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Relative Environmental Impact?

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Relative Environmental Impact?

Old 29th Mar 2006, 23:40
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Relative Environmental Impact?

Aviation is now increasingly in the sights of the environmentalists.

Air transport is known to be a major contributor of nitrogen oxides, unburned hydrocarbons and carbon monoxide, is claimed to be the greatest single source of CO2 emissions, and is claimed to be uniquely dangerous because of the fact that its emissions are high in the atmosphere. Aircraft released more than 600 million tonnes of CO2 into the atmosphere in 1990. Aircraft currently cause about 3.5% of global warming from all human activities.
Aircraft greenhouse emissions will continue to rise and could contribute up to 15% of global warming from all human activities within 50 years.

Air Transport is never going to go away, but I wondered whether there was ant significant difference in emissions, per passenger/mile between piston-engined, turboprop and modern high bypass turbofan powered aircraft of similar capacity and range? And is there any technical possibility of using lower emission eco-friendly fuels in new piston engines - and would there be any environmental advantage in doing so?

We're probably never going to return to the days of struggling through the weather at propliner heights, nor of my father's RAF York taking the best part of a week to get to Singapore, but could piston or turboprop powered aircraft advantageously replace jets on shorter sectors?

I'd rather see aviation reacting to these challenges and solving some of the problems than see it being forced to meet its external environmental and social costs in full, through huge taxes on fuel and tickets, or being subjected to artificially subsidised and supported rail transport. We're in the 21st Century, after all, and while we've already lost supersonic transport, I'm loathe to see us going back to the 19th Century's favoured means of travel. Nor would I be content to see aviation being priced out of the reach of ordinary people.

I know one should never post after a night in the pub, but I've asked myself these questions when sober, and I don't know the answers.

But I'll bet many of my fellow PPRuNers do.....
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Old 30th Mar 2006, 02:03
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Jacko

ATR and Bombardier would argue that props already replace jets on short sectors - their order books are ticking over nicely with $60 oil while BBD has halted their CRJ200 line and are looking at stretching their Q400 to 90 seats.
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Old 30th Mar 2006, 09:02
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I wonder what the seat/mile emissions are like compared to a 737-900 or a CRJ?
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Old 30th Mar 2006, 10:18
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Jackonicko:

The graph below is from the ATR website - it partially answers your question. (Note that the "train" figure includes the worst-case type of electricity generation from the emissions point of view.) Unfortunately the assumptions are not spelt out on the website, but based on this document elsewhere on the ATR site , the aircraft seems to be assumed to be 100% full and the car to have two passengers.

Cheers
C.


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Old 30th Mar 2006, 11:08
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Originally Posted by Jackonicko
I'd rather see aviation reacting to these challenges and solving some of the problems than see it being forced to meet its external environmental and social costs in full, through huge taxes on fuel and tickets, or being subjected to artificially subsidised and supported rail transport.
So who do you think should meet its external environmental and social costs?
Regarding taxes - just compare those on fuel for avaiation and those on fuel for ground transportation. So the question is, what is currently beeing subsidised in this aspect.

The fuel efficiency calculation from the ATR website is just a joke.
Comparing a 100% full modern plane against a car with 2 pax consuming 9l/100km...

Anybody knows on what miracle that emission diagram is based on?
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Old 30th Mar 2006, 11:48
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Aviation will not escape the imposition of taxes for, I suggest, one simple reason. The industry is seen as that - an industry - whereas cars are seen as personal and individual. It is easier to tax a 'faceless' industry than to tax individuals. It won't take long and it will start in Europe and cover all carriers who operate there, be they intra-European or inter-Continental. Certainly within ten years and probably sooner.
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Old 30th Mar 2006, 14:48
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Cyrano,

Even taking into account the source of that diagram, it's interesting. With four pax in the car (you can bet the aircraft are assumed full to bursting) it would still look bad CO-wise, while the train would look more similar to the ATR.

But it does seem to show a stark difference between the ATR and the 70-seat jet.

I still wonder how a modern piston engined airliner would compare, and how/whether a next gen piston could improve.

It certainly looks as though there would be an environmental case for encouraging greater use of turboprops on short haul routes - I wonder what the range figure would be at which turboprops would not be acceptable to pax?

Perhaps the answer would be to tax emissions rather than fuel?
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Old 30th Mar 2006, 15:09
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And what if we were considering new high speed turboprops - the Tu-95 showed what was possible in the 1950s, with an environmental 'push' an advanced turboprop could surely operate at height, in comfort, and at speeds that would make fairly long sectors practicable, and all at lower seat/mile and environmental costs than the jets?
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Old 31st Mar 2006, 15:18
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I agree. For me, the most interesting part of the recent face-saving Bombardier "we've-postponed-the-C-series-but-not-killed-it-oh-no-sirree" announcements was the fact that they are planning a stretch of the Q400. I think that as fuel prices stay high (or rise further) and as environmental-impact issues gain more importance, larger turboprops will become more attractive. A few years ago, the Q400 line was on its last legs - I remember seeing an article along the lines of "The Q400 will probably be the last turboprop airliner ever built." How times change.


Given that Dornier managed to design a common wing for the 328 (prop) and 328JET, I don't suppose there's any chance that the smallest model of the next-gen 737 replacement or A320 replacement could be designed to use (large) turboprops as an alternative powerplant (with conventional turbofans or geared fans available for operators who need the higher speed for longer sectors)? Boeing are reported to be considering a new design down as low as 90-110 seats, and I think a couple more years of high oil prices and looming emissions-related taxation may start to make turboprops an attractive option at least for the shorter sectors currently operated by 737s/A320s. That's my hope anyway.

C.
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Old 31st Mar 2006, 15:46
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The biggest problem with turboprops from the pax point of view, based on discussions with people in airport lounges, is the noise and vibration with the derivative perception that turboprops are less safe, as well as being less comfortable. I know when paxing I avoid a seat in the rotation plane of the prop and to a lesser extent the engines. Seems this may take some work to overcome, if for no other reasons than so many years were spent selling the punters on the smooth, quiet jet service.

Maybe the place where there is more to be made on this is the all cargo carriers. FEDEX launched on the Cessna Caravan, wonder what the economics are? When FEDEX's replacement for MD-11s etc is a turboprop we'll know the time has come (maybe)
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Old 31st Mar 2006, 22:12
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Many PPRuNers will think of aircraft like the 250 kt Jetstream or the 300 Kt Hercules when they think turboprop - or will summon up claustrophobic high winged turbine engined airliners like the F27 or Dash 8.

But turboprops don't have to be like that, do they?

The Tu-114 (the civvy 'Bear') could reach 490 kts, and cruised at 436 kts.

The aircraft had a ceiling of just under 40,000 ft, and a range of almost 5,000 miles.

And that's near A340 levels of performance from a turboprop airliner with its feet firmly planted in the 1950s - what could be achieved with modern aerodynamics, modern engines and modern props?

Better than the 460-485 kt A400M, I'll be bound.
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Old 2nd Apr 2006, 18:54
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The Tu-95 had unprecedented noise levels as well as performance. I remember reading that some Western fighter pilots reported actually hearing the Tu-95's prop roar above the noise of their own aircraft!

As much as I love air travel, the fact that aviation fuel is not taxed is a massive anomaly in transport policy and a significant distortion of the market. Rail travel uses a small fraction of the fuel per passenger mile, despite offering the passenger vastly improved comfort and amenities (space, restaurant, etc.), but is having a tough time competing with low-cost airlines because the latter have dirt cheap fuel. To dismiss rail as 19th century technology is, I think, rather short sighted, considering the likes of the TGV and progress such as this.
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Old 2nd Apr 2006, 21:59
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Are you also going to tell me that rail travel is not subsidised? And how are grants and EU development assistance issued for the puchase and construction of new railways? And do they get their VAT back on their fuel costs? And what of the passenger tax that rail travellers pay? Level playing field yes, we can hold our own - but don't let the tree huggers and yoghurt knitters near aviation. Before we know it, we'll all be eating lentils and living in ditches whilst the railways trundle on with our cash, as usual.
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Old 3rd Apr 2006, 05:55
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With due respect for your traditional views, Piltdown Man, "tree huggers and yoghurt knitters" is highly inappropriate language to describe the overwhelming scientific consensus that humankind has caused, and continues to cause, irreparable damage to the environment by burning hydrocarbons. Furthermore, it is almost unanimously agreed by these scientists (who spend their lives studying these phenomena and are in a far better position to know than you or I) that a significant reduction of our eco-footprint would result in a significant reduction in damage, namely, a slowing of global warming.

Regarding rail subsidies, I am not in a position to know the exact nature of government incentives to promote rail, but in a climate of zero tax on aviation fuel, I would certainly hope that some level of subsidisation is offered to rail. But it could never amount to more than a drop in the bucket compared to the effective subsidisation aviation receives due to no fuel taxation. I'm sure you're aware that fuel costs are already a large proportion of overall aviation costs; if fuel costs were increased by literally an order of magnitude you can easily see that aviation's viability over short routes on land would suddenly be thrown into great doubt.
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Old 3rd Apr 2006, 07:34
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Originally Posted by HCB
overwhelming scientific consensus that humankind has caused, and continues to cause, irreparable damage to the environment by burning hydrocarbons. Furthermore, it is almost unanimously agreed by these scientists (who spend their lives studying these phenomena and are in a far better position to know than you or I) that a significant reduction of our eco-footprint would result in a significant reduction in damage, namely, a slowing of global warming.
Sorry not true. There is no overwhelming consensus, or even broad agreement among the scientific community about human effects on global warming. Climate change is happening and always will, but exactly what our contribution to it is is still very much up for debate.
the problem is that no rational debate has taken place with all views aired and a common consensus reached. There are just some who shout louder than the rest, and the media being very biased in their reporting.
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Old 3rd Apr 2006, 08:15
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I also cannot completly calculate and compare the subsidisation of each transport system. But when I recognise that the tickets for a lot of flights are much cheaper than the train tickets to the airport - I doubt that this is only due to the unbeatable efficiency of air transportation. OK - there are certainly many more reasons for that, but the zero fuel taxation is certainly one major point that can hardly be justified.

Jonty - so the Kyoto Protocol is ratified by 162 countries just to face a natural random phenomenon?
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Old 3rd Apr 2006, 08:20
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Well, Jonty, you can claim that, but it doesn't make it so. Even the airline industry itself, a party with highly vested interests and therefore likely to have a high degree of bias, now publicly admits that aviation contributes to man-made global warming. Given the results of the Intergovernmental Panel on Climate Change, the most comprehensive study on climate change to date, it would be patently absurd for an airline to continue to maintain innocence in this matter. As such, BA has published a simplified summary of its actions on its website, available here.

Specifically, BA states that, "…aviation was responsible for 2% of CO2 emissions - the most important greenhouse gas - and around 3.5% of man-made global warming in total… …According to UK government estimates, aviation emissions of CO2 are about 5% of the national total… …The contribution of aviation to total radiative forcing is likely to be higher." It goes on to assert that "[a]irlines can therefore make a contribution to reducing global warming by buying fuel efficient aircraft and operating them efficiently."

Now I'm not saying there is a consensus among the general public, the vast majority of whom do not have sufficient information to take a qualified decision on the matter. But airlines are fully aware of the role they play in global warming, as are governments (hence the Kyoto Protocol and other measures, which are very difficult to stomach for MPs because they risk reducing economic competitiveness). The reason these officials take the actions they do is because they have been comprehensively advised by scientists, the vast majority of whom do share in the consensus that you claim does not exist.

Furthermore, if we take your premise - that we might be contributing to global warming - it stands to reason that our action must still be to limit our emissions in case it proves that we do cause global warming. Only by adopting the absurdly optimistic stance that our actions cannot contribute whatsoever to global warming could we possibly justify not curbing our emissions. Such an approach is tantamount to a four-year-old sticking his fingers in his ears and chanting "I can't hear you!" repeatedly. And about as effective.
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Old 3rd Apr 2006, 08:56
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I should also answer skorpio's earlier question about ATR's diagram: the diagram is no miracle, although it does present the worst-case scenario for the other modes of transport versus the best-case scenario for aviation. This is normal in such documents. Additionally, because gas-turbines are highly efficient, they do reduce nitrous oxide and carbon monoxide emissions to levels far below those of inefficient small piston engines. The critical problem with the diagram is that it doesn't measure the right variable. One could chart ice-creams consumed per passenger km, but it wouldn't be very on-topic.

The most important gas affecting global warming - by a country mile - is carbon dioxide. The amount of CO2 produced is directly proportional to the weight of fuel burned, and aircraft burn vastly more fuel than other modes of transport. There is no way around this: an aircraft must pull a huge wing through the air merely to keep itself aloft, with all the pressure, skin, and induced drag associated with that. Additionally, it does that at high speed, where efficiencies are inherently lower.

This high-speed element is of course why aviation is so well-suited to long distances and crossing water. My only point in all this is that aviation is inherently ill-suited to short distance over land, and is only able to compete with rail and road over short distances because of the market distortion caused by zero tax on aviation fuel.
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Old 3rd Apr 2006, 09:24
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Though I agree with environmental conversation I would like to point out the distinction between that and government tax. The latter is clearly disguised as the wolf in sheep's clothing in order to extract money from people and industry.

The inevitable outcome will be the implementation of taxation and no progress on the environmental responsibilites. So from my perspective NO TAX. Aircraft for rather obvious reasons cannot simply switch to another powerplant as easily as ground based motor vehicles and also power stations that can generate power by ever increasing methods.

As someone earlier in the thread quite rightfully pointed out this aviation is nothing more than another easy target as it's an industry and won't affect the votes whereas consumers are to be exempt. Indeed industry has alot of waste but that's because it's on an industrial scale yet if you compared the waste per unit to that of an average household you'll probably be surprised to note that industry in some respects is alot more efficient.

Open eyes to the environment and push for better education about what's really going on about the environment and what we can realistically do about combatting this problem. Let's have a short and medium term plans with a longer outlook rather than political headline grabbing "Ministers to have a big get together and jolly to sort out the world's environmental problems". Other countries around the world are making progress and it's not just the self appointed 'west' that can save the world.
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Old 3rd Apr 2006, 10:06
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boogie-nicey: I strongly disagree that the inevitable result of an aviation fuel tax would be "no progress on the environmental responsibilities". Money talks. Airlines are updating their fleets because the price of oil is rising, and if the price of fuel were further increased by taxation, you can be sure Boeing and the rest would pump huge resources into developing fuel efficient and "zero emission" alternatives. The fuel cell for example, specifically the hydrogen cell, consumes hydrogen and oxygen to produce electricity, in the process emitting water vapour. Water vapour is also problematic when dumped in the upper troposphere, but less so than CO2. Airlines could be given incentives to fly at low altitudes, using planes with a very high wing loading to minimise the effects of turbulence. On the ground, the hydrogen and oxygen needed for fuel cells would be extracted from water with electricity, which should be supplied by "green" power sources.

This is all technologically achievable on a small scale today, but it's far too expensive to implement commercially. This is why I favour smart legislation encouraging technological development. When George Bush says we can rely on technology to save us he is probably right: he just fails to appreciate that the free market will not produce this technology within several decades without careful regulation. The reason that American cars are so inefficient compared to European and Japanese models boils down to fuel taxation differences.
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