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CO2 car emissions: % to g/litre

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  • CO2 car emissions: % to g/litre

    I'm trying to work out the environmental impact of our car, with a view to carbon offsetting. I live in France, where tailpipe emissions are measured as a percentage, presumably of total gas emission. This isn't very useful, so I'd like to convert to the standard unit of g/litre, or kg/litre, I suppose.

    Can anyone help?

    Many thanks,

    Louise

  • #2
    Originally posted by LouiseSJPP View Post
    I'm trying to work out the environmental impact of our car, with a view to carbon offsetting. I live in France, where tailpipe emissions are measured as a percentage, presumably of total gas emission. This isn't very useful, so I'd like to convert to the standard unit of g/litre, or kg/litre, I suppose.

    Can anyone help?

    Many thanks,

    Louise
    Essentially all the carbon in a hydrocarbon fuel is burnt to carbon dioxide (a small fraction of the exhaust is carbon monoxide or unburnt hydrocarbons, which are worse).
    You don't mention whether your car uses diesel or gasoline (petrol). A liter of gasoline is around 0.74 kg, diesel around 0.84 kg. Both are about 85% carbon by weight.

    So a liter of gasoline is 0.74 kg/L x 0.85 carbon or 0.629 kg carbon

    Carbon has an atomic weight of 12, CO2 has a molecular weight of 44 so

    0.629 kg C x 44 g CO2/12 g C = 2.31 kg CO2 per liter of gasoline

    If your car uses diesel, work through the same steps using its mass per liter

    Density of fuel varies slightly lot to lot, so if you have an accurate, measured density for either fuel, use it in places of "typicals" above.

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