January 24, 2014 – Vol.18 No.45
 

Question. What Happens to Jet Exhaust?
by Bruce Mulliken, Green Energy News

 

This I've wondered for years. What happens to copious amounts of burnt jet fuel that comes out of the aft end of the most fuel hungry beasts on the planet? Per flight an airliner can gobble up thousands of gallons of fuel. What happens to the waste of combustion – all that exhaust?

Think about it. Cruising along at about more than 500 miles per hour and 7 miles from terra firma, jet aircraft are injecting ton after ton after ton of water, unburned hydrocarbons, carbon dioxide, and other pollutants, into the very thin air nearer the upper end of the Troposphere than to the ground. What happens to it all?

This is already known. Under certain conditions water vapor, and presumably some particulates of burned fuel to act as nuclei for water condensation, then ice formation, form to create contrails which can later become high thin clouds. On busy air routes these wispy clouds can reflect a little sunlight and, trap a little heat too, I would guess.

But what about the CO2 and other stuff? I'm pretty sure it doesn't float off into space. Heavier pollutants, like bits of unburned fuel or black carbon, will eventually succumb to the grip of gravity and fall to the ground. But CO2 is a gas. Where does it go?

Down here at ground level most carbon dioxide that's removed from the air is done by plants and organisms in water. But at 6,7, or 8 miles in the air, carbon dioxide doesn't come in contact with tree leafs or plankton in the water, at least anytime soon after its blown into the air by jet engines at these high altitudes.

True, the atmosphere is a turbulent thing (it's fairly windy) but it's not that turbulent. It's not as if everything in the air gets constantly churned up and is evenly mixed all the time. Generally speaking things that go into the air go in irregularly and in different concentrations. There are higher concentrations of CO2 in cities where there are lots of plumes and puffs of exhaust, than in rural areas where few live. There is no mechanism to equally and instantly mix up all the stuff we put into the air. If all of the pollutants, including CO2, had a different color so that we could see them from space, our planet would probably look more like Jupiter with its colorful gases churning about. (Earth could very have looked like Jupiter in its early days: As a gas giant.)

The CO2 from burned jet fuel will take a long time to get down 7 miles to anywhere near where that it might be sucked out of the air by trees and such. While it's miles from the surface it's contributing to the greenhouse effect, is it not? How much? More than we think? At least CO2 emitted by cars along a tree lined road has at least has some chance to be removed. CO2 from jets doesn't have that luxury.

This is a completely wild thought, but if it turns out that jet aircraft exhaust has a greater impact on climate than currently thought? If it did the fix might be relatively easy: Build electric aircraft. Unlike getting people to switch to electric cars, electric planes might actually be met with open arms by the airline companies. After all, expensive and unstable fuel is the thorn in the side of airlines. They just want to fly planes, carry passengers and make money - things they can control - not diddle around dealing with something they have no control over: The cost and supply of fuel. Electric planes would save them from the constant pain they go through. In the end, stable predictable energy costs might actually lower the cost of flying and allow airlines to reduce the number of sardines in the can (us) and make flying fun again.

Then there's climate change. If jet airliners contribute to a warming planet, and the warming planet is causing wacko weather, which in turn causes flight delays, cancellations and thus lost revenue and profits, it would be in the airlines best interest to walk away from burning fossil fuels.

Finally here's another wild thought without base: Looking at the temperature anomaly curve of the planet - the famous hockey stick - temperature anomalies really get cooking at the beginning of the jet age, the early 1960's. Just sayin'.

 

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