What gives off more CO2- flying or driving?

Question

I used to think it was driving for sure, but I recently read that taking a long distance flight gives off 500 pounds of CO2 for each person on the plane!

Answer 1

An answer to this question is a bit complicated because it depends on both the type of car and the type of aircraft used, plus the details of the trip!!!

However, we'll make some simple assumptions to come up with a general idea of how much carbon dioxide each trip will produce.

In general, automobile engines release about 19.6 pounds of carbon dioxide per gallon of gasoline. Thus, the amount of carbon dioxide released for a given trip depends upon the gasoline mileage of the car. Assuming the family is driving a new Ford Taurus, which gets 23 miles per gallon, and the trip from Boston to Orlando is 1280 miles, the car trip will release

(19.6(lb/gal) * .453(kg/lb) * 1280(miles) ) / 23(mpg) = 494.1 kg CO2 into the air, or 494.1kg/4 = 123.5 kg CO2 per person.

Airplane engines generally release 3.15 kilograms carbon dioxide for each kilogram of fuel burned. We will assume the family is flying in a full Boeing 737-400 aircraft, which can carry 146 people, and flies at about 440 miles per hour. Therefore, a trip to Orlando from Boston would take about 2.9 hours. The amount of fuel that a plane uses per hour depends on what the plane is doing. For example, it takes 6869 kilograms of fuel per hour for a Boeing 737 to climb from the ground to its cruising altitude, while it only takes about 893 kilograms of fuel per hour for the same plane to fly at cruising altitude. We will assume that the plane spends 15 minutes, or .25 hours climbing, and the rest of the time (2.65 hours) at cruising altitude. We will ignore any carbon dioxide that might be emitted from the plane during taxiing or idling at the airport, although these can be significant sources as well.

So the amount of fuel used by the Boeing 737 during the flight is:

6869(kg/hour)*.25(hours) + 893(kg/hr)*2.65(hours) = 4083.7 kg fuel

And, therefore, the total carbon dioxide emitted is:

4083.7 (kg fuel) * 3.15 (kg CO2/kg fuel) = 12863.65 kg CO2

Obviously the airplane emits more carbon dioxide than the car during the trip, about 26 times as much. However, if the airplane is filled to capacity (146 people for the B737-400), then the plane emits 88.1 kilogram of carbon dioxide per person, which is less than that emitted by the car.

Keep in mind, however, that this is a pretty rough estimate of carbon dioxide emitted by the airplane, as we don't really know how long the airplane spends at different fuel consumption levels, and we are ignoring any emissions while at the ground at the airport. Also, this is assuming the airplane is at full capacity. If the airplane were only at about 70 percent capacity (102 people), than the carbon dioxide emissions per person would be 125.9 kilograms of carbon dioxide per person, or about the same as the automobile emissions.

Answer 2

Am glad to see the correct ideas expressed here, except for the website mentioned above. Just thinking about it, a car must expend its energy for its size pushing through the air at ground level and a small airplane, which has a larger size with its wings, etc,, must expend its energy pushing through air at a somewhat higher elevation and with a less efficient form of motive power - the propeller. So small airplanes cannot be much more efficient than a car. The table on the website shows a small airplane with 500 gallons of fuel in its tank and 15 passengers getting 36 mpg. This would enable it to fly nearly 20,000 miles or almost around the world - seems an exaggeration. It also shows a motorcycle getting only 45 mpg - seems low. A misconception that many have is that flight is a much more efficient mode of transportation and small helicopters will be someday how everyone commutes to work and this is not true.

Answer 3

Simple answer if what we are comparing is one plane vs one car over a set distance. Even excluding taxi and idle time, unless the plane is a microlight with a lawn motor engine, it will always give off more absolute CO2.

ON the other hand, if what you are measuring is the total CO2 generated to move a set number of people a set distance, the answer will vary based on a number of conditions. Assuming one car for each person vs one plan for all people the following guidelines help.

As you add people and/or the extend distance, CO2 emission efficiency (CO2/person/mile) for driving steadily worsens, while for flying it dramatically improves

Answer 4

Well, with the number of cars on the road compared to the number of planes in the sky, I would assume that worldwide, cars probably produce more. However planes are worse individually compared to a car for sure, and they contrinute more toward the greenhouse effect because their emissions are much higher up off the surface of the earth than that of cars. I think that with the growing market for planes, they will eventually beat cars in total emissions around the world too.
Thats what I think, hope it gave you some more ideas!

Answer 5

driving - on a per person per mile basis, small planes are more efficient
http://www.personal.psu.edu/users/l/a/lam409/transportation.html

However
Most fuel-efficient vehicle period is:
The record for the most fuel-efficient vehicle is 0.01857 litre of petrol for 100 km (15,212 mpg) and was achieved by PAC-Car II from the Swiss Federal Institute of Technology Zurich on the Shell Eco Marathon in the Michelin Technology Centre, Ladoux, France on June 26, 2005.

Answer 6

Definitely Flying.

Answer 7

in not too sure, flying burns a lot more fuel in one flight across the country than a soccer mom burns an about 6 months with a van or SUV