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It turns out planes are even worse for the climate than we thought

newscientist.com

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Re: It turns out planes are even worse for the climate than we thought

#11

Post by toomuchtodo »

m463 wrote: post #10
originalvichy wrote: post #8

During the 9/11 aircraft grounding, climatologists had a pretty unique chance to measure temperature variance compared to historical data. Just the few days of data showed that days became warmer and nights became cooler. I pretty much had no idea that just trails could impact weather so noticeably until I read up on this experiment. As a european citizen I’d vote for all subsidies that go towards intra-European air…

I think there is probably some low-hanging fruit with airplane design. Techniques to prevent or reduce contrails by modifying the engines or the flight times or flight paths of planes.

There’s profit to be had if you can use meteorological modeling along with a carbon tax to send market signals to air travel consumers.

Re: It turns out planes are even worse for the climate than we thought

#12

Post by thecount122195 »

avmich wrote: post #7
mc32 wrote: post #6

Earlier quoted context omitted.

Aren’t those less efficient and less reliable as well? I don't see going back to props. What's the mean time before overhaul on both? Also lower ceiling.

Rockets - perhaps, for today, but maybe they could be improved. Propeller planes - why? They were used for long time and many technologies are quite mature.

Propellers have a fundamental speed limit on them, the tips can not exceed the speed of sound or else shock waves form which cause the efficiency to drop off sharply, as well as creating massive noise pollution from the sonic boom constantly coming off the propeller. Todays commercial "jet" engines are actually closer related to propeller planes than pure jets, turbofans provide the majority of their thrust from the ducted fan rather than the jet exhaust coming out the back.

Re: It turns out planes are even worse for the climate than we thought

#13

Post by astrodust »

originalvichy wrote: post #8

During the 9/11 aircraft grounding, climatologists had a pretty unique chance to measure temperature variance compared to historical data. Just the few days of data showed that days became warmer and nights became cooler. I pretty much had no idea that just trails could impact weather so noticeably until I read up on this experiment. As a european citizen I’d vote for all subsidies that go towards intra-European air…

The other thing astonishing about 9/11 was how quiet it was. The ambient white noise of aircraft was non-existent, and it is considerable in any major urban area.

Re: It turns out planes are even worse for the climate than we thought

#14

Post by astrodust »

avmich wrote: post #5

Wonder how much contrails are created by rockets? If we'd move the travel above the atmosphere, how much could be saved? An alternative is to move back to slower propeller planes, maybe with electric motors (improving over Tu-95?) but that would increase flight times.

A large part of the propulsion of a modern turbofan jet plane is provided by so-called "bypass" air, air that flows around the core of the engine. If you can spin those turbine blades electrically you can get nearly as much thrust as the jet version.

The challenge is in finding out how to do this. You could do this with some other mechanism if you can come up with a way of storing lots of energy in a liquid or solid that isn't too heavy.

Some discussion here: https://aviation.stackexchange.com/questions/26910/could-an-...

Re: It turns out planes are even worse for the climate than we thought

#16

Post by sjg007 »

astrodust wrote: post #13
originalvichy wrote: post #8

During the 9/11 aircraft grounding, climatologists had a pretty unique chance to measure temperature variance compared to historical data. Just the few days of data showed that days became warmer and nights became cooler. I pretty much had no idea that just trails could impact weather so noticeably until I read up on this experiment. As a european citizen I’d vote for all subsidies that go towards intra-European air…

The other thing astonishing about 9/11 was how quiet it was. The ambient white noise of aircraft was non-existent, and it is considerable in any major urban area.

I think people underestimate just how bad noise pollution is for you...

Re: It turns out planes are even worse for the climate than we thought

#17

Post by averros »

160 mW/m2? The average solar irradiation at the surface is around 500 W/m2. Oh, and radiative thermal flux is 4th degree of temperature (so this is equivalent to, well, 0.008% or 0.023C increase in temp to compensate). Talk about completely inconsequential.

Re: It turns out planes are even worse for the climate than we thought

#18

Post by saltcured »

avmich wrote: post #5

Wonder how much contrails are created by rockets? If we'd move the travel above the atmosphere, how much could be saved? An alternative is to move back to slower propeller planes, maybe with electric motors (improving over Tu-95?) but that would increase flight times.

Most of the visible contrail seems to come from engine emissions, though you can also see condensation effects purely from the dynamic pressure changes around the plane. Those are more obvious with fighter jets and acrobatic planes though, where they are generating more severe aerodynamic effects rather than sustained level flight.

Assuming the visible contrail correlates well with the part causing climate effects, an electric ducted fan might be a big improvement, by removing the combustion emissions. I don't know if some other fuel-burning engine could be combined with a ducted fan and sufficient emission controls to also serve this purpose.

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