Fly and be damned - our suicide pact with aviation 30 March 06

and even wondered if the contrails helped reflect solar radiation but the passionate focus in the UK against air flights made me wonder so I discussed this issue with others on the blog and changed my mind. Almuth earlier provided me a link which helped me understand the science better. The link is below:

www.rcep.org.uk/aviation/av05-s3.pdf (Royal Society on Environmental Pollution)

I also discovered where my original confusion came from when I thought that contrails helped. I thought it important enough to share and the original post is below:

http://www.marklynas.org/wind/message/2923.html

In my original post above, I mentioned the idea of returning to propeller driven craft instead of using jet aircraft. My reasoning based on the science lesson from Almuth is:

1. Flying may never be banned altogether so we will still use planes.

2. Propeller driven planes travel at slower speeds enabling them to fly in the troposphere where they do less harm.

3. Propeller driven planes use ICEs which can be made to run at lower temperatures eliminating the nitrous oxide emissions. I just cannot see how a jet engine can be designed to do this. The technology is already in use with current pollution controls on automobile ICEs.

4. I think propeller-driven planes use less energy per mile than a jet does. This reduces the carbon emissions.

5. Further enhancements with non-carbon fuels such as liquid hydrogen would eliminate the carbon and the water vapor in the exhaust would be less of a problem when flying in the troposphere.

6. If we have to consider sulfate additives or another compound in a measured response to increase reflectivity, then this could be added to the fuel. Of course this is a dirty way to do it but if it is measured and done over desert areas of the ocean, then the side effects can be managed. Maybe! I am only a messenger and had to include this.

7. Greater fuel economy may help with rising fuel costs if less fuel is used per travel mile. This could be the other benefit to encourage changing from jet engines to ICEs.

As I said in my original post, this topic of plane flight is unknown in the USA even among the most informed here. I have only learned about the effects of flying on climate from participating on this blog site and I appreciate the discussion I had with Martin and Almuth.

This is an important topic and I wonder if anyone knows of any study done on going back to propeller-driven aircraft. This would not be done quickly since these types of planes are in short supply.

It would be nice if any aeronautical engineers wanted to share their expertise on this blog about how we can go to the older technology and if current jet engines can be replaced with propeller engines using the same aircraft. In other words, change the engine but recycle the body. Just wondering!

In any event, I think we could cut down on flying quite a bit since most of this is at our own convenience. For many flights, there are ground-transport alternatives which create less harm.

All the best,

Dan

Check out www.flybe.com. If you’re in a position to book well enough in advance you can get tickets at unbelievable prices – for example, Edinburgh to Southampton at Â0.64 each way. Madness.

Big beast (Airbus 380) vs Sleek, Fast and Fuel efficient (Boeing 787)

Airbus and the EU have a lot at stake since it was heavily subsidized by government to get it into production. The plane is huge and requires longer runways, modified terminal access and more air space. The Airbus can hold up to 800 passengers crammed into it and is 49% larger inside than a 747. Airbus claims its plane is more fuel efficient than a car. However, a BBC estimate puts this at 90.6 miles per gallon, per passenger.

:compared to:

Boeing’s new 787-8 Dreamliner has unmatched fuel efficiency of 20% less fuel on comparable missions than any similarly sized airplane. Responding to airlines preference around the world, Boeing focused on the 787 Dreamliner, a super-efficient airplane high tech and ergonomically appealing plane. The interior has light emitting diodes on the ceiling to mimic the changing colors of the skies. Yet it flies at .85 mach and gets better efficiency through reduced weight materials, minimized drag coefficients and redesigned fuel sipping engines.

In this new oil conscious world, Boeing is looking like the better choice…

Paragraph 3.27 of the Royal Society analysis (http://www.rcep.org.uk/aviation/av05-s3.pdf) admits there are no empirical data to support the supposition that aircraft affect the radiation balance of the Earth. The observation was of an increase in day/night temperatures. If the observed change in day/night temperatures holds up to scrutiny, it will be the first observation of a change in radiation balance. The observation will have been of a change in day/night temperature difference it will not document that aircraft emissions will warm the climate.

“It should be noted that a recent comparison of the three-day period following 11 September 2001, when all commercial aircraft in the United States were grounded, has shown some evidence of a 1°C to 2°C increase in the day-night difference in temperature over the USA. This is consistent with the theoretical proposition that aircraft contrails and related cirrus cloud act to lower day-time temperatures by reducing solar radiation and raising night-time temperatures by reducing heat loss. If the result turns out to be robust it will be the first empirical evidence that aircraft contrails and related cirrus cloud are indeed significant in the Earth’s radiation balance.”

The entire hypothesis is nothing but supposition and guesswork, augmented by assumptions about the behavior of aircraft-emitted substances. All of it leads to a final guess that aircraft emissions may be responsible for as much as 3.5% of the theoretical but unproven, human contribution to climate warming. See the last sentence in paragraph 3.22.

” . . . Consequently, aircraft were seen as being responsible for 3.5% of the total radiative forcing in 1992.”

All of this hypothetical supposition seems to me to be a poor reason to stop flying around in airplanes.

Great news. All I have to do is ensure that my family and friends fly on Boeing aircraft in future, in the safe and secure knowledge that the world will be a healthier place to be in.

I’m going to sleep much better tonight as a result of this revelation.

Thank you.

the report you and Dan refer to is in fact by the Royal Commission on Environmental Pollution, but it draws heavily on work by the IPCC (Intergovernmental Panel on Climate Change) that makes similar predictions.

The Royal Society, however, did last year release an unprecedented joint statement with the other G8 countries’ science academies calling for immediate action to cut greenhouse gas emissions: www.royalsoc.ac.uk/news.asp?id=3226

Climate/earth scientists have mathematical models which predict that aircraft increase the levels of cirrus cloud and other aerosols; that the effect of these will reduce the difference between day and night temperatures, as confirmed by the data just after 9/11 compared with other times; and that these aerosols’ net effect is additional warming.

Just as their mathematical models have for many years predicted a net warming effect from increasing CO2 and other gases. And now there is compelling evidence from around the world that we have seen the warmest years in recent human history within the last decade; and associated droughts affecting millions, retreating polar ice caps and glaciers, the strongest and longest hurricane season on record, etc.

Norbert, do you have some surprise alternative explanation for why the world is warming which all the climate scientists, astronomers etc are unaware of, when their mathematical models say that the observed warming of the past two centuries is mostly accounted for by the increased levels of greenhouse gases from human activity?

You can read more about climate scientists’ findings on www.realclimate.org.

Last year New Scientist magazine ran the following excellent articles on the extent of scientific consensus for human-induced global warming: www.newscientist.com/channel/earth/mg18524861.400, www.newscientist.com/channel/earth/mg18725134.400,

and the climate change denial groups receiving money from the oil industry: www.newscientist.com/article.ns?id=mg18524861.500.

What do you say to all this Norbert?

One aspect of all these proposals to carry on a massive expansion of air travel which I don’t understand is where is the oil coming from to maintain the anticipated level of flights?

The more I read about this (“The End of Oil”, “The Long Emergency..” etc) the more it becomes clear that global supplies are getting tight and there are going to be problems with securing a sufficient supply and/or what is available is going to become increasingly expensive. That in itself will presumably at some point act to reduce aviation demand?

This is the main problem. It should not be cheaper to fly than take the train.

Europe has to take a grip on the aviation tax issue. I thought i heard a while ago now, a couple of countries including Germany are interested in adding duty to aviation fuel but Blair is not interested.

The fact air emissions are not included in the countries emissions as a whole does not warrant the government doing anything about it.

Planes like cars will not go away. We just have to use them a lot less and the only way is to make them expensive to use.

Hi Dan,

I quite like the idea of High Tech “Sailing Boats” to cross the Atlantic. I put the inverted commas as I think they will be quite different to 19th Century Clippers etc. They would have offices to allow connection to the Internet and phone etc. etc. If anyone started-up a service like that, I would buy into it!

I’ve been reading Tim Flannery’s The Weather Makers this week and on p.162 he talks about the theory of contrails, air-craft and their role in Global Dimming. An excellent book! I am not sure how substantiated this particular theory is though.

All the best,

Peter

Dan, I generally agree with you that we must find as many alternative technologies to reduce greenhouse gas emissions as possible, and think creatively. I would, however, agree with the George Monbiot article here http://www.monbiot.com/archives/2006/02/28/we-are-all-killers/ where he argues that high-speed long-distance travel is the one area where no climate-friendly alternative is available.

The airfleet has an incredibly long life-time -well over 50 years, so today’s Airbus could still be flying in the second half of this century. There has been lots of research by the aviation industry into making aircraft more fuel efficient, but far less gains are expected in the foreseeable future than there have been in the past few decades – for technical reasons, not lack of effort. And, of course, the old and least efficient planes will still be flying for decades, too. I really think that this is the one area where we absolutely have to curb an industry. It is about going back to the ordinary lifestyles of the 70s and 80s – and not to the stone age.

And, as somebody else has said here, this will be a major issue for global oil supply. I read somewhere that, if peak oil happens before 2010 then by 2030 30% of crude oil will be for jet engines. In which case something will have to give. Maybe oil for heating, being swapped for most polluting coal, maybe ordinary people’s ability to afford any sort of transport whilst the rich fly, and most certainly world peace! We had a good talk from somebody in the Stop the War Movement once who made a very clear link between Middle Eastern wars and the strong motivation which a government committed to massive aviation expansion has to secure oil supplies at absolutely any cost. That’s certainly another reason to focus on aviation.

Almuth Ernsting

I agree that flying has to diminish and the long life of the current fleet of planes is a problem. However, if we fly less, then we have surplus planes not using their useful life.

I still wonder how much of a benefit propeller-driven planes with pollution controls offer us to reduce the impact over flying jet-aircraft in the stratosphere as well as flying in the troposphere and other strategies.

I also wonder if jet planes are capable of be refitted with engines and propellers. Only a qualified aeronautical engineer can answer that question. If they can, then this may offset some of the costs. If the fuel economy can be increased, then this may also be an incentive to change over to propeller craft or retrofit jet planes.

I understand that we have to reduce travel but we are not yet doing this. It appears we will still be flying at some level, so what are our best options to minimize the climate impact on a passenger or cargo per mile basis. If we reduced flights by 50 percent and those flights had a 50 percent lower impact, then this would add to a 75 percent reduction in climate impact. I do not know the actual numbers but it would be nice to know what is possible.

I like the smoking-addition analogy used by Bryce. Better aircraft are like using cigarettes with less tar and nicotine. If we can smoke less, then this is progress.

I guess the best I have to offer is to suggest a better cigarette in this case. Another side benefit to reduced flights is that propeller-driven aircraft are slower so the cigarette is less desirable and it may help us smoke less of them so we use the train more.

Best Wishes,

Dan

In reflecting on our quest for solutions, looking to the past for answers seems beneficial and it has become apparent to me that our desire for speed in our modern world has to be sacrificed. Faster speeds save us time.

For example, every one of these transport options requires more travel time:

Propeller-driven craft versus Jets

Trains versus planes

Sailing ships versus planes.

Bicycles versus passenger vehicles.

And even with slower speeds, we still desire instant communications and we have never talked about the electrical energy required to power the Internet. It is not insignificant.

So, I offer this side-topic for others to ponder over. Time is something we hate to give up and even with all the time-saving aspects of modern amenities, many of us seems to feel we have less time. It appears contradictory given the fact of our longer lifetimes.

So, when we consider life-style changes as the major focus to solutions, an analysis on the aspect of our perception of time may provide important insights. I guess since our life is finite, time is our most precious commodity. Most technology involves saving time for humans. We opt for making decisions on saving time more than saving energy or reducing emissions.

Time is a factor involved in so much of our thinking and the basis for modern economics as the concept of the time value of money. Our concepts of time are at the heart of changing our perceptions and habits. I would love anyone here to expand on this theme.

Best Wishes,

Dan

The one thing Government policy should do is to provide an economic stimulus to encourage better environmental choices. In the USA, we have less train options available and bus transport no fun at all.

I hate to travel by bus because so much time is spent on the road and much travel is done at night. It is a horrible experience when compared to plane travel or travel by car. The time taken is twice as long as compared to drivng a car.

A train is much better than a bus (I think). I assume travel at night time would not be disturbed on a train. If one can sleep during traveling hours, then night travel-time is not wasted personal-time and this was my original reason for trying the bus system.

But with our bus system, it has to refuel along the way and everyone has to leave the bus while refueling which means if you are taking a nap, you have to wakeup in the early AM and wait an hour at a transfer station. It ruins your sleep patterns making your life miserable when you reach your destination.

So, when the convenience of flying is combined with lower prices, then it is hard to resist. For me, it is inconceivable that plane travel would be cheaper than taking a bus. Also, rent-a-car prices are less expensive when traveling by plane since you can get package discounts.

I do not think anyone of us likes to spend additional money or have other factors which make other available options most unpleasant. It is too easy to rationalize flying.

Best Wishes,

Dan

Dan wrote: “I also wonder if jet planes are capable of be refitted with engines and propellers.”

I’m not an aeronautical engineer, but I don’t think it’s that simple. Changing from jet engines to ICE will change the dynamics of the aircraft completely. Think about weight distribution, stresses on the wings, etc. Many jet aircraft have engines mounted inside or beside the tail of the aircraft, and propellers are not going to work well in these locations. You would probably have to change the wings anyway – the amount of lift that you get from an aerofoil depends on the speed that you’re travelling at, so a turboprop aircraft would need a bigger wing area for the same lift as a higher speed jet. In addition, jet aircraft are designed to operate best at high altitudes – they use a lot of fuel getting up there, but once they’re there in thin air (low friction) they are pretty efficient at cruising speeds. At lower altitudes the efficiency isn’t going to be nearly as good.

Sorry – it was a nice idea – but I don’t think it will work in practice.

but I still would like to hear from the people who design and build them. Maybe the seats and fuselage can be salvaged if not the wings.

On the thin air, that was my main point Stewart!

In the northern latitudes, flying in the stratosphere is making matters worse so we may have to travel in air that is not quite that thin. We already know jets flying in the stratosphere is not the answer so what are the facts supporting propellers?

Now, I did find a few links to substantiate my case for propellers:

http://history.nasa.gov/SP-4219/Chapter14.html

And a simple link below which says this about turboprops:

“Turboprops are more fuel efficient than turbojets at low altitudes, where the thicker air gives a propeller a lot more ‘traction.’ This makes them popular on planes used for short flights, where the time spent at low altitudes represents a greater percentage of the overall flight time.”

http://www.keveney.com/jets.html

On ICEs, I also mentioned the elimination of nitrous oxides (a greenhouse gas) which I do not believe can be lowered in jet engines because of their high operating temperatures.

This can be done in ICEs but I am not sure of their efficiency as compared to turboprops. ICEs require a lot of maintenance.

Best Wishes,

Dan

Dan,

Ground based gas turbines operate with low NoX emissions.

The question is why is this technology not applied to aero gas turbines? There must be a reason….... Cant remember what it is though..

Martin

Dan,

I did a gas turbines course at uni, which covered some ground about jet engines, so I can make a first start at answering some of your questions.

The reason planes fly in the stratosphere is because the air is thin. Therefore less drag, therefore more fuel efficient (i.e. less CO2)

The engine is designed for the height at which the plane is expected to fly and the speed at which it is expected to fly.

Essentially energy supplied by the engine is the difference in kinetic energy between the air entering and the air leaving. Thrust is the difference in momentum.

Therefore theoretically, the most efficient engine would exhaust gas at the same velocity as the plane, but would be infinitely large. So there is a trade off between size & engine efficiency to achieve the overall most efficient design for a a given flight pattern. This is done by varying the bypass ratio (how much thrust is provided by the big fan at the front and how much from the main, thin jet in the middle) Modern jet engines have a high bypass ratio. Turboprops have a very high bypass ratio.

Short haul favours lower altitude because the energy to lift the plane up to the thinner air makes a relatively much larger chunk of the flight fuel. Hence also lower speeds. Hence turboprops.

I don’t think there’s much of a viable way of getting round jet engines for long haul, ocean crossing flights. But they should be able to do something about the nox emissions (since the necessary gas turbine technology exists in the power generation industry).

Jet engine NoX emissions are already a lot lower than those of the old cigar shaped engines (low bypass ratio / turbojet type).

You can tell by how yellow the exhaust appears. Lots of yellow = lots of NoX.

Best Regards Martin

Norb,

You’ve got to make decisions based on the best information you have.

If this is it, then this is it.

And the best decision based on available info is to reduce air travel.

It might even pay for the funding gap in essentail services…..

Or could be included in the Emissions Trading Scheme.

The fact that avaition is not included in the emissions trading system is a crime, which distorts the whole thing

Regards Martin

Ah but dan,

in europe we have this crazy system which taxes vehicle fuel heavily, but does not tax aviation fuel.

We pay about 95 pence per litre of petrol (gasoline) This equates to about $6.20 per US gallon.

Around half this price is the duty, so aviation fuel must be at least half the price of road fuel…..

So Jimbo,

What’s the miles per gallon per passenger figure for the dreamliner?????

The 787 & A380 are not similar sized planes!

Regards Martin

Jimbo,

Also be aware that there are two different gallon measures out there. You need to be sure which type of gallon the BBC were using.

UK gallon = 4.546 litres

US gallon = 3.785 litres

Regards Martin

Jimbo,

you should also be aware that Boeing gets significant government subsidy, indirectly through NASA and directly through defence contracts.

This particular issue is politically a very hot potato between the US and Europe.

Regards Martin

Martin,

This explains a lot about jet travel.

The reason for avoiding the stratosphere is from what I read on Almuth’s link. The water vapor from the jet exhaust lingers for years in the stratosphere while in does not in the troposphere. It is the water vapor accumulation which adds to the carbon emissions which make flying in thin air much worse.

So, I reasoned that flying in the troposphere would help but because of higher drag, a slower speed would be more fuel efficient.

For long duration flights, would the decrease in speed reduce drag sufficiently to increase fuel economy? The sites I found support the idea that turboprops are more efficient than jets overall.

I wonder if the use of high speed jets is more for the convenience of passengers to reduce their air-travel time. So, I wonder if the turboprop with a focus on reducing NOx and flying below the stratosphere would lower the climate impact.

It would be nice to know how much a reduction in climate impact is possible with modern aviation if reduced speeds and travel times were considered as a small compromise for the sake of the planet.

As I mentioned before, a combination of eco-friendlier aviation plus reduced flying may help us reduce the aviation impact significantly.

I appreciate your comments. There are so many tradeoffs. If you use jets for short flights, less water vapor is in the stratosphere but less fuel efficiency. Longer flights have higher fuel efficiency but add more water vapor when flying in the stratosphere where it accumulates and lingers.

As usual, it is always much more complex than it appears at face value. It would be nice to quantify it so the numbers can tell us exactly the bottom line on fuel economy, travel time, and climate impact and, what other options exist which can reduce flying altogether. How much could hydrogen fuel help by eliminating carbon emissions when combined with these other ideas? Then do we need to add sulfates in a controlled matter to add a reflective compound to the air?

I think aviation deserves a special detailed study in this light looking at ways it can be improved if this has not already been done. I think it has but not in the light of us “giving up something” like a little bit of our “time”.

Thanks again for your comments,

Dan

Got this in my email today:

Chevrolet is running a promotion where you can make your own Tahoe commercial, and I don’t think it’s going as planned. These will be pulled down in a few hours by Chevy…so check out what happens when you turn creative over to the audience

http://www.chevyapprentice.com/view.php?country=us&uniqueid=42019b68-10ac-1029-98eb-0013724ff5a7

http://www.chevyapprentice.com/view.php?country=us&uniqueid=2f96c6f2-10b5-1029-98eb-0013724ff5a7

http://www.chevyapprentice.com/view.php?country=us&uniqueid=40a895fc-10eb-1029-98eb-0013724ff5a7

(The Story) From the Grist: http://gristmill.grist.org/story/2006/3/29/122054/644?source=daily

I agree. We should found our decisions on the best available information.

However, in this case, we have no information. We have only unsubstantiated speculation resting solely on the base of unproven computer models and unbridled speculation. No observations or measurements of any kind imply that the models and speculations are credible.

I think it folly to burden our economic well being by curtailing a valuable mode of transport based on this kind of non-information.

Ground-based turbine engines attain low NOx emission rates by injecting water into the flame zone, which cools the flame, or by injecting ammonia into the exhaust gas, which reacts with the NOx to reduce it to nitrogen.

Water injection creates maintenance difficulties. In addition, I do not believe that it would be practical to have passenger aircraft carry enough water to maintain low NOx emissions for an entire trip.

The most effective of the ammonia injections systems divert the exhaust gases through catalysts; others do not. Both inject an excess of ammonia in order to maximize NOx reduction. The excess ammonia emitted into the stratosphere would create other, perhaps more severe problems than the existing NOx emissions.

The NASA history link you posted was a thoroughly good read, I enjoyed it immensely. :)

Just sticking with CO2 for now (I appreciate your comments about H20 in the Stratosphere, but purely for simpicity’s sake) – if turboprops can deliver a 30% improvement in fuel efficiency, all well and good. But (assuming all jets were converted to turboprops overnight, again for simplicity) if aviation continues to grow at 10% p.a. then in just under four years we’d be back to where we are now.

But:

“What is life if, full of care,
We have no time to stand and stare.
No time to stand beneath the boughs
And stare as long as sheep or cows.
No time to see, when woods we pass,
Where squirrels hide their nuts in grass.
No time to see, in broad daylight,
Streams full of stars, like skies at night.
No time to turn at Beauty’s glance,
And watch her feet, how they can dance.
No time to wait till her mouth can
Enrich that smile her eyes began.
A poor life this if, full of care,
We have no time to stand and stare.”

(William Henry Davies)

You missed out “walking versus bicycles”. :)

As far as I’m concerned, you’ve touched a nerve. I’m at my happiest when I’m ambling along the coast, especially when my mobile has no signal.
But, sadly, beachcombing doesn’t pay the mortgage.

anyone else reading this please read my post below entitled “Dear Norbert”.

As you can see from the dates, “Norb” had plenty of opportunity to read it before he wrote the post I’m now replying to.

Regular readers may also be interested to read the following reference to a “Snorbert Zangox”: www.langston.com/Fun_People/1994/1994AXG.html

I agree with nearly everything in your post so I saw no reason to respond.

You said that the Royal Society released a joint statement with the G8 countries that calls for immediate action to cut greenhouse gas emissions. I seem to recall that they did and am not surprised. However, this thread relates to the Royal Society document specifically about aircraft emissions and mostly about the chemical and physical effects of contrails on the stratosphere; the statement was general.

You said (and I paraphrase here) that those who claim that aircraft contrails affect climate base their positions solely on the output of computer models, by omission, you acknowledge that there are no observational data that demonstrate that aircraft contrails are a significant cause of the ongoing climate warming. In fact, you refer to the same arbitrary and non-verified computer models that the Royal Society document discussed in detail. The Royal Society paper discussed the data support for those models and admitted that no observations of an aircraft effect on climate exists. The Royal Society document also admits that at worst, aircraft contrails can account for a couple of percent of the putative AGW.

You go on to admit that all of the claims of AGW are based on the output of computer models.

You say that the climate is warmer now than anytime within recent human history. That is true. However, it was as warm in 1200 AD as it is now and as warm approximately 1,000 years before that. Our climate appears to cycle.

Scientists since Arrhenius have tried to make accurate estimates of the extent to which rising carbon dioxide might affect the warmth of the climate. The models and calculation procedures have grown continually more complex, but they still are superficial compared to the complexity of the system that they seek to model. None of them can accurately predict the present from the recent past. Dano will claim that they do, either because he does not know or because he will claim as fact anything that he wishes to believe, but they do not.

You ask if I have alternative explanations. I have only questions. What caused the warmth of the Medieval Climate Optimum and the Roman Warm Period before that? Why did the polar ice caps retreat then, why were the Danes able to farm in Greenland? What caused the climate to begin cooling suddenly in about 1300 AD; is there evidence that carbon dioxide concentrations plummeted then? Why did the climate begin warming in the early 1800s before carbon dioxide concentrations began increasing?

NOAA data do not support your claim that last year was the strongest and longest hurricane season on record.

I have never received a dime from the oil industry.

Spot on. The price of UK petrol (including tax)is about 5 times higher than aviation fuel and this is one of the main reasons behind the economics of cheap flights. Taxing aviation fuel will require careful international coordination/agreement otherwise weird arbitrage behaviour will occur.