HomeMy WebLinkAbout2018_9.18 - Study Session Attachment A - Draft GHG Inventory2018
Provisional Community
Greenhouse Gas Emissions
Inventory Update DRAFT
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City of San Luis Obispo - 2018 Provisional GHG Inventory Update
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Table of Contents
Executive Summary .................................................................................................................... 1
1. Community GHG Inventory Overview ................................................................................... 3
2005 Community GHG Inventory ........................................................................................... 3
2005 Updated Community GHG Inventory ............................................................................ 3
2016 Community GHG Inventory ........................................................................................... 5
Progress Toward 2020 Target ............................................................................................... 6
Progress to State GHG Reduction Targets ............................................................................ 7
2. Community Energy ................................................................................................................. 8
Community Energy Sector Overview ..................................................................................... 8
Updated Inventory Data and Methods ................................................................................... 8
Total Energy GHG Emissions .............................................................................................. 13
3. Transportation ....................................................................................................................... 14
Transportation Sector Overview .......................................................................................... 14
Updated Inventory Data and Methods ................................................................................. 14
Total Transportation GHG Emissions .................................................................................. 15
Transportation Sector Caveats and Considerations ............................................................ 15
4. Solid Waste ............................................................................................................................ 16
Solid Waste Sector Overview .............................................................................................. 16
Updated Inventory Data and Methods ................................................................................. 16
Total Solid Waste GHG Emissions ...................................................................................... 21
5. Wastewater ............................................................................................................................ 22
Wastewater Sector Overview ............................................................................................... 22
Inventory Data and Methods ................................................................................................ 22
Wastewater Treatment Types .............................................................................................. 23
Total Wastewater GHG Emissions ...................................................................................... 25
6. Off-Road ................................................................................................................................. 25
Off-Road Sector Overview ................................................................................................... 25
Inventory Data and Methods ................................................................................................ 25
Total Off-Road GHG Emissions ........................................................................................... 27
List of Abbreviations ................................................................................................................ 28
Appendix A ................................................................................................................................ 29 DRAFT
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List of Tables
Table ES-1. Provisional GHG Inventory Summary Results (MTCO2e) ........................................ 1
Table 1.1. San Luis Obispo Community GHG Emissions (2005) ................................................. 3
Table 1.2. 2005 update baseline GHG emissions. ....................................................................... 4
Table 1.3. 2016 GHG emissions. .................................................................................................. 5
Table 1.4. GHG emissions, 2005-2016 (MTCO2e). ...................................................................... 6
Table 1.5. Progress to AB32 and SB 32 target (MTCO2e). ........................................................... 7
Table 2.1. Community electricity activity data, 2005-2016 (kWh). ................................................ 8
Table 2.2. Electricity conversion factor (MTCO2e/kWh). ............................................................... 9
Table 2.3. Community electricity GHG estimates, 2006-2015 (MTCO2e). .................................. 10
Table 2.4. Community natural gas activity data, 2005-2016 (Therms). ...................................... 11
Table 2.5. Local Government Operations Protocol (LGOP) natural gas CO2 equivalent. ........... 12
Table 2.6. Community Natural Gas GHG estimates, 2005-2016 (MTCO2e). .............................. 12
Table 2.7. Energy GHG emissions, 2005-2016 (MTCO2e). ........................................................ 13
Table 3.1. 2005 and 2016 VMT estimates. ................................................................................. 14
Table 4.1. City solid waste activity data, 2008-2016 (Disposal Ton). ......................................... 16
Table 4.2. Total percent of waste degradable based on waste type. .......................................... 18
Table 4.3. Conversion to metric tons of methane. ...................................................................... 19
Table 4.4. Recorded methane capture rates from Cold Canyon Landfill. ................................... 19
Table 4.5. Percent of emissions reaching the atmosphere. ........................................................ 20
Table 4.6. Disposed solid waste conversion factor with Fifth Assessment Report global warming
potential (MTCO2e/Disposal Ton). .............................................................................................. 20
Table 4.7. Total solid waste disposed emissions (MTCO2e). ...................................................... 21
Table 5.1. Digester gas produced. .............................................................................................. 23
Table 5.2. Digester gas produced. .............................................................................................. 23
Table 5.3.Service population estimates. ..................................................................................... 24
Table 5.4. Estimation and emissions factors for treatment with nitrification or denitrification. .... 24
Table 5.5. GHG Emissions from treatment with nitrification or denitrification. ............................ 24
Table 5.6. Total GHG estimates from wastewater treatment. ..................................................... 25
Table 6.1. Off Road equipment. .................................................................................................. 26
Table 6.2. County off-road GHG emissions. ............................................................................... 26
Table 6.3. City off-road GHG emissions. .................................................................................... 27
Table 6.4. Total GHG estimates from off-road use. .................................................................... 27
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List of Figures
Figure 1.1. 2005 Updated baseline GHG emissions by sector (MTCO2e). ................................... 4
Figure 1.2. 2016 GHG emissions by sector (MTCO2e). ................................................................ 5
Figure 1.3. GHG emissions, 2005 to 2016 (MTCO2e). ................................................................. 6
Figure 1.4. Progress to AB32 and SB 32 target. ........................................................................... 7
Figure 2.1. Electricity emissions factor (MTCO2e/kWh). ............................................................. 10
Figure 2.2. Total community electricity activity data and GHG estimates, 2006-2016. ............... 11
Figure 2.3. Energy GHG emissions, 2005-2016. ........................................................................ 13
Figure 4.1. Total City solid waste (Disposal Ton). ...................................................................... 17
Figure 4.2. Total disposed solid waste and GHG emissions (MTCO2e). .................................... 22
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Executive Summary
A greenhouse gas (GHG) inventory is a comprehensive measure of GHG emissions that have
occurred as the result of activity in a jurisdiction or a geographic area in a calendar year. This
report provides an overview of the community-wide GHG emissions, measured in metric tons of
carbon dioxide equivalent (MTCO2e), that have been emitted from activities occurring in the city
from 2005 to 2016. The five emission sectors that are included in this report are community
energy, transportation, solid waste, wastewater, and off-road.
Community GHG emissions decreased by approximately 10 percent from 2005 to 2016 (Table
ES-1). This is largely the result of significant decreases in the energy sector, but also includes
decreases in nearly every sector except for direct emissions from wastewater processing, which
are a small part of the total inventory. Notable findings include:
1. Vehicle miles travelled in the city are estimated to have increased by approximately three
percent. However, due to lower carbon content of vehicle fuels and increasing fuel
efficiency, transportation sector emissions decreased by six percent.
2. Residential energy dropped steeply as the result of decreased electricity and natural gas
consumption, as well as decreasing carbon intensity of electricity in Pacific Gas and
Electric (PG&E) service territory.
3. Solid waste emissions decreased by approximately 11 percent due to decreasing
landfilled waste and increased diversion of green waste from landfills to composting
facilities.
Table ES-1. GHG Inventory Summary Results (MTCO2e)
Sector 2005 2016 Percent Change
Transportation 130,210 122,920 -6%
Commercial/Industrial Energy 57,800 53,410 -8%
Residential Energy 55,190 43,580 -21%
Solid Waste 15,540 13,880 -11%
Waste Water 170 190 12%
Off-Road 10,810 8,230 -24%
TOTAL 269,720 242,210 -10%
The key driver for updating the community GHG inventory is to assess progress toward the City’s
GHG emissions reduction target. Consistent with Assembly Bill (AB) 32, the City’s current adopted
target is to achieve a 15 percent reduction below baseline emissions by 2020. The 2016 emissions
estimate of 242,210 MTCO2e represents a 10 percent reduction in GHG emissions, notable
progress toward the 2020 target. Since adoption of the City’s CAP in 2012, the state adopted a
2030 target through Senate Bill (SB) 32. If the City prefers a 2030 goal that matches the state
target of reducing GHG emissions 40 percent below the 2020 target levels, the target for San Luis
Obispo would be 137,560 MTCO2e. DRAFT
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1.Community GHG Inventory Overview
In 2012, the City of San Luis Obispo (City) adopted the City of San Luis Obispo Climate Action
Plan (CAP) to achieve GHG emission reductions consistent with state law and City General Plan
policy. The foundation of the CAP is the 2005 baseline GHG inventory (completed in 2009), which
estimates the GHG emissions that occurred as the result of activity in the city.
The City recently prepared a 2016 comprehensive community-wide and local government GHG
emissions inventory update compliant with all relevant protocols and guidance documents
including the Local Government Operations Protocol (LGOP), the Global Protocol for Community
Scale GHG Emissions, and the Intergovernmental Panel on Climate Change (IPCC) Guidelines
for National GHG Inventories. Both community-wide and local government GHG inventories will
be presented and adopted as part of the CAP update in 2019.
This report provides an overview of the community -wide sector GHG emissions that have been
emitted from activities occurring in the city from 2005 to 2016. The five emission sectors that are
included in this report are energy, transportation, solid waste, wastewater, and off-road. This
report presents a summary of the updated 2005 GHG emissions and details the 2016 community
GHG inventory completed in 2018.
2005 Community GHG Inventory
In 2009, the community’s total 2005 baseline GHG emissions were estimated to be 264,237
metric tons of carbon dioxide equivalent (MTCO2e). The inventory included energy (residential
and nonresidential), transportation, and waste sectors. Of the three sectors, transportation
contributed the largest amount of GHG emissions with estimated emissions of 132,142 MTCO2e
or 50 percent of the total City emissions. The second largest sector was commercial and industrial
energy use with estimated emissions of 57,950 or 22 percent of the total City emissions. The
commercial and industrial energy and waste sectors made up the remaining 28 percent of the
total city emissions. Table 1.1 presents the original estimated 2005 GHG emissions by sector and
their percent of total emissions.
Table 1.1. San Luis Obispo Community GHG Emissions (2005)
Community Sector MTCO2e Percent of Total
Transportation 132,142 50%
Nonresidential Energy 57,950 22%
Residential Energy 55,377 21%
Waste 18,768 7%
Total 246,237 100%
Source: City of San Luis Obispo Climate Action Plan (2009)
2005 Updated Community GHG Inventory
To assess climate action progress, the City updated the 2005 baseline inventory for consistency
with current protocols and best practices. This section provides updated GHG emissions data
estimates for the baseline year of 2005 to allow for an equitable comparison to the 2016 GHG
inventory. The City updated the 2005 GHG inventory to reflect an updated scientific understanding DRAFT
City of San Luis Obispo - 2018 Provisional GHG Inventory Update
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of how different greenhouse gasses contribute to global warming, and to respond to changes to
data privacy rules and collection methods that affect how data is provided.
Table 1.2 and Figure 1.1 provide the updated 2005 baseline GHG emissions inventory with
updated total GHG emissions of 269,720 MTCO2e. Two sectors have been included in the
updated 2005 inventory: wastewater and off-road equipment, in order to comply with the guidance
in the GHG inventory protocols. Similar to the original 2005 inventory, the largest sector
contributing to the City’s total GHG emissions was transporta tion with an estimated emissions
total of 130,210 MTCO2e or 48 percent of the City’s total. The commercial and industrial energy
sector was the second largest sector contributing a total of 57,800 MTCO 2e GHG emissions or
21 percent of the City’s total. The remaining sectors of residential energy, solid waste, off -road,
and wastewater made up the remaining 30 percent of the City’s total emissions in 2005.
Table 1.2. 2005 update baseline GHG emissions.
Sector Subsector Subsector
MTCO2e
Sector
MTCO2e
Sector Percent
of Total
Transportation On-Road Transportation 130,210 130,210 48%
Nonresidential
Energy
Commercial/Industrial electricity 35,380
57,800 21% Commercial/Industrial natural gas 22,420
Residential
Energy
Residential electricity 20,800
55,190 20% Residential natural gas 34,390
Solid Waste
Community-wide municipal solid
waste disposal tons 15,540 15,540 6%
Off-Road
Lawn and Garden Equipment 1,540
10,810 4% Construction Equipment 9,270
Wastewater
Wastewater treatment facility direct
emissions 170 170 <1%
Total 269,720 100%
Figure 1.1. 2005 Updated baseline GHG emissions by sector (MTCO2e).
0 50,000 100,000 150,000 200,000 250,000 300,000
2005
Residential Energy Nonresidential Energy Transportation
Solid Waste Waste Water Off-RoadDRAFT
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2016 Community GHG Inventory
In 2018, the City prepared a community-wide inventory of GHG emissions for the 2016 calendar
year. Table 1.3 and Figure 1.2 provide the 2016 GHG emissions inventory results. In 2016, San
Luis Obispo’s total GHG emissions were estimated to be 242,210 MTCO2e. As in 2005,
transportation was the largest contributor to the City’s total GHG emissions with an estimated
122,920 MTCO2e or 51 percent of the City’s total emissions. Commercial and Industrial energy
was the second largest sector with GHG emissions of 53,410 MTCO2e or 22 percent of the City’s
total emissions. The sectors of residential energy, solid waste, off-road, and wastewater account
for the remaining 27 percent of the City’s total 2016 GHG emissions.
Table 1.3. 2016 GHG emissions.
Sector Subsector Subsector
MTCO2e
Sector
MTCO2e
Sector Percent
of Total
Transportation On-Road Transportation 122,920 122,920 51%
Nonresidential
Energy
Commercial/Industrial electricity 31,310
53,410 22% Commercial/Industrial natural gas 22,100
Residential
Energy
Residential electricity 14,650
43,580 18% Residential natural gas 28,930
Solid Waste
Community-wide municipal solid
waste disposal tons 13,880 13,880 6%
Off-Road
Lawn and Garden Equipment 1,270
8,230 3% Construction Equipment 6,960
Wastewater
Wastewater treatment facility direct
emissions 190 190 <1%
Total 242,210 100%
Figure 1.2. 2016 GHG emissions by sector (MTCO2e).
0 50,000 100,000 150,000 200,000 250,000 300,000
2016
Residential Energy Nonresidential Energy Transportation
Solid Waste Waste Water Off-RoadDRAFT
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Progress Toward 2020 Target
Table 1.4 and Figure 1.3 provide a comparison overview of emissions from baseline year 2005 to
2016 to show the City’s progress toward its target to reduce GHG emissions 15 percent below
2005 emission levels. Over the eleven-year period, emissions were estimated to have dropped
by approximately 10 percent. The most significant changes occurred in the residential energy,
solid waste, and off-road sectors.
•Residential energy emissions dropped by approximately 21 percent and reflects a
significant change in the carbon intensity of grid consumed electricity, a substantial
increase in rooftop renewable energy systems, and investment in energy efficiency.
•Solid waste emissions decreased by approximately 11 percent due to a decrease in the
amount of solid waste produced by San Luis Obispo residents and businesses.
•Off-road emissions (including construction equipment) dropped by approximately 24
percent, primarily due to the decrease in new construction projects within the city.
Section 2 provides a detailed report for each GHG emissions sector and the changes in emissions
from each sector from 2005 to 2016.
Table 1.4. GHG emissions, 2005-2016 (MTCO2e).
Sector 2005 2016 Percent Change
Transportation 130,210 122,920 -6%
Nonresidential Energy 57,800 53,410 -8%
Residential Energy 55,190 43,580 -21%
Solid Waste 15,540 13,880 -11%
Wastewater 170 190 12%
Off-Road 10,810 8,230 -24%
Total 269,720 242,210 -10%
Figure 1.3. GHG emissions, 2005 to 2016 (MTCO2e).
0
100,000
200,000
300,000
2005 2016
Residential Energy Nonresidential Energy
Transportation Solid Waste
Waste Water Off-RoadDRAFT
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Progress to State GHG Reduction Targets
The key driver for updating the community GHG inventory is to assess progress toward the City’s
GHG emissions reduction target. Consistent with Assembly Bill (AB) 32, the City’s target is to
achieve a 15 percent reduction below baseline emissions by 2020. Since the baseline inventory
was updated through this inventory process, resulting in a slightly increased baseline, a new
target must be calculated.
As noted in Table 1.5 and Figure 1.4, a 15 percent reduction in baseline emissions is 229,260
MTCO2e from the updated baseline year emissions of 269,720 MTCO2e. The 2016 emissions
estimate of 242,210 MTCO2e represents a 10 percent reduction in GHG emissions, notable
progress toward the 2020 target.
Since adoption of the City’s CAP in 2012, the state adopted a 2030 target through Senate Bill
(SB) 32. If the City prefers a 2030 goal that matches the state target of reducing GHG emissions
40 percent below the 2020 target levels, the target for San Luis Obispo would be 137,560
MTCO2e.
Table 1.5. Progress to AB32 and SB 32 target (MTCO2e).
Year Emissions
2005 (Updated) 269,720
2016 242,210
2020 Target (Updated) 229,260
2030 Target (40% below 1990) 135,560
2050 Target (Carbon Neutral) 0
Figure 1.4. Progress to AB32 and SB 32 target.
269,720
242,210 229,260
137,560
00
50,000
100,000
150,000
200,000
250,000
300,000
2005 2016 2020 Target
(Updated)
2030 Target (40%
below 1990)
2050 Target
(Carbon Neutral)MTCO2eDRAFT
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2. Community Energy
Community Energy Sector Overview
This section presents the GHG emissions for the energy sector, specifically emissions generated
from residential and non-residential energy use that has occurred within City limits. This section
presents the updated 2005 GHG emissions along with updated emissions for 2016.
Updated Inventory Data and Methods
The update to the 2005 inventory for the energy sector incorporate s changes in scientific
understanding of how different greenhouse gasses contribute to global warming and changes to
data privacy rules that affect how energy data is retained and provided. This section provides
updated electricity and natural gas activity data and emissions estimates for the baseline year of
2005, as well as electricity and natural gas activity data and GHG emissions estimates for years
2005 through 2016.
Electricity
Pacific Gas & Electric (PG&E) Company provides electric service to the community and offers
community electricity data to local agencies through the PG&E Green Community Portal. The
electricity data (presented in kilowatt-hours, or kWh) in Table 2.1 is separated between residential
and non-residential uses, which is the finest resolution possible to prevent data from being
removed for privacy purposes. Nonresidential electricity use includes commercial, governmental,
agricultural, and industrial usage. From 2005 to 2016, residential electricity usage decreased by
18 percent and non-residential electricity consumption increased approximately 3 percent.
Between 2005 and 2016, electricity use decreased by 5 percent.
Table 2.1. Community electricity activity data, 2005-2016 (kWh).
Year Residential Nonresidential Total
2005 93,045,220 158,267,695 251,312,915
2006 94,844,802 165,562,683 260,407,485
2007 92,479,221 170,259,426 262,738,647
2008 91,007,229 176,783,866 267,791,095
2009 89,252,248 183,654,370 272,906,618
2010 87,910,124 218,185,988 306,096,112
2011 86,239,267 172,742,643 258,981,910
2012 85,773,964 172,045,211 257,819,175
2013 84,492,752 171,842,797 256,335,549
2014 78,932,662 171,846,749 250,779,411
2015 78,069,529 170,606,678 248,676,207
2016 76,376,280 163,204,691 239,580,971
Total 1,038,423,298 2,095,002,797 3,133,426,095 DRAFT
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The 18 percent decrease in residential electricity usage may be due to low residential growth, a
significant increase in residential renewable energy installations, increases in energy efficiency
investments, and overall trends toward conservation. Additional assessment investigating
reductions from existing actions will be completed in support of the CAP update.
To calculate GHG emissions, an emissions factor is applied to the activity data. Table 2.2 shows
the electricity emissions factors for the three major greenhouse gasses occurring as the result of
electricity use in the city. PG&E staff provided CO2 emissions factors via the Green Community
Portal data request in 2018. In addition to carbon dioxide (CO2), small amounts of methane (CH4)
and nitrous oxide (N2O) are released in the electricity generation process. CH4 and N2O emissions
factors are provided by PG&E’s third-party-verified GHG inventory. Variability of the emissions
factors occur primarily due to two factors: 1) fluctuations in hydro power production as the result
of precipitation variability, and 2) increasing renewable energy sources in PG&E’s power portfolio.
CO2 is the most commonly referenced GHG, however, numerous gasses have green house
characteristics. Methane and nitrous oxide are commonly accounted for in GHG inventories.
These gasses have a greater global warming potential; CH4 traps approximately 28 times as much
heat as CO2 over a 100-year period and N2O traps approximately 265 times as much heat. To
account for these differences, a factor is applied to the gasses emissions to calculate aCO2
equivalence.
Table 2.2 provides the emissions factors for 2005 through 2016. Due to changes in PG&E’s
energy portfolio (and particularly an increase in renewable energy supplies), the 2016 emissions
factor is approximately 14 percent lower than the 2005 factor. Figure 2.1 illustrates the changes
in MTCO2e/kWh factors from 2005 to 2016.
Table 2.2. Electricity conversion factor (MTCO2e/kWh).
Year kWh/MTCO2e
2005 0.000224
2006 0.000208
2007 0.000290
2008 0.000292
2009 0.000262
2010 0.000203
2011 0.000179
2012 0.000203
2013 0.000195
2014 0.000198
2015 0.000185
2016 0.000192
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Figure 2.1. Electricity emissions factor (MTCO2e/kWh).
Table 2.3 provides the GHG emissions from electricity use in the city by residential and
nonresidential subsectors from 2005 to 2016. During this time, electricity related residential GHG
emissions decreased by approximately 30 percent, while nonresidential electricity emissions
decreased by approximately 12 percent. Overall emissions decreased approximately 18 percent
over the same period.
Table 2.3. Community electricity GHG estimates, 2006-2015 (MTCO2e).
Year Residential Nonresidential Total
2005 20,800 35,380 56,180
2006 19,760 34,490 54,250
2007 26,810 49,360 76,170
2008 26,580 51,640 78,220
2009 23,380 48,100 71,480
2010 17,840 44,280 62,120
2011 15,470 30,980 46,450
2012 17,410 34,910 52,320
2013 16,450 33,450 49,900
2014 15,650 34,060 49,710
2015 14,410 31,500 45,910
2016 14,650 31,310 45,960
0.000000
0.000050
0.000100
0.000150
0.000200
0.000250
0.000300
0.000350
2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016MTCO2e/kWhDRAFT
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Figure 2.2 illustrates GHG and kWh activity data trends between 2005 and 2016 on the same
chart. It is important to note that while overall electricity use has been steadily decreasing, GHG
emissions have been more variable due to changes in PG&E’s power portfolio and the related
carbon intensity of the electricity it supplies.
Figure 2.2. Total community electricity activity data and GHG estimates, 2006-2016.
Natural Gas
Southern California Gas Company (SoCalGas) provides natural gas utility services in the city.
Table 2.4 provides the natural gas activity data in therms from 2005-2016 separated by residential
and nonresidential uses. Non-residential use combines commercial and industrial use.
Table 2.4. Community natural gas activity data, 2005-2016 (Therms).
Year Residential Nonresidential Total
2005 6,460,870 4,211,790 10,672,660
2006 6,643,410 4,501,180 11,144,590
2007 6,702,810 4,532,760 11,235,570
2008 -- -- --
2009 -- -- --
2010 -- -- --
2011 -- -- --
2012 -- -- --
2013 -- -- --
2014 5,275,340 3,987,264 9,262,604
2015 5,068,160 3,952,562 9,020,722
2016 5,435,586 4,151,275 9,586,861
0
10,000
20,000
30,000
40,000
50,000
60,000
70,000
80,000
90,000
0
50,000,000
100,000,000
150,000,000
200,000,000
250,000,000
300,000,000
350,000,000
2005 2007 2009 2011 2013 2015 MTCO2ekWhkWh MTCO2e
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As a company policy, SoCalGas only retains community natural gas data back to 2014, which
means the data in the original 2005 baseline inventory must be used in conjunction with the data
provided via an Energy Data Request Portal request submitted by City staff in 2017. Since
SoCalGas cannot confirm the 2005 inventory data, the comparison in natural gas consumption in
the baseline year and years 2014-2017 should be observed with caution. The natural gas data
provided in Table 2.4 shows an 18 percent decrease in residential therms and a 29 percent
increase in non-residential usage between 2005 and 2016. Combined, the natural gas sector has
a net decrease of 3 percent.
Just as with electricity, GHG emissions are estimated from activity data by applying a n emission
coefficient. Table 2.5 shows the emission coefficient for converting therms of natural gas to
MTCO2e. Unlike electricity, the inventory assumes no changes in the carbon intensity of
combusting natural gas in any given year, as the composition of natural gas does not vary from
year to year.
Table 2.5. Local Government Operations Protocol (LGOP) natural gas carbon dioxide
equivalent.
Greenhouse Gas MTCO2e/Therm
CO21 0.005310
CH41 0.000011
N2O1 0.000003
CO2e2 0.005320
Table 2.6 provides GHG emissions estimates in MTCO2e for natural gas consumption in the city
from 2005-2016. As noted in the natural gas activity data, there was a decrease in MTCO2e for
residential and an increase for non-residential sectors with a total decrease natural gas-related
emissions of 3 percent.
Table 2.6. Community Natural Gas GHG estimates, 2005-2016 (MTCO2e).
Year Residential Nonresidential Total
2005 34,390 22,420 56,810
2006 35,360 23,960 59,320
2007 35,680 24,130 59,810
2008 -- -- --
2009 -- -- --
2010 -- -- --
2011 -- -- --
2012 -- -- --
2013 -- -- --
2014 28,080 21,220 49,300
2015 26,980 21,040 48,020
2016 28,930 22,100 51,030 DRAFT
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Total Energy GHG Emissions
Table 2.7 and Figure 2.3 show the total energy-related GHG emissions separated by energy type
and subsector. The residential energy subsector saw a 22 percent decrease in emissions
between 2005 and 2016. The nonresidential subsector emissions increased by 2 percent. Overall,
energy GHG emissions dropped by 11 percent over the 11-year period. Note that Figure 2.3
provides total energy sector emissions with a dark blue line; the dashed line indicates a total
emissions estimate necessitated by SoCalGas’s inability to provide historical data.
Table 2.7. Energy GHG emissions, 2005-2016 (MTCO2e).
Year Residential Nonresidential Total Electricity Natural Gas Electricity Natural Gas Res. Nonres. Total
2005 20,800 34,390 35,380 22,420 55,190 57,800 112,990
2006 19,760 35,360 34,490 23,960 59,320 58,450 117,770
2007 26,810 35,680 49,360 24,130 59,810 73,490 133,300
2008 26,580 -- 51,640 -- -- --
2009 23,380 -- 48,100 -- -- --
2010 17,840 -- 44,280 -- -- --
2011 15,470 -- 30,980 -- -- --
2012 17,410 -- 34,910 -- -- --
2013 16,450 -- 33,450 -- -- --
2014 15,650 28,080 34,060 21,220 43,730 55,280 99,010
2015 14,410 26,980 31,500 21,040 41,390 52,540 93,930
2016 14,650 28,930 31,310 22,100 43,580 53,410 96,990
Figure 2.3. Energy GHG emissions, 2005-2016.
0
20,000
40,000
60,000
80,000
100,000
120,000
140,000
160,000
2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016MTCO2e
Electricity and Natural Gas Electricity OnlyDRAFT
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3. Transportation
Transportation Sector Overview
This section presents the GHG emissions for the transportation sector, specifically emissions from
all on-road trips (including cars, trucks, buses, etc.) that have occurred within City limits. This
section presents the updated 2005 GHG emissions along with updated emissions for 2016.
Updated Inventory Data and Methods
This section provides updated activity data and emissions estimates for baseline year 2005 and
activity data and emissions estimates for 2016. Since the 2005 baseline inventory was completed
in 2009, the state has updated emissions factors and legislation on fuel economy standards. The
2005 and 2016 follow the same geographic system boundary method which considers
transportation activity occurring solely within city boundaries, regardless of where a trip’s
destination begins or ends.
The 2005 GHG inventory was updated to use the 2014 Emissions Factor (EMFAC) model.
EMFAC represents the state’s current understanding of motor vehicle travel activities and their
associated emission levels. EMFAC 2014 is the latest U.S. Environmental Protection Agency
(EPA) approved motor vehicle emission model that assesses emissions from on -road vehicles
including cars, trucks, and buses in California. The City used EMFAC 2014 to estimate emissions
factors for this updated report.
The 2005 and 2016 inventories rely on the City’s traffic counts program for roadways within city
limits and from CalTrans traffic volume data. Table 3.1 presents vehicle miles traveled (VMT) for
2005 and 2016, which was estimated by applying average daily trip (ADT) to traffic volume and
converted to an annual amount.
Table 3.1. 2005 and 2016 VMT estimates.
Measure 2005 2016
Daily 768,240 791,147
Annual 266,579,280 274,528,170
Source: City of San Luis Obispo, Public Works Department,
Transportation Division (City-wide Traffic County Program) and
CalTrans Traffic Volumes
Table 3.2 provides the VMT and associated GHG emissions for each vehicle class in San Luis
Obispo County for 2005 and 2016. GHG emissions were estimated using the California Air
Resources Board (CARB) EMFAC 2014 tool. Using VMT as inputs, EMFAC 2014 generated VMT
and CO2 emission results for both 2005 and 2016 for each type of vehicle common in San Luis
Obispo County. The City used this information to generate a CO2/VMT emissions factor specific
to San Luis Obispo County, reflecting the unique balance of different vehicle types, vehicle ages,
and vehicle fuels used county-wide.
EMFAC 2014 does not model CH4 and N2O emissions, so a standard practice is to multiply CO2
emissions factors by 100/95 (approximately 1.05) to convert CO2 emissions to CO2e. As the
emissions factor generated by EMFAC is in tons of CO2/VMT, the City also converted the units of DRAFT
City of San Luis Obispo - 2018 Provisional GHG Inventory Update
Page 15
this factor to metric tons. The City then applied this converted emissions factor to the total City
VMT given in Table 3.1. This resulted in the total annual greenhouse gas emissions.
Total Transportation GHG Emissions
Table 3.2 shows that as VMT increased from 2005 to 2016 by 3 percent, the total GHG emissions
from on-road transportation decreased by approximately 6 percent. The decrease in GHG
emissions is attributed to state and federal fuel efficiency standards, low carbon fu el standards,
and an increasingly efficient overall fleet of vehicles (including an increased uptake of electric,
hybrid, and high efficiency vehicles) within the city that is resulting in the emissions decline,
despite an increase in miles driven. Appendix A includes more detailed information about VMT
and emissions factors for individual vehicle types.
Table 3.2. Total annual VMT emissions.
2005 2016
Total VMT Total Emissions Total VMT Total Emissions
All vehicles
266,579,280 130,210 274,528,170 122,920
Transportation Sector Caveats and Considerations
As noted above, the VMT data used for this inventory is estimated from traffic counts on local
roadways conducted by the City and Caltrans. This approach follows the “geographic boundary”
method, meaning that it measures only the VMT occurring in City limits. According to guidance
documents and protocols, the geographic boundary method is an appropriate method for
determining VMT. This method was also used in the 2005 GHG inventory in San Luis Obispo’s
adopted CAP, and so using the same method for the 2016 GHG inventory maintains consistency
between the two inventories. The geographic boundary method has been the best method for the
City to use to-date based on data availability.
Although the geographic boundary method is an acceptable method, it can have some limitations,
particularly for a community like San Luis Obispo. The limitations are described below and include
how the method includes or excludes types of VMT and roadways.
Pass-through VMT - The method captures traffic in the City limits, including what are called “pass-
through trips”. These are trips that start and end outside of San Luis Obispo but pass through the
City, typically on major roads and freeways such as US 101 and State Highway 1. Because these
trips do not begin or end with in San Luis Obispo, the City has very little ability to reduce VMT
associated with these trips. However, under the geographic boundary method, these VMT are still
attributed to the City.
Commute VMT - San Luis Obispo is a major regional job center, and so is responsible for
significant commute traffic. More than 75 percent of people who work in San Luis Obispo commute
in from outside the community, and 30 percent commute from another county. However, the
geographic boundary method only counts the portion of these commute trips that occur within the
City limits, which is likely a small amount of the total VMT from these trips. Because of this, it is
likely that the geographic boundary method does not show the full impact of the City’s role as a
job center. DRAFT
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Page 16
Exclusion of some roadways - The traffic counts that inform the VMT data do not include all
roadways within the city. While a significant portion of VMT is being captured through this method,
there is some VMT (most likely on minor roadways) that is not included in these counts.
The current best practice for calculating VMT is to use an “origin-destination” approach. Under
this method, VMT from trips that begin and/or end in the community are included in San Luis
Obispo’s VMT count (trips that begin and end in the City limits are fully counted, trips that begin
elsewhere but end in San Luis Obispo or vice-versa have 50% of their VMT counted), but trips
that begin and end elsewhere are not included, even if they pass through the City. The City will
require an updated transportation model before following the origin-destination approach. The
City is currently preparing such a model, and will use this to obtain updated VM figures that will
be incorporated into the planned CAP update in 2019.
4. Solid Waste
Solid Waste Sector Overview
This section presents the GHG emissions for the solid waste sector, specifically emissions from
the disposal of solid waste produced within City limits into a landfill. This section presents the
updated 2005 GHG emissions along with updated emissions for 2016.
Updated Inventory Data and Methods
This section provides updated solid waste activity data for the baseline year of 2005, as well as
activity emissions estimates for years 2005 through 2016 to estimate the City’s total greenhouse
gas emissions. The City of San Luis Obispo deposits all waste generated within city limits into the
Cold Canyon Landfill. Cold Canyon Landfill provided solid waste disposal data. Table 4.1 and
Figure 4.1 provide the City’s solid waste disposal tonnage for 2005 to 2016. Data for 2005 to 2007
was not able to be collected; therefore 2008 data was used as a pro xy.
Table 4.1. City solid waste activity data, 2008-2016 (Disposal Ton).
Year Total Waste
(Disposal Ton)
2008 53,011
2009 47,483
2010 44,836
2011 39,497
2012 40,469
2013 42,094
2014 40,200
2015 44,530
2016 46,857
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Figure 4.1. Total City solid waste (Disposal Ton).
Green Waste
Greenwaste data was provided by the City of San Luis Obispo Utilities Department for years 2006
through 2016. Greenwaste is a part of the diverted waste stream to the Cold Canyon Landfill,
which means that it is not buried at the plant and hauled to locations outside of city limits. Because
the diverted waste is hauled outside of city limits, the emissions associated with greenwaste are
considered to be within a different scope and boundary than what this GHG inventory is
considering. For consistency with the scope and boundary of this GHG inventory, emissions from
out-of-boundary waste disposal are not included in the 2005 and 2016 inventories.
Municipal Solid Waste GHG Emissions Conversion Factor
This inventory follows the “methane commitment method” to account for the future emissions
produced from annually deposited solid waste. This method requires the following steps:
1. Estimate the percent of degradable organic materials in landfilled waste.
2. Identify the conversion factor to translate tons of carbon dioxide to metric tons of methane.
3. Estimate the amount of methane per ton of landfilled waste that will enter the atmosphere.
4. Convert the estimate of methane to carbon dioxide equivalence.
1. Estimate the percent of degradable organic materials in landfilled waste.
The CARB Municipal Solid Waste Characterization Landfill Tool v. 1.3 provides landfill was te
characterization estimates for the amount of waste by type sent to California landfills. The waste
types identified in the waste characterization studies are listed in Table 4.2. For each of these
waste types, the tool includes California average estimates of the fraction of waste-in-place
0
10,000
20,000
30,000
40,000
50,000
60,000
2008 2009 2010 2011 2012 2013 2014 2015 2016 2017Tonnage
Landfilled Waste
DRAFT
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(WIPFRAC), total degradable organic carbon (TDOC), and the decomposable anaerobic fraction
(DANF) of the waste type. There are two relevant waste characterization studies for this inventory:
one from 2003 to 2006 and the other from 2007 to the present. Table 4.2 provides information
about waste characterization estimates used in this inventory, as well as the degradable organic
content (DOC) percent per ton of solid waste, which is calculated by multiplying WIPFRAC,
TDOC, and DANF for each waste type.
Table 4.2. Total percent of waste degradable based on waste type.
2003-2006 2007-Present
Waste Type WIPFRAC TDOC DANF DOC WIPFRAC TDOC DANF DOC
Newspaper 2.20% 47.09% 15.05% 0.16% 1.65% 47.09% 15.05% 0.12%
Office Paper 1.95% 38.54% 87.03% 0.65% 1.84% 38.54% 87.03% 0.62%
Corrugated Boxes 5.75% 44.84% 44.25% 1.14% 4.80% 44.84% 44.25% 0.95%
Coated Paper 11.09% 33.03% 24.31% 0.89% 8.98% 33.03% 24.31% 0.72%
Food 14.55% 14.83% 86.52% 1.87% 15.50% 14.83% 86.52% 1.99%
Grass 2.81% 13.30% 47.36% 0.18% 1.90% 13.30% 47.36% 0.12%
Leaves 1.41% 29.13% 7.30% 0.03% 3.24% 29.13% 7.30% 0.07%
Branches 2.59% 44.24% 23.14% 0.26% 1.95% 44.24% 23.14% 0.20%
Lumber 9.65% 43.00% 23.26% 0.96% 14.51% 43.00% 23.26% 1.45%
Textiles 4.44% 24.00% 50.00% 0.53% 5.47% 24.00% 50.00% 0.66%
Diapers 4.36% 24.00% 50.00% 0.52% 4.33% 24.00% 50.00% 0.52%
Construction/
Demolition 12.06% 4.00% 50.00% 0.24% 5.48% 4.00% 50.00% 0.11%
Medical Waste 0.04% 15.00% 50.00% 0.00% 0.00% 15.00% 50.00% 0.00%
Sludge/Manure 0.09% 5.00% 50.00% 0.00% 0.05% 5.00% 50.00% 0.00%
Source: CARB Municipal Solid Waste Characterization Landfill Tool v. 1.3
2. Identify the conversion factor to translate tons of carbon dioxide to metric tons of methane.
The next step in calculating the emissions factor is estimating the metric tons of methane to be
generated from the organic content in the landfilled waste. Solid waste activity data is reported in
tons, while the standard unit for GHG reporting is metric tons. Table 4.3 presents the conversion
factors to metric tons. As the decomposing organic content in landfilled solid waste transitions
from carbon to methane, the atomic mass changes as well. Since the CO2e in this inventory is
presented as mass (metric tons), this change in mass is accounted for with the stoichiometric
ratio between CH4 and carbon.
Finally, of the total landfill gas generated from decomposing waste, approximately half is methane
so a methane gas fraction is applied to remove other gasses from the total. The remainder is
biogenic CO2 from vegetation from natural areas, crops, and urban vegetation and de minimus
amounts of N2O. The GPC advises against accounting for either of thes e gases in a community
inventory. DRAFT
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Table 4.3. Conversion to metric tons of methane.
lbs/ton1 MT/lbs 1 Stoichiometric ratio
between CH4 and carbon2
Fraction of CH4 Gas in
Landfill Gas 3
Metric Tons of Methane
2000 0.000454 1.333333 0.5 0.604796
1 Standard conversion factor.
2 16/12, provided by the Global Protocol for Community-Scale Greenhouse Gas Emission Inventories.
3 IPCC Good Practices Guidance and Uncertainty Management in National Greenhouse Gas Inventories
(2000) default range.
3. Estimate the amount of methane per ton of landfilled waste that will enter the atmosphere.
The next factor in the solid waste emissions coefficient is the amount of landfill gas that is collected
by landfill gas capture systems. The San Luis Obispo County Air Pollution Control District (APCD)
provides landfill capture rates for Cold Canyon Landfill, as provided in Table 4.4 for the years
2008 – 2013. The landfill capture rate for 2006 is sourced from the County of San Luis Obispo
EnergyWise Plan Appendix A. Given the lack of data availability for several years, including 2005,
2007, 2014, 2015, and 2016 and the significant variability across years, this inventory relied on
the EPA’s standard landfill methane capture rate of 75 percent.
Table 4.4. Recorded methane capture rates from Cold Canyon Landfill.
Year Cold Canyon
2005 Not Available
2006 60%
2007 Not Available
2008 70%
2009 99%
2010 85%
2011 85%
2012 85%
2013 75%
The next phase of the equation considers the amount of methane that is oxidized in the soil. As
reported in Table 4.5, only 25 percent of landfill gas enters the atmosphere. Of that 25 percent,
10 percent is oxidized on site in the soil of the land fill co ver. Of the 75 percent of the methane
that is captured, approximately 99 percent enters the atmosphere as CO 2 due to the methane
being combusted as part of the flaring process. Approximately 23 percent of the total methane
emitted enters the atmosphere. Table 4.5 shows the factors used in this calculation.
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Table 4.5. Percent of emissions reaching the atmosphere.
Fraction of methane
recovered (frec) 1
Oxidation factor (OX)
2
Methane correction
factor (MCF) 3
Percent of Emissions
Reaching Atmosphere
75% 10% 99% 23.3%
1 Landfill gas capture rate, as provided by the Environmental Protection Agency
2 IPCC Good Practices Guidance and Uncertainty Management in National Greenhouse Gas Inventories
(2000) well-managed landfills factor.
3 IPCC Good Practices Guidance and Uncertainty Management in National Greenhouse Gas Inventories
(2000) managed landfill factor.
4. Convert the estimate of methane to carbon dioxide equivalence.
The solid waste CO2e conversion factor was calculated by multiplying the total degradable content
of each weight type (DOC), metric ton conversion factor, methane generation, and the IPCC Fifth
Assessment Report methane global warming potential (Table 4.6). The factors for each waste
type are then weighted by the waste composition data to obtain a single emission s factor for a
ton of mixed waste. In 2005 to 2006, each ton of solid waste deposited in a landfill is estimated to
produce approximately 0.293 MTCO2e per ton as it degrades over time. For 2007 to 2016, the
conversion factor is 0.296 MTCO2e per ton of solid waste.
Table 4.6. Disposed solid waste conversion factor with Fifth Assessment Report global
warming potential (MTCO2e/Disposal Ton).
Waste Type 2003-2006
DOC1
2007-
Present
DOC1
Metric Ton
(MT)
CH4
emissions
CH4
GWP2
2003-2006
MTCO2e/
Ton
2007-
Present
MTCO2e/
Ton
Newspaper 0.16% 0.12% 0.604796033 0.2325 28 0.006151 0.004606
Office Paper 0.65% 0.62% 0.604796033 0.2325 28 0.025770 0.024312
Corrugated Boxes 1.14% 0.95% 0.604796033 0.2325 28 0.044892 0.037482
Coated Paper 0.89% 0.72% 0.604796033 0.2325 28 0.035062 0.028387
Food 1.87% 1.99% 0.604796033 0.2325 28 0.073522 0.078335
Grass 0.18% 0.12% 0.604796033 0.2325 28 0.006969 0.004722
Leaves 0.03% 0.07% 0.604796033 0.2325 28 0.001176 0.002709
Branches 0.26% 0.20% 0.604796033 0.2325 28 0.010418 0.007865
Lumber 0.96% 1.45% 0.604796033 0.2325 28 0.037980 0.057146
Textiles 0.53% 0.66% 0.604796033 0.2325 28 0.020980 0.025837
Diapers 0.52% 0.52% 0.604796033 0.2325 28 0.020582 0.020455
Construction/
Demolition 0.24% 0.11% 0.604796033 0.2325 28 0.009494 0.004312
Medical Waste 0.00% 0.00% 0.604796033 0.2325 28 0.000113 0.000000
Sludge/Manure 0.00% 0.00% 0.604796033 0.2325 28 0.000089 0.000050
Total -- -- -- -- -- 0.293 0.296
Note: Values are rounded causing final values to be inconsistent with calculations.
1 Source: CARB Municipal Solid Waste Characterization Landfill Tool v. 1.3.
2 IPCC Fifth Assessment Report DRAFT
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Total Solid Waste GHG Emissions
To estimate the solid waste GHG emissions, the carbon dioxide equivalency conversion factor
was multiplied by the disposal ton activity data. Once these were applied, the annual solid waste
disposal ton emissions were calculated. As shown in Table 4.7 and Figure 4.2, from 2005 to 2016,
solid waste disposed experienced a decrease in emissions by 11 percent.
Table 4.7. Total solid waste disposed emissions (MTCO2e).
Year Total Waste
(Disposal Ton)
MTCO2e Conversion
Factor
Solid Waste Disposed
MTCO2e
2005 53,011 0.293 15,540
2006 53,011 0.293 15,540
2007 53,011 0.296 15,700
2008 53,011 0.296 15,700
2009 47,483 0.296 14,070
2010 44,836 0.296 13,280
2011 39,497 0.296 11,700
2012 40,469 0.296 11,990
2013 42,094 0.296 12,470
2014 40,200 0.296 11,910
2015 44,530 0.296 13,190
2016 46,857 0.296 13,880
DRAFT
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Figure 4.2. Total disposed solid waste and GHG emissions (MTCO2e).
5. Wastewater
Wastewater Sector Overview
This section presents the GHG emissions for the wastewater sector, specifically emissions from
the direct treatment processes and fugitive sources that have occurred within City limits. It must
be noted, energy emissions generated from wastewater treatment are included within the
nonresidential community energy sector. In this section, methods are discussed to calculate a
baseline emissions inventory for 2005 along with an updated inventory year of 2016. This section
concludes with the sector’s total GHG emissions.
Inventory Data and Methods
The 2005 inventory prepared in 2009 did not account for process emissions generated from
treatment of wastewater within the city. This section provides activity data and emissions
estimates for the baseline year of 2005, as well as 2016.
The City of San Luis Obispo Water Resource Recovery Facility (WRRF) is the City’s only
wastewater treatment facility serving the City’s residents and Cal Poly campus. The two primary
sources of emissions accounted for in this inventory include the process emissions from the
incomplete combustion of digester gas and the treatment from nitrification.
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
16,000
18,000
0
10,000
20,000
30,000
40,000
50,000
60,000
2008 2009 2010 2011 2012 2013 2014 2015 2016 MTCO2eTonnageLandfilled Waste MTCO2e
DRAFT
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Wastewater Treatment Types
Digester Gas
The first source of emissions is from stationary methane generation as the result of the operation
of anaerobic digesters. Anaerobic digesters are pieces of equipment that use microbes to break
down organic material in an oxygen-free environment and are utilized to treat the excess biosolids
produced by the treatment process. Methane that is generated from the process is fed back in to
the co-generation system, where it is used to power WRRF operations. The methane not
reintroduced into the system is flared onsite, adjacent to the co -generator. Table 5.1 provides an
estimate of the yearly methane generation rates of the WRRF’s two digesters.
Table 5.1. Digester gas produced.
Wastewater Treatment Facility 2005 2016
WRRF generated digester gas (ft3/day) 56,000 67,412
To calculate GHG emissions from the incomplete combustion of digester gas, a conversion factor
is applied to the total digester gas activity data. Table 5.2 presents the LGOP’s method of
calculating methane emissions from anaerobic digester gas based on the available gas
generation activity data. Table 5.2 also presents the total calculated metric tons of carbon
equivalent (MTCO2e) emissions generated from the incomplete combustion of digester gas.
Table 5.2. Digester gas produced.
2005 2016
Methane Digester Gas Generation
Measured standard cubic feet of digester gas produced per day (ft3)
(City measure) 56,000 67,412
CH4 fraction in biogas (F CH4) (City measure) 0.55 0.55
Methane density ρ(CH4) (standard measure) 662.00 662.00
CH4 destruction efficiency DE (standard measure) 0.99 0.99
Conversion Factors of Methane Digester Gas Generation Potential (MTCO2e)
Cubic feet to cubic meters (standard measure) 0.0283 0.0283
Days per year (standard measure) 365.25 365.25
Grams to metric tons (standard measure) 0.000001 0.000001
GWP of methane (standard measure) 28 28
Annual CH4 emissions (MTCO2e) 60 70
Source: Local Government Operations Protocol (LGOP) DRAFT
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Nitrification
According to the IPCC Guidelines for National Greenhouse Gas Inventories (2006), nitrification
occurs through an aerobic process converting ammonia and other nitrogen compounds into
nitrate (N3O). Though the WRRF does not utilize denitrification in its treatment process, according
to LGOP, the calculation of nitrification is the same as calculating emissions from denitrification
systems. Due to site specific treatment data unavailability, nitrous oxide generation from
nitrification or denitrification is estimated using service population data. The service population
was estimated by accounting for all City residents and half the number of jobs within the city. Cal
Poly’s population was excluded from the service population estimate since Cal Poly is not within
the City’s jurisdiction. Table 5.3 provides the service population for 2005 and 2016.
Table 5.3.Service population estimates.
Wastewater Treatment Facility 2005
Population Served
2016
Population Served
Water Resource Recovery Facility (WRRF) 60,476 62,767
Table 5.4 presents the LGOP’s method of calculating nitrous oxide emissions from nitrification or
denitrification based on the service population. The nitrous oxide generation is then converted to
MTCO2e by using the following emissions factors also provided in Table 5.4.
Table 5.4. Estimation and emissions factors for treatment with nitrification or
denitrification.
2005 2016
Treatment Lagoons Methane Generation
Industrial and commercial co-discharge factor (Find-com) 1 1
Nitrification/denitrification emissions factor (EF nit/denit) 7 7
Conversion Factors for Treatment with Nitrification/Denitrification N2O Generation (MTCO2e)
Grams to metric tons 0.000001 0.000001
GWP of nitrous oxide 265 265
Annual N2O emissions per person (MTCO2e) 0.001855 0.001855
Source: Local Government Operations Protocol (LGOP)
The coefficient for nitrous oxide generation from nitrification or denitrification is then applied to the
total service population presented in Table 5.3. Table 5.5 shows the total GHG emissions
generated from nitrification.
Table 5.5. GHG Emissions from treatment with nitrification or denitrification.
Nitrification Treatment Emissions (MTCO2e) 2005 2016
Water Resource Recovery Facility (WRRF) 110 120 DRAFT
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Page 25
Total Wastewater GHG Emissions
Table 5.6 reports the final calculated wastewater GHG emissions data of the combined treatment
types of methane generation from the incomplete combustion of digester gas and nitrous oxide
generation from nitrification processes. The increase in emissions for both treatments is likely due
to the increase in activity data for each treatment type. As the population increased overtime, the
city saw an increase in the total wastewater requiring treatment from 2005 and 2016.
Table 5.6. Total GHG estimates from wastewater treatment.
Subsector
Activity Data
Unit
Emissions Factors
(MTCO2e/person)
GHG Emissions (MTCO2e)
2005 2016 2005 2016 20051 20161 %
Change
Stationary CH4 from
Incomplete
Combustion of
Digester Gas 56,000 67,412 ft3 Gas 0.001054 0.001045
60
70 17%
Process N2O
Emissions from
WWTP with
Nitrification/
Denitrification 60,476 62,767
Populatio
n 0.001855 0.001855
110
120 9%
Total -- -- -- -- 170 190 12%
1 Rounded to nearest tenth
6. Off-Road
Off-Road Sector Overview
This section presents the GHG emissions for off-road activity, specifically emissions from
construction and lawn and garden equipment use within City limits. In this section, methods are
discussed to calculate a baseline emissions inventory for 2005 along with an updated inventory
year of 2016. This section concludes with the sector’s total GHG emissions.
Inventory Data and Methods
To estimate emissions from off-road equipment, this sector considers emissions generated from
construction and lawn and garden equipment.
Off-road emissions data for the county was gathered from the CARB OFFROAD2007 modeling
tool. Table 1 provides an overview of the equipment modeled in the CARB tool. Since the CARB
tool models emissions for the entire county, city specific emissions data was proportioned out
using demographic housing information. Table 6.1 provides the aggregated emissions data
collected and the total GHG emissions in proportion to the rest of the county. DRAFT
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Table 6.1. Off Road equipment.
Construction Lawn and Garden
Tampers/Rammers, Plate Compactors, Asphalt
Pavers, Rollers, Paving Equipment, Surfacing
Equipment, Signal Boards, Trenchers, Bore/Drill
Rigs, Concrete/Industrial Saws, Cement and Mortar
Mixers, Cranes, Graders, Off-Highway Trucks,
Crushing Equipment, Rough Terrain Forklifts,
Rubber Tired Loaders, Rubber Tired Dozers,
Tractors, Loaders, Backhoes, Crawlers, Skid Steer
Loaders, Off-Highway Tractors, and Dumpers
Lawn Mowers, Chainsaws, Trimmers, Leaf
Blowers, Shredders, Commercial Turf Equipment,
Tillers, Rear Engine Riding Mowers, Front
Mowers, Shredders, Lawn & Garden Tractors,
Wood Splitters, Chippers/Stump Grinders,
Commercial, Turf Equipment, Other Lawn &
Garden Equipment
Source: CARB OFFROAD2007 modeling tool
Data from the OFFROAD2007 modeling tool was compiled and summed according to emission
type and is presented in Table 6.2. The emissions presented in Table 6.2 are then converted to
carbon dioxide equivalent by applying the most recently available global warming potential values.
Table 6.2. County off-road GHG emissions.
2005 2016
Construction Lawn and Garden Construction Lawn and Garden
t CO2/day1
(row 1) 169.033 16.805 199.982 18.189
t CH4/day1
(row 2) 0.001 0.013 0.018 0.027
t N2O/day1
(row 3) 0.031 0.032 0.001 0.012
t CO2e/day2
(row 4) 177.315 25.871 200.781 22.093
t CO2e/year
(row 5) 64,716.466 9,442.729 73,285.229 8,064.056
MTCO2e/year3
(row 6) 58,710.393 8,566.387 66,483.924 7,315.663
1 CARB OFFROAD2007 modeling tool
2 Sum of rows 1-3, with row 2 multiplied by the CH4 GWP value of 28 and row 3 multiplied by the GWP
value of 265 (IPCC Fifth Assessment Report)
3 Conversion from tons to metric tons
To estimate the emissions occurring in the city an adjustment factor was applied to the final
MTCO2e estimates in Table 6.3. The adjustment factor used for construction equipment was
15.79 percent for 2005 and 10.47 percent for 2016. The adjustment factor use for lawn and garden
equipment was 18.02 percent for 2005 and 17.41 percent for 2016. These adjustment factors
represent the proportion of new households in the city relative to the county as a whole. Table 6.3
provides the adjustment factor applied to the total yearly MTCO2e of the county.
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Table 6.3. City off-road GHG emissions.
2005 2016
MTCO2e
% of
City1
Total
MTCO2e
MTCO2e1 % of Unincorporated
County1
Total
MTCO2e3,5
Construction 58,710 15.79% 9,270 66,484 10.47% 6,960
Lawn and
Garden 8,566 18.02% 1,540 7,316 17.41% 1,270
Total -- -- 10,810 -- -- 8,230
1 Proportion of unincorporated county households to number of total county households
Total Off-Road GHG Emissions
From 2005 to 2016, the City of San Luis Obispo experienced a 24 percent decrease in emissions
from lawn and garden and construction equipment (Table 6.4). This significant decrease in
emissions from 2005 and 2016 is likely due to the lack of building construction activity that took
place during this time period. As new construction projects decreased, there were less
greenhouse gases emitted from off-road equipment use.
Table 6.4. Total GHG estimates from off-road use.
2005 2016
Construction and Mining Equipment 9,270 6,960
Lawn and Garden Equipment 1,540 1,270
Total 10,810 8,230
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List of Abbreviations
AB: Assembly Bill
ADT: Average daily trips
APCD: Air Pollution Control District
Caltrans: California Department of Transportation
CAP: Climate Action Plan
CARB: California Air Resources Board
CH4: Methane
CO2: Carbon dioxide
CO2e: Carbon dioxide equivalent
DANF: Decomposable anaerobic fraction
DOC: Degradable organic content
EPA: US Environmental Protection Agency
GHG: Greenhouse gas
IPCC: Intergovernmental Panel on Climate Change
kW: Kilowatt
kWh: Kilowatt-hour
LGOP: Local Government Operations Protocol
MSW: Municipal solid waste
MTCO2e: Metric tons of carbon dioxide equivalent
N2O: Nitrous oxide
PG&E: Pacific Gas & Electric Company
RPS: Renewables Portfolio Standard
SB: Senate Bill
TDOC: Total degradable organic carbon
VMT: Vehicle miles traveled
WIPFRAC: Fraction of waste in place
WRRF: Water Resource Recovery Facility
ZNE: Zero net energy
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Appendix A
As described in the main body of this report, the City used the California Air Resources Board’s
EMFAC 2014 model to determine county-wide VMT and CO2 emissions for 2005 and 2016.
Table A.1 shows the county-wide numbers from the EMFAC 2014 model.
Table A.1: County of San Luis Obispo 2005 and 2016 EMFAC aggregated data.
2005 2016
Vehicle Class County
VMT
% VMT of
County
CO2 (Ton) VMT % VMT of
County
CO2 (Ton)
All Other Buses 5,796 0.07% 8 7,987 0.10% 11
LDA 4,029,232 46.73% 1,431 4,293,311 51.58% 1,404
LDT1 377,679 4.38% 157 331,725 3.99% 128
LDT2 1,789,539 20.75% 880 1,664,158 19.99% 751
LHD1 543,694 6.31% 435 353,435 4.25% 274
LHD2 84,062 0.97% 70 80,207 0.96% 65
MCY 53,994 0.63% 9 53,227 0.64% 9
MDV 1,417,007 16.43% 865 1,219,021 14.64% 714
MH 31,041 0.36% 44 19,918 0.24% 28
Motorcoach 2,759 0.03% 5 2,870 0.03% 6
OBUS 6,438 0.07% 9 10,023 0.12% 14
PTO 4,602 0.05% 12 4,295 0.05% 11
SBUS 6,889 0.08% 8 7,079 0.09% 9
T6 117,434 1.36% 159 114,479 1.38% 155
T7 141,272 1.64% 290 150,263 1.81% 295
UBUS 11,346 0.13% 28 11,961 0.14% 29
Total 8,622,783 100.00% 4,410 8,323,959 100.00% 3,903
The City applied the percent of VMT by vehicle type for the County to the City’s VMT, resulting
in estimated VMT for the City of San Luis Obispo by vehicle type. Table A.2 shows these
numbers.
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Table A.2. Annual City VMT estimates.
2005 2016
Vehicle Class % VMT of County Total VMT % VMT of
County
Total VMT
All Other Buses 0.07% 179,174 0.10% 263,423
LDA 46.73% 124,566,476 51.58% 141,595,456
LDT1 4.38% 11,676,212 3.99% 10,940,462
LDT2 20.75% 55,324,841 19.99% 54,884,738
LHD1 6.31% 16,808,663 4.25% 11,656,462
LHD2 0.97% 2,598,841 0.96% 2,645,260
MCY 0.63% 1,669,263 0.64% 1,755,458
MDV 16.43% 43,807,733 14.64% 40,203,905
MH 0.36% 959,665 0.24% 656,910
Motorcoach 0.03% 85,306 0.03% 94,647
OBUS 0.07% 199,027 0.12% 330,551
PTO 0.05% 142,284 0.05% 141,648
SBUS 0.08% 212,968 0.09% 233,465
T6 1.36% 3,630,558 1.38% 3,775,563
T7 1.64% 4,367,509 1.81% 4,955,749
UBUS 0.13% 350,761 0.14% 394,473
Total 100.00% 266,579,280 100.00% 274,528,170
The City used the results of the EMFAC model to determine the tons of CO2/VMT for each vehicle
type, and combined these individual emissions factors to prepare a weighted average CO 2/VMT
emissions factor that reflects the specific mix of vehicles in San Luis Obispo County. The City
next converted the tons of CO2/VMT to metric tons of CO2e/VMT, using industry-standard figures,
and applied this emissions factor to the total City VMT to calculate total emissions. Table A.3
shows San Luis Obispo’s VMT, emissions factors, and total emissions by individual vehicle type.
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Table A.3. Total annual VMT emissions.
2005 2016
Vehicle Class Total VMT MTCO2e/
VMT
Total
Emissions
Total VMT MTCO2e/
VMT
Total
Emissions
All Other Buses 179,174 0.001275 230 263,423 0.001312 350
LDA
124,566,476 0.000339 42,230 141,595,456 0.000312 44,220
LDT1 11,676,212 0.000396 4,620 10,940,462 0.000369 4,040
LDT2 55,324,841 0.000470 25,990 54,884,738 0.000431 23,650
LHD1 16,808,663 0.000765 12,860 11,656,462 0.000741 8,640
LHD2 2,598,841 0.000799 2,080 2,645,260 0.000774 2,050
MCY 1,669,263 0.000154 260 1,755,458 0.000167 290
MDV 43,807,733 0.000583 25,530 40,203,905 0.000559 22,480
MH 959,665 0.001349 1,300 656,910 0.001322 870
Motorcoach 85,306 0.001890 160 94,647 0.001888 180
OBUS 199,027 0.001382 280 330,551 0.001373 450
PTO 142,284 0.002420 340 141,648 0.002398 340
SBUS 212,968 0.001136 240 233,465 0.001162 270
T6 3,630,558 0.001291 4,690 3,775,563 0.001295 4,890
T7 4,367,509 0.001962 8,570 4,955,749 0.001876 9,300
UBUS 350,761 0.002365 830 394,473 0.002291 900
Total
266,579,280 -- 130,210 274,528,170 -- 122,920
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