Agnes,

I didn't check the atom balance, good catch. But the CO2 balance is correct and that's all that's relevant in this case. Agreed that the 4.0L/km/passenger average might be off by a few percent if it's weighted more on longer range flights. But Airbus claims much better fuel economy so I stuck with the more conservative value.

>>kerosene combustion reaction: C12H28 + 37/2 O2 -> 12C02 + 13H20
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>where is the single H2 where do you get a half O2?
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>28 Atoms H on the left does not equal 13H2 equal 26 Atoms on the right
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>it must be
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>C12H28 + 37/2 O2 -> 12C02 + 13H20 +H2
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>but this sounds not likely, why shouldn't the free H2 not react? If there is not enough oxygene I always thought it would react with the hydrogen rather then carbon.
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>or
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>C12H28 + 19 O2 -> 12C02 + 14H20
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>If you use a more complex equation where the H2 goes to something else you need to put this into the equation and its remnants into acount to the rest of your view.
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>Short range flights consume more fuel then average. No idea how much. But just consider the repeated acceleration, climbing and lower flight altitude.
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>Universe is non linear.