Energy and the Environment

Greenhouse Gas Equivalencies Calculator - Revision History

This page describes the revisions and updates made to the Greenhouse Gas Equivalencies Calculator since it was first posted on EPA’s website in February 2008.

December 19, 2019

Many of the equivalencies have been updated based on the latest available data and sources.

Updates

In addition to the changes noted below, the electricity line-loss factor (used in calculating emission factors for home electricity use and home energy use) has been updated to 6.87%. The previous value was 7.09%.

Passenger vehicles per year: The emission factor has been updated to 4.63 metric tons of CO₂ equivalent/vehicle/year. The previous value was 4.71 metric tons.
Miles driven by the average passenger vehicle per year: The emission factor has been updated to 4.03 x 10^-4 metric tons of CO₂ equivalent/mile. The previous value was 4.09 x 10^-4 metric tons.
Mcf of natural gas: The emission factor has been updated to 0.0549 metric tons of CO₂/Mcf. The previous value was 0.0551 metric tons.
Home electricity use: The emission factor has been updated to 5.906 metric tons of CO₂/home/year. The previous value was 5.734 metric tons.
Home energy use: The emissions factor has been updated to 8.67 metric tons of CO₂/home/year. The previous value was 8.35 metric tons.
Acres of U.S. forest storing carbon for one year: The emissions factor has been updated to -0.77 metric ton CO₂/acre/year. The previous value was -0.85 metric ton.
Acres of U.S. forest preserved from conversion to cropland: The emissions factor has been updated to -147.83 metric tons CO₂/acre/year. The previous value was -123.22 metric tons.
Railcars of coal burned: The emissions factor has been updated to 181.85 metric tons of CO₂/railcar. The previous value was 183.29 metric tons.
Pounds of coal burned: The emissions factor has been updated to 9.08 x 10^-4 metric tons of CO₂/pound of coal. The previous value was 9.15 x 10^-4 metric tons.
Tons of waste recycled instead of landfilled: The emissions factor has been updated to 2.94 metric tons of CO₂ equivalent/ton of waste recycled instead of landfilled. The previous value was 2.87 metric tons.
Number of garbage trucks of waste recycled instead of landfilled: The emissions factor has been updated to 20.58 metric tons CO₂ equivalent/garbage truck of waste recycled instead of landfilled. The previous value was 20.07 metric tons.
Trash bags of waste recycled instead of landfilled: The emissions factor has been updated to 2.35 x 10^-2 metric tons of CO₂ equivalent/trash bag of waste recycled instead of landfilled. The previous value was 2.29 x 10^-2 metric tons.
Number of wind turbines running for a year: The emissions factor has been updated to 4,632 metric tons of CO₂/year/wind turbine installed. The previous value was 4,719 metric tons.

December 17, 2018

Many of the equivalencies have been updated, and the calculator has a few new features in response to user requests. Details on all data sources and formulas used in the calculator are provided on the Calculations and References page.

New Equivalencies

EPA added three new equivalencies to the calculator:

Gallons of diesel consumed
Trash bags of waste recycled instead of landfilled
Number of smartphones charged

Updates

In addition to the updates noted below, the electricity line-loss factor (used in calculating emission factors for home electricity use and home energy use) has been updated to 7.09%. The previous value was 7.26%.

Electricity use: The emission factor has been updated to the most recent national weighted average CO₂ marginal emission rate from AVERT, which is 7.07 x 10^-4 metric tons of CO₂/kWh. The previous value was 7.44 x 10^-4 metric tons of CO₂/kWh.
Passenger vehicles per year: The emission factor has been updated to 4.71 metric tons of CO₂E/vehicle/year. The previous value was 4.67 metric tons.
Miles driven by the average passenger vehicle per year: The emission factor has been updated to 4.09 x 10^-4 metric tons CO₂E/mile. The previous value was 4.08 x 10^-4 metric tons.
Mcf of natural gas: The emission factor has been updated to 0.0551 metric tons CO₂/Mcf. The previous value was 0.0550 metric tons.
Number of incandescent bulbs switched to LEDs: The emission factor has been updated to 2.63 x 10^-2 metric tons CO₂/bulb replaced based on the national weighted average CO₂ marginal emission rate from AVERT, which is 1,559 lbs CO₂/MWh (7.07 x 10^-4 metric tons of CO₂/kWh) and accounts for losses from transmission and distribution. The previous value was 2.99 x 10^-2 metric tons CO₂/bulb replaced based on the national average non-baseload emission rate from AVERT, which was 1,641 lbs CO₂/MWh (7.44 x 10^-4 metric tons of CO₂/kWh).

As of AVERT v1.5 released in March 2017, AVERT emission rates adjust for line losses from transmission and distribution. Since AVERT emission rates now factor in line losses, the calculation for line losses in the previous methodology was removed to avoid double-counting.

For comparison, if the 2018 updated methodology for estimating CO₂ per bulb replaced were applied to the previous conversion factor, the amount of CO₂ per bulb replaced would have been 2.77 x 10^-2 metric ton CO₂.

Home electricity use: The emission factor has been updated to 5.734 metric tons CO₂/home/year. The previous value was 6.672 metric tons.
Home energy use: The emission factor has been updated to 8.35 metric tons CO₂ per home/year. The previous value was 9.26 metric tons.
Acres of U.S. forests storing carbon for one year: The emission factor has been updated to -0.850 metric ton CO₂ sequestered annually by one acre of average U.S. forest. The previous value was -0.849 metric ton CO₂.
Acres of U.S. forest preserved from conversion to cropland: The emission factor has been updated to -123.22 metric tons CO₂/acre/year. The previous value was -122.56 metric tons CO₂.
Railcars of coal burned: The emission factor has been updated to 183.29 metric tons CO₂/railcar. The previous value was 183.22 metric tons.
Pounds of coal burned: The emission factor has been updated to 9.15 x 10^-4 metric tons CO₂/pound of coal. The previous value was 9.14 x 10^-4 metric tons.
Coal-fired power plant emissions for one year: The emission factor has been updated to 3,893,003 metric tons CO₂/power plant. The previous value was 4,038,687 metric tons.
Number of wind turbines installed: The emission factor has been updated to 4,719 metric tons CO₂/wind turbine installed based on the national annual wind marginal emission rate from AVERT, which is 6.74 x 10^-4 metric tons of CO₂/kWh. The previous value was 3,948 metric tons based on the previous wind marginal emission rate from AVERT, which was 7.06 x 10^-4 metric tons of CO₂/kWh.
Number of urban tree seedlings grown for 10 years: A weighted average of coniferous and deciduous trees was used to estimate the amount of carbon sequestered by a medium growth tree allowed to grow in an urban area. The emission factor has been updated to 0.060 metric tons CO₂ per urban tree planted. The previous value, which only captured coniferous trees, was 0.039 metric tons CO₂ per urban tree planted.

September 18, 2017

New Features

Display and printing of the calculator results are improved over previous versions.

Updates

In addition to the updates noted below, the electricity line-loss factor (used in calculating emissions factors for home electricity use, home energy use, and for converting conventional light bulbs to LEDs) has been updated to 7.26%. The previous value was 7.25%.

Electricity use: The emissions factor has been updated to the most recent national weighted average CO₂ marginal emission rate from AVERT, which is 7.44 x 10^-4 metric tons of CO₂/kWh. The previous value was the national average non-baseload CO₂ output emission rate from eGRID, which was 7.03 x 10^-4 metric tons.
Passenger vehicles per year: The emissions factor has been updated to 4.67 metric tons of CO₂E/vehicle/year. The previous value was 4.73 metric tons.
Miles driven by the average passenger vehicle per year: The emissions factor has been updated to 4.08 x 10^-4 metric tons CO₂E/mile. The previous value was 4.17 x 10^-4 metric tons.
Mcf of natural gas: The emissions factor has been updated to 0.0550 metric tons CO₂/Mcf. The previous value was 0.0547 metric tons.
Number of incandescent bulbs switched to LEDs: The emissions factor has been updated to 2.99 x 10^-2 metric tons CO₂/bulb replaced based on the national weighted average CO₂ marginal emission rate from AVERT, which is 1,641 lbs CO₂/MWh (7.44 x 10^-4 metric tons of CO₂/kWh). The previous value was 2.82 x 10^-2 metric tons CO₂/bulb replaced based on the national average non-baseload emission rate from eGRID, which was 1,549 lbs CO₂/MWh (7.03 x 10^-4 metric tons of CO₂/kWh).
Home electricity use: The emissions factor has been updated to 6.672 metric tons CO₂/home/year. The previous value was 6.772 metric tons.
Home energy use: The emissions factor has been updated to 9.26 metric tons CO₂ per home/year. The previous value was 9.47 metric tons.
Acres of U.S. forests storing carbon for one year: This equivalency assumes the revised methodology for estimating carbon stored in forests in the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2015, which differentiates between forests remaining forests for at least 20 years and land converted to forests within that same time period (EPA 2017). This is a change from the previous version of the Greenhouse Gas Equivalencies Calculator and the Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2013, which did not differentiate between forests remaining forests for at least 20 years and land converted to forests within that same time period. The new emissions factor is -0.85 metric ton CO₂ sequestered annually by one acre of average U.S. forest. The previous value was -1.06 metric ton CO₂.

For comparative purposes, if the 2017 updated methodology for estimating carbon stored in U.S. forests from the U.S. Inventory (EPA 2017) were applied to the previous conversion factor, the amount of carbon sequestered in one year by one acre of average U.S. forest would have been -0.89 metric ton CO₂.

Acres of U.S. forest preserved from conversion to cropland: The emissions factor has been updated to be consistent with the update made above; the new emissions factor is -122.56 metric tons CO₂/acre/year (in the year of conversion). The previous value was -125.46 metric tons CO₂.

For comparative purposes, if the 2017 updated methodology for estimating carbon stored in U.S. forests from the U.S. Inventory (EPA 2017) were applied to the previous conversion factor, the amount of carbon sequestered by one acre of forest preserved from conversion to cropland would have been -121.42 metric ton CO₂.

Railcars of coal burned: The emissions factor has been corrected to assume the heat content and carbon content of coal consumed by the electric power sector. The new emissions factor is 183.22 metric tons CO₂/railcar. The previous value was 187.78 metric tons.
Pounds of coal burned: The emissions factor has been updated to be consistent with the update made above; the new emissions factor is 9.14 x 10^-4 metric tons CO₂/pound of coal. The previous value was 9.37 x 10^-4 metric tons.
Tons of waste recycled instead of landfilled: The emissions factor has been updated to 2.87 metric tons CO₂ equivalent/ton of waste recycled instead of landfilled. The previous value was 3.15 metric tons.
Number of garbage trucks of waste recycled instead of landfilled: The emissions factor has been updated to 20.07 metric tons CO₂E/garbage truck of waste recycled instead of landfilled. The previous value was 22.06 metric tons.
Coal-fired power plant emissions for one year: The emissions factor has been updated to 4,038,687.23 metric tons CO₂/power plant. The previous value was 3,435,617.88 metric tons.
Number of wind turbines installed: The emissions factor has been updated to 3,948 metric tons CO₂/wind turbine installed based on the national annual wind marginal emission rate from AVERT, which is 7.06 x 10^-4 metric tons of CO₂/kWh. The previous value was 3,960 metric tons based on the national average non-baseload emission rate from eGRID, which was 7.03 x 10^-4 metric tons of CO₂/kWh.

May 31, 2016

New Features

HCFC-22 has been added to the “If You Have Emissions Data” (in the Hydrofluorocarbon gases drop-down menu). Its 100-year GWP is 1,810.
The “If You Have Energy Data” tab now allows you to enter values for mcf of natural gas (in the drop-down menu). The emissions factor is 0.054717 metric tons CO₂/mcf

Updates

Electricity use: The emissions factor has been updated to the most recent national average non-baseload value from eGRID, which is 7.03 x 10^-4 metric tons of CO₂/kWh. The previous value was 6.9 x 10^-4 metric tons.
Passenger vehicles per year: The emissions factor has been updated to 4.73 metric tons of CO₂E/vehicle/year. The previous value was 4.75 metric tons.
Miles driven by the average passenger vehicle per year: The emissions factor has been updated to 4.17 x 10^-4 metric tons CO₂E/mile. The previous value was 4.20 x 10^-4 metric tons.
Number of incandescent bulbs switched to compact fluorescents: This equivalency now assumes the bulbs are switched to LEDs instead of compact fluorescents. The emissions factor is 2.82 x 10^-2 metric tons CO₂/bulb replaced.
Home electricity use: The emissions factor has been updated to 6.772 metric tons CO₂/home/year. The previous value was 7.270 metric tons.
Home energy use: The emissions factor has been updated to 9.47 metric tons CO₂ per home/year. The previous value was 10.97 metric tons.
Acres of U.S. forests storing carbon for one year: The emissions factor has been updated to -1.06 metric ton CO₂ sequestered annually by one acre of average U.S. forest. The previous value was -1.22 metric tons.
Acres of U.S. forest preserved from conversion to cropland: The emissions factor has been updated to -125.46 metric tons CO₂/acre/year (in the year of conversion). The previous value was -129.51 metric tons.
Railcars of coal burned: The emissions factor has been updated to 187.78 metric tons CO₂/railcar. The previous value was 186.50 metric tons.
Pounds of coal burned: The emissions factor has been updated to 9.37 x 10^-4 metric tons CO₂/pound of coal. The previous value was 9.31 x 10^-4 metric tons.
Tons of waste recycled instead of landfilled: The emissions factor has been corrected to account for avoided landfill emissions, and updated to the most recent emissions factors from WARM. The new emissions factor is 3.15 metric tons CO₂ equivalent/ton of waste recycled instead of landfilled. The previous value was 2.79 metric tons.
Number of garbage trucks of waste recycled instead of landfilled: The emissions factor has been updated to be consistent with the correction and update made above; the new emissions factor is 22.06 metric tons CO₂E/garbage truck of waste recycled instead of landfilled. The previous value was 19.51 metric tons.
Coal-fired power plant emissions for one year: The emissions factor has been updated to 3,435,617.88 metric tons CO₂/power plant. The previous value was 3,808,651 metric tons.
Number of wind turbines installed: The emissions factor has been updated to 3,960 metric tons CO₂/wind turbine installed. The previous value was 3,633 metric tons.

April 16, 2014

The eGRID national average non-baseload emissions factor per kWh of electricity was updated based on final published data. The previous factor used in the calculator was 6.89276 x 10^-4 metric tons of CO₂ per kWh; the new value is 6.89551 x 10^-4 metric tons of CO₂ per kWh.

Based on the updated eGRID value above, the equivalency for wind turbines was updated from 3,631 metric tons of CO₂ avoided per wind turbine to 3,633 metric tons.

March 21, 2014

The calculator now uses global warming potentials (GWPs) from the Intergovernmental Panel on Climate Change’s Fourth Assessment Report (AR4). Previously it used GWPs from the Second Assessment Report (SAR).

A table showing the previous GWPs from the SAR and the new ones from AR4 is provided below.

100 Year GWPs

Gas	SAR GWP	AR4 GWP
CO₂	1	1
CH₄	21	25
N₂O	310	298
HFC-23	11700	14800
HFC-32	650	675
HFC-125	2800	3500
HFC-134a	1300	1430
HFC-143a	3800	4470
HFC-152a	140	124
HFC-227ea	2900	3220
HFC-236fa	6300	9810
HFC-43-10mee	1300	1640
SF₆	23900	22800
CF₄	6500	7390
C₂F₆	9200	12200
C₄F₁₀	7000	8860
C₆F₁₄	7400	9300
R-404A	3260	3921.6
R-407A	1770	2107
R-407C	1525.5	1773.85
R-410A	1725	2087.5
R-507A	3300	3985

March 12, 2014

Starting Points (using the calculator’s “If You Have Energy Data” tab)

Electricity (kilowatt-hours): Updated the source to the latest available eGRID data. The previous emissions factor used by the calculator was 0.00070555 metric tons/kWh; the new value is 0.00068927 metric tons/kWh.
Gallons of gasoline consumed: Updated the emissions factor to be consistent with the value used by EPA and the Department of Transportation in national fuel economy standards. The previous emissions factor used by the calculator was 0.00892 metric tons/gallon of gasoline; the new value is 0.00887 metric tons/gallon of gasoline.
Passenger vehicles: Updated the average fuel economy and the emissions factor for the combustion of gasoline. The emissions factor for passenger vehicles was changed from 4.80 metric tons/vehicle/year to 4.75 metric tons/vehicle/year
Therms of natural gas: Updated the heat content and carbon coefficient of natural gas based on the latest published U.S. greenhouse gas inventory data. The emissions factor was updated from 0.005306 metric tons/therm.

Equivalencies
Note that the data sources for most equivalencies have been updated; only the ones whose emissions factors have changed are described below.

Tanker trucks filled with gasoline: Updated the emissions factor for gasoline. The previous emissions factor for this equivalency was 75.82 metric tons/tanker truck; the new factor is 75.54 metric tons/tanker truck.
Home electricity use: Updated the emissions factor for electricity based on the latest eGRID data, and updated the number of homes and the transmission losses factor based on data from the latest Annual Energy Outlook from the Energy Information Administration. The previous emissions factor was 7.268 metric tons/home; the new factor is 7.270 metric tons/home.
Home energy use: Updated the electricity emissions factor as described above in “home electricity use,” and changed the data source for home consumption of other fuels from the Residential Energy Consumption Survey to the Annual Energy Outlook. This improves consistency in the data year across all fuels, and also effectively weights the fuels according to their use by households in the United States. These changes have significantly reduced the emissions factor for home energy use, from 20.02 metric tons/home to 10.96 metric tons/home.
Railcars of coal burned: The heat content and carbon coefficient of coal were updated using the latest data from EPA and the Energy Information Administration. The previous emissions factor was 232.74 metric tons/railcar; the new factor is 186.5 metric tons/railcar.
Coal-fired power plant emissions in one year: This equivalency was updated using the most recent eGRID data. The previous emissions factor was 3,533,098 metric tons/year; the new factor is 3,808,651 metric tons/year.
Tons of waste recycled instead of landfilled: This equivalency was updated to use global warming potentials from the IPCC’s Fourth Assessment Report. The previous value was 2.67 metric tons/ton of waste recycled; the new value is 2.79 metric tons/ton of waste recycled.

New Equivalencies
EPA added five new equivalencies to the calculator:

Miles driven by the average passenger vehicle per year
Number of garbage trucks of waste recycled instead of landfilled
Number of wind turbines installed
Pounds of coal burned
Number of incandescent bulbs switched to compact fluorescents

December 11, 2013

Therms of natural gas: Updated the conversion factor from 0.005306 to 005302 metric tons of CO₂ per therm.
Tanker trucks filled with gasoline: Updated the conversion factor from 75.82 to 75.86 metric tons of CO₂ per tanker truck.
General updates and new equivalencies:
- Reviewed all equivalencies and updated their sources and references to the most recent sources available.
- Added new equivalencies for:
  - Miles/year driven by an average passenger vehicle.
  - Garbage trucks of waste recycled instead of landfills
  - Pounds of coal burned
  - Wind turbines installed
  - Incandescent lamps switched to compact fluorescents

September 17, 2013

Home electricity use: Updated the data and sources for this calculation. The previous emissions factor used by the calculator was 6.68 metric tons CO₂/home; the new value is 7.268 metric tons CO₂/home.
Home energy use: The updated electricity factor above brings the overall emissions factor per home from 19.43 metric tons CO₂/home to 20.02 metric tons of CO₂/home.

April 25, 2013

Passenger vehicles per year: Updated the assumptions for average fuel economy and vehicle miles traveled in 2010 to account for revisions made in December 2012 to the Federal Highway Agency's published statistics. Note that the emissions factor (4.8 metric tons of CO₂E per vehicle per year) is not affected by these updates.
Therms of natural gas: Unrounded the value given for CO₂ emissions per therm of natural gas burned to be consistent with the value given in EPA's proposed rule for the Greenhouse Gas Reporting Program. The former value used by the calculator was 0.005 metric tons of CO₂ per therm; the new value is 0.005306 metric tons of CO₂ per therm.

October 17, 2012

Starting points: Emissions of Hydroflurocarbon gases: Added five additional HFC blends (R-404A, R-407A, R-407C, R-410A, and R-507A) to the drop-down list of HFCs.
Electricity reductions: Updated the CO₂ emissions factor to reflect the updated eGRID 2012 version 1.0.
Passenger vehicles per year: Updated assumptions for vehicle miles traveled and average fuel economy based on the most recent available sources.
Home electricity use and Home energy use: Updated the electricity emission factor to reflect the updated eGRID 2012 version 1.0; updated average energy consumption figures based on the latest Residential Energy Consumption Survey data.
Forestry equivalencies: The methodologies and sources used to calculate equivalencies for the number of acres of U.S. forests and the number of acres of U.S. forests preserved from conversion to cropland have been completely revised and updated.
Railcars of coal: The average heat content and emission factors for coal have been updated to the most recent figures available.
Tons of waste recycled: The conversion factor has been updated based on the emission factors in the current (2012) version of WARM.
Coal-fired power plants: The number of coal-fired power plants and their CO₂ emissions have been updated based on eGRID 2012.

November 1, 2011

Home energy use: Corrected a typographical error in the final equation; the correct value for liquid propane is 0.34 metric tons CO₂ (not 0.32 as previously shown), and the total emissions per household per year are 11.55 metric tons CO₂ (not 11.53 as previously shown).
Coal-fired power plant emissions for one year: Deleted the conversion to metric tons, which is not needed in the final equation and was inadvertently retained in the text from a previous version of the calculator. The result shown was correct and has not been changed.

May 20, 2011

Electricity use, Home electricity use, Home energy use: Updated the CO₂ emissions factor to reflect the updated eGRID2010Version 1.1.

April 29, 2011

Electricity use: Modified the electricity use emissions factor to an unrounded value so it more closely matches the value given for the U.S. annual non-baseload CO₂ output emission rate in eGRID2010 Version 1.0.

February 28, 2011

Electricity use: Updated the electricity use calculation when converting reductions of kilowatt-hours into avoided units of carbon dioxide emissions: the Emissions & Generation Resource Integrated Database (eGRID) U.S. annual non-baseload CO₂ output emission rate was updated from eGRID2007 Version 1.1 to eGRID2010 Version 1.0.
Passenger vehicles per year: Updated the amount of carbon dioxide emitted per gallon of motor gasoline burned from 8.89 to 8.92*10^-3 metric tons to reflect latest U.S. EPA Greenhouse Gas Inventory data. This gives a result of 5.1 metric tons of carbon dioxide equivalent per vehicle per year, consistent with EPA figures provided in the 2011-2016 light-duty fuel economy standards analysis.
Gallons of gasoline consumed: Updated the amount of carbon dioxide emitted per gallon of motor gasoline burned from 8.89 to 8.92*10^-3 metric tons to reflect latest U.S. EPA Greenhouse Gas Inventory data.
Barrels of oil consumed: Updated the heat content and carbon coefficient of crude oil to reflect latest U.S. EPA Greenhouse Gas Inventory data. The conversion factor used in the calculator is unaffected by these updates and remains the same.
Tanker trucks filled with gasoline: Updated the average heat content and carbon coefficient of motor gasoline to reflect latest U.S. EPA Greenhouse Gas Inventory data. These updates change the conversion factor from 74.89 to 75.82 metric tons of carbon dioxide per tanker truck.
Home energy use: Updated the carbon coefficients for natural gas, distillate fuel oil, liquefied petroleum gases, and kerosene to match those in the latest U.S. EPA Greenhouse Gas Inventory data. These updates change the conversion factor from 11.75 to 11.77 metric tons of carbon dioxide per home per year.
Acres of forest carbon preserved from avoided deforestation: Updated the average carbon density of U.S. forests to reflect the latest U.S. EPA Greenhouse Gas Inventory. The updates change the conversion factor from 105.38 to 100.94 metric tons of carbon dioxide per acre converted.
Propane cylinders used for home barbecues: Changed the percentage of carbon in propane from 81.8% to 81.7% to reflect the latest U.S. EPA Greenhouse Gas Inventory. The conversion factor remains unchanged.
Railcars of coal burned: Updated the average heat content of coal and the average carbon coefficient of coal to reflect the latest U.S. EPA Greenhouse Gas Inventory. These updates change the conversion factor from 191.5 to 183.65 metric tons of carbon dioxide per railcar.
Tons of waste recycled instead of landfilled: Updated the net emission reduction from recycling mixed recyclables to 0.78 from 0.81 metric tons of carbon equivalent per short ton to reflect figures given in the latest U.S. EPA WARM. This update changes the conversion factor from 2.97 to 2.87 metric tons of carbon dioxide equivalent per ton of waste recycled instead of landfilled.
Coal-fired power plant emissions for one year: Updated the number of power plants using coal and their carbon dioxide emissions to reflect the latest eGRID data for 2007. These updates change the conversion factor from 3,850,479 to 4,023,304 metric tons of carbon dioxide per power plant.

March 8, 2010

Home electricity use: Corrected CO₂ emissions factor from 7.70 metric tons CO₂/home to 8.24 metric tons CO₂/home to account for emissions associated with transmission and distribution losses. The figure of 7.70 metric tons is for electricity generated at the plant; the figure of 8.24 metric tons is for delivered electricity.
Home energy use: Based on the correction described above, increased the annual CO₂ emissions per home from 11.21 metric tons to 11.75 metric tons.
Propane cylinders used for home barbecues: The conversion from pounds to kilograms was inadvertently omitted from the calculation; this was corrected and the result changed from 0.054 metric tons CO₂ per cylinder to 0.024 metric tons CO₂ per cylinder.

November 20, 2009

Passenger vehicles per year: Updated fuel economy and vehicle miles traveled figures to reflect 2007 data; previous figures were for 2005. Also adjusted the ratio of carbon dioxide emissions to total emissions based on 2007 data. Result is now slightly lower (5.23 metric tons CO₂ equivalent per vehicle per year, compared with 5.46 previously).
Gallons of gasoline consumed: Revised the methodology used to calculate emissions per gallon of gasoline; the new methodology yields a slightly different result (8.89*10^-3 metric tons CO₂/gallon compared with 8.81*10^-3 metric tons CO₂/gallon previously).
Tanker trucks filled with gasoline: Corrected the result from 74.88 to 74.89 metric tons CO₂/tanker truck.
Home electricity use: Updated electricity use per home and the number of homes to reflect 2008 Residential Energy Consumption Survey (RECS) data. The changes result in a slightly higher level of annual CO₂ emissions per home (7.70 metric tons based on 2008 RECS data versus 7.21 metric tons based on 2003 RECS data).
Home energy use: Updated energy use per home and the number of homes to reflect 2008 Residential Energy Consumption Survey (RECS) data. The changes result in a higher level of annual CO₂ emissions per home (11.21 metric tons based on 2008 RECS versus 10.99 metric tons based on 2003 RECS data).
Number of tree seedlings grown for 10 years: Revised the caveats to the assumptions.
Acres of pine or fir forests storing carbon for one year: Revised and updated the calculations; the new result is slightly higher than before (4.69 metric tons of CO₂ per acre of pine or fir forests, compared with 4.4 previously).
Acres of forest preserved from deforestation: Updated to reflect data from the 2009 U.S. Greenhouse Gas Inventory. The new result is lower than before (105.38 metric tons of CO₂ per acre converted, compared with 143.37 previously).
Propane cylinders used for home barbeques: Revised the calculation methodology to account for the fact that pure propane (rather than LPG) is used in propane tanks. The previous calculation mistakenly assumed that LPG is used in these tanks. The new result is higher than before (0.054 metric tons CO₂/cylinder, compared with 0.024 previously)
Tons of waste recycled instead of landfilled: Updated this calculation to reflect data from the 2009 version of WARM. The new result is slightly higher than before (2.97 metric tons CO₂E per ton of waste recycled, compared with 2.90 previously).
Coal-fired power plant emissions for one year: Changed the data source to eGRID from the Clean Air Markets Division. The new result is lower than before (3,850,479 metric tons CO₂ per power plant, compared with 4,643,734 previously).

February 17, 2009

Electricity Use: Updated the electricity use calculation when converting reductions of kilowatt-hours into avoided units of carbon dioxide emissions: the Emissions & Generation Resource Integrated Database (eGRID) year 2005 U.S. annual non-baseload CO₂ output emission rate updated from eGRID2007 Version 1.0 to eGRID2007 Version 1.1.
Home Electricity Use: Updated the home electricity use calculation when converting units of avoided CO₂ emissions into annual electricity use of number of homes: the eGRID U.S. annual CO₂ output emissions rate was updated from eGRID2006 Version 2.1 (year 2004 data) to eGRID2007 Version 1.1 (year 2005 data).
Home Energy Use: Updated the home energy use calculation when converting units of avoided CO₂ emissions into annual energy use of number of homes: the eGRID U.S. annual CO₂ output emissions rate was updated from eGRID2006 Version 2.1 (year 2004 data) to eGRID2007 Version 1.1 (year 2005 data).

December 8, 2008

Electricity Use: Updated the electricity use calculation when converting reductions of kilowatt-hours into avoided units of carbon dioxide emissions: the eGRID non-baseload national average emissions rate was updated from eGRID2006 Version 2.1 (year 2004 data) to eGRID2007 Version 1.0 (year 2005 data).