CDM conducted an assessment and update of the City of Charlotte’s (City) 2006 greenhouse gas (GHG) emissions inventory of city government operations, buildings, vehicles, and facilities as part of the project to develop an Energy Strategy for the
Energy Efficiency and Community Block Grant (EECBG) Program. This report provides a summary of the process, the major changes compared to the initial city operations inventory, and an overview of the inventory results.
The City previously conducted a voluntary city operations GHG inventory for FY2006 prepared by student interns and supervised by Engineering and Property
Management. This inventory was conducted in 2008 using the 2003 version of the
ICLEI – Local Governments for Sustainability (ICLEI) Clean Air and Climate
Protection (CACP) software. Since the preparation of the initial inventory, The
Climate Registry published a comprehensive standard for conducting local government GHG inventories in late 2008. The Climate Registry (TCR) is a 501(c)(3) non-profit organization that was formed with the intent of improving the consistency and accuracy of GHG emissions reporting in North America. TCR is subscribed to by
41 U.S. states (including North Carolina), 11 Canadian provinces and 6 Mexican states, and currently provides the leading unifying GHG inventory guidance in North
America. A partnership of TCR, the California Air Resources Board, the California
Climate Action Registry, and ICLEI developed the sector-specific GHG protocol, Local
Government Operations Protocol For Quantification and Reporting of Greenhouse Gas
(GHG) Inventories, Version 1.0, September 25, 2008.
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CDM conducted a review of the FY2006 city operations inventory and updated the data and calculations to meet the standards and guidelines of the Local Government
Operations Protocol (LGOP). The LGOP is described in the next section, followed by a discussion of the methodology and results of the updated and LGOP 2006 GHG emissions inventory for city government operations. In a separate report,
“Community Greenhouse Emissions Inventory Report”, the city operations emissions are included within the context of the entire Charlotte community.
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1
California Air Resources Board, California Climate Action Registry, ICLEI-Local Governments for
Sustainability, & The Climate Registry. Local Government Operations Protocol . Version 1.0. The
Climate Registry, September 2008.
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The LGOP was created to provide standardized methods and guidelines for local governments choosing to quantify and report GHG emissions from city operations.
City operations are defined as buildings, facilities, vehicle fleets including transit vehicles, streetlights, airport facilities and emissions from employee commuting. The
LGOP is based on guidelines and methodology used in the World Resources Institute and World Business Council for Sustainable Development Greenhouse Gas Protocol.
Taking into account the unique structure of local governments as compared with private companies, the LGOP provides general guidance on how to determine what emissions sources to include in a GHG inventory and how to calculate those emissions. Using these methods, local governments may complete transparent and accurate GHG inventories that are based on the most up-to-date calculation methodologies and emissions factors.
The ICLEI Clean Air and Climate Protection (CACP) 2009 Software was designed as an update to the 2003 version, and is intended to be consistent with the LGOP. For example, the 2009 software includes new sectors such as airports, transit, refrigerants and modified methods for calculating waste and wastewater treatment emissions.
There was also a major change in how GHG emissions from electricity use are calculated. These changes and the current calculation methods are outlined in
Sections 3 and 4.
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Figure 1 lists the six Kyoto Protocol GHGs, along with example emissions sources.
These GHGs are: carbon dioxide (CO
2
), methane (CH
4
), nitrous oxide (N
2
O), hydroflourocarbons (HFCs), perflourocarbons (PFCs), and sulfur hexafluoride (SF
6
).
As shown in Figure 1 , the primary sources of GHG emissions are: combustion of fossil fuels, releasing CO
2
and N
2
O; releases of CH
4
and N
2
O from biological processes; releases of HFCs, PFCs from refrigeration and fire suppression equipment; and releases of SF
6
from high-voltage electrical equipment typically owned by utilities.
For the purposes of a city operations emissions inventory, it is not practical to measure the GHG emission rate from every emissions source controlled by the City.
The LGOP provides GHG emission factors for each source type, based on recent literature and research, and methods for calculating total annual GHG emission rates as a function of annual fuel usage, numbers of equipment or vehicles, and other activity data. Activity data for all emissions sources including electricity use, natural gas combustion, mobile sources and wastewater treatment were gathered with the help of employees from the City of Charlotte and local CDM employees.
The activity data were input into the ICLEI software, which contains the emission factors for each GHG, calculates the resulting GHG emission rates, and converts the emission rates into carbon dioxide equivalents (CO
2 e) using emissions factors and global warming potentials (GWP). A GWP represents the ability of each GHG to trap heat in the atmosphere and is the ratio of the heat trapping ability normalized to that for CO
2
(i.e., CO
2
has a GWP of 1). GWP values from the Intergovernmental Panel on
Climate Change (IPCC) Second Assessment Report 2 were used, as shown in Table 1 below and recommended by the LGOP. Although these are not the most up-to-date
GWP values available according to the latest IPCC reports, they are currently used by the LGOP and other accounting protocols.
Table 1. Applicable Global Warming Potential (GWP) Values
GHG Pollutant
CO
2
CH
4
N
2
O
HFC – 134a
HFC – 143
GWP Values
1
21
310
1,300
300
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2
Intergovernmental Panel on Climate Change. IPCC Second Assessment Report: Climate Change . 1995.
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Section 3
Methodology
CDM gathered the 2006 activity and emissions data from the 2003 Clean Air and
Climate Protection software from the City. Comparing this data to the new LGOP standards for organizational boundaries and emission sources, CDM identified the following outstanding data that was not included in the original inventory and was obtained to update it for LGOP standards:

Hydrofluorocarbons (HFCs) and perfluorocarbons (PFCs) emissions from refrigerant sources occur during the recharge or disposal of HVAC and mobile source air conditioning equipment. Limited data on refrigerants from FY2006 is available at this time. A further discussion on refrigerant emissions is outlined below;

Charlotte Area Transit System (CATS) fuel usage in transit buses, and trolleys that were operational in FY2006;

Fugitive methane (CH
4
) emissions from incomplete combustion of digester gas during wastewater treatment processing; and

Nitrous oxide (N
2
O) emissions from nitrification and effluent discharge during wastewater treatment processing.
CDM worked with the City of Charlotte to collect this information, and then worked with ICLEI to transfer the original data into the updated ICLEI Clean Air and Climate
Protection (CACP) 2009 Software.
While most emissions calculations were completed by the software, in some cases it was necessary to prepare separate calculations in order to accurately follow the LGOP guidance. In these instances, GHG emissions were calculated following the LGOP equations, and then input as total GHG emissions into the software. For example,
CDM calculated emissions from wastewater and refrigerants separately from the software.
Emission Scopes
The LGOP separates GHG emissions into three categories, referred to as “operational boundaries” which allows for more effective GHG management and serves to minimize the potential double counting of emissions. The categories, also called
Scopes, include:

Direct / Scope 1 Emissions associated with fuel consumption by stationary and mobile combustion sources, and fugitive emissions from refrigerant equipment and landfill sources, directly owned and operated by the City;

Indirect / Scope 2 Emissions from purchased electricity or steam generated by utilities or service providers; and
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Section 3
Methodology

Optional / Scope 3 Other indirect emissions, such as those from employee commuting and outsourced activities.
Emissions are organized by Scopes to facilitate the assessment of responsibility associated with GHG emissions. Direct emissions under Scope 1 are those that are under the control of the City. Examples include city- owned or -operated vehicle fleets and closed landfills (see Figure 1 ). Indirect emissions in Scope 2 are the result of the
City’s electricity consumption – the power generation is provided by external companies over which the City has no control or operational involvement. Optional emissions included in Scope 3 address all other sources of indirect and direct emissions of which the City has little to no direct operational control or ownership, such as employee
C ommuting – while these emissions are caused by City employees, the vehicle is under the control of the employee and not the City.
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Figure 1. Direct and Indirect Emissions Sources
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In addition to the use of different software and the inclusion of new emissions sources, several additional significant differences between the initial inventory conducted by the City and the updated LGOP inventory are discussed below.
In the 2003 version of the CACP software, electricity emission factors were based on the regional fuel mix used in electric power generation. The emissions factor previously used for Charlotte as provided by the 2003 version of the CACP software was determined by the regional grid structure and power generation using the
Southeast Electric Reliability Council emissions data for the region, excluding Florida.
The newly updated, 2009 version of the CACP software contains updated electricity emissions factors, which are now based on the U.S. Environmental Protection
Agency’s (EPA) EGrid database, as recommended by the LGOP. These EGrid emissions factors are developed from actual emissions data from electricity generation nation-wide. These data are then aggregated by electric grid-region, to create regionally based electricity emission factors. The EGrid regions, shown in
Figure 2 , are smaller than those used in the previous ICLEI software and more accurately represent regional power pools. As shown in Figure 2 , Charlotte’s electricity, and the associated GHG emissions, come from the SRVC EGrid region.
In addition, electricity emission factors change every year based on the actual fuel mix
(nuclear, coal, natural gas) used at power plants; EGrid data is a more recent reflection of GHG emissions than the previous version of the ICLEI software. As a result of these changes, the electricity emission factor has decreased by approximately
21%, thus decreasing emissions from electricity-based emissions sources by the same amount, as shown in Table 2 .
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Section 4
Key Inventory Updates
Figure 2. EPA EGrid Regions
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Section 4
Key Inventory Updates
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Table 2. Electricity Emission Factors
CACP 2003* CACP 2009
(EGrid)
Percent change
CO
2
(lbs / MWh)
CH
4
(lbs / MWh)
1457.2 1146.39
0.018 0.029
-21%
61%
N
2
O (lbs / MWh) 0.023 0.019 -17%
CO
2 e (lbs /
MWh)
1464.71 1152.89
*Based on Southeast Electric Reliability Council, excluding Florida
-21%
The LGOP guidelines recommend the inclusion of GHG emissions from refrigerant sources including fugitive GHG emissions from the refrigeration used to cool city buildings, city vehicles and from fire suppression equipment. These equipment types use and release small quantities of hydrofluorocarbons (HFCs) or perfluorocarbons
(PFCs) when they are recharged with the gaseous refrigerants. The GWPs of HFCs and PFCs range from a few hundred to several thousand times that of CO
2
, rendering them a potentially significant source of GHG emissions due their more potent characteristics in contributing to the greenhouse effect in the atmosphere.
The LGOP recommends calculating emissions from refrigerants using a mass balance method, in which the base inventory of refrigerants is compared to the amount of purchased refrigerants used to replace fugitive refrigerant emissions. The total annual emissions for each HFC and PFC is then totaled and converted to units of CO
2 e. The alternate methods calculate HFCs and PFCs based on the refrigerant capacity of the equipment or simply based on the number of each type of cooling equipment owned by the City.
The City has been able to provide some insight on the refrigerant emissions and is working to obtain the data to complete these calculations for future year inventories.
The current inventory includes HFC-134a emissions from a chiller system and HFC-
143 emissions from airport vehicles. For emissions from the chiller, CDM used a default capacity and leakage rate from Section 6.6.3.3 of the LGOP. For emissions from the airport vehicles, records of refrigerant use were available. So, CDM entered the amount of HFC-143 used in 2006 directly into the ICLEI software.
Although data on these emission sources are incomplete at the this time, it is reasonable to assume that even with complete data, HFCs and PFCs would represent a very minor (less than three percent of the total) sources of emissions for City operations. A recent inventory performed by the City of Atlanta following the LGOP
4-3

Section 4
Key Inventory Updates guidance found that emissions from refrigerants made up less than one percent of their GHG emissions inventory.
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The City provided annual gasoline and diesel fuel consumption data for city-owned and operated vehicles for the following sources: Aviation, Employee Business Miles,
Equipment Management Division, and Fire Department. The data contained fuel consumption for several different general vehicle types, but not specific model year information for each vehicle. While CO
2
emissions are based on fuel consumed, in order to calculate CH
4
and N
2
0 emissions specific make and model year data is required for each vehicle. In order to input vehicle fuel consumption into the 2009
CACP software, CDM used fuel consumed data and the alternative method from the
LGOP which recommends using a default emissions factor by vehicle type to calculate emissions in the absence of make and model year data.
4
CDM calculated GHG emissions from City employees commuting to work using total annual vehicle miles traveled (VMT). The VMT were calculated based on employee zip code data, and these data were added into the CACP software under the passenger car alternative method category.
5
CDM calculated the CATS transit fleet GHG emissions using the same alternative method. This method is based on estimated average fuel efficiency for each vehicle type. For the transit bus fleet, emissions were calculated using the alternative method emissions factor for heavy duty vehicles.
6
Methane and nitrous oxide emissions from wastewater treatment plants are two of the new emissions sources which were added to the city operations inventory based on the latest guidance in the LGOP. Additionally, McDowell Creek electricity and biogas usage were unintentionally omitted from the original inventory and are now included in the emissions totals.
Five wastewater treatment plants handle Charlotte’s wastewater: McAlpine Creek,
Irwin Creek, Sugar Creek, McDowell Creek, and Mallard Creek. Because these treatment facilities serve more than the population within the City of Charlotte, the calculated GHG emissions were scaled back based on the ratio of the population of
Charlotte to the total population served by the plants. CDM calculated fugitive methane emissions for each treatment plant with anaerobic digestion processes, based on measured digester gas flow rate information provided by the City, and an
3
Borin, Seth, Joy Wang, and Valerie Thomas. City of Atlanta Greenhouse Gas Emissions Inventory .
Rep. Georgia Institute of Technology, March 2009.
4
LGOP, Chapter 7, Equation 7.2 and Section 7.1.3
5
LGOP, Chapter 7, Section 7.1.3 and Table G.13
6
LGOP, Chapter 7, Section 7.1.3 and Table G.13
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Section 4
Key Inventory Updates assumed 99% methane destruction efficiency of the digester gas flares.
7 Nitrous oxide emissions from the nitrification process for each treatment plant were calculated based on the total population that is served by the plant and the emission factors from the LGOP for a wastewater treatment plant with nitrification.
8 Nitrous oxide emissions from effluent discharge were calculated using the measured average of total nitrogen discharged for each plant and the effluent emission factor provided by the LGOP 9 .
Emissions from Charlotte-Douglas International Airport (CDIA) buildings, facilities and vehicle fleet were included in the original inventory conducted in 2008. In complying with the LGOP, these emissions are now called out separately as an individual sector in the city operations inventory, as opposed to being included in the
Buildings and Facilities sector. CDIA emissions do not include emissions from aircraft because these emissions sources are typically considered to be Scope 3, or optional emissions sources, over which an airport has little to no financial or operational control.
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7
8
LGOP, Chapter 10, Equation 10.1.
9
LGOP, Chapter 10, Equation 10.7.
LGOP, Chapter 10, Equation 10.9
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The City of Charlotte’s total GHG emissions for City operations in FY2006 is approximately 310,000 metric tons of CO
2 e, which is five percent higher than the original inventory results. Figure 3 shows the breakdown of these emissions by the
LGOP recommended sectors.
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Section 5
Results
A simplified, consolidated perspective of the city operations emissions is provided in
Figure 4 . This figure combines transit fleet, vehicle fleet and employee commute emissions under mobile sources, and combines water and wastewater emissions under utilities emissions.
Broken down by emissions scopes as discussed in Section 3 and shown in Figure 1 , emissions from city operations are mainly attributed to indirect emissions from electricity use in city facilities under Scope 2. These Scope 2 emissions account for
60.5% of emissions, as shown in the Table 3 . Direct emissions from mobile and stationary combustion and fugitive emissions from city operations and facilities account for about one third, or 33% percent of emissions. Scope 3 emissions sources are not under the direct control of the local government and are optional for inclusion in the inventory. The city’s employee commuting emissions are the only Scope 3 emissions source included at this time, accounting for 6.8% of city operations emissions.
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Section 5
Results
Biogas
Table 3. 2006 Emissions by Scopes 1,2 and 3
14 CO
2 e (tons)
Refrigerants
Natural Gas
606 CO
2
2,873 CO
2 e (tons) e (tons)
Wastewater Processing
City-owned Landfills
4,742 CO
2 e (tons)
24,363 CO
2 e (tons)
Vehicle Fuel 68,797 CO
2 e (tons)
Total Direct / Scope 1 Emissions = 32.7%
Electricity 10 187,530 CO
2 e (tons)
Total Indirect / Scope 2 Emissions = 60.5%
Employee Commuting 20,961 CO
2 e (tons)
Total Other / Scope 3 Sources = 6.8%
Table 4 provides a side-by-side comparison of the original inventory with the updated, LGOP inventory version. The slightly higher total emissions result from the additions of transit fleet and refrigerants emissions, as well as the addition of methane and nitrous oxide emissions from wastewater treatment plants. The lowered emissions factors for electricity and vehicle fleets have largely offset the increases from the additional emissions sources. Emissions factors for vehicle fleets and employee commuting in particular have decreased significantly from the 2003 to the
2009 version of the CACP software. This is likely due to slight improvements in the average fuel economy as well as the enhanced accuracy of emissions factors in the
LGOP as a more updated resource that has been vetted by regulatory experts.
In addition, the original GHG emissions report from the CACP 2003 software was provided in short tons (2000 lbs), which was converted to metric tons (1 short ton =
.907 metric tons) for the purposes of a side-by-side comparison. According to best practice internationally and as recommended by the LGOP, GHG emissions are reported in metric tons.
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10
Electricity us in Scope 2 includes 77 tons of CO2e from the CATS system
5-3

Section 5
Results
Table 4: Comparison of the City of Charlotte 2006 GHG Emissions
CACP 2003* CACP 2009, LGOP Standard
Sector CO
2 e
(metric tons)
Buildings (inc. Airport facilities)
Sector CO
90,519 Buildings and Facilities factors)
(updated electricity emission
Airport Facilities (new sector)
2 e
(metric tons)
Percent change
33,699 -25.8%
30,444
Water/Sewage 69,658 Wastewater facilities
( includes fugitive & process emissions, McDowell Plant)
54,986 29.2%
Water delivery facilities 35,043
Vehicle Fleet
Streetlights/Traffic Signals
41,269 Vehicle Fleet
48,343 Streetlights and Traffic
(updated electricity emission factors)
22,766 Employee Commute
35,531 -13.9%
37,810 -21.8%
Employee Commute
Waste
Other (Former York Road
Landfill, Statesville Ave
Landfill)
67 Solid Waste Facilities
22,131
20,961 -7.9%
24,464 10.2%
Transit Fleet (new sector)
Refrigerants (new sector)
33,343 n/a
605 n/a
Total 294,751 Total 309,886 5.1%
*GHG emissions in this table are in metric tons, in the CACP 2003 software, data was originally reporting in short tons. These totals have been converted, 1 short ton = .907 metric tons.
Electricity use in buildings, facilities, streetlights and traffic lights is the largest source of emissions in city operations, accounting for approximately 60% of emissions followed by transportation emissions from gasoline and diesel fuel combustion which account for a combined 29% of the total as shown in Figure 5 .
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Section 5
Results
This is a very typical emissions source profile for local governments that own and operate a variety of building types and vehicles. Electricity consumption, although an indirect emissions source, commonly results in the majority of emissions generated by local governments. This profile is also relatively comparable to other GHG inventories for city operations, including those recently completed by the City of Atlanta, GA, and the City of Dallas, TX shown in Table 5.
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Section 5
Results
Table 5. Comparison of Municipal Emissions in other US Cities
Source Charlotte,
NC
Dallas,
TX 11
Atlanta,
GA 12
Refrigerants
Natural Gas
Wastewater Processing
City-owned Landfills
Transportation Fuel
Electricity
0.2%
0.9%
1.5%
7.9%
0.0%*
3.4%
0.0%*
0.0%**
0.5%
8.4%
1.0%
5.4%
29.0%
60.5%
15.6%
81.0%
* not available ** not applicable
5.2%
79.5%
Table 6 highlights individual sources contributing to more than five percent of the total emissions for the Charlotte’s city operations. These eight emissions sources (or groups of sources) account for 85% of the total emissions from city operations. The
McAlpine Creek wastewater treatment plant is called out separately from all other water/wastewater facilities because of its significant size as a single emissions source, at nearly 10% of city operations emissions as a single source. These significant emission sources are an appropriate starting point for considering projects for EECBG funding, as they may provide the best potential for return on investment and energy use reduction.
11
City of Dallas Greenhouse Gas Inventory (City of Dallas, CDM) http://www.greendallas.net/pdfs/GHG_Emissions_Summary.pdf
12
Borin, Seth, Joy Wang, and Valerie Thomas. City of Atlanta Greenhouse Gas Emissions Inventory.
March 2009. Georgia Institute of Technology.
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Section 5
Results
Table 6. Significant Emissions Sources
Sources Contributing > 5%
Water/Wastewater Treatment Plants
(excluding McAlpine Plant)
Streetlights
Vehicle Fleet
CATS Transit Fleet
Charlotte-Douglas International Airport
McAlpine Creek Wastewater Treatment Plant
Employee Commuting
Former York Road Landfill
Total
CO
2 e
(metric tons)
Percent of
Total
Emissions
19.6% 60,603
36,570 11.8%
35,531 11.5%
30,735 9.9%
30,444 9.8%
29,426 9.5%
20,961 6.8%
17,618 5.7%
261,888 84.6%
Finally, it is important to consider city operation emissions in the context of GHG management, reporting, and emerging regulations. On September 22, 2009, the EPA finalized mandatory GHG reporting requirements under the authority of the federal
Clean Air Act 13 . Multiple Direct/Scope 1 sources will be required to report GHG emissions to the EPA if they trigger certain thresholds for reporting. Under the EPA rule, direct (Scope 1) emissions sources greater than 25,000 metric tons of CO
2 e annually will be required to report GHG emissions on a quarterly basis beginning in
2011. For City of Charlotte operations, this may require reporting for stationary fossil fuel combustion sources or groupings of sources at the same site. This is approximately the equivalent emissions of a 50-250 MMBtu/hr natural gas-fired boiler. Because emissions from electricity are considered indirect (Scope 2) emissions, they will not be subject to this rule.
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13
EPA. Final Mandatory Reporting of Greenhouse Gases Rule . September 2009. http://epa.gov/climatechange/emissions/ghgrulemaking.html
5-7

Section 5
Results
The City of Charlotte has taken a significant first step in energy and GHG management by determining a GHG emissions baseline for city owned buildings, facilities and vehicles. By conducting a rigorous review of the initial inventory and updating it according to the LGOP standards and guidelines, the inventory now meets the highest standards available for local governments. With this knowledge and information, the City can make more informed energy management decisions and focus funding and resources to areas that will yield the greatest results. The GHG emissions inventory is also a key building block in the foundation for a long-term energy roadmap for the City of Charlotte.
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