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Perhaps aviation biggest challenge....

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Perhaps aviation biggest challenge....

Old 22nd May 2019, 21:13
  #41 (permalink)  
 
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Originally Posted by jantar99 View Post
Energy density per kg and per litre are important in aviation.
Which, according to https://hypertextbook.com/facts/2005/MichelleFung.shtml and https://hypertextbook.com/facts/2003/EvelynGofman.shtml is better for hydrogen.

Storage and safety are legitimate concerns, which is why I mentioned "working on a safe way"

The effect of water emissions at high altitude are not so great in terms of contrails, that is indeed what some studies have suggested. However, the water formed by hydrogen combustion might just freeze and fall to the ground. I'm not saying that this is happening, I'm saying that it would be worth studying.
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Old 22nd May 2019, 21:22
  #42 (permalink)  
 
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Originally Posted by .Scott View Post
The long answer is all those IPCC (Intergovernmental Panel on Climate Change studies that examine climate change and its causes very, very extensively.
I certainly haven't read all of those studies and reports. But I have read enough to get a good picture.

1) Global warming is a fact. In Physics, something is considered "discovered" if without it, the likelihood of the experimental results it at least 5 standard deviations away from normal. The evidence for global warming goes way beyond that criteria.

2) To go much further, we need a climate model. And we have many of these - none are fully convincing. But there is one sure thing that can be said: CO2 is a major factor. You can create models that include changes in water content, solar effects, contrails, etc - but if you don't include CO2 in your model, your model will not work.

3) You will often hear statements such as: "If we don't keep CO2 levels down, we will loose 1 million species over the next century." In most cases, they are based on good arguments and are good likelihoods. But there are a few problems with these statements.
They suggest that if we do control CO2 the bad result will not happen - in most cases, that's just false. In other cases, it is pushing the models well beyond their predictive powers. For example, even if we miraculously brought CO2 level back to what they were in 1900, that might not be enough to end climate change. Agriculture pumps huge amounts of water into the air and water is a far more potent green house gas - though one that is not persistent.
They also suggest that what we would need to do to avoid or reduce the consequence would be worth it. In the extinction example, they don't mention that that would leave 2.5 million species. I think most people would be happy with 2.5 million species in exchange for job security.
it all depends if humans are one of the extinct species. The planet does not care. Human activity caused by too many humans is the real problem, every other ďsolutionĒ is just noise avoiding the root issue. Finite resources, infinite expectations, result, extinctions.
in my lifetime, to date, the human species has doubled. Btw I have no progeny.
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Old 22nd May 2019, 21:47
  #43 (permalink)  
 
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Originally Posted by bzh View Post
Bio fuel will take over as cost is lowered and black oil cost increased, the Arizona desert will be covered by Algae farms, Pacific salt water pumped on way and biofuel the other...

https://www.flysfo.com/media/press-r...aviation-fuels
What right do we have to cover the Arizona desert with algae farms? Must every piece of dirt be developed? I suggest covering the LA basin with algae farms if that's where you want bio fuel.
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Old 22nd May 2019, 21:48
  #44 (permalink)  
 
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Originally Posted by AAKEE View Post
I looked at the OP only two posts...
Some lazy journo doing their "research".
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Old 22nd May 2019, 21:50
  #45 (permalink)  
 
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Originally Posted by cappt View Post
Some lazy journo doing their "research".
Who cares - it's triggered a good debate.

"From small acorns are mighty oaks grown" and all that...
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Old 22nd May 2019, 23:02
  #46 (permalink)  
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Originally Posted by cappt View Post
Some lazy journo doing their "research".
you could not be more wrong - airline captain with huge interest in tackling this issue.

I dont post often. But have not seen any professional discussion about this - so here is my 2nd post. But its not about me
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Old 22nd May 2019, 23:23
  #47 (permalink)  
 
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Originally Posted by CargoOne View Post


bio fuel doesnt come for free. It takes large territories to grow thus reducing space available for the food-related agriculture and as far as I remember the process is producing co2 too... it is like Tesla - it doesnt make the world greener it is rather shifting pollutions to a different territories.
Precisely.

Out of sight, out of mind.

Tesla has tapped in to that part of the human psyche that comforts people thinking they aren't part of the problem.

Until base load electricity is generated from renewable energy sources, then plugging a 'green car' into the electric grid is just shifting the pollution to somewhere else. That somewhere else is often a power plant using fossil fuel.

Bio-fuel does exactly the same thing for the aviation industry. It provides comfort.
The marketing PR release say Airline X bought 30,000,000 gallons of Bio-fuel. Sounds impressive, yet in a few weeks that huge amount of fuel is gone. For the remainder of the year billions more gallons of jet fuel are fueling the aircraft.
The industry does not have a viable alternative. Assuming continued efficiency advances into perpetuity is fanciful.
Other purported 'alternatives' come at huge opportunity cost and that is ignored in favour of the 'technology will fix it'

IFF, the world focuses more attention of big emitters, then the airline industry may face a problem that PR won't fix; declining demand and additional cost pressure.


As Emma Thompson found out recently, saying one thing but doing another does get noticed.

https://www.dailymail.co.uk/news/art...-New-York.html
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Old 23rd May 2019, 06:47
  #48 (permalink)  
 
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I think it is hilarious that very basic and well understood physics, like the scattering of electromagnetic radiation by gas molecules, can be dismissed as wrong by people whose life depends daily on far more complicated physics, like the interaction of gas molecules at high densities and velocities.
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Old 23rd May 2019, 07:24
  #49 (permalink)  
 
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But this isn’t a very basic and well understood issue we are discussing. There is consensus, and it would be an interesting personality type to happily swim against the tide of scientific opinion at this stage, but climate change is not at all basic and not at all well understood. Why? Because we can’t go into a Lab and reproduce experiments ( too many variables) and instead have to rely on models that in a decade will no doubt be considered crude.
The wiggle room for conjecture and argument is what makes this something we debate. If it was straight forward science ( like scattering of electromagnetic radiation by gas molecules) there would be no debate in mainstream society.
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Old 23rd May 2019, 08:19
  #50 (permalink)  
 
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Originally Posted by 73qanda View Post
But this isnít a very basic and well understood issue we are discussing. There is consensus, and it would be an interesting personality type to happily swim against the tide of scientific opinion at this stage, but climate change is not at all basic and not at all well understood.
Really? Hereís a list of 200 worldwide bodies that hold it to be a fact that human caused climate change exists (almost every credible scientific organisation on earth):

List of Worldwide Scientific Organizations

When I looked at lists of scientists who deny human caused climate change I found no serious bodies prepared to deny it, scientists in other fields apart from climate science, a lot linked to the mining and oil industries and a lot connected to far right politics. And very few overall at that.

97% of scientific papers published recently find human caused climate change to be real. For the remaining 3% they were excluded because, like any good piece of science, their conclusions and methods were found, on peer review, to be flawed or contain significant errors. Thereís no debate amongst the credible scientific community, only amongst special interests with agendas:

Those 3% of scientific papers that deny climate change? A review found them all flawed

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Old 23rd May 2019, 08:44
  #51 (permalink)  
 
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Originally Posted by 73qanda View Post
If it was straight forward science ( like scattering of electromagnetic radiation by gas molecules) there would be no debate in mainstream society.
1. The mechanism behind green house gases literally is exactly that, and it is straight forward to show it experimentally.
2. What is difficult to model is precisely where what will happen as a result, but the thermodynamics are unforgiving in that somewhere something must happen to accommodate the excess energy.

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Old 23rd May 2019, 09:19
  #52 (permalink)  
 
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Dr Dre, I don’t think you understood the intent of my post ( maybe my fault).
I’ll try again when I get to the hotel but I wasn’t saying that there isn’t consensus, I was saying it isn’t basic, and it isn’t well understood. It is in fact incredibly complex with many many variables each having an effect on each other. ( as I’m sure you’re aware).
If someone agrees that there is man made climate change it doesn’t mean they understand man made climate change, or that it is basic. I was trying to make the point that because you can’t repeat an experiment in a Lab 500 times and say “ see.....global temperatures are going to rise by 2.3 degrees in the next 50 years” , we have a debate in society about whether or not climate change is as big a problem as most are saying it is. The only reason we can’t predict the future climate with certainty is because of the incredible complexity of the interactions that go to make it up. It isn’t basic and it isn’t well understood.
TehDehZeh
1. The mechanism behind green house gases literally is exactly that, and it is straight forward to show it experimentally.
I agree but the debate around climate change is much more complex than that due to the large number of variables. A good example of this is when people ( quite legitimately) ask why we are under such time pressure to limit CO2 emissions when they have been many times higher in the earths long history without accompanying high temperatures. This can be explained of course but only through estimates of solar radiation emission from the same time periods....complex, not well understood. Not able to be proven. Would you agree?
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Old 23rd May 2019, 09:30
  #53 (permalink)  
 
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I would say that, to the contrary, precisely because it is very hard to forecast just how nature will dump the excess energy on us, it is vital to keep the amount of excess energy low.
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Old 23rd May 2019, 10:03
  #54 (permalink)  
 
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Originally Posted by 73qanda View Post
we have a debate in society about whether or not climate change is as big a problem as most are saying it is. The only reason we canít predict the future climate with certainty is because of the incredible complexity of the interactions that go to make it up. It isnít basic and it isnít well understood.
Well I donít for one second claim to know more than the vast majority of climate scientists in the world (unlike most deniers). But when all of the worldís pre-eminent scientific bodies are saying it is essential we, as a planet, act quickly and decisively to stop what is happening I think itís time governments started listening and acting on their recommendations.

I donít know whether Aviation has a big part to play (although new technologies with electric propulsion and fuel reduction are interesting) and I certainly donít know what the exact solutions to the problems are but itís now increasingly clear something must be done.

Last edited by dr dre; 23rd May 2019 at 10:31.
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Old 23rd May 2019, 10:13
  #55 (permalink)  
 
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If the IPCC is correct then the consequences of inaction are horrendous, potentially catastrophic and fatal for our species. If the IPCC is wrong, but we still take their recommendations the consequences are survivable, but society will change.

Are you a gambling man? (rhetorical)
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Old 23rd May 2019, 10:29
  #56 (permalink)  
 
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Originally Posted by cappt View Post
What right do we have to cover the Arizona desert with algae farms? Must every piece of dirt be developed? I suggest covering the LA basin with algae farms if that's where you want bio fuel.
That is typical of many folk - whatever solution is found to make clean energy they will object to it.

Nuclear - dangerous and ďno waste in my back yardĒ
Wind - looks bad and kills birds
Sun- looks bad and diverts sunís warmth from nature
Hydro - takes natural land and habitat and causes stress to rock structures
Plant solutions - not here
etc.

Often these are the same environmentalists who object to traditional fuels and methods.

Only solution is to give up the rat race and go bush...
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Old 23rd May 2019, 10:32
  #57 (permalink)  
 
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What these tree huggers, and those that naively want is to return to the era of the horse and cart, seem to forget is there are many very poor countries whose only source of income is tourism. By drastically reducing air travel, you cut these people off at the knees and create another crisis. Without travellers dollars, many nations with poor economies will inevitably resort to more nefarious or polluting means to raise income.
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Old 23rd May 2019, 10:34
  #58 (permalink)  
 
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Originally Posted by beardy View Post
If the IPCC is correct then the consequences of inaction are horrendous, potentially catastrophic and fatal for our species. If the IPCC is wrong, but we still take their recommendations the consequences are survivable, but society will change.
That sort of reminds me of this:



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Old 23rd May 2019, 10:37
  #59 (permalink)  
 
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Without travellers dollars, many nations with poor economies will inevitably resort to more nefarious or polluting means to raise income.
That assumption may or may not be true, there is no proof. You are using it to justify your opinion, since it may not be true your opinion may not be true.
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Old 23rd May 2019, 10:38
  #60 (permalink)  
 
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Originally Posted by BehindBlueEyes View Post
What these tree huggers, and those that naively want is to return to the era of the horse and cart, seem to forget is there are many very poor countries whose only source of income is tourism. By drastically reducing air travel, you cut these people off at the knees and create another crisis. Without travellers dollars, many nations with poor economies will inevitably resort to more nefarious or polluting means to raise income.
Thatís quite a strawman. No one except extremists are calling for a ban on air travel.

What can be done is for more research and development in electric propulsion, alternative fuels, more aerodynamic airframes, fuel reduction methods, more efficient flight paths, less holding, etc.

Isnít that something to aim for?
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