He is likely to burn more fuel in his Prius than he would if he flew coach direct. (esp when you take into account the indirect route, etc)

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Mike you assume correctly.

Say he was going to fly Southwest Airlines from Oakland to BWI Airport just outside of Washington DC. As the crow flies that is around 2450 miles. Southwest Airlines uses Boeing 737-700s. These planes cruise at 531 mph. So the trip time would be 4.6hrs (let's round up and say 5hrs). 737-700s burn fuel at 740lbs of fuel per hour (taken from the Airline Monitor 2003). So that's 3700 gallons of jet fuel for the trip. Southwest has an average of 137 seats per plane. So per passenger the fuel used is 27 gallons.

A prius will get let's say 55 mpg. Google maps cites the driving distance from Oakland to BWI airport as 2800 miles. So fuel use is 51 gallons (and that's being generous on the MPG).

So Ed, who I think is cool, you are using TWICE as much fuel to drive to the Washington, DC area.
Take the plane, then use a flexcar hybrid or just use the train/metro like we do.

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There will only be a negative impact on Ed's mileage if he drives above 35 MPH. He's not in a hurry is he?

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I'm sure Ed has his own reasons. Some things are more "green" in one aspect than they are in another.

For example, I don't know for sure but I think it's a fair assumption, the Prius has cleaner emissions than an airplane, but as according to "a54" the airplane uses more fuel. Some people put emissions over fuel-consumption or vice-versa.

And by the way "a54" I believe your calculations are incorrect anyway.

Before I begin let me point out on your mistake. You assumed that a pound of fuel is one gallon. (That gallon of milk at the supermarket isn't one pound!)

1 gallon of gas = 6 pounds*

1 gallon of standard Jet fuel = 6.7 pounds*



Now, according to British Airways a 747-400 planes uses 3378 gallons of fuel an hour at 576mph.
By Airplane it's about 6,000 miles of flying overall. So 10 hours of flight or so and that would equal...33780 gallons, divided by each of the 409 passengers is... aprox. 82 gallons of fuel each!

On a Prius Ed will probably get 55 mpg since I'd imagine he tries to hypermile. (Though on the highway all you could really do is go 55mph and maybe try to gang up behind a trucker" So 6500 miles of driving divided by 55mpg is about 120 gallons.

Your right "a54." An airplane does use less fuel, your calculations to get to that conclusion just seem a little off.

If Ed went in an Insight he'd only use 92 gallons of fuel though. I'm surprised he didn't rent an Insight, of course assuming that he tock the trip alone.

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is his camera crew following him in a fleet of suburbans?

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Joseph,

The only mistake I made was that I put 740lbs/hr when it should been 740 gallons/hour. I made no assumptions about lbs=gallons. I also did not choose a 747 for a short haul trip. I compared a frugal airline, Southwest, that uses economical planes 737-700.

Ed's portion of fuel used travelling by plane is lower than the amount of fuel used if Ed drove the same distance in a Prius. It's that simple.

Now if he's packing his entire family in the Prius then the balance tips in his favor. But if Ed's traveling alone, he's not choosing the best path.

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Ed's main loss will be his time. His gain will be the memory of the trip, though he would not want to do that many times in a life time, think of the risk to life. His trip can be made more environmentally friendly with the use of E85 fuel (not available generally and very controversial). Ethanol is currently produced in the US at about 780 litres per hectare from corn. In Brazil they routinely produce 7000 litres per hectare from cane, and in Australia yields of up to 10,000 litres per hectare from cane are being reported. There is a further 8000 litres per hectare soon to be yielded from the same cane when the cellulose is also converted to ethanol. This last yield has been long anticipated but remains allusive. One Brazillian company has, rather than waiting for the slow to materialise cellulose converting enzymes, proceeded with conventional mild acid cellulose conversion and are reporting costs comparable with petrol and are projecting to be able to halve that cost again. Australia has the very real potential of achieving E85 nationally if 1 million hectares of land are used for cane production for ethanol specifically, if the projected yields are achieveable on the larger scale. All indications are that that is possible.

The other way Ed can travel the distance is in a Pipistrel Virus. This plane travels at 240 klms per hour on as little a 9 litres per hour. The trip would require 95 gallons. Using the new GPS and HITS navigation equipment this trip can be done more quickly and safely than road offers. The fuel is standard unleaded or E85 in the fuel injected Rotax 912 engine.

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A few thoughts:

1. Are we sure the airlines' numbers aren't very likely
to be a tad on the most optimistic side, under estimating
fuel used?

2. Critically, when they say this or that plane
burns this many pounds or gallons of fuel per hour
at 500mph or what have you, that would be great if an
entire airline flight consisted only of horizontal
travel. The take-off will add to the total. They must 'idle' their engines somewhat since many of us can smell it and get nausia while waiting for the plane to take off if it is taxi'ing for a long while.. Maybe not a huge addition, but unless we look at numbers that
include the entire journey, taxi on the ground for 5 to sometimes 50+ minutes, take off and landing, it's not realistic.

3. Flights are often not full, so the denominator
(the number of passengers) on average, despite
airlines bottom line incentive to maximize
booking, will still be less than the total plane capacity...we cannot just divide by the number of seats in the plane..this will add only a little bit
to the gallons wasted per person, but its yet another addition on top of the more substantial ones

4 Worst of all is that CO2 emitted at high altitudes
does that much more damage than CO2
emitted at the surface. Perhaps someone else
can google for what the scaling factor is in terms
of damage...but I recall having seen it a
while back and it was non trivial..that is,
82 gallons (even if we take that rather than
the 100 miles quoted here http://tinyurl.com/2jwqku) those 82 gallons do damage equivalent to a much
greater number of gallons burned at the surface. Hmm, some folks at realclimate.org claim they aren't
sure if the CO2 at high altitudes are worse after all,
but then again on BCC I found that if we change
the question from "is the CO itself doing
more harm" to "let's look at the CO plus
other harmful effects" then we do get a datum suggesting that the 82gallons (or whatever the real figure is) is still understating the problem:

"It said air travel was also responsible for "high-altitude release of other harmful emissions", adding that the total climate change impact of aviation could be two to four times the CO2 impact."

http://news.bbc.co.uk/2/hi/uk_news/politics/6248889.stm

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