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Jun 8, 2009 12:01 AM | 17
Jet-setters get a bad rap for their role in spewing greenhouse gases into the upper atmosphere, but a new study says that flying is really no worse for the environment than taking the train.
When most people think about air pollution and carbon emissions, they usually just consider just what’s coming from a vehicle’s exhaust pipe. But a new study in the journal Environmental Research Letters compares the impact of different transportation modes by taking into account everything from the steel in train tracks to the tires on aircraft landing gear.
A large aircraft emits about three times the greenhouse gases per passenger kilometer traveled than a train during operation. But if you consider the infrastructure that supports train and light rail travel, it effectively increases greenhouse gas emissions by a factor of 155 percent. A similar calculation for jets only increases the effective greenhouse gas emissions by 31 percent.
The two modes of transport are basically neck-and-neck, but on the U.S. east coast, where fossil fuels provide electricity for rail travel, trains end up being bigger greenhouse gas emitters than planes.
Trains also fared worse off when the study authors considered airborne pollutants like sulfur dioxide, which causes acid rain. The Boston Light Rail, for instance, emits more than seven times the amount of sulfur dioxide per passenger kilometer traveled than a typical large aircraft. That’s because today’s airplane fuels are low in sulfur, and power plants now dominate sulfur dioxide emissions.
The take-home message, says lead author Mikhail Chester at University of California, Berkeley, is not that eco-conscious travelers should shun rail lines in favor of planes. Instead, he says we should be looking at ways of reducing emissions in our infrastructure, by using, for instance, low carbon dioxide cement.
“We’ve done a lot by going at the tailpipe of the car,” says Chester, “That’s good thing, but we should start looking beyond the tailpipe.”
Image of train courtesy TroyMason via Flickr
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17 Comments
Add CommentUnsurprisingly in an American magazine, this is somewhat US-centric, and deals with diesel trains.
Reply | Report Abuse | Link to thisThe calculus for France, where nuclear power provides the energy for electric trains, would be very different.
This proves that it is daft to generate electricity using coal when you can use lean nuclear energy, and also to run diesel trains when you can electrify.
One thing that is important to take into consideration as well is the marginal carbon emissions for each ticket purchased. How much sunk carbon costs exist in each system regardless of number of tickets sold. For example, the rails which were smelted 60 years ago will continue to exist even if no new rail tickets are purchased, and those same rails are used for freight lines. Air travel is very different. If 200 fewer tickets are sold for a route, that flight will be canceled.
Reply | Report Abuse | Link to thisWhile it's important to look at the whole consumption chain when calculating carbon emissions, where behavior is concerned, it's more helpful to look at the marginal carbon difference each behavioral decision will make.
If sunk costs are taken into account and are high, doesn't it make sense for individuals to maximize the marginal advantage per ticket in that system?
When planning a whole new system where we can control the future infrastructure costs, then we'd want to look at the full consumption chain rather than the marginal differences.
Thanks to Mr. Voortman's Econ 101 class.
@DaveMart
Reply | Report Abuse | Link to thisGood point, but how does one measure the environmental impact of nuclear? While it may have carbon advantages over coal and petroleum, there may be huge biological consequences of nukes which our grandchildren will be dealing with... or their grandchildren...
If trains were powered by much cleaner wind, solar or geothermal... then we'd be talking real change.
Wait wait wait! If a train emits 100 units per passenger mile and a jet emits "about 3 times as much" (300 units per passenger mile) how does increasing the trains output 155% when accounting for infrastructure( now yielding 255 units per passenger mile) run neck and neck with the jet (300+ 31%=393 units per passenger mile)? am I missing something here?
Reply | Report Abuse | Link to thisIs a near 50% difference not statistically signifigant?
Manbearpig, I was asking myself the exact same question when I read this article. The study is providing great information, and I commend the author for undertaking this project. But, could they explain why they feel that train and air travel are running neck and neck? Based in what is written in this article, I still see a big advantage to train travel.
Reply | Report Abuse | Link to thismrcantor,
Reply | Report Abuse | Link to thisThe emissions and waste of nuclear is a tiny fraction of that produced by coal, which has managed to externalise most of it's cots - witness the recent dam break of waste, which released millions of tonnes.
Just the mercury and uranium emitted by coal routinely vastly outweighs nuclear emissions.
Present methods of nuclear production in any case can be greatly improved, although they are already very good, and waste could be burnt up whilst efficiencies could be increased from around 0.7% to nearly 100%.
The liquid fluoride thorium reactor was discontinues after successful demonstration in the States, as it was lousy at producing weapons grade materials!
No major breakthroughs are needed to upgrade to this technology - a half-way house would be to convert present CANDU reactors to thorium burn.
For discussion on this technology see:
http://www.energyfromthorium.com/forum/index.php
Again, it should be emphasised that France already gets most of it's electricity from nuclear with present technology cleanly and safely - most concerns are grossly exaggerated - coal kills tens of thousands a year - civilian nuclear production has never killed anyone in the West.
The rail infrastructure is very much the same for passenger and
Reply | Report Abuse | Link to thisfreight traffic and carriage.
[Except insofar as the United States can, if it will, shift from the auto for Detroit and get rather more into producing rolling stock for passengers and freight.]
So surely one needs to factor in the huge environmental
benefits of rail freight..surely 4 or 8 dozen 18 wheelers emit vastly more
than one train?
Long ago, the 1930's I think, there was a lot more electrified rail in the US; it was replaced by diesels. For instance the Milwaukee Road crossed the Rockies with electric locomotives that used regenerative braking on the downhill side so they helped the ones going uphill. The change happened about the same time that local light rail was torpedoed by diesel buses.
Reply | Report Abuse | Link to thisHave they taken account of the climate impact of aircraft being "two to four times greater" than the effect of their carbon dioxide emissions alone?
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/Aviation_and_the_environment#Total_effect
Air travel emits vapour trails that disturb the radiaton balance at high altitude and thereby effect climate change to a far greater extent than was previously considered.
Reply | Report Abuse | Link to thisThe high speed train in France was run at 500kph on a test run. It consumed the electrical power equivalent of a large city. The exact consumption figures of the high speed train have not yet been published, so it is difficult to compare to a standard diesel-electic locomotive.
Fuel consumption increases proportionally to the cube of velocity, so to save energy drive at less than 50mph...
Gasoline-driven cars are almost as energy efficient as electric bicycles if they carry five passengers. It is driver-only travelling which should be discouraged in favour of car-sharing.
Some expert should write a detailed book on energy efficiency in transport, as the public is full of misconceptions on the subject, which is indeed complex.
Occupancy makes up the difference.
Reply | Report Abuse | Link to thisMost passenger jets are full of passengers and cargo most commuter trains run less than half full except during rush hours. Jets are operated to maximize passenger use for outgoing and incoming flights. Most commuter trains do quick turnaround returns with almost empty return trips and daily dead head travel. Except for maintenance most passenger jets have little dead head travel.
In an ideal(electric w/ static transmission) vehicle should have fuel consumption increasing closely to the cube of the speed. However, internal combustion engines don't have the most linear power vs. rotational speed curves and generally have transmissions, so the ideal argument isn't very adequate.
Reply | Report Abuse | Link to thisBecause of the transmission (esp. in automatics and possibly CVTs), near 50 is the bottom of 5th gear, so it is generally the most efficient speed:
http://www.fueleconomy.gov/feg/images/speedVsMpg2.gif
Even though fuel consumption is more, less fuel is used because it takes less time to reach the destination.
Actually, it may be more useful to say that the fuel consumed increases proportional to the square of the velocity. The total energy used=power*time and power increases with the velocity cubed, so total energy used=constant*distance traveled*velocity squared.
Reply | Report Abuse | Link to thisThat great American engineer and scientist recognised way back in the 1940's, if not before, that the only high speed transport system that made any sense from the engineering and scientific point of view, was evacuated tube transport (ETT ). The physics haven't changed and all the requisite technologies are advanced enough to make a working test track and vehicles acheivable. There is no doubt that a successfully developed system would outperform all present transport means on many of the important criteria ( energy efficiency, immunity to bad weather, low environmental impact, quietness, point to point speed, reliability,durability, construction cost, running cost, safety ). 10% of the steel arising from the cars annually scrapped in the US would suffice for a thousand kilometers of double tube ( one each way ). Putting money into this development rather than underwriting the gambling habits of greedy bankers would be a much better way of working the way out of recession. A transport system that is cheaper, faster, and more reliable in real terms is beneficial in real terms, and not just in the smoke and mirrors realm of high finance.
Reply | Report Abuse | Link to thisOops I forgot to mention that the great american scientists name was Robert Goddard, of liquid propelled rocket fame.
Reply | Report Abuse | Link to this
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