Emissions Factors, Global Warming Potentials, Unit Conversions

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					              EMISSIONS FACTORS,
 GLOBAL WARMING POTENTIALS,
 U N I T CON V E R S I ON S , E MI S S I ON S ,
         AND RELATED FACTS
                             CONTENTS:

I.      Carbon and CO2 Conversions
II.     Emissions Factors
III.    Global Warming Potentials
IV.     Other Conversions
V.      Energy and Emission Reduction Equivalents
VI.     Emissions Related to Energy Use
VII.    Facts (by sector)
VIII.   List of Abbreviations
IX.     Glossary




                      Compiled by ICF Consulting

                          November 23, 1999
I. Carbon and CO2 Conversions:
To Convert                       To                                Multiply By
Carbon (tons)                    CO2 (tons)                        3.67 or 44/12
CO2 (metric tons)                CO2 (tons)                        1.102
CO2 (pounds)                     CO2 (metric tons)                 4.535 x 10-4
CO2 (billion pounds)             Carbon (million metric tons);     0.1237
                                 often expressed as Million
                                 Metric Tons Carbon
                                 Equivalent (MMTCE)- see
                                 glossary
Source: U.S. DOE/EIA, 1996 Emissions of Greenhouse Gases in the United States, U.S. DOE/EIA, 1997.




                                                1
II.    Emission Factors:
        A. Average Marginal CO2 Emissions Factors for Electricity Generation by
        EPA Region (2000):

         EPA Region                   States Within Region                 lbs. CO2/kWh
           Region 1                MA, CT, ME, NH, RI, VT                       1.726
           Region 2                          NY, NJ                             1.679
           Region 3                PA, VA, MD, WV, DC, DE                       2.096
                                   FL, NC, GA, TN, AL, SC,
           Region 4                                                             2.215
                                           KY, MS
           Region 5                 OH, IL, MI, IN, WI, MN                      1.988
           Region 6                  TX, LA, OK, AR, NM                         1.186
           Region 7                     MO, IA, KS, NE                          1.404
           Region 8                CO, UT, MT, WY, ND, SD                       1.244
           Region 9                        CA, AZ, NV                           1.240
          Region 10                        WA, OR, ID                           1.202
           National                                                             1.640
Source: The Cadmus Group, Inc., Regional Electricity Emission Factors Final Report, The Cadmus
Group, Inc., 1998, Exhibit 6.

Notes:
Average Marginal Rates are derived from modeling where the difference in emissions and demand
is calculated so that the change in CO2 (lbs) divided by the change in kWh equals the Average
Marginal System Rate.

Average Rates (for NOx and SO2 that follow) are derived from dividing total in-state emissions by
total in-state generation so that NOx (lbs) divided by kWh equals the Average State System Rate.
Transmission is not accounted for.

The source for the following NOx and SO2 tables is the E-GRID (Emissions & Generation
Integrated Database) from the EPA’s Acid Rain Program. To get lbs/kWh, divide the number by
1000.

The state factors from E-GRID exclude nonutility plants for which data are not available.
The national factors are based on NERC regional information that includes nonutility plant data.




                                                2
  B. Average NOx Emissions Factors for Electricity by State (1996 lbs/MWh):
Alabama                                                             3.81
Alaska                                                              6.61
Arizona                                                             2.06
Arkansas                                                            2.32
California                                                          0.37
Colorado                                                            4.89
Connecticut                                                         1.50
Delaware                                                            4.93
District of Columbia                                                3.41
Florida                                                             4.81
Georgia                                                             3.35
Hawaii                                                              6.97
Idaho                                                               0.13
Illinois                                                            4.02
Indiana                                                             6.73
Iowa                                                                4.90
Kansas                                                              4.99
Kentucky                                                            8.31
Louisiana                                                           2.79
Maine                                                               0.31
Maryland                                                            4.87
Massachusetts                                                       2.51
Michigan                                                            3.80
Minnesota                                                           4.35
Mississippi                                                         3.66
Missouri                                                            5.53
Montana                                                             1.96
Nebraska                                                            3.70
Nevada                                                              4.68
New Hampshire                                                       2.22
New Jersey                                                          3.15
New Mexico                                                          5.48
New York                                                            1.55
North Carolina                                                      5.31
North Dakota                                                        6.93
Ohio                                                                7.86
Oklahoma                                                            4.10
Oregon                                                              0.31
Pennsylvania                                                        2.93
Rhode Island                                                        3.86
South Carolina                                                      2.89
South Dakota                                                        3.25
Tennessee                                                           5.81
Texas                                                               3.05
Utah                                                                4.57
Vermont                                                             0.09
Virginia                                                            3.66
Washington                                                          0.41
West Virginia                                                       3.66
Wisconsin                                                           4.16
Wyoming                                                             5.24
National                                                            4.28
 Source: Emissions & Generation Integrated Database (E-GRID), EPA/Acid Rain Program.


                                          3
   C. Average SO2 Emission Factors for Electricity by State (1996 lbs/MWh):
Alabama                                                            10.17
Alaska                                                              1.17
Arizona                                                             3.40
Arkansas                                                            4.37
California                                                          0.03
Colorado                                                            5.46
Connecticut                                                         4.63
Delaware                                                           10.39
District of Columbia                                               13.90
Florida                                                             8.82
Georgia                                                             9.63
Hawaii                                                              6.60
Idaho                                                               0.00
Illinois                                                           10.25
Indiana                                                            17.15
Iowa                                                                9.50
Kansas                                                              5.88
Kentucky                                                           14.56
Louisiana                                                           3.45
Maine                                                               1.45
Maryland                                                           11.44
Massachusetts                                                       7.56
Michigan                                                            7.92
Minnesota                                                           4.18
Mississippi                                                         7.66
Missouri                                                           10.76
Montana                                                             1.32
Nebraska                                                            4.97
Nevada                                                              4.51
New Hampshire                                                       6.72
New Jersey                                                          4.61
New Mexico                                                          5.28
New York                                                            4.63
North Carolina                                                      9.07
North Dakota                                                       11.55
Ohio                                                               21.07
Oklahoma                                                            4.48
Oregon                                                              0.23
Pennsylvania                                                       11.59
Rhode Island                                                        0.03
South Carolina                                                      5.28
South Dakota                                                        2.71
Tennessee                                                          11.56
Texas                                                               4.89
Utah                                                                1.99
Vermont                                                             0.00
Virginia                                                            6.78
Washington                                                          1.40
West Virginia                                                       6.78
Wisconsin                                                           7.99
Wyoming                                                             4.93
National                                                            7.79
 Source: Emissions & Generation Integrated Database (E-GRID), EPA/Acid Rain Program.


                                          4
D. CO2 Emission Factors by Fuel Type per Unit Volume, Mass, and Energy:

       Fuel            Pounds CO2 per         Pounds CO2         Pounds Carbon         Million metric
                       Unit Volume or        per million Btu       per mmBtu          tons Carbon per
                            Mass                (mmBtu)                                  Quad Btu
 Motor Gasoline        19.64 per gallon          157.04               42.40                 19.23
                       824.94 per barrel
  Distillate Fuel      22.38 per gallon          161.39               43.57                 19.76
                       940.11 per barrel
     Methane          116.38 per 1000 cf         115.26               31.12                 14.11
   Natural Gas        120.59 per 1000 cf         117.08               31.61                 14.34
  Coal (typical)       3723.95 per ton            212.7               57.43                 26.00
Source: U.S. DOE/EIA, Instructions for Form 1605: Voluntary Reporting of Greenhouse Gases, 1998,
Appendix B.




                                                 5
III. Global Warming Potentials (GWP):
GWPs allow scientists and policymakers to compare the ability of each greenhouse gas to trap heat
in the atmosphere relative to other gases. GWP of a greenhouse gas is the ratio of radiative forcing
(both direct and indirect), from one kilogram of greenhouse gas to one kilogram of CO2 over a
period of time, 100 years in this case as recommended by the Intergovernmental Panel on Climate
Change (IPCC) and employed for US policymaking and reporting purposes. CO2 was chosen as
the reference gas to be consistent with the IPCC guidelines.

        A. List of GWPs of the six Kyoto-covered gases:

Chemical                                             Global Warming Potential (100 Years)
CO2                                                  1
Methane                                              21
N2O                                                  310
HFCs                                                 140-12,100
SF6                                                  23,900
PFCs                                                 6,500-9,200
Source: U.S. DOE/EIA, 1996 Emissions of Greenhouse Gases in the United States, U.S. DOE/EIA, 1997,
Table 3.

        B. To determine the carbon equivalent of a greenhouse gas:

                1. Convert greenhouse gas to CO2 = MMT of GHG x GWP

                2. Convert CO2 to Carbon Equivalent = CO2 x 0.27

        For example:

                1. 2 MMT methane x 21 (GWP of Methane) = 42 MMT CO2

                2. 42 MMT CO2 x 0.27 = 11.34 MMTCE




                                                 6
IV. Other Conversions:
         A. Energy Unit Conversions:

To Convert                        To                                  Multiply By
mmBtu                             Btu                                 106
Quads                             Btu                                 1015
kWh                               Wh                                  103
MWh                               kWh                                 103
kWh                               Btu                                 3,412 (delivered)
kWh                               Quads                               3.412 x 10-12 (delivered)
kWh                               Btu                                 10,338 (primary)*
                                                                      (10,000 is often used for
                                                                      convenience)
Therms                            Btu                                 105
Horsepower (hp)                   kW                                  0.746
Btu                               Joule (J)                           1,055
kWh                               Joule (J)                           3.6 x 106 (delivered)
Source: U.S. DOE/EIA, Instructions for Form 1605: Voluntary Reporting of Greenhouse Gases, 1998,
Appendix E.
Primary kWh to Btu number from U.S. DOE/EIA, 1997 Annual Energy Review, 1998, Appendix A.
* Based on this heat rate, electric generation is approximately 34% efficient.

         B. Energy (Heat) Content (kWh, Btu) of Fuels (Coal, Oil, Natural Gas, and
         Gasoline):

Fuel                                                 Energy (heat) Content (Btu)
Coal (1 ton)                                         2.1 x 107
Oil (1 barrel)                                       5.8 x 106
Natural Gas (1 cubic foot)                           0.97 x 103
                                                     (1,000 is often used for convenience)
Gasoline (1 gallon)                                  1.2 x 105
Source: U.S. DOE/EIA, 1997 Annual Energy Review, 1998, Appendix A.




                                                 7
          C. Mass Conversions Between the Following:

To Convert                         To                                Multiply By
Grams                              Pounds                            2.2 x 10-3
Pounds                             Grams                             453.6
Pounds                             Tons                              5 x 10-4
Tons                               Pounds                            2,000
Tons                               Metric Tons                       0.9072
Metric Tons                        Tons                              1.102
Sources: U.S. DOE/EIA, Instructions for Form 1605: Voluntary Reporting of Greenhouse Gases, 1998,
Appendix E, and U.S. DOE/EIA, 1998 Annual Energy Outlook, U.S. DOE/EIA, 1997, Table H2.

          D. Volume Conversions:

To Convert                         To                                Multiply By
Barrels                            Gallons                           42
Gallons                            Liters                            3.785
Cubic Feet                         Liters                            28.32
Source: U.S. DOE/EIA, Instructions for Form 1605: Voluntary Reporting of Greenhouse Gases, 1998,
Appendix E.

          E. Methane Conversions:

                                                     = 1,030 Btu
1 Cubic Foot (cf) of natural gas
                                                     (1,000 is often used for convenience)
                                                     = 1,012 Btu
1 cf of methane
                                                     (1,000 is often used for convenience)
1 mcf                                                = 1 mmBtu*
1 bcf                                                = 1 Trillion Btu*
52 Billion cf (bcf)                                  = 1 teragram (1012 grams)
1 cf landfill gas (50% methane)                      = 500 Btu
Source: U.S. DOE/EIA, 1997 Annual Energy Review, 1998, Appendix B and U.S. DOE/EIA, 1996
Emissions of Greenhouse Gases in the United States, U.S. DOE/EIA, 1997, Appendix E.
* Based on a 1,000 Btu to 1 cf conversion




                                                 8
V.   Energy and Emission Reduction Equivalents:
     A. Annual Emissions and Fuel Consumption for an “Average” Passenger
     Car:

           Average CO2 emissions:             10,000 lbs/year (5 tons/year)
           Average fuel consumption:          556 gallons/year

           Source: U.S. EPA, Annual Emissions and Fuel Consumption for an “Average”
           Passenger Car, U.S. EPA, 1997.



     B. Average Annual CO2 Emissions for a Household:

           22,750 lbs/year (11.38 tons of CO2)

           Source: U.S. DOE/EIA, 1996 Emissions of Greenhouse Gases in the United States, U.S.
           DOE/EIA, 1997, Table 10.

     The average household adds more than twice as much greenhouse gas (CO2)
     emissions to the atmosphere as a typical car.


     C. Emission Reductions as Compared to Tree Plantings:

           1 acre of forest sequesters 7,333 lbs CO2/year (3.67 tons of CO2)


           Source: US EPA/APPD, calculated from DOE/EIA, Sector-Specific Issues and
           Reporting Methodologies Supporting the General Guidelines for the Voluntary
           Reporting of Greenhouse Gases under Section 1605(b) of the Energy Policy Act of
           1992, Appendix 5E, using an average carbon sequestration rate, across tree types and
           land status, of 5 year old trees.




                                             9
VI. Emissions Related to Energy Use:

    A. Emissions Related to Energy Use by Sector (Includes Electricity Used by
    Sector) (1996).

    The following section presents the emissions associated with energy use by each sector,
    which includes the emissions related to that sector’s electricity consumption.




                                                                      NOx
                                                                               Residential
      NOx (Thousand Tons):                                                        13%

      Residential     2,992                                                            Commercial
      Commercial      2,328                                                               10%
      Industrial      5,143
      Transportation 11,811               Transportation
                                              54%


                                                                                     Industrial
                                                                                       23%




                                                                       SO2
                                                              Transportation
                                                                   4%
                                                                                     Residential
                                                                                        26%
        SO2 (Thousand Tons):

        Residential   4,579
        Commercial    4,623                      Industrial
        Industrial    7,521                        44%
        Transportation 738


                                                                                   Commercial
                                                                                      26%




    Source: U.S. EPA, National Air Pollution Emission Trends 1900-1996, U.S. EPA, Appendix A
    Utility emissions distributed to sectors according to AEO 98 electricity breakdown




                                            10
                                                                 CO2

                                                                            Residential
                                                                               20%
                                         Transportation
 CO2 (Million Tons):                         32%

 Residential      316
 Commercial       254                                                                 Commercial
 Industrial       526                                                                    16%
 Transportation   517



                                                            Industrial
                                                              32%




Source: U.S. DOE/EIA, 1996 Emissions of Greenhouse Gases in the United States, U.S.
DOE/EIA, 1997, Figure 5 and Table 6.




                                        11
B. Emissions Related to Energy Use by Sector (With Utilities Separated Out)
(1996).

The following section presents the emissions associated with energy use by each sector,
with electric generation listed separately. Unlike Section A above, each sector’s emissions
from electricity consumption are included in the electric utilities sector.



                                                                  NOx
                                                                      Residential
                                                      Utilities          4%
NOx (Thousand Tons):                                   27%                          Commercial
                                                                                       2%
Residential      886
Commercial       403                                                                   Industrial
Industrial      3,170                                                                    14%
Transportation 11,781
Utilities 6,034



                                             Transportation
                                                 53%




                                                                   SO2
                                                                              Residential
                                                                                 1%
SO2 (Thousand Tons):
                                                                                       Commercial
Residential          180                                                                  3%
Commercial           602                       Utilities
Industrial         3,399                        73%
                                                                                            Industrial
Transportation       675
                                                                                              19%
Utilities 12,604


                                                                                    Transportation
                                                                                         4%



    Source: U.S. EPA, National Air Pollution Emission Trends 1900-1996, U.S. EPA, Appendix A




                                        12
                                                                   CO2
                                                                             Residential
                                                                                7%
CO2 (Million Tons):                             Utilities
                                                 36%
                                                                                           Commercial
Residential    117
                                                                                              4%
Commercial      71
Industrial     338
Transportation 516                                                                          Industrial
Utilities 570                                                                                 21%




                                                            Transportation
                                                                32%


Source: U.S. DOE/EIA, 1996 Emissions of Greenhouse Gases in the United States, U.S. DOE/EIA,
1997, Figure 5 and Table 6




                                     13
 VII. Facts:

                 1. RESIDENTIAL SECTOR:

                 Total energy consumption, 1996:         19.36 Quads
                 Energy Intensity, 1996:                 110.9 delivered mmBtu per
                                                         household
                 Source: U.S. DOE/EIA, 1998 Annual Energy Outlook, U.S. DOE/EIA, 1997, Table A4.


                 Residential Fuel Mix, 1996:


                                                     Petroleum
                                                        7%

                                                             Natural Gas
                                                                28%
                                   Primary
                                  Electricity
                                     62%                   Other
                                                            3%



                Source: U.S. DOE/EIA, 1998 Annual Energy Outlook, U.S. DOE/EIA, 1997, Table
                A2.


                 Residential End-use Energy Consumption, 1996:

 Electricity Consumption                                           On-Site Fuel Consumption


                       Space
                      Heating                                Other Uses
 Other Uses             13%                                     1%
    21%
                             Space
                                                                                          Space
                            Cooling
                                                         Appliances                      Heating
                              12%                           3%
Lighting                                                                                  76%
   9%                        Water
                            Heating                              Water
                                                                 Heating
                             10%
                                                                  20%
  Appliances
                        Refrigeration
    24%
                            11%


    Source: U.S. DOE/EIA, 1998 Annual Energy Outlook, U.S. DOE/EIA, 1997, Table A4.


                                                14
Residential Energy Expenditures, sector and average household:

Sector:                 $124 billion (1993)
                        $90.6 billion for electricity (1996)
Average household:      $1,282 (1993)

Sources: U.S. DOE/EIA, 1993 Household Energy Consumption and
Expenditures, 1995, p. vii and U.S. DOE/EIA, 1998 Annual Energy Outlook, U.S.
DOE/EIA, 1997, Table A8.


Residential Emissions, 1996:

Average household:      3.1 tons of carbon
Average household:      58.8 pounds of NOx

Sources: U.S. DOE/EIA, 1996 Emissions of Greenhouse Gases in the United States,
U.S. DOE/EIA, 1997, Table A4, and U.S. EPA, National Air Pollution Emission Trends
1900-1996, U.S. EPA, Appendices A and B.




                               15
                             2. COMMERCIAL SECTOR:

                             Total energy consumption, 1996:        15 Quads
                             Energy Intensity, 1996:                105.3 delivered kBtu per
                                                                    square foot
                                    Source: U.S. DOE/EIA, 1998 Annual Energy Outlook, 1997, Table A5.

                             Commercial Fuel Mix, 1996:
                                                           Petroleum
                                                              5% Natural
                                                                     Gas
                                                                     22%

                                                                      Other
                                                                       1%
                                              Primary
                                             Electricity
                                                72%
                             Source: U.S. DOE/EIA, 1998 Annual Energy Outlook, 1997, Table A2.

                             Commercial End-use Energy Consumption, 1996:

                    Electricity Consumption                                     On-Site Fuel Consumption

                                       Space
                Other Uses           Heating and
                                      Cooling                                            Other Uses
                   24%                                                                      46%
                                        19%
     Office
   Equipment                                 Ventilation
      8%                                        5%                        Cooking
                                                                            4%
                                               Water
Refrigeration                                 Heating                         Water
                                                                                                         Space
     4%                                         5%                            Heating
                                                                                                        Heating
                                  Lighting                                     12%
                                                                                                          and
                                    34%                                                                 Cooling
                Cooking                                                                                  38%
                  1%



            Source: U.S. DOE/EIA, 1998 Annual Energy Outlook, 1997, Table A5.




                                                           16
Commercial Energy Expenditures, sector and per building:

Sector:        $69.9 billion (1995)
               $75.1 billion for electricity (1996)
Building:      $15,300 (1995)

Sources: U.S. DOE/EIA, 1995 Commercial Building Energy Consumption
Survey, U.S. DOE/EIA, 1997, Table 4 and U.S. DOE/EIA, 1998 Annual Energy
Outlook, U.S. DOE/EIA, 1997, Table A8.




                               17
                       3. INDUSTRIAL SECTOR:

                       Total energy consumption, 1996:         34.8 Quads
                               Source: U.S. DOE/EIA, 1998 Annual Energy Outlook, 1997, Table A2.

                       Industrial Fuel Mix, 1996:


                                                              Petroleum
                                     Primary
                                                                 23%
                                    Electricity
                                       32%
                                                                  Feedstocks
                                                                     4%
                                   Renewable
                                      5%
                                                             Natural Gas
                                            Coal
                                                                29%
                                            7%


                       Source: U.S. DOE/EIA, 1998 Annual Energy Outlook, 1997, Table A2.

                       Manufacturing End-use Energy Consumption, 1994:

                Electricity Consumption                                On-Site Fuel Consumption

                                Process
                  Other Uses    Heating
                     9%          11%      Process                                             Machine Drive
                                                                     Boiler Fuel
                                          Cooling                                                 1%
                                                                        43%
HVAC/Lighting                               5%
   15%


   Electro-
  Chemical
  Processes                                                           HVAC
    10%                                                                3%                          Process
                                  Machine Drive                                                    Heating
                                                                   Other Uses                        50%
                                      52%
                                                                      3%



      Source: U.S. DOE/EIA, 1994 Manufacturing Energy Consumption Survey, U.S. DOE/EIA, 1997, Table
      A8.




                                                      18
Industrial Energy Expenditures:

$69.2 billion total (1994)
$46.6 billion for electricity (1996)

Sources: U.S. DOE/EIA, 1994 Manufacturing Energy Consumption Survey, U.S.
DOE/EIA, 1997, Table A17 and U.S. DOE/EIA, 1998 Annual Energy Outlook, U.S.
DOE/EIA, 1997, Table A8.




                                 19
VIII. List of Abbreviations
Energy
Btu               British Thermal Unit
KBtu              Thousand Btu
mmBtu             Million Btu
TBtu              Trillion Btu
Quad              Quadrillion Btu
kWh               Kilowatt-hour

Emissions
GHG               Greenhouse Gas
GWP               Global Warming Potential
CE                Carbon Equivalent
MMT               Million Metric Tons
MMTCE             Million Metric Tons Carbon Equivalent
CO2               Carbon Dioxide
CH4               Methane
N2O               Nitrous Oxide
NOx               Nitrogen Oxides
VOCs              Volatile Organic Compounds

Other
cf                Cubic Feet
HVAC              Heating, Ventilation, and Air Conditioning




                                    20
IX.        Glossary
Area Sources: Stationary and non-road sources that are too small and/or too numerous to be
handled individually as point sources, but which can contribute collectively to ozone formation.
Area source emissions have historically been underestimated because of few appropriate inventory
procedures or little emphasis on obtaining area source data.

British Thermal Unit (Btu): A common unit used in measuring energy equal to the amount of heat
needed to raise the temperature of 1 pound of water by 1º F.

Carbon Equivalent: A common unit used in measuring emissions. Other greenhouse gases have
conversion factors to relate them to their equivalent amounts of carbon in order to more easily
compare emissions.

Carbon Sink: A reservoir that absorbs or takes up released carbon. Vegetation and soils are
common carbon sinks.

Chloroflourocarbons (CFCs): A family of inert, nontoxic, and easily liquefied chemicals used in
refrigeration, air conditioning, packaging, and insulation, or as solvents or aerosol propellants.
Because they are nonreactive, they drift into the upper atmosphere where they are disassociated by
solar radiation and where their components destroy ozone.

Cogeneration: The sequential use of energy to generate electricity and another form of useful
thermal energy such as heat or steam.

Conversion factor: A unique value used to convert one unit (e.g., pounds) to another appropriate
unit (e.g., tons).

Criteria Pollutant: A pollutant determined to be hazardous to human health and regulated under
EPA’s National Ambient Air Quality Standards. The 1970 amendments to the Clear Air Act
require EPA to describe the health and welfare impacts of a pollutant as the “criteria” for inclusion
in the regulatory regime.

Electric losses: The difference between primary electricity and delivered electricity. Losses are
due to the conversion and transportation of electric energy to the final customer.

Electricity, delivered: The amount of electric energy delivered to the final customer after electric
losses. For example, on average, it takes roughly 3,412 Btu of fuel to generate 1 kWh of delivered
electricity.

Electricity, primary: The amount of energy (fuel) an electric generator must consume to generate
and supply electric energy to consumers. For example, on average, it takes roughly 10,338
(10,000 for convenience) Btu of fuel to generate 1 kWh of primary electricity.

Emission coefficient/factor: A unique value for scaling emissions to activity data in terms of a
standard rate of emissions per unit of activity (e.g., pounds of CO2 emissions per barrel of fossil
fuel consumed).




                                                 21
Emissions: Anthropogenic releases of greenhouse gases to the atmosphere (e.g., the release of CO2
during fuel combustion).

Emissions, direct: Emissions from sources owned or leased by an entity. (e.g., on-site boilers)

Emissions, indirect: Emissions from sources not owned or leased by an entity that occur, wholly
or in part, as a result of its activities. (e.g., emissions from off-site electricity generation)

Energy conservation: Activities that reduce end-use demand for energy by reducing the service
demanded.

Feedstocks: Fossil Fuels that are used as inputs to manufacture final products and are not
combusted. These include oil used to produce asphalt and lubricants and natural gas to produce
nylon.

Fossil fuel: A hydrocarbon fuel, such as petroleum, derived from living matter of a previous
geologic time.

Fuel cycle: The entire set of sequential processes or stages involved in the utilization of fuel,
including extraction, transformation, transportation, and combustion. Emissions generally occur at
each stage of the fuel cycle.

Fuel switching: The substitution of one type of fuel for another. The fuel substitution may be
either temporary (as in a case of a power plant that temporarily switches from coal to natural gas)
or permanent (as in the case of a fleet operator who replaces gasoline-powered automobiles with
electric cars).

Greenhouse effect: A popular term used to describe the roles of water, vapor, carbon dioxide, and
other trace gases in keeping the Earth’s surface warmer than it would be otherwise. These
radatively active gases are relatively transparent to incoming shortwave radiation, but are relatively
opaque to outgoing longwave radiation. The latter radiation, which would otherwise escape to
space, is trapped by these gases within the lower levels of the atmosphere. The subsequent
reradiation of some of the energy back to the Earth maintains surface temperatures higher than they
would be if the gases were absent. There is concern that increasing concentrations of greenhouse
gases, including carbon dioxide, methane, and man-made halogenated substances, may enhance the
greenhouse effect and cause global climate change.

Greenhouse gases: Those gases, such as water vapor, carbon dioxide, troposhperic ozone, nitrous
oxide, and methane that are transparent to solar radiation but opaque to longwave radiation thus
preventing longwave radiation energy from leaving the atmosphere. Increasing levels of
greenhouse gases in the atmosphere may contribute to an increase in average global temperatures
resulting in adverse climate changes.

Halogenated substance: A volatile compound containing halogens, such as chlorine, fluorine, or
bromine.

Heat rate: A measure of the fuel required in Btu by a generator to produce one kWh of electricity.




                                                 22
Intergovernmental Panel on Climate Change (IPCC): A panel established jointly in 1988 by the
World Meteorological Organization and the United Nations Environment Program to assess the
scientific information relating to climate change and to formulate realistic response strategies.

Kilowatt-hour (kWh): A common unit used in measuring power, the rate at which work is done,
equivalent to 3,412 Btu per hour.

Off-Site Fuel Consumption: Fuel consumption at electric generating stations that produce
electricity to meet the needs of residences, business, and industries.

On-Site Fuel Consumption: Fuel consumed at industrial, commercial, or residential locations.
Examples include a chemical manufacturer that burns natural gas in a boiler to produce steam at
the facility, or a residential consumer who burns natural gas in their hot water heater at home.

Ozone: A molecule made up of three atoms of oxygen. In the stratosphere, it occurs naturally and
provides a protective layer shielding the Earth from harmful ultraviolet radiation. In the
troposphere, it is a chemical oxidant and major component of photochemical smog.

Ozone precursors: Chemical compounds, such as carbon monoxide, methane, nonmethane
hydrocarbons, and nitrogen oxides, which in the presence of solar radiation react with other
chemical compounds to form ozone.

Point Sources: Pollution emanating from a specific source such as a factory and released at a
known discharge point.

Sequestered carbon: Carbon which is removed from the atmosphere and retained in a carbon sink
such as a growing tree or soil.

Source: U.S. DOE/EIA, 1996 Emissions of Greenhouse Gases in the United States, 1997.




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