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New Study Suggests Flying Is Greener Than Driving
New submitter Desert Leap writes: The Washington Post reports a new study that suggests it is more environmentally friendly to fly rather than to drive. Analysis from the University of Michigan Transport Research Institute found that driving uses 57% more energy than flying per passenger mile. This is largely due to the number of occupied plane seats increasing while passengers per car decreased. Of course, "results may vary" for individual trips depending on many factors, such as distance flown (long flights are more fuel efficient) and the kind of car, and how many riders. One factoid is interesting: it takes 4,211 BTUs per person mile to drive. This number will fall as we switch over to electric vehicles. For example, a Tesla Model S takes about 1,100 BTUs per vehicle mile. Will future aircraft be able to also make the switch to electric?
Using the same logic, using a but or going by train is also more efficient since the many seats versus a couple is also true.
Can you imagine 300 people driving from Seattle to Florida in separate cars?
Will future aircraft be able to also make the switch to electric? Yes, of course. Electric driven propellers should do the trick.
Of course, the size of the batteries needed will preclude carrying any passengers or cargo.
How come Slashdot never gets Slashdotted?
Nothing really too new. If you take the bus and the bus is full you are more efficient for the work being performed.
Most of the energy goes into moving the actual machine, only a small fraction goes into moving its content.
That is why the Train shipping companies advertise 1 gallon of fuel, for 500 miles per Ton of goods.
If something is so important that you feel the need to post it on the internet... It probably isn't that important.
Either compare flying a small plane to driving a car, or compare a huge bus to a plane.
Being Robbed by the TSA, Groped and Accosted, or Simply not allowed to fly at all because of your views on social media.
I'd rather drive or walk...
> One factoid is interesting: it takes 4,211 BTUs per person mile to drive.
do we all drive the same car? Is this a chevy suburban or a fiat punto?
If an experiment works, something has gone wrong.
When I travel far enough to fly, I don't usually travel by myself, I'm usually on vacation with family or on a business trip with coworkers, so by adding just one person to the car, that makes driving and flying almost equivalent -- probably even moreso since I can drive from my house directly to my destination instead of driving 20 miles to the airport on one end, then another 30 miles on the other end.
They already exist - http://www.washingtonpost.com/news/morning-mix/wp/2014/06/02/meet-solar-impulse-2-the-solar-powered-plane-that-never-has-to-land/
I don't think they'll ever be practical though, batteries are heavy, and they aren't fast enough.
"Fly me to the supermarket.... I need some milk."
"Fly me to the supermarket.... I need to buy some milk."
When are we going to do something about the price and make it more competitive to driving?
Select from tblFriends where interesting >= 4;
That circles around towns lowering 'hooks' to grab people at designated points, pick them up, whisks them through the air aways -- without having to load them up into a cabin, and drops them off at their destination when they push their personal 'eject' button.
Since when has traveling by car and plane been comparable? For long distances, I suppose. I'm not going to drive between NYC and LA. But on a daily basis it is not. Compare Plane Travel to Boat travel maybe, especially cargo. Or compare planes to trains. Cars should be compared to buses. Same travel medium, more directly comparable. Most cities, at least near me, have moved to around 50% mix of hybrid buses and eco-diesel buses. With that the numbers would be interesting to see.
Are airports more efficient than interstates in terms of infrastructure costs? And I read somewhere (Freakonomics?) that there are seven parking spaces per car in the U.S. Is that the same for airplanes?
Why does this use BTUs and not MJ or kWh? 4211 BTU = 4.44 MJ or 1.234 kWh. Real units.
They need to define the "minimum cost", ie the part the doesn't change regardless of distance.
For airplanes that would be takeoff and landing, as they have to do that no matter where they go or for what distance. Additionally it's usually the most energy intensive part of the flight (since they rarely fly at max speed/power). So determine that cost, and you can determine the minimum distance below which cars are more efficient (ignoring logistics for the moment).
Another thing I find interesting, they say its basically a 2:1 ratio....so what about a full car? wouldn't that flip the relationship back in favor of the car and be more efficient than a plane?
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Yet the study picked the best of air travel and compared it to the worst of road-based travel.
I wonder how efficient it would be for me to fly from my house to the supermarket (a mile away), or any of the other numerous trips I make via automobile?
Let me see, first I have to drive three miles to the nearest airport. Get in a plane. Take off. Land at the same airport. Then drive four miles to the supermarket.
Yeah, that's more efficient than driving.
Show me the math for both ICE cars and Tesla, from well-head to road. Because generating electricity takes energy, and there are losses in the distribution system, and the charging systems are not 100% efficient either. Of course, getting oil out of the ground, refining it into gasoline, and moving the gasoline to refueling stations takes energy, too. Show me the end-to-end math, and then let's talk. A 4:1 advantage for the Tesla seems optimistic to me.
I have the same gripe with calling Teslas "zero emission vehicles". They are not. They are "displaced emission vehicles". Of course, it is easier to control pollution at a single point, and pollution controls scale up quite well, so the overall emissions are less for a Tesla versus an ICE vehicle. But don't claim the emissions are zero, they are just someplace else. (And I will grant that there are benefits to simply displacing emissions -- the Los Angeles valley, for instance, is a bowl, and so pollution tends to hang around in the air for a long time certain months of the year. Displacing the emissions outside the bowl has it's own benefits.)
Flying costs a lot more, and involves a period of being completely at the mercy of the no-background-check employees of the TSA.
I don't care if it is green. The TSA is horrible. Get rid of it, and I might fly again. Until then, I will spring for the road trip.
Exactly how will switching over to electric power lower the # of BTUs required when what we're talking about here is switching over to a less efficient medium of energy transfer IE Continually shoving coal into a furnace to create heat that spins a turbine that produces electricity vs a single gallon of gas creating an explosion that could take you 50+ miles depending on the efficiency of your vehicle.
...and boy are my arms tired!
I also value my time, which I don't want to waste on a 200 mile trip waiting in line, and security theater
“He’s not deformed, he’s just drunk!”
Before ICBMs became a reality, nuclear-powered planes were significantly researched. Probably the craziest was Project Pluto, whose concept was to have an open to the air nuclear core inside a ramjet housing, acting as the heat source instead of combusting fuel. The unmanned craft was designed to be able to fly around for months at a time holding numerous atomic bombs. When given orders to attack it would have bombed Soviet cities... then with its cargo spent, continued the rest of its lifespan flying low over Soviet territory damaging everything its path with sonic booms and the radioactive plume spewing out the back. Then when finally shot down or out of power, it'd crash as a dirty bomb in Soviet territory.
The engine was actually tested on a railcar, but there were way too many concerns about the craft, and the advancement of ICBMs just seemed a better route. Among the many concerns was that the US didn't want the Soviets to feel that they had to develop a similar such craft as a countermeasure.
"...but Republicans plan to come back with a new plan, where they just slash the tires on all the ambulances."
This is absolutely useless metric. How about taking your clothes to dry cleaner or doing grocery using a plane? Cars are efficient compared to planes for the purposes where cars are used. Sometimes I go from SF to LA and I rarely see another car with a single passenger. This is the case where a plane can replace cars but even in this case planes would be inefficient once you take into account 3 passengers per car, 90% plane occupancy and take off, landing and airport infrastructure energy usage (even with the most modern energy efficient aircraft). So on case by case basis, planes will almost always lose if they try to replace the cars. Vice versa, cars may lose if they try to replace planes in many cases.
Most other forms of transport have no chance against a decent modern passenger car with 4+ passengers. Most passenger cars are comparatively light, well below 500kg per passenger, which is very hard to beat. They do that because there is hardly any wasted space. A bus needs a walkway and it has to be tall enough to stand in, and trains are just horrendously heavy. While rubber-on-tarmac is a bit wasteful compared to metal-on-metal, it is not that bad, and the lower weight helps a lot.
Electric trains can sometimes play in that efficiency range, but it is tempting to make them faster and then the savings mostly evaporate. Cars are useful despite their lower speeds because of the time saved by almost going door-to-door.
Finally! A year of moderation! Ready for 2019?
Why is energy here measured in BTUs? I've usually seen total energy use expressed in Watts, especially in the mechanical realm.
My Other Computer Is A Data General Nova III.
Not just that, there are a LOT of efficiencies that airplanes can take advantage of that are just not available to ground transportation. For distances above ~400 miles, air freight can be more efficient than even a freight train for hauling just about anything with a higher value per pound than rocks and gravel.
* gas turbine engines can reach peak thermodynamic efficiencies of ~50% around 30,000 feet, where the intake air is coldest but not too thin. Any combustion engine running at surface conditions can do maybe 20 - 30% efficiency tops. ... at enormous expense.
* air at 30,000 feet is still thin enough to greatly reduce drag compared to ground transportation. Only the vacuum tube trains like Elon Musk's "Hyperloop" will be able to beat that
Not to mention all of the "bonus efficiencies" not related to lower ton-mile/fuel costs that you get "for free"
* Time is money, and air freight also happens to be the fastest mode of transportation. It actually takes more fuel to cruise slower than the design cruise speed of Mach 0.84 or whatever.
* just need an airport with a mile or two of runway at each end, no other infrastructure needs to be built between point A and point B
* lots of old used passenger airplanes are refurbished for freight for relatively cheap at the end of their passenger service life
* lots of excess airport capacity at night when the passengers aren't flooding them
The "distances above 400 miles" is a pretty significant caveat, of course... that's roughly the break-even point for the extra fuel you need to get your cargo airplane up to 30,000 feet so you can save enough fuel during cruise/descent.
Also, with electric batteries and brushless motors also gradually approaching 50% efficiency (when taking advantage of regenerative braking), ground transportation kinda has a shot at achieving gas-turbine-like energy efficiency... at sufficiently slow speeds to keep drag down.
I highly recommend this book:
http://mitpress.mit.edu/books/...
While interesting, this study is also sort of meaningless for making any sort of policy decision. I take far away vacations because the plane makes it possible. If planes weren't an option (due to price or policy), then I would shift to taking vacations closer to home (with maybe 1 trans-Atlantic cruise to explore Europe late in life), and my business travel would shift to teleconferencing. Would the resulting environmental footprint be better or worse? Hard to say. And presumably train usage would (after a few years of infrastructure investment) boom under this scenario, changing things again...
There are too many variables interacting for this study to "prove" anything.
-1, Too Many Layers Of Abstraction
Purely energy wise, maybe, but what about the soot?
I recall hearing that one of the issues with flying is the amount of soot that is left in the upper atmosphere by a jet. The net result being that flying across North America (NY - LA) caused more greenhouse warming than driving an SUV for a full year (say 20,000km). The very black soot put out over the flight (cumulatively) causes more warming than the exhausts from the SUV (which for various reasons is not exhausting all that soot)
At least from the perspective of it being very efficient. Planes burn a lot of fuel but they also complete their task very quickly.
I've decided to stop wasting my time responding to AC trolls/sockpuppets... so if you want a response from me... login.
Electric traction motors are far more efficient than ICEs. That's why diesel locomotives don't actually connect the diesel engine to the wheels. The diesel engine generates electricity, which turns electric traction motors.
Same with the really big earthmoving equipment - those gigantic dump trucks down at the strip mine are using electric traction motors powered by diesel generators.
Why don't we do this in cars? Space and complexity.
So what's the point of all electric cars? It separates the energy generation from the energy consumption, allowing flexibility in the energy generation. That coal plant you decry is a lot more efficient than an ICE. And other electricity generation sources have other benefits. The problem has been getting the power from the power plant to the car so that you can use electric traction motors.
I have the same gripe with calling Teslas "zero emission vehicles". They are not.
True, but unlike petrol driven cars they could be. Both renewable and nuclear power power are zero carbon methods of generating power and while renewable has issues with cost, limited locations and variability if it were supplemented by nuclear we could significantly reduce greenhouse gas emissions. In fact if you charge your Tesla in France then 75% of that power comes from nuclear so you might not be zero emission but you will be getting close.
any recent data to suggest that cars have bested are better than trains recently? I imagine aerodynamic losses per person is a greater handicap than friction for passenger vehicles (or greater advantage for trains).
Even the most inefficient modern coal plants are significantly more efficient than an internal combustion engine.
The added bonus of electric cars is that, as the power generation shifts to less polluting sources (we hope), the electric car will become less polluting over time. The ICE powered car, however, will likely decrease in efficiency and increase the amount of pollutants it expels over time.
As for coal power, most of the electric cars in the US are located in CA, OR, and WA. Those states are primarily powered by natural gas, hydro, and nuclear power plants. Less then 15% of their energy comes from coal.
Is it just my observation, or are there way too many stupid people in the world?
what about that huge battery? Tesla's weigh more than similar gasoline sized cars because of the battery
Small prop driven aircraft, ALREADY.
The market was almost nonexistent about five years ago but it's growing quite fast. Don't underestimate what the major and ongoing advances in motors, controllers, and batteries will bring in the future. There's many radically new technologies in the works to partially or completely electrify aircraft transportation, far beyond just electrically driven propellers.
"...but Republicans plan to come back with a new plan, where they just slash the tires on all the ambulances."
Probably no, as about 10 inches of water shield nearly all radiation that comes from the wreck of the plane.
Better than that. There are internal combustion engines which reach 50% at sea level. The Wartsila-Sulzer RTA96-C 108,920 hp marine diesel exceeds 50%. Heck, even the TDI diesel engine in my 1999 Golf tops out at very close to 40%. The LM-2500+ gas turbine, a derivative of the CF6 which powers some 747s, adapted for shaft output, is over 39%.
Newton is a unit of force. BTU is a unit of energy. You should be using megajoules.
1 BTU = 0.001055055853 MJ, or 1000 BTU = 1.055055853 MJ
1000 BTU per person mile = 0.6555813132 MJ/passenger-km
My Nissan Armada seats 8 and gets 19mpg on the highway, give or take (yes, fully loaded with 8 people, it still gets 19 on average).
That's 152 person-miles per gallon.
That's 736 BTU per person-mile fully loaded, or 5895 BTU per person mile solo. The only people who feel like they are sitting in an airplane are those in the third row, too. I usually just stuff the smallest people back there.
The energy consumption of a takeoff depend on the mass of the plane at that time (I think), so for a given plane with a given number of passenger, it's not exactly independent of the distance. (more fuel needed for longer distance, bigger take off mass)
You are high. The diesel engine turns fuel into mechanical energy. If you change that mechanical energy into electricity and then back into mechanical energy, there is no way that could give you more efficiency than a simple mechanical transmission (which is typically well over 90% efficient). The reason for the electric transmission is flexibility. It does away with a big honking clutch and a multi-speed gearbox and gives you very smooth transition from standstill to forward motion.
"“When you consider all of the man-made radiative forcing and all the changes we’re making that can affect climate, contrails are one of the smaller effects, compared to carbon dioxide and other emissions,” Spangenberg said. “Globally, you would have to increase the contrail effect by roughly 100 times to get the same effect as all of the anthropogenic carbon dioxide in the atmosphere.”"
I agree that in terms of emissions commericial flight miles are close to car miles. However I usually fly much further than I drive per trip or over a year. That jacks up my carbon contribution considerably.
While your point may be true about moving people, the weight of what is being moved is less than the device doing the moving, it doesn't apply necessarily for moving freight by train. For moving typical goods, say by intermodal transport, the goods can easily exceed the weight of the unloaded train (including locomotives). When you get to moving heavier material, say iron ore, the material can weigh more than the 5 times that of the unloaded train.
I thought train travel was until I poked around the web.
www.buses.org/files/ComparativeEnergy.pdf
That's really old news. I read something similar 20 years ago. The question is why hasn't aircraft fuel efficiency improved in twenty years?
So if you fill up your car (4 or 5) people, then you have quadrupled the efficiency pr. person compared to driving alone and thus getting double mileage compared to flying.
Further benefits are: No TSA, No waiting, instant change of route and no even more hours of waiting and eating overly expensive mediocre food.
Flying to work isn't really a very practical commuting method, because my 747 won't fit in any of the spaces. Plus, what would I do with the crew?
No it doesn't. 1100 BTU (0.322 kWh) is the energy consumption from the battery to the wheels. You need to include the entire energy generation chain to get a fair comparison. Add in a 40% efficient coal plant generating the electricity, 97% transmission efficiency over high-power electrical lines, and 75% charging efficiency and the Tesla actually uses 1100 / (.4*.97*.75) = 3780 BTU per vehicle mile.
The vast majority of the reason an EV is cheaper to operate is because coal is so much cheaper than gasoline. Coal costs about $50 per ton. A ton of coal has approximately 24 GJ of energy. That's about 0.21 cents/MJ. Gasoline costs about $3/gallon, and has about 120 MJ/gallon, or 2.5 cents/MJ. For the same amount of energy, coal is an order of magnitude cheaper than gasoline, which gives the EV a huge advantage in terms of operating costs. This is not a bad thing - being able to transfer a cheaper but traditionally static energy source into use in a mobile application is an economic win. But don't confuse it for better efficiency.
Yes you could argue that we can make electricity from renewables. But the vast majority of the cost of renewables is in the initial production of the turbine or PV panels. Operating costs are nearly nil (limited to maintenance). So for a fair comparison you then need to incorporate production and transport costs. At which point renewables lose because on a per Joule delivered basis, even with coal plants being only 40% efficient, coal is still cheaper than wind and solar power. (Wind is only about twice the cost of coal, so cheaper than gasoline, but I suspect solar would be about the same cost as gasoline.)
Your link to mh-aerotools.de pretty clearly illustrates why this isn't going to be happening to commercial aircraft anytime soon. By making some fairly absurd assumptions about efficiency gains from changing aircraft design (and ignoring all aspects of aircraft design other than efficiency) you still need batteries that have 6x the energy density of modern technologies. Using some numbers that might actually be realistic and you'd need more like 10x the energy density.
I am pretty sure, both trains and busses have lower footprints, esp. if you consider that its trivial to run trains from renewable sources (as they normally run on electricity). Also the study probably forgets to include the fuel it takes me to get to the airport, which is often a considerable amount (eg. for me it would mean driving nearly 80km per direction).
British Thermal Units? What century are you living in?
A pox on web designers who feel that window.innerWidth == screen.availWidth
Planes show an even greater advantage for me, as when I drive a car I tend to throw cigarette butts and plastic bottles out the windows, and they pollute the side of the road.
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Once, a long time ago, I read an article stating that flying was the 2nd most dangerous mode of travel, (1st was motorcycle) but the author stressed it depends on how you look at it.
Miles travelled, or per trip.
"If any question why we died, Tell them because our fathers lied."
Aerospace is a huge hole in our plans for a carbon less energy future; you can replace fossil fuels with ships (nuclear) and transit (electric cars and trains) but I haven't seen any technology (real or imagined) that can do the job in aerospace. Short haul trucking is another hole that's going to be hard to fill, long haul can conceivably be replaced with trains but you're still going to need something to move goods from the rail network to their final destination.
Not to mention tanks.
And the combination of domestic heating and electricity demand. Politicians are afraid of building nuclear plants, and green energy projects aren't getting us anywhere near where we need to be.
Cool, I guess flying will easily get me to the corner of 14th and Pennsylvania Ave. Really, the exact corner...
Really, all this shows it that the more precise location you need to be in, the more energy you'll use. Sure, flying may theoretically get you closer, but if you factor in the infrastructure required vs a dirt road, it's more expensive (today's street cost a lot for robustness.
Goes with my mantra: More precision == more effort (i.e. cost in this case). Applies to pretty much everything.
And there are tons of other costs. What is the difference in cost to manufacture? Amortized over the mileage travelled? Are you driving your own car (and avoiding the need for a driver) and are you including the bus driver's carbon usage as a carbon cost?
Does it take into consideration that on any plane trip you have to drive to and from the airport?
Troll is not a replacement for I disagree.
DSB (Danish Railways) has a table on http://www.dsb.dk/om-dsb/dsbs-... saying that their long-distance trains do 33g CO2 per person km. Regional trains are considerably worse. Modern cars should hopefully do better than 133g per km.
Urban trains do better because people are standing up, which significantly lowers the train weight per person.
Now, Denmark is admittedly a bit of a developing country when it comes to trains. Obviously a pure electrified system running on hydro power would do a lot better. DSB's long distance trains use 0.12kWh per person km. A Tesla uses about 0.35kWh per km, which comes to 0.09kWh per person km with 4 people.
Finally! A year of moderation! Ready for 2019?
where they don't build grocery stores within walking distance.
That is soooo.... 1950s/60s/70s.
Where are we going and why are we in a handbasket?
Members of congress have a library? Don't they know libraries are full of liberals? "There's only one book worth reading!" I was pretty sure they stayed far away from libraries, and radical interwebs and such.
Where are we going and why are we in a handbasket?
Nope. You forgot about the transmission. The diesel is most efficient in a narrow RPM range. When it's connected to a generator, it can remain in that RPM range. When it's attached to a transmission that is attached to the wheels, it can't. The worst is low-speed acceleration, where electric motors do quite well.
Since you're so new to the subject, you could start here: http://science.howstuffworks.c...
When you're talking about trains or earthmovers, there is no battery. It's generated as-needed.
When you're talking about all-electric cars, the battery hurts range. Whether or not that's a problem depends on your driving patterns. If you're a typical commute-to-work-and-a-few-errands urban/suburban driver, the range is likely well beyond what you would consume in a day. If you are not that kind of driver then the range may be a factor.
The study only looked at the fuel consumption of the two modes of travel. Unsurprisingly, a packed plane did well compared to a car with one person in it. The ground travel can do better in a number of ways: a more fuel-efficient car, putting more people in the car, instead studying multi-passenger vehicles like buses and trains.
The current study also fails to look at another important issue: the high impact of air travel on the ozone layer. Because it takes place at high altitudes (and thus releases pollutants into the upper atmosphere), studies have shown that flying causes a lot of damage to the ozone - much more than the same level of polluting activity at ground level.
....that there is no plane going from by car port to my workplace.
thanks for the follow up