How green are trains, public transportation, and hybrid cars? It depends.
By Judy Lowe | 06.09.09
Most of us assume that some things are givens when it comes to environment-friendly transportation choices. Among those assumptions: Taking the subway is better than driving an SUV, riding a train tops hopping on a plane, and a hybrid car is much preferred over a conventional gasoline-powered vehicle.
But that’s not always true. Recent research [PDF] points to just the opposite, sometimes.
Environmental engineers Mikhail Chester and Arpad Horvath of the University of California found that instead of taking a train into the city from suburbia, there are times when “people would be better off traveling through town in a gas-guzzling, high emission SUV,” reports Red Orbit. Ouch!
But it gets even worse: Taking the commuter train across Boston results in higher greenhouse gas emissions than traveling the same distance in a jumbo jet, says New Scientist.
How could that possibly be?
Part of it comes down to how the power that fuels the transportation is generated. Boston’s electric commuter trains use electricity that comes mostly from burning fossil fuels.
What makes this study different from some in the past: Instead of comparing the climate effect of modes of transport according to their emissions, the researchers looked at emissions caused by building and maintaining various types of transportation,the infrastructure associated with them, and the generation of the fuel required for each.
To represent short, medium, and long-haul travel, they measured light rail systems in San Francisco and Boston, three types of gas-powered vehicles (2005 models of Toyota Camry, Chevrolet Trailblazer SUV, and Ford F-150 truck), and Embraer 145, Boeing 737, and Boeing 747 airplanes.
Then they figured out how many passengers each would carry over its lifetime, how many miles it would travel, and the life expectancy of its infrastructure – tracks, roads, and airports.
According to New Scientist:
“Including these additional sources of pollution more than doubles the greenhouse gas emissions of train travel. The emissions generated by car travel increase by nearly one third when manufacturing and infrastructure are taken into account. In comparison to cars on roads and trains on tracks, air travel requires little infrastructure. As a result, full life-cycle emissions are between 10 and 20 per cent higher than ‘tailpipe’ emissions.
Occupancy also matters when it comes to measuring greenness – almost-empty buses at off-peak hours were less efficient than even SUVs and pickup trucks.
This way of measuring the environmental impact of transportation should be taken into account when planning new initiatives, say the researchers.
“We should avoid building rail systems that are disconnected from major population areas and require car trips and parking to access,” Chester advises.
Electric cars were mentioned by Chester and Horvath (their green score can depend on how the electricity is generated), but hybrid cars didn’t make the report. Still, they were in the news this week: Hybrid cars are great for air quality, they save money at the pump, and they make the owner feel good, but, in the words of the Houston Chronicle, “They’re terrible for roads.”
Do hybrids cause huge potholes? Do they emit some kind of chemical that destroys blacktop?
Well, no. “Fuel-efficient cars are draining government coffers of money needed to repair roads and build new ones,” the Chronicle says.
In other words, because hybrids use less gas, they generate fewer tax dollars to pay for transportation infrastructure.
Many think that the fairest way to tax car use is not on gas purchased but on the number of miles driven. Hybrids and electric cars could certainly hasten that.
Of course, none of this is to deny the long list of benefits of buying a hybrid vehicle (or even taking the train or bus). But it does point out the complexity of many environmental issues.
ADDED LATER: Click here for a discussion about the latest in hybrid buses.
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2. Chris | 06.10.09
Anyone who actually reads the “Recent Research” PDF will see that this whole article draws its “wow” factor from the most extreme statistcal disparities. When examining the actual graphs and the total environmental benefits of public transportation become obvious once again. This being said there is room for improvement. Electric trains running on coal powered electricity doesn’t do anyone any good and once this infrastructure is modernized as it is in other parts of the world to be compatible with sustainable sources of energy generation, I think the environmental “debate” will be over. Public transport also provides a greater PUBLIC good, allowing those who may lack the ability to purchase a car the mobility to find better jobs, and access to education and healthcare in order to improve their quality of life.
3. Paige Varney | 06.10.09
A half empty bus may use up more carbon per person than a gas guzzling SUV, but the bus has to run when it’s half empty to ensure that people can rely on it to get them from point A to point B when they need it; if you can’t count on your public transportation to give you the odd one-off trip, then you will be less likely to rely on it during rush hour.
And your bus might use more carbon per capita on an off-peak trip than your SUV, but the math isn’t half-empty bus or SUV, it’s half-empty bus or half-empty bus minus one rider plus one SUV.
4. bob davis | 06.10.09
The airline comparison called into question this whole article. Lets compare 3 or 4 buses going from Boston to San Francisco to one airliner.
Don’t forget food, lodging etc. Of course food is no longer an issue on airplanes.
Perhaps buses should not be running during low occupancy time peroids.
5. Grant | 06.10.09
I second Chris on the importance of actually reading this one. It’s only 8 pages and well worth it — the “gee whiz” result that this write-up focuses on really is a very narrow reading of this research. The message is simply that empty diesel buses are wasteful, hence public transit needs to be organized to maximize passengers. When at capacity, this and other forms of mass transit are still more efficient than personal automobiles.
6. editorial | 06.10.09
I agree that everyone should read the report. It makes a number of interesting points. I would add to the points made by commenters about the report: The researchers’ conclusions on whether the US should build a network of trains is interesting in light of the recent push for more light rail. - Judy Lowe
7. Patrick | 06.10.09
Here’s a shorter, more graphical comparison that makes this easier to understand at a glance.
http://www.sightline.org/maps/charts/climate-CO2byMode
Paige is right that we need to have consistent transit service to make it a viable use.
The fact that the rail lines are powered by electricity means that they could easily be switched to electricity powered by renewable sources, while switching the power source for autos & SUVs currently on the road will take a considerable amount of time.
Finally, people living in areas dense enough to be served well by transit are likely to take fewer trips, have smaller homes requiring less energy, and be able to walk and bike for some of their trips, all secondary environmental benefits of transit.
8. trafamadore | 06.10.09
I second the idea that you should read the primary article. Allot there.
After reading it, I cant understand why anyone would complain about any on the rail options, they are clear winners.
As for the car comparisons, too bad they didn’t use an economy or hybrid car in there. I wonder if they would be in the rail range?
The average ridership they use is at about 2 people? Not sure I see that around here.
With airplanes, remember that you go the way of the airplane, even if you must go backwards. Havent you ever flown over your city on the way to the hub only to be flown back again later in the day?
9. Richard Bruce | 06.10.09
There is another difficulty for public transit the article misses. Public transit often does not take you directly to the place you want to go. You frequently wind around on a bus, or you may have to go into a central hub and come back. So you go more miles to reach the same place.
On the other hand, public transit can assist car pools. You can join a car pool knowing that if you have to stay late you can send the car pool home and take the bus instead.
Hybrids and electric cars are great because they are new technology. In the future we may be able to produce clean electricity from many sources and use them this new technology we are developing to go green. To much of our analysis of green is static. My bike is low carbon, but it does not add new technology. The electric car has a negative foot print.
10. Brian Eason | 06.10.09
Good find. Although I would point out that by taking a train — even a high-polluting one — an individual isn’t actually adding any pollution. The train is going to run anyway, pollute anyway, with or without the individual deciding to ride it. So a person deciding to take the rail instead of their SUV actually does still reduce their emissions, albeit not as efficiently as one would like.
11. donee | 06.10.09
Hi CSM,
Hybrids are a small fraction of the cars on the road. They have only been around in 1 % of the cars on the road for a year, maybe two. Saying they are reponsible for damage to roads as they are now is irresponsible.
Civil Engineers have known for years that most of the damage is caused by heavy trucks, thanks to spectral analysis of road ripples.
It makes no sense to tax by miles driven. In such a scenario lightweight vehicles with little to no impact on roads are taxed at the same rate as large. The extreme of this is a motorized bycycle would get the same tax bill as a 18 wheel truck. Silly, No ?
The vehicles that use the most gas, do the most damage to roads. A high powered vehicle creates tremedous forces within the road bed during a quick accelleration, and it costs more gas and tax to do this. Fair.
So, fuel consumption taxation is the fairest.
Politicians are affraid to raise the rate. That is the real problem. So, they want to abuse the minority here - the hybrid owner. Hybrid owners have already paid extra sales tax when they bought their cars, over what they could have bought. And now they want more.
As vehicle mileage goes up - as mandated by federal government, local governments will have to raise the fuel consumition tax rate to stay even. Its only right, it can easily be graduated over years and years so that its not severe impact. And its fair.
12. Brian | 06.11.09
It is important to understand the full energy implications of any endeavor, and the research referred to here helps us make informed decisions about public policy and our personal decisions (never mind that it gives some an ample supply of half-truths with which to sow discord). It’s particularly vital to consider the carbon emissions of the energy required to charge electric cars, whose widespread availability is coming over the next few years. Unless we have a simultaneous investment in green power production, electric cars will present little improvement in the overall carbon footprint over conventional gasoline vehicles (except that electric cars will be smaller and hence inherently more efficient overall).
13. Jerry McIntire | 06.11.09
Brian: even with the current mix of electrical power generation, electric cars reduce air pollution significantly and carbon emissions as well. Research has shown this again and again over the past 20 years. Having said that, we do have a great opportunity to reduce carbon emissions significantly by switching to green power production. Let’s do it! Start at home and at your place of business.
14. Aaron Huertas | 06.12.09
The Union of Concerned Scientists published a similar report which is more geared toward individuals and families taking vacation travel. It depends mostly on the number of people traveling and how far they’re going: ucsusa.org/gettingtheregreener.
-Aaron
15. Jimmy Petrol | 06.13.09
I take the Monitor to task for publishing an article, or indeed employing a writer, that takes a such a skewed look at data in order to provide the sensational, counter intuitive headline. It reeks of Yellow Journalism and is expected only in publications like the Wall Street Journal when they editorialize.
This is NOT what I came to expect from the Monitor as a youth.
I suggest we all head for higher ground, Mr. or Ms. editor…and look for writers who are either more intelligent or more honest…before you loose the electronic edition of your paper as well.
After all, there only needs to be ONE USA TODAY. Only about 35% of humans ever reach a level of cognitive function that allows them to use logic effectively, but that might be enough to pay your salaries, eh?
Jimmy Petrol, “Fueled by Petrol” at http://www.TucsonCitizen.com (at least until they fire me).
16. Aaron Antrim | 06.13.09
“Instead of taking a train into the city from suburbia, there are times when ‘people would be better off traveling through town in a gas-guzzling, high emission SUV’.”
Since the train is already running, your marginal impact (the added impact) will always be less taking the train (in other words, a train with 2 or 200 passengers consumes the same energy, roughly). Off-peak low-ridership transit service often does have low passenger-MPG figures, but it enables people to depend on the transit system at other times, and it serves an important social service function. Peak high-ridership service gets very high passenger-MPG.
For more on the idea of passenger-MPG see this article:
http://www.green-wheels.org/transportation-log
This article picked out statistical extremes. The statement I quoted is not a responsible or accurate statement.
17. Hasan | 06.16.09
When analysing carbon emissions in transportation, we usually fail to realize how much CO2 is produced by the energy source. What good is a fully electric car if its electricity comes from coal power plants? The answer to sustainable transportation comes in three levels: biking, buses, and carpooling. A company that I am interning with, TransLoc, helps make taking the bus more convenient by creating interactive live bus maps. It has helped me take the bus to and from work!
18. Muddy Buddy | 06.29.09
This article has major holes.
1. Buses run most of the night, empty or not. Thus, taking the bus should be decided on the additional cost of one additional passenger as opposed to taking a SUV, or hybrid. I betting public transportation easily wins on this account. Charging the whole energy use of the Bus to single passenger is an intentional distortion if I have ever seen one.
2. Charging by the mile may be fair in terms of road wear, but not in terms of reducing gas use to ensure the USA remains independent and the world healthy.
19. WaitaMinit | 07.31.09
“Good find. Although I would point out that by taking a train — even a high-polluting one — an individual isn’t actually adding any pollution. The train is going to run anyway, pollute anyway, with or without the individual deciding to ride it.”
Mmmnn… unless the train makes one less run per day. Or is canceled entirely, saving the other energy and dollar costs of maintaining the line.
The conclusion people reach regarding this article seems to reflect
i) What they want to believe
ii) What they want you to believe and
iii) Whether they actually read the research report, or just the sound bites quoted in this article.
The blog post was entertainment extracted from a factual report. Sort of like the Prius vs Hummer comparisons - a provocative bit of trivia standing out of a very useful study which attempted to determine the true energy costs or a road vehicle throughout its life cycle. But that doesn’t fit TV nation’s attention span.
FWIW, public transit’s overall efficiency is *roughly* 25mpg/passenger. That is an approximate figure, not an exact measurement. Idiots seem to think it’s infinity, or that public transit runs on fairy dust rather than coal or uranium. Here in NYC people seem to think that the MTA’s 40 ton subway cars (400 tons per train) and 12-20 ton buses run on some form of magic, thus requiring no fuel.
Is it any wonder we have to import engineers and scientists to actually build stuff, but we have an unlimited supply of Wall Street traders, rent-seekers and salesmen dressed in wizard’s robes.
Maybe everyone should be required to pass a freshman physics exam in order to vote.
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1. Jim | 06.09.09
“Taking the commuter train across Boston results in higher greenhouse gas emissions than traveling the same distance in a jumbo jet,”
Of course, such comparisons are ridiculous. You can’t fly from one end of Boston to the other in a jumbo jet. A fully loaded airliner at cruising speed may be able to traverse Boston’s airspace more efficiently than the commuter train on the ground. But it won’t be able to pick people up and drop them off along the way. Even if such a feat were possible, the jet would not be anywhere near as efficient as the train under stop and go conditions. you might as well be comparing apples and fish.