Aircraft and CO2

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Planes are they if pollutants?

We read récement this on the Nouvel Observateur website:

"I would like a Paris-Bangkok return flight in a recent and well-filled plane". This is what a traveler very concerned about fighting the greenhouse effect could ask his travel agency. By plane, a passenger emits on average 140 grams of CO2 kilometer, against 100 on average by car, said the French Institute of the Environment (Ifen) in a synthesis on the air transport contribution to the greenhouse effect. Even taking into account emissions related to the manufacture of cars and petroleum refining, the plane rejects 16% carbon dioxide per passenger.

Even in the best filling conditions such charter flight, a round-trip Paris-New York is the rejection of a tonne of CO2 per passenger, says Ifen in the latest issue of environmental data. The most polluting flights are shorter.

The CO emissions2 are not the only air transport contribution to the greenhouse effect continues Ifen. The aircraft also emit nitrogen oxides and water vapor which promotes the formation of condensation trails (contrails).
The work of Patrick Minnis, Langley Research Center of NASA, have shown that these trails form cirrus clouds that trap heat.

The global air transport represents 2,5% of global emissions of CO2 related to fossil energy consumption. The room for maneuver to improve the energy efficiency of aircraft is very limited, the Ifen article says. As a result, with increasing traffic, the impact on the climate will intensify. "

And this is our response:

This news is completely eronée yet here is the proof by calculation.


I recently calculated mass discharges starting from the complete combustion of equation (and ideal).

It resulted in the following figures: An engine consuming 1 L petrol is going to reject a bit more than a kilo of water and 2.3 kg CO2.

But the kerosene, fuel the reactor is heavier than gasoline (see its properties here: properties of petroleum fuels ). Take a number of carbon atoms of 12, a forumthe average chemical level of C12H26.

D'after combustion formulas, we get:

Application to kerosene. n = 12
[C12H26] = 12 12 * + = 26 1 170 * g / mol.
Mass CO2 rejected by mole of consumed kerosene is: * 44 12 528 = g.
The mass consumption of kerosene report on releases of CO2 is 528 / 170 3.10 =

This means that for 1 3.1 kilo of kerosene consumed kilogram CO2 are issued.

Details of combustion calculations are on this page: combustion equations and emissions of hydrocarbons CO2

Let us return to the article.

According to one: a round-trip Paris-New York rejects 1 ton of CO2 per passenger.

This means that 1000 / 3.1 322 = kerosene kilogram have been consumed, either 322 / 0.8 402 = L because the density of the kerosene is in the range of 0.8.

The Paris New York 5850 km distance is about is * 5850 2 11700 = km for a return trip.

The 402 11 700 km to ... this gives us an average consumption per passenger of the 3.43 100 L km.

What current car consumer is capable of such low consumption? No without hesitation!

And yet the article still sinks a little nail:

"A passenger plane emits about 140 CO2 grams per kilometer, against 100g / km for a car driver."

Here then ? In suposant that the driver is alone in the vehicle and in the same opposite approach, petrol car emits 100 CO2 g / km * consume 100 100 / 2.3 4.3 = L / 100 ... Very little gasoline vehicles are capable of such consommation..Je not talking recess city traffic! The reality is rather close to twice ...

Another reason would the plane consumes 40% more than the car, or conversely that the car consumes 28% below the plane ...

A small digital application with the number of L in 3.43 100 km for the consumption of an aircraft gives a consumption of a vehicle * 3.43 0.72 2.46 = L / 100.

Again: What current car is capable of such consumption? No (twice)!

Note: The average occupancy rate of european cars is between 1.2 and 1.6 person / car, a correction calculation is possible with these figures for releases or average consumption for cars in g CO2 by km.passager or L / 100km.passager. In any case, and according to the initial figure of 1 ton of CO2 for a round-trip Paris / New York, the plane remains less than consumer cars.


Here I stopped me to say that I feel that the figures reported in this article are éronés is that air transport, mass long-distance, is less polluting than road transport ...Yet the authors of the article have not really stated this.

The major problem of the future are indeed land transport and increased global fleet.


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