Which methane and nitrous oxide factor should I use for a liquefied petroleum gas forklift when the off-road table of the Intergovernmental Panel on Climate Change has no row for it?

The Intergovernmental Panel on Climate Change (IPCC) off-road table has rows for diesel and petrol only, not liquefied petroleum gas (LPG). Its road table gives LPG 62 kilograms of methane and 0.2 of nitrous oxide per terajoule (TJ); its stationary table gives 1 and 0.1. Either way the two gases add under 3% to the carbon dioxide.

What the IPCC tables hold for LPG

• Off-road machinery, Table 3.3.1 of the 2006 Guidelines (Volume 2, Chapter 3): rows for diesel, motor gasoline 4-stroke and motor gasoline 2-stroke only. The chapter text names forklifts as off-road machinery, so a forklift belongs here, but the table has no LPG row.
• Road transport, Table 3.2.2: LPG gets 62 kilograms of methane (CH4) and 0.2 kilograms of nitrous oxide (N2O) per TJ, with no lower or upper range printed. The table note says the methane figure comes from 3.1 grams of CH4 per kilogram of LPG at 50 megajoules per kilogram, from TNO, the Netherlands Organisation for Applied Scientific Research (2003).
• Stationary combustion in manufacturing industries, Table 2.3: LPG gets 1 kilogram of CH4 per TJ (range 0.3 to 3) and 0.1 of N2O (range 0.03 to 0.3).
• Table 3.2.4 also lists LPG vehicles, but in milligrams per kilometre (heavy duty: 67 of CH4 and 93 of N2O). A forklift has no useful kilometre count, so that table does not help.

Which row to pick: our reading, not the IPCC's

The IPCC does not say which of the two per-TJ rows a forklift should use. Our reading is to take the road LPG row (62 and 0.2). The engine is a spark-ignition engine burning LPG, like the road engines behind that row, and it gives the larger and so the more cautious figure. The stationary row (1 and 0.1) describes burners and boilers. Whichever you choose, write it in the methodology note and keep it for every year.

How much the choice changes the answer

Convert both gases with the global warming potentials (GWP) of the IPCC Fifth Assessment Report (AR5), 28 for CH4 and 265 for N2O. Road row: 62 x 28 + 0.2 x 265 = 1,736 + 53 = 1,789 kilograms of carbon dioxide equivalent (CO2e) per TJ, which is 2.8% of the 63,100 kilograms of carbon dioxide (CO2) per TJ. Stationary row: 28 + 26.5 = 54.5, which is 0.09%.

For comparison, off-road diesel in industry carries 4.15 of CH4 and 28.6 of N2O per TJ, which adds about 10% to its CO2. LPG forklifts add far less of these two gases than diesel ones, and the choice of row moves the total by under 3%.

What to keep on file

• LPG kilograms by month, from invoices and the net weight of each cylinder, not the cylinder's printed gross weight.
• A split between forklift gas and other uses such as a canteen, if the same bill covers both.
• The row you used, its TJ factor, the net calorific value (47.3 megajoules per kilogram in IPCC Table 1.2) and the GWP set.

Example: 12,000 kilograms of LPG a year in forklifts

• Energy: 12,000 x 47.3 megajoules = 567,600 megajoules = 0.5676 TJ
• CO2: 0.5676 x 63,100 = 35,816 kilograms (about 2.98 per kilogram of LPG)
• Road row: CH4 0.5676 x 62 = 35.19 kilograms x 28 = 985 kilograms CO2e; N2O 0.5676 x 0.2 = 0.1135 kilograms x 265 = 30 kilograms CO2e; added 1,015, total 36,831
• Stationary row: CH4 0.5676 kilograms x 28 = 16; N2O 0.0568 kilograms x 265 = 15; added 31, total 35,846
• Gap between the two choices: 1,015 minus 31 = 984 kilograms, 2.7% of the CO2

The 12,000 kilograms is an example quantity. Use your own invoices. GWP values are IPCC AR5 without climate-carbon feedback. The IPCC row assumes 50 megajoules per kilogram, the example uses 47.3, so the methane works out near 2.9 grams per kilogram, not 3.1.

What Senseible does here

Senseible reads fuel invoices and bills into records, so the LPG kilograms you buy are on file. Its LPG factor counts carbon dioxide only. It cannot tell which cylinders went to forklifts and which to a canteen, so tag cylinders or keep an issue register.

• One 19 kg LPG cylinder in CO2
• Diesel forklift against electric forklift
• Do I need methane and nitrous oxide from diesel?
• Scope 1 from LPG and piped gas bills
• Free calculators

Sources: IPCC 2006 Guidelines, Volume 2 Chapter 3 (Mobile Combustion), Tables 3.2.2, 3.2.4 and 3.3.1, IPCC 2006 Guidelines, Volume 2 Chapter 2 (Stationary Combustion), Table 2.3, IPCC 2006 Guidelines, Volume 2 Chapter 1, Table 1.2 (net calorific values), IPCC Fifth Assessment Report, Working Group I, Chapter 8, Table 8.7

Last reviewed 2026-11-05. These are IPCC 2006 Guidelines defaults. The 2019 Refinement is a separate document that this page does not use. Re-check if a buyer, lender or reporting framework names a different factor set or GWP set.