Explain how 1,200 lbs of Jet A gets converted to 40 tons (80,000 lbs) of carbon dioxide in a hour? I think you need to correct your graphic. My estimate is that 1,200 lbs of Jet A would produce to about 470 lbs of carbon dioxide (at standard altitude & temperature).
There’s 1200 lbs of carbon. Add 3200 lbs of oxygen, and you get 4400 lbs of CO2.
These comments from a web site discussing global warming impact of jets landing at Aspen CO shows that the problem lies with the units being quoted and cross-quoted: Total fuel available on board (gals and lbs), fuel used per flight, per flight hour, fuel used per passenger, fuel weights and CO2 weights, etc. Each number we see is accurate, but used differently.
B4 Cell:
Rick Heede: Comment:
A survey of jet turbine aircraft parked at Aspen Base Operations and Airport ramps totaled 38 on 30Jul05 in size ranging from light
Cessna Citations and Lears to large Gulfstream and Challenger aircraft with ramp weights from 10,800 to 91,400 lb.
The preponderance of aircraft were of the heavier, longer-range, larger-capacity variety of personal or corporate jets. We averaged the
fuel consumption for a basket of business jets from the Citation Bravo up to the Gulfstream 550.* The eleven jets sampled average
674 gallons (4,517 lb) of jet fuel for a 1,000 nautical mile trip, which is a standard operational and cost estimation mission in the jet
fleet management business. This also equals the performance of a Bombardier Challenger 604 and 1.11 times the fuel consumption of
a Raytheon Hawker 800 XP — both typical of the variety of aircraft flying into Aspen. **
It is likely that the selected baseline trip of 1,000 nm is conservative relative to the origins and destinations of the “average” flight to
Aspen. It is, however, a standard industry measure, and fuel consumption data will be published annually for a variety of production
aircraft.
Another conservatism in the 2004 fuel and carbon emissions estimate is that we have used the fuel performance of mostly new
production models, and the fleet average is somewhat lower “mpg” than the new aircraft. Specific fuel consumption for each type of
aircraft has (and will continue to) improve.
Finally, we have not accounted for the other atmospheric impacts of buring jet fuel at high altitudes, namely vapor trail formation,
particulates such as sulfur dioxide, NOx, and other impacts on the radiative balance of the atmosphere. Some researchers estimate
such impacts are approximately 1.5 to 3.5 times the direct impact of the carbon emissions. See IPCC 1999.
* Citation Bravo (371 gallons) up to the Gulfstream III (1,069 gallons). Other aircraft performance in our review (all fuel consumption
per 1,000 nm mission): Lear 45 (433 gallons); Lera 60 (477 gallons); Hawker 800XP (604 gallons); Citation X (576 gallons); Falcon
2000 (540 gallons); Challenger 604 (674 gallons); Gulfstream 550 (834 gallons), Gulfstream G-III (1,069 gallons); Gulfstream G-IV
(972 gallons); and Gulfstream G-V (865 gallons). See Business & Commerical Aviation (2004) Operations Planning Guide, pp. 56-85. A
“mission” includes fuel consumed for a typical sequence from start, taxi, clearance, take-off, climb, cruise, descent, landing, and taxi
to stop.
** The Hawker 800XP specification sheet (www.raytheonaircraft.com/hawker/) lists trip fuel used for a 1,000 nm trip (with 4
passengers) as 4,069 lb. The flight time is 2 hrs 25 minutes, or 4,069 lb / 6.7 lb/gallon = 607 gallons; 607 gallons / 145 minutes =
4.19 gallons per minute. This means an average fuel rate 1.90 “miles per gallon” for the whole trip, with better cruise performance
once the aircraft is at altitude. With six passengers, this equates to 1.85 lb CO2 per passenger-mile (compare to air carriers’ average
of 0.574 lb CO2 per passenger-mile).
A Gulfstream G-IV will use ~0.97 gallons fuel per nm, or 1.18 statute mpg, and a 1,000 nm trip would emit 10.25 tons of carbon
dioxide (2.54 tonnes carbon). With eight passengers this means an emissions rate of 2.23 lb CO2 per passenger mile. This “Hummer
of the Sky” is outperformed (in terms of fuel, not time efficiency) by a street Hummer H2 at, say, 9 mpg and four on-board: 0.54 lb
CO2 per pax-mile. Or rouhly equivalent if the Hummer is transporting only the driver (2.17 lb CO2/pax-mile).
However, “the larger the aircraft the fewer the passengers” seems to hold true at Aspen’s GA operations. Gulfstream aircraft — often
configured for eight or nine passengers — typically carry one or two passengers. With two passengers, a 1,000 nm trip in a G-II would
consume about 1,220 gallons of fuel and emit 12.84 tons of CO2 or 11.2 lb CO2 per passenger-mile (25,680 lb CO2 / 1,151 miles /
2 pax).
The G-IV will use an average of 7.1 gallons per minute, or 7.6 ounces per second. On take-off, however, the older G-II will consume
12,000 lb/hr at full thrust (three times cruise fuel consumption of 4,000 lb/hr). 12,000 lb/hr = 200 lb/min = 3.33 lb/sec = 0.5
gallons/sec = 10.5 lb CO2/sec = 1.3 kgC/sec.