-2017.24

E.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.

24 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