The Climate Trust, M.J. Bradley & Associates and the other Initiative Participants request project developers use the following conversion tables for 2007 RFP offset project calculations. If an alternative conversion factor is used, clearly state the source.
Please note that the volume of greenhouse gas offsets must be converted to short tons of carbon dioxide equivalent on project applications.
Global Warming Potentials
Global warming potentials (GWPs) are used to compare the abilities of different greenhouse gases to trap heat in the atmosphere. GWPs are based on the heat-absorbing ability of each gas relative to that of carbon dioxide (CO2), as well as the decay rate of each gas (the amount removed from the atmosphere over a given number of years) relative to that of CO2. The GWP provides a construct for converting emissions of various gases into a common measure denominated in carbon or carbon dioxide equivalent (CO2e).
The generally accepted authority on GWPs is the Intergovernmental Panel on Climate Change (IPCC). In 2001, the IPCC updated its estimates of GWPs for key greenhouse gases and the table below is reflective of that update.
Gas
2001 IPCC GWP
Carbon Dioxide
1
Methane
23
Nitrous Oxide
296
HFC-23
12,000
HFC-125
3,400
HFC-134a
1,300
HFC-143a
4,300
HFC-152a
120
HFC-227ea
3,500
HFC-236fa
9,400
Perfluoromethane (CF4)
5,700
Perfluoromethane (C2F6)
11,900
Sulfur Hexafluoride (SF 6)
22,200
Note: All measurements of offsets in the Product Information Document submitted by project applicants to the US Offset Acquisition Initiative 2007 RFP must be denominated in short tons of carbon dioxide equivalents. Please see examples below for converting to shorts tons of CO2e.
Example 1: to convert 2,500,000 pounds of methane to short tons of carbon dioxide equivalent:
1. Convert pounds of methane into short tons of methane:
2,500,000 lbs. divided by 2,000 (pounds in a short ton) = 1,250 short tons of methane
2. Convert the amount of short tons of methane into short tons of carbon dioxide equivalent:
1,250 multiplied by 23 (the GWP of methane from the table above) = 28,750 short tons of CO2e
Example 2: to convert 2,500 metric tons of methane to short tons of carbon dioxide equivalent:
1. Convert metric tons of methane into short tons of methane:
2,500 metric tons multiplied by 1.10231131 (metric tons in a short ton) =
2,755.78 short tons of methane
2. Convert the amount of short tons of methane into short tons of carbon dioxide equivalent:
2,755.78 multiplied by 23 (the GWP of methane from the table above) = 63,382.94 short tons of CO2e
A Energy Information Administration, “Comparison of Global Warming Potentials from the Second and Third Assessment Reports of the Intergovernmental Panel on Climate Change (IPCC),”
http://www.eia.doe.gov/oiaf/1605/gwp.html.
B Intergovernmental Panel on Climate Change, Climate Change 2001: The Scientific Basis (Cambridge, UK: Cambridge University Press, 2001).
32.397 per gallon
1356.461 per barrel
6768.667 per short ton
225.130
Residual Fuel (No. 5 and No. 6 Fuel Oil)
26.033 per gallon
1,093.384 per barrel
173.906
Natural Gas and Other Gaseous Fuels
Natural Gas (Pipeline)
120.593 per 1000 ft3
117.080
Propane
12.669 per gallon
532.085 per barrel
139.178
Coal
Anthracite
3852.16 per short ton
227.400
Bituminous
4931.30 per short ton
205.300
Sub-bituminous
3715.90 per short ton
212.700
Lignite
2791.60 per short ton
215.400
*The Initiative reserves the right to use alternative conversion factors for the purpose of offset quantifications.
Sources:
Intergovernmental Panel on Climate Change. Greenhouse Gas Inventory Reference Manual: Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories.
U.S. Environmental Protection Agency. Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-1998.
Electricity: The Climate Trust has created an Electricity Sector Baselines Resources page for data on the quantification of projects that displace grid electricity.
Forest Sequestration: The Initiative does not have standard quantification metrics for forestry-based projects. Carbon sequestration levels vary according to site location, tree species, and project activity. The Trust encourages project developers to make use of the best available data.
Industrial Processes and Other Carbon Factors:
The IPCC's Emission Factor Database is a great resource for industrial carbon factors, as well as most other sectors.
The GHG Protocol has a variety of spreadsheets/tools and guidance to assist in the quantification of GHG emissions from a variety of sectors.
