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Carbon Dioxide from Flared Gas (Combustion Efficiency and Gas Composition)

Also known as flare CO2 · CO2 from flaring · flared gas emissions · carbon dioxide from a gas flare · flare combustion efficiency · flaring emissions · CO2 from gas flares per cubic metre · gas flaring carbon dioxide · flare stack emissions · CO2 from burning waste gas

mCO2=VVm MCO2(η yC+yCO2)m_{CO_2} = \frac{V}{V_m}\,M_{CO_2}\left(\eta\,y_C + y_{CO_2}\right)
sig figs

Worked example: 1 000 000 m³ of methane at 98 percent, 24.055 L/mol → 1 792.9 t CO2. Press Try an example to run it live, then adjust anything.

Enter your known values, leave one input blank, and solves for the missing one. Tap a variable’s symbol to see what it means, with a typical value. Change any unit and the answer follows.

Constant used: built into this formula, no need to enter
M(CO2)=0.044009 kg/molM(\mathrm{CO_2}) = 0.044009\ \text{kg/mol}Molar Mass of Carbon Dioxide

Where Carbon Dioxide from Flared Gas (Combustion Efficiency and Gas Composition) fits

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See also

Energy Flow of a Natural Gas Stream (Volume Flow Times Heating Value): The heat in the same gas, from its flow and heating value: the energy that is wasted when it is flared.Emission Rate from Stack Concentration: The mass emission rate of a stack from the concentration and the flow, for a stack that is measured instead of calculated.Gas Volume at STP: The moles in a standard volume of gas, which the molar volume here stands in for.Heat Release Rate from Fuel Area: The heat a burning fuel releases, from its mass loss rate: the fire-science view of burning.
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Carbon Dioxide from Flared Gas (Combustion Efficiency and Gas Composition) explained

ηVVmone moleyCyCO2flaremCO2

A flare burns the gas sent to it, and this page counts the carbon dioxide that comes out by a carbon balance. The volume of gas VV, at standard conditions, divided by the molar volume VmV_m at those conditions, is the number of moles of gas. Each mole carries yCy_C moles of carbon in its hydrocarbons and yCO2y_{CO_2} moles of carbon dioxide. The hydrocarbon carbon is oxidized to carbon dioxide with combustion efficiency η\eta, while the carbon dioxide already in the gas passes straight through; so the moles of carbon dioxide out per mole of gas in are η yC+yCO2\eta\,y_C + y_{CO_2}. Multiplying by the molar mass MCO2M_{CO_2}, 44.009 grams per mole, gives the mass.

The carbon number yCy_C is 1 for methane, 2 for ethane, 3 for propane, 4 for butane and 5 for pentanes and heavier, each weighted by its mole fraction, so a gas with heavier hydrocarbons in it makes more carbon dioxide per cubic metre than pure methane. The molar volume has to match the standard conditions the volume is quoted at: 23.64 L/mol at 15 °C and 101.325 kPa, 24.06 at 20 °C, 23.69 at 60 °F and 14.7 psia. For the efficiency, the IPCC (2006) takes 0.98 for flares at production and processing facilities and 0.995 at refineries, and the United States EPA's refinery flare rule uses 0.98. The EPA's rule for oil and gas facilities, as revised in 2024, gives 96.5 per cent as the combustion efficiency of a flare that meets its tests, with 98 per cent as the methane destruction efficiency.

The worked example is a million cubic metres of pure methane at 98 per cent, with a molar volume of 24.055 litres per mole (20 °C): 1 792.9 tonnes of carbon dioxide. The IPCC gives 2.0 Gg of carbon dioxide per million cubic metres for a gas of 91.9 % methane, 6.84 % non-methane hydrocarbons and 0.58 % carbon dioxide. It does not give the carbon number of those hydrocarbons, but any average from 2.4 to 3.2 rounds to the same 2.0 Gg, and 2.8 gives yC=1.11052y_C = 1.11052.

This page does not count the methane that escapes unburned, which is a separate release with far more warming per kilogram than the carbon dioxide. The sources are the IPCC 2006 Guidelines for National Greenhouse Gas Inventories, Volume 2, chapter 4, and the United States EPA's rules at 40 CFR 98.233(n) for flare stacks and 40 CFR 98.253(b)(1) for refinery flares.

Carbon Dioxide from Flared Gas (Combustion Efficiency and Gas Composition) formula

mCO2=VVm MCO2(η yC+yCO2)m_{CO_2} = \frac{V}{V_m}\,M_{CO_2}\left(\eta\,y_C + y_{CO_2}\right)
Where
  • mCO2m_{CO_2}= Carbon dioxide emitted (t)
  • VV= Gas flared, at standard conditions (m³)
  • VmV_m= Molar volume at those standard conditions (L/mol)
  • η\eta= Combustion efficiency (%)
  • yCy_C= Hydrocarbon carbon per mole of gas
  • yCO2y_{CO_2}= Carbon dioxide in the gas (%)
Where this comes from
  • IPCC (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 2 Energy, Chapter 4 Fugitive Emissions, read 23 Oct 2026: Equation 4.1.5 takes the CO2 from flared methane as 0.98 times the volume flared times the methane density times the stoichiometric mass factor 2.75, with 0.98 'the combustion efficiency of natural gas that is flared'; for oil and gas a flaring efficiency of 0.98 'for those used at production and processing facilities' and 0.995 for refineries; and the emission factor for flared gas of 2.0 Gg of CO2 per million cubic metres 'based on a flaring efficiency of 98% and a typical gas analysis at a gas processing plant (i.e. 91.9% CH4, 0.58% CO2, 0.68% N2 and 6.84% non-methane hydrocarbons by volume)'. Read it
  • U.S. Environmental Protection Agency, 40 CFR 98.233(n), Flare stack emissions (US federal work, public domain), read on 23 Oct 2026 in the Legal Information Institute's copy of the current text: the flare combustion efficiency is 'the fraction of hydrocarbon compounds in gas that is oxidized to CO2 by a burning flare'; the Tier 1 defaults are a destruction efficiency of 98 percent and a combustion efficiency of 96.5 percent; the CO2 is worked from the mole fractions Y_j and carbon numbers R_j of the hydrocarbons (1 for methane to 5 for pentanes and heavier) and the CO2 mole fraction X_CO2. Equations W-19 and W-20 are printed as images and could not be read as text here. Read it
  • U.S. Environmental Protection Agency, 40 CFR 98.253(b)(1), Calculating GHG emissions from refinery flares, 2014 edition (public domain), read 23 Oct 2026: Equation Y-1b works the flare CO2 from the flare gas volume, 0.98 'the assumed combustion efficiency of a flare (mole CO2 per mole carbon)', the carbon mole number CMN of each carbon-containing compound other than CO2, the CO2 mole percent, 44 for the molecular weight of CO2 and a molar volume conversion of 849.5 scf per kg-mole at 68 degrees Fahrenheit or 836.6 at 60 degrees Fahrenheit and 14.7 psia. The equation itself is an image and could not be read as text here. Read it
Revised 30 October 2026
Cite this page

formula.expert. (2026, October 30). Carbon Dioxide from Flared Gas (Combustion Efficiency and Gas Composition) Calculator. https://formula.expert/solvers/flare-gas-co2-emission

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