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Aviation industry tries to go green

phys.org

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Re: Aviation industry tries to go green

#101

Post by Leherenn »

belorn wrote: post #67
jamil7 wrote: post #56

Is a large part of this also a political issue? with subsidies and tax breaks on fuel the aviation industry is not really incentivised to innovate and cosumers are not incentivised to seek other modes of transport since flying is often the cheapest and fastest.

Every single mode of transport is subsidized so its hard to say if air transportation is getting more or less incentives. Using Swedish numbers and some estimates. Tax on car owners only pay around 1/3 of the road network. The ticket price on train, according to a person working in that space, said that the ticket paid about 2/3 of the costs that the train company paid for any given trip. The train network also get i…

I have no data to back this up, but I would say train is the most subsidised.

The infrastructure required for trains, as well as the maintenance of those tens thousands of miles of tracks have to dwarf whatever tax break planes get on fuel.

Plus airports scale much better than train stations, once it's built you're automatically linked by the most efficient route to everywhere else in the world.

Re: Aviation industry tries to go green

#102

Post by [deleted] »

rezgi wrote: post #90
dangus wrote: post #79

Earlier quoted context omitted.

I’d argue that not a lot of air flights in the United States would be served better by train when you think of some of these distances. The east coast is already covered by an excellent train line. That line could be made faster to be more competitive but it already handles far more passengers than air. Now let’s look at some other popular routes. Chicago to LA? 2,000 miles. That would take around 10 hours nonstop on…

Chicago > LA flights look like they take 5h (time on the plane.) Add the time to go through the security theater, transfers from and to the airport, and you're not that far off from how long it would take by train. I'm not even considering the delays because of weather, technical, etc. Trains don't have as much potential for being delayed (train schedules have a lot less variance because the track is pretty much fixe…

[deleted]

Re: Aviation industry tries to go green

#103

Post by cgrealy »

ShorsHammer wrote: post #49
cgrealy wrote: post #8

The big win would obviously be electric aircraft, but I doubt we'll see that in my lifetime (barring a massive breakthrough in battery technology). The problem is even the best batteries have a much lower energy density compared with traditional fuels. Also, a battery that weighs 100kg when full weighs pretty much 100kg when empty. Real Engineering did a pretty good video on the topic https://www.youtube.com/watch?v=…

It is a certainly an untenable problem for longhaul, though with the current pace of advances in battery tech (mainly driven by smartphone companies of all things) shorthaul electric flight could certainly find some support in the near future. Electric offers dramatic reductions in engine noise and maintenance, along with far more reliability/safety. I can see that being a selling point to some aviation execs, Norway…

I think .5 micrograms falls under "pretty much" :D

But that was interesting to read... thanks!

Re: Aviation industry tries to go green

#104

Post by chrisseaton »

ncmncm wrote: post #99
yason wrote: post #61

Earlier quoted context omitted.

I can see this in my car. If the engine isn't warmed up, pulling into traffic often meant it would stall right in the middle of the lane I'm trying to cross, leaving me vulnerable to being rammed. Sounds like your car is broken if that really happens. A functioning car engine won't stall when pulling into traffic because of cold oil. Surely it will just wear out horribly and its lifespan will shorten to a fraction if…

Cold oil lubricates better. It has higher viscosity, meaning it takes more energy to move it out of the way. As it warms up, its lubricating power decreases, but not too much, and its viscosity decreases, enabling better engine efficency. A cold engine is less efficient, but only for a short time, until it heats up. Oil too thick to pump rarely happens in normal life. In arctic and subarctic conditions people use ele…

> Cold oil lubricates better.

By this logic a solid would be the best lubrication, which it clearly isn’t.

Re: Aviation industry tries to go green

#105

Post by ncmncm »

chrisseaton wrote: post #104
ncmncm wrote: post #99

Earlier quoted context omitted.

Cold oil lubricates better. It has higher viscosity, meaning it takes more energy to move it out of the way. As it warms up, its lubricating power decreases, but not too much, and its viscosity decreases, enabling better engine efficency. A cold engine is less efficient, but only for a short time, until it heats up. Oil too thick to pump rarely happens in normal life. In arctic and subarctic conditions people use ele…

> Cold oil lubricates better. By this logic a solid would be the best lubrication, which it clearly isn’t.

If you had solid oil -- i.e., wax -- between your moving parts, metal would not be touching metal, so no wear, but the force needed to move the parts would be large. With cold but not solid oil, the effect is similar, but less.

Re: Aviation industry tries to go green

#106

Post by leetcrew »

ed_balls wrote: post #69
leetcrew wrote: post #65

Earlier quoted context omitted.

it solves the greenhouse gas issue, but burning hydrogen still produces NOx.

Is NOx an issue if it's far away from humans?

probably not, but the plane still has to takeoff and land sometimes.

tbh, I'm not sure exactly how hydrogen combustion compares to hydrocarbon combustion in terms of environmental harm. I suspect it's still a lot cleaner overall. a lot of people think hydrogen combustion is totally clean and just creates water as exhaust, so I like to point this out.

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