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Sept
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Section 1
Introduction
The City of Charlotte conducted a 2006 baseline greenhouse gas (GHG) emissions
inventory for its own buildings, facilities and operations to help identify areas for
improvement in energy use and GHG reduction. In addition to assessing and
updating this inventory for city operations, CDM also conducted a 2006 baseline GHG
emissions inventory for the community, as part of the project to develop an Energy &
GHG Action Plan for the Energy Efficiency and Community Block Grant (EECBG)
Program.
Community emissions are defined by the geographical boundary of the City of
Charlotte, and include all emissions from private sector buildings, transportation
emissions from all vehicle miles traveled within the city, and solid waste generated by
city residents and businesses. The city operations emissions are included as one
component of the larger, comprehensive emissions inventory for the Charlotte
community.
This community GHG inventory summary report presents annual community
emissions for calendar year 2006 from major sources within the City of Charlotte
including those from electricity, natural gas, and fuel oil consumed in residential,
commercial, and industrial buildings; from private vehicles traveling within the city;
and from methane generated by the decomposition of solid waste generated within
the city. The emissions from city operations are included in this inventory as a
component of the entire community emissions inventory. For a detailed account of
city operations emissions, see “City Operations Greenhouse Gas Emissions Inventory
Report,” September 25, 2009. The inventory highlights the major GHG emissions
sources in the entire Charlotte community, and also identifies the contribution of the
private sector and households to the overall emissions profile, facilitating efforts of
city and community energy planning currently underway and funded by the EECBG
program.
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Section 2
Methodology
In contrast to conducting a GHG inventory for city operations, there is not yet a
nationally or internationally recognized standard for developing community GHG
inventories. CDM followed best practices for community inventories based on
common practices, extensive experience, and general recommendations from ICLEILocal Governments for Sustainability (ICLEI). While U.S. cities have been conducting
these inventories for over a decade, they vary widely in scope and methodology. This
is important to note when considering the comparison of Charlotte’s results to other
communities, as discussed in Section 3.
GHG emissions are calculated based on annual fuel usage and activity data
multiplied by the appropriate emissions factor to determine the metric tons of GHG
emissions per source or sector. Annual fuel use and activity data for electricity,
natural gas, fuel oil, mobile sources and solid waste was gathered with the help of
City staff, Duke Energy, and Piedmont Natural Gas.
The community inventory was conducted using the ICLEI Clean Air and Climate
Protection (CACP) 2009 software, the same program used for the city operations
inventory. The activity data were input into the CACP software, which contains the
emission factors for each GHG, calculates the resulting GHG emission rates, and
converts the emission rates into carbon dioxide equivalents (CO2e) 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 CO2 (i.e., CO2 has a GWP of 1). GWP values from the
Intergovernmental Panel on Climate Change (IPCC) Second Assessment Report1 were
used, as shown in Table 1 below. 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 Potentials (GWP)
GHG Pollutant
CO2
CH4
N2O
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GWP Values
1
21
310
Intergovernmental Panel on Climate Change. IPCC Second Assessment Report: Climate Change. 1995.
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Section 2
Methodology
The following energy and activity data were collected for the community inventory:

Annual electricity purchased by residential, commercial, and industrial customers;

Annual natural gas purchased by residential, commercial, and industrial
customers;

Estimated fuel oil consumption by residential, commercial, and industrial
customers based on statewide data for 2006;

Modeled annual vehicle miles traveled within City limits;

Annual tons of solid waste disposed from residential curbside pickup in the City
and total waste tonnage from Mecklenburg County, scaled back for the City;
The process and methodology for calculating emissions from each of these
sources is described below.
Electricity
Aggregated annual electricity consumption by sector were provided by Duke Energy
and input into the ICLEI software in the residential, commercial, and industrial
sectors. 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 LGOP2. These
EGrid emissions factors are developed from actual emissions data for electricity
generation nation-wide. These data are then aggregated by electric grid-region, to
create regionally based electricity emission factors. As shown in Figure 1, Charlotte’s
electricity, and the associated GHG emissions, come from the SRVC eGrid region. To
avoid double counting of electricity consumption and emissions, CDM subtracted
electricity consumption for city operations from the commercial sector total electricity
consumption.
2
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LGOP, Section 6.2 and Table G.7
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Section 2
Methodology
Figure 1. EPA EGrid Regions
Natural Gas
Aggregated annual natural gas consumption data by residential, commercial and
industrial sectors were provided by Piedmont Natural Gas and input into the ICLEI
software in the residential, commercial, and industrial sectors. The software
automatically applies emission factors for natural gas from the LGOP3. CDM
subtracted natural gas consumption for city-operations from the commercial sector
total to avoid double-counting of natural gas use in city buildings and facilities.
Fuel Oil
Actual fuel oil consumption data within the City of Charlotte is not readily available
as there is not a central vendor or tracking system. To estimate fuel oil consumption,
CDM used statewide 2006 annual consumption data provided by the U.S. Energy
3
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LGOP, Tables G.1 and G.3
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Section 2
Methodology
Information Administration (EIA) and extrapolated community usage based on the
City’s 2006 population as compared with the statewide population.
The CACP 2009 software provides for the input of distillate fuel oil (#1, 2, 4), but not
residual fuel oil consumption. Since the national EIA data provided residual fuel oil
consumption data (#5, 6) for commercial and industrial facilities, CDM calculated
GHG emissions separately and input the total kilograms of GHG into the software.
GHG emissions were calculated using the EIA residual fuel oil data and applying the
appropriate GHG emission factor from the LGOP4.
Vehicle Emissions
The Charlotte Department of Transportation (DOT) calculated CO2 emissions from
community vehicles using the EPA MOBILE6.2 software. The MOBILE 6.2 software
creates a CO2 emission factor for vehicles traveling in Charlotte using vehicle makes,
models and ages specific to the area for the specific year. Vehicle make and model
information is derived from state vehicle registrations. The CO2 emission factor
generated by the model was applied to annual vehicle miles traveled data from the
City to determine CO2 emissions from vehicles traveling within the City of Charlotte.
This calculation takes into account the total annual vehicle miles traveled within the
city, including freeway travel. Because only a very small percentage of freeway travel
is considered through traffic not local to the City of Charlotte, this segment of the
emissions is included in the inventory as local transportation emissions. The City
vehicle fleet, employee commuting, and transit fleet emissions were subtracted from
the total vehicle emissions calculated in order to avoid double counting.
CO2 is the only GHG that MOBILE 6.2 currently provides modeled emission rates for.
CO2 is most prevalent GHG from the combustion of gasoline and diesel fuel.
Emissions of CH4 and N2O are also dependent on vehicle make, model, age, and
tailpipe air pollution control equipment, and cannot reliably be estimated based on
fuel use or CO2 emissions. Collecting the vehicle make, model, and age distribution
information from the MOBILE6.2 input files and performing the CH4 and N2O
emission calculations outside the model was determined to be too labor intensive for
the value of the information. Together, CH4 and N2O emissions are likely to make up
less than one percent of the total CO2e emissions from roadway vehicles.5
Solid Waste Emissions
To calculate GHG emissions from solid waste, the LGOP recommends calculating the
amount of the fugitive landfill gas (LFG) produced by solid waste6. This methodology
provides guidelines on estimating methane emissions generated by the
4
LGOP, Tables G.1and G.3
Based on default emission factors for gasoline and diesel fuel oil combustion in LGOP, Appendix G.
6
LGOP, Chapter 9
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Section 2
Methodology
decomposition of the waste in the landfill, and the percentage of that methane which
escapes into the atmosphere.
The City of Charlotte’s residential curbside waste is disposed of at the Charlotte
Motor Speedway Landfill in Concord. The commercial waste from the City is
disposed of at a number of different landfills throughout the surrounding area7. While
the actual amount of residential waste disposed of at Charlotte Motor Speedway
Landfill for 2006 is quantifiable and available, the actual tonnage of commercial waste
generated within the City of Charlotte is not available. CDM estimated commercial
waste generated in the City based on known total waste tonnage for 2006 at the
county level, and assuming a percentage of that from the City based on City versus
County 2006 population.
For the purposes of simplifying data and calculations, CDM assumed that all waste
that did not go to Charlotte Motor Speedway landfill was disposed of at the smaller
landfills. The smaller landfills accepting commercial waste do not have landfill gas
(LFG) collection and control systems. In order to estimate 2006 fugitive methane
emissions from waste decomposing in these landfills, a first order decay (FOD) model
was used. The FOD model calculates CH4 emissions attributable to waste disposed of
in uncontrolled landfills and is the recommended methodology of the IPCC and the
LGOP for estimating emissions from landfills without LFG collection systems8.
The FOD model was also used to determine the LFG flow rate at Charlotte Motor
Speedway, which does have an active LFG collection system. Using the estimated
LFG flow rate, the amount of LFG collected was determined based on default
assumptions of collection efficiency of 75% and 50% LFG methane content, as
recommended by the EPA and LGOP9. In accordance with the LGOP, only fugitive
CH4 emissions are quantified as N2O emissions from waste are difficult to determine
and no default emission factor exists at this time. LFG emissions from the former
York Road Landfill and Statesville Avenue Landfill were subtracted from the
calculated total to avoid double counting these emissions. These landfills are owned
by the City and the emissions are already accounted for in the city operations GHG
emissions inventory.
7
Mecklenburg County Land Use & Environmental Services Agency, Mecklenburg County Solid Waste
Management Plan 2009-2019. July 1, 2009
8
LGOP, Section 9.3.1
9
LGOP, Equation 9.1
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Section 3
Results
Charlotte’s community GHG emissions for calendar year 2006 totaled approximately
10,446,000 metric tons of CO2e. The largest source of emissions is electricity use,
which accounts for 47.6% of the total inventory, with vehicle fuels accounting for
35.3% of the total as shown in Figure 2.
Source
A
Metric Tons CO2e
Percent of Total
Waste
237,153
2.3%
Fuel Oil
304,127
2.9%
Natural Gas
1,244,830
11.9%
Vehicle Fuels
3,691,969
35.3%
Electricity
4,967,813
47.6%
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Section 3
Results
This analysis of emissions by source is similar to inventory results at the state level as
shown in Figure 3.10
When analyzed by sector including city operations, community transportation is the
largest emissions sector, followed closely by commercial and residential sectors as
shown in Figure 4. This breakdown by sector is typical for community GHG emission
inventories and illustrates the point that most emissions occur within commercial and
residential buildings, and from vehicle travel within the community. Emissions from
solid waste typically account for a very small percentage, from one to three percent,
when considered against the emissions from buildings and transportation. Although
city operations as a sector within the community accounts for only three percent of
the total emissions, there is enormous potential for the City to lead by example and
demonstrate the potential for energy management, cost savings, air quality
improvement and GHG emission reductions within their own operations.
10
Peterson, T., Hausker, K. and others. Final North Carolina Greenhouse Gas Inventory. Center for
Climate Strategies & NCDENR, September 2007.
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Section 3
Results
Sector
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Metric Tons CO2e
Percent of Total
Waste
237,153
2.20%
City Operations
309,886
2.88%
Industrial
1,077,067
10.01%
Residential
2,557,829
23.78%
Transportation
3,691,969
34.33%
Commercial
2,881,876
26.79%
3-3
Section 3
Results
It is also interesting to view the community GHG inventory results on a per capita
basis, especially when planning for future population and economic growth.
Charlotte residents’ per capita emissions in 2006 were 16.5 metric tons CO2e as shown
in Table 2. This is less than both the 2000 North Carolina state per capita emissions
from 2000 which was estimated at 22 tons CO2e and the 2000 national per capita
emissions of 25 tons CO2e.11 It should be noted, however that on the state and
national levels additional sources such as agricultural and industrial sources are
included and much more prevalent.
Table 2. Per Capita Metrics (metric tons CO2e)
City of Charlotte 2006 per capita emissions
16.5
North Carolina 2000 per capita emissions
2211
U.S. 2000 per capita emissions
2512
City of Dallas, TX, 2005 per capita emissions
16.213
City of Denver, CO, 2005 per capita emissions
19.114
While U.S. cities have been conducting community GHG emissions inventories for
over a decade, they vary widely in scope and methodology. This is important to note
when considering the comparison of Charlotte’s per capita results to other
communities, as shown in Table 2. Regional differences in heating and cooling needs,
as well as transportation patterns also contribute to the differences in community
GHG emissions per capita.
The results of the City of Charlotte community GHG inventory, combined with the
GHG inventory for city operations, provide highly valuable information for
identifying priorities and specific projects and policy development to help the City
and the broader community reduce energy use and GHG emissions. These results will
facilitate the development of a focused, long-term plan to reduce energy use, realize
energy cost savings, improve local air quality, and reduce GHG emissions for the
entire City of Charlotte.
11
Peterson, T., Hausker, K. and others. Final North Carolina Greenhouse Gas Inventory. Center for
Climate Strategies & NCDENR, September 2007.
12
U.S. Environmental Protection Agency (EPA), “Inventory of U.S. Greenhouse Gas Emissions and
Sinks, 1990-2008” April 15, 2010
13
City of Dallas Greenhouse Gas Inventory (City of Dallas, CDM)
http://www.greendallas.net/pdfs/GHG_Emissions_Summary.pdf
14
City of Denver Climate Action Plan, Greenprint Denver, October 2007
http://www.greenprintdenver.org/docs/DenverClimateActionPlan_P2.pdf
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