I’m leaving on a jet plane …
On the group I mentioned earlier (which is called 90% reduction: Riot for Austerity) has had numerous arguments discussions about whether commercial airline flights are bad or good. One person said it was like “driving in an SUV with the a/c on and the windows open”.
Hmm. Sounds bad. Or at least not very fuel-efficient.
But I take my kids to see their grandparents every year, and since I’m tracking my own fuel usage, I decided to go online and find out how many mpg a plane gets.
Not an easy thing to do!
They don’t talk about airplane gas at all like they do car gasoline.
Airplanes are funny beasts. I don’t claim to be an expert, but this is what I’ve gleaned from reading some papers on the subject. Gas mileage (or as they say, megaJoules of energy per available seat-kilometer) is dependent on how much weight the plane is carrying. This weight includes the weight of the plane itself, the people in it, the fuel, and all the equipment and luggage along for the ride.
Empty planes get better gas mileage, but the company doesn’t make any money on empty planes. They make money on full planes. So I would imagine that there’s a optimal point where they make the most money and use the least gasoline. This is probably why they charge you when you bring a dozen bags to check in, or bring overweight baggage.
Now, the energy per available seat-kilometer has been improving over the years (1), which is a good thing. This might explain the perception that airplanes are gas hogs, because thirty years ago, they were.
On looking at the tables given by the US Bureau of Transportation statistics, it says that the average domestic flight in 2001 got 21 seat-kilometers per liter, or (using my lightning mathematics skills and a calculator) 49 mpg (2). Not motorcycle efficiency, but not Hummer-class either.
Maybe some of you rocket scientists out there can give more insight into this, but on a straight gasoline usage standpoint, it looks like it would be better to fly than drive my SUV.
In any case, I’ll be gone all week. Play nice.
- Fuel efficiency of commercial aircraft: An overview of historical and future trends Peeters P.M., Middel J., Hoolhorst A.
- Bureau of Transportation Statistics, US Department of Transportation, Table 4-21M: Energy Intensity of Certificated Air Carriers, All Services
July 30th, 2007 at 11:58 am
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July 31st, 2007 at 7:03 am
49MPG is the equivalent rating per person. Looking at the Chevy Tahoe (a fairly popular SUV, seats 4 very comfortably ofr long trips) we have a fuel economy of 19MPG on the highway via: http://www.fueleconomy.gov/feg/2008car1tablef.jsp?column=1&id=22950
Assuming that these numbers are calculated only with a driver and that three more individuals lower the fuel efficiency by, say 10%, we have 17MPG. But there are four people riding in the car, so we need to find the equivalent MPG per person. We do this by multiplying the MPG by the number of passengers, for a result of 68MPG/person!
Imagine what the resultant personal MPG’s are for more fuel efficient vehicles out there! There’s no two ways about it, flying and flying at modern speeds especially, is an energy intensive and innefficient form of travel, unless you always travel alone in big SUV’s.
Let’s also consider buses, http://www.greyhound.com/company/media/facts.shtml
Greyhound states a per passenger MPG of 162MPG!
What about trains? http://en.wikipedia.org/wiki/Fuel_efficiency_in_transportation#Trains
Wikipedia references figues from various sources from 300-500 passenger MPG for passenger trains….
So flying IS the least efficient, however these calculations do not take into account the massive amount of infrastructure required for land based travel (especially cars). If you are looking for the most ecological responsible choice, I say go for the train! Best MPG and far less infrastructure required than cars and buses!
August 6th, 2007 at 11:02 am
Hmmm, I’m not sure what happened to my comment regarding fuel efficiency but I’ll paraphrase.
Airliners get 49MPG per PERSON, so even something like a Chevy Suburban, at say 17MPG and with four passengers, gets 68MPG per person. With smaller vehicles, like say a Chevy Malibu at a conservative 28 MPG rating gets 112 MPG per passenger with four occupants.
It gets better with mass transit too, Greyhound states 162MPG per passenger (http://www.greyhound.com/company/media/facts.shtml)
And trains rate anywheres from 250 to 1400MPG! (http://en.wikipedia.org/wiki/Fuel_efficiency_in_transportation)
So, yes flying is an extremely innefficient way to travel, unless you were travelling alone by passenger car.