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Aerodynamic Heavy-Duty Truck Trailer Cuts Fuel Consumption and Emissions By Up to 15%
17 April 2008
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| Trailer with aerodynamic sideskirts. |
Creating an improved aerodynamic shape for heavy-duty truck trailers by mounting sideskirts can cut fuel consumption and emissions by up to 15%, according to road testing by the Dutch research partnership PART (Platform for Aerodynamic Road Transport). PART is a partnership between TU Delft, TNT, Scania Beers BV, FOCWA Carrosseriebouw, Ephicas, Kees Mulder Carrosserieën, Van Eck Carrosseriebouw, Syntens, Squarell Technology, Emons Group and NEA.
Sideskirts are plates which are mounted on the sides of trailers, primarily with a view to underrun protection. The new aerodynamic design of the sideskirts substantially reduces the air currents alongside and under the trailer and thereby also the air resistance.
Initial driving tests with a trailer equipped with the aerodynamic sideskirts over a straight stretch of public road revealed a cut in fuel consumption of between 5% and 15%. Subsequent research comprising long-term operational tests by TNT displayed a fuel reduction of 10%.
These results confirm calculations and findings from the wind tunnel tests that had established that the observed 14 - 18% reduction in air resistance led to 7 - 9% less fuel consumption. In practice, the figures are in fact even better.
PART expects that the cost of fitting aerodynamically-shaped sideskirts will be recouped within two years. Furthermore, the sideskirts can be fitted to approximately half the trucks currently in use in the Netherlands as the skirts can also be retrofitted.
In 2005, 10,000 new trailers were taken into use in the Netherlands. With an average fuel consumption of 30 liters per 100 kilometers [7.8 mpg US], that translates into 750 million liters of diesel consumption in the Netherlands each year. We can cut fuel consumption by 5% or more for 50% of those trailers. That means a reduction of 50 million tons of CO2 emissions a year. This research can therefore result in a substantial, structural contribution to cutting fuel consumption and an annual saving of tens of millions of Euros, next to that cut in CO2 emissions by the road transport sector.
Together with this sector we have created a practical platform for further research and development, but we still need active government participation. Just obtaining permits for all the road tests has involved a huge amount of time, energy and frustration. The next step is realizing a practical partnership between the government and industry in order to put the solutions into practice.
—Prof. Michel van Tooren of TU Delft’s Aerospace Engineering faculty
Road tests have also already been initiated on boat tails. These constructions on the rear of a trailer ensure a reduction in the wake—the vacuum and air currents which arise when the trailer is moving. In theory, a boat tail could also mean a cut in air resistance of 30%, with a fuel reduction of 10 - 15%. These road tests should also confirm the earlier, highly positive results from the windtunnel.
Boat tails, however, are limited in practical use, in particular when loading and unloading—safety aspects and problems with exceeding maximum vehicle sizes prevent these being used for many types of vehicles.
April 17, 2008 in Fuel Efficiency, Heavy-duty | Permalink | Comments (40) | TrackBack (0)
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Comments
It took them this long to figure it out. When you can draft behind a large truck, you are punching one seriously big hole in the air. It is pretty obvious.
Posted by: sjc | Apr 17, 2008 9:39:47 AM
Other studies like this have been done here
http://www.greencarcongress.com/2006/11/study_improveme.html
and companies like WalMart have been using these for years
http://www.greencarcongress.com/2005/12/walmart_seeks_t.html
and you know that if WalMart is doing it, it's for the bottom line (and not for environmental reasons).
So why isn't everyone getting getting a truck skirt? Especially those independent truckers that went on a silly strike a few weeks ago to protest diesel prices.
Posted by: Karkus | Apr 17, 2008 9:58:37 AM
Rather than just covering a void, cannot the space beneath the trailer floor also provide useful storage or hauling space? Sure, place skirts over the wheels, but place cabinets below the floor.
My guess is the skirts will also serve to mitigate the spray mist ejected from the tire wells while driving on wet pavement - a safety hazard to moving traffic in the immediate vicinity.
Posted by: Mark Gutting-Kilzer | Apr 17, 2008 9:59:17 AM
Here's a company that sells them
http://www.freightwing.com/index.html
I wonder how much these things cost?
Posted by: Karkus | Apr 17, 2008 10:04:58 AM
Inflatable boat tail.
Also, whatever happened to the (I thought brilliant) idea of using compressed air jets out of nozzles on the rear to make the vehicle effectively longer and streamlined?
Posted by: clett | Apr 17, 2008 10:31:44 AM
it seems to me that the biggest component of drag is the square tail. has anyone looked at the various components of drag (nose, wetted area, tail etc)?
Posted by: jmilner | Apr 17, 2008 10:58:12 AM
This is a good idea also for safety reasons. Everyday a lot of peatons, cyclists and motorcyclists die under trucks wheels.
Posted by: Mario | Apr 17, 2008 12:03:31 PM
It seems that maybee a decade ago in Europe there was interest in installing inflatable spoilers on the end of trailers. It wouldn't help the first truck on fuel use but it would reduce the fuel consumption on the trucks following close. There must have been a GPS-device regulating the rear trucks engine speed for safety reasons. The main reason at the time was to be able to cram more trucks in the lane.
Posted by: ken | Apr 17, 2008 12:15:04 PM
A 5-15% reduction in fuel consumption. That seems like pretty low hanging fruit to me. We are talking about billions of gallons of oil saved per year.
Honestly, I can't see a downside.
Posted by: GreenPlease | Apr 17, 2008 12:18:57 PM
sjc, you said:
"So why isn't everyone getting getting a truck skirt? Especially those independent truckers that went on a silly strike a few weeks ago to protest diesel prices."
Waitaminute. I don't think anyone has thought about fuel efficiency with a truck much less a heavy duty or an 18 wheeler. I get the feeling that truck companies should be considering testing their trucks in a wind tunnel to improve fuel efficiency.
Posted by: Gerald Shields | Apr 17, 2008 1:06:20 PM
"Also, whatever happened to the (I thought brilliant) idea of using compressed air jets out of nozzles on the rear to make the vehicle effectively longer and streamlined?"
probably the cost of installing the system too high; also doubtful if you save more energy than you spend compressing the air.
Posted by: eric | Apr 17, 2008 1:07:35 PM
One can also place partition pieces out in front of the nose of a truck and create a more streamlined shape.
Posted by: John | Apr 17, 2008 1:18:11 PM
Renault tried the air jet thing in a concept car
http://www.greencarcongress.com/2006/02/renault_altica_.html
They put the jets on the top of the rear which would be a problem for container trucks.
But you could do it for buses, SUVs, MPVs etc.
However they quote the savings at 80mph which is probably faster than they want people to go.
[ Green types anyway ]
I wonder could you electronically link trucks together so they could slipstream (and keep it safe) - imagine being hit by a convoy of 10 trucks!
Posted by: mahonj | Apr 17, 2008 1:22:08 PM
Gerald,
You attributed Karkus' quote to me. I saw a video of a pickup truck that hit the side of a jack knifed trailer and sheared the top of the pickup cab right off. It is a safety issue as well as a fuel savings and by extension, national security issue to get more mileage out of truck travel.
I would guess the reason that independent truckers have not done something like this is cost. They are paying for their rigs and fuel, they do not want to pay for this. Maybe the government and tax payers could help. It is good to save fuel for lots of reasons and when you combine safety, it is in the public interest to do so.
Posted by: sjc | Apr 17, 2008 1:35:21 PM
Didn't everybody know that moving a very large brick at 75-80 mph takes a lot of energy. Truck/bus builders and operators should have known that and figured ways to reduce drag decades ago.
Posted by: Harvey D | Apr 17, 2008 2:04:53 PM
The fuel saving idea is not really new.
Side skirts help, but so will underskirts, as will either boat-tails or some other rear square-reducing method to improve airflow.
However, often trailers are owned by the transport company, while the truck is owned by the independent trucker.
It would be nice to see side-skirt and under-skirt kits made available for all standard sized trailers, with perhaps a tax incentive or grant program to have them installed, and perhaps extra charges at tolls for trucks without them.
Posted by: John Taylor | Apr 17, 2008 2:28:03 PM
Well, John beat me to the answer. Independent truckers just own the rig, not the trailer. They get a contract to go somewhere, latch it on, and bring it somewhere else.
Posted by: steve | Apr 17, 2008 2:53:49 PM
I am seeing and expect to see more good ideas being used by the large in house over road truck operators such as Wal-Mart. They probably control both the truck and the trailer.
I would be interested in seeing a trade off between this type of add on and the reduction in speed in 5 mph increments. My guess is you could get some very quick results close to these just by changing driving habits.
Posted by: Ed | Apr 17, 2008 4:08:09 PM
Another option would be to have a spoiler that extends from the front bumper at highway speeds to improve the aerodynamic profile of the vehicle.
Posted by: GreenPlease | Apr 17, 2008 4:37:31 PM
Frontal configurations have the most effect on aerodynamic drag as compared to rear aerodynamics. Frontal streamlining & rear boattails make the truck-trailer combination longer which are already at the maximum legal length. One method from 1960's station wagons would be an aluminum fixed curved spoiler at the top rear of the trailer(& spoilers along the verticle rear edge if possible) which would skim boundary layer air & force it to fill the vacuum behind the trailer. These devices would often be subject to damage.
Making the sideskirt bottom strong enough to carry extra cargo would make placing cargo down between the wheels difficult & would require extra power equipment other than folklifts. Special strapping so forklifts could lower cargo between the wheels would really reduce a cargo area already pretty small.
Posted by: litesong | Apr 17, 2008 5:19:33 PM
Question. In the US many truckers are independent. They own and operate their rig. Is that true in the EU?
It seems to me that independent truckers would have a greater desire to maximize profit and employed drivers would be more content to follow parameters set by the employer. And employers will at least try to look socially responsible by minimizing fuel consumption.
As for all this drag reduction. The Arabs announced an embargo in 1973 during a war with Israel. For a month or so there were shortages in the US. In the aftermath the merits of various skirts and shapers were studied and many were added to trucks. The current rising fuel costs will lead to further adaptions.
But this time I expect we will see mandated improvements rather than leaving it up to the truckers.
Posted by: K | Apr 17, 2008 5:25:51 PM
I beliefe most truck drivers are just contractors or employed staff here in europe. The percentage of truckers
owning the rig is probably less than double-digit.
Even at european diesel prices (currently at around 7,70 USD/gal) most trucks are speeding (typically, the speed limiter is set by default to the legal speed limit + 10 kph; however, a lot of trucks are going even faster, and this not only downhill...).
Obviously, the gain from being on time at all cost is larger than the cost of fuel - still. It seems to happen
a lot that if a driver is caught speeding with and has to hand over his driving licence, he is immediatily fired and replaced by another driver... Staff cost is
probably low too, as these companies employ mostly eastern europe citizens (low wages there).
Not really a job I'd like to have.
Anyway, obviously fuel at nearly 8 USD/gal is still way
too cheap to really think about transportation and
logistics in a grander scheme (ie. using rail instead of
road for distances > 200km; currently, long distance truck traffic is growing rapidely with typical routes around 1500 km.
Unfortunately, the oil price is not fundamentally high,
but the USD is weak; I'd think with USD and EUR were
still around parity, and Oil being that high then,
this would really make people reconsider (that'd be around 12 USD/gal for diesel).
Any bets when this mark will be exceeed?
Posted by: realarms | Apr 17, 2008 5:59:50 PM
Mahonj, i like your idea. In some places it wouldn't work so well when it's icy(do you really want the computer driving when conditions are marginal) however i was thinking maybe linking 2 or 3 trailers together, i know they already do 2 at a time but it seems few and far between and far more often than not you see just the 1 trailer at a time
Posted by: Brad | Apr 17, 2008 8:34:50 PM
One idea I thought of and have heard about are cruise control range sensors. They estimate that many rear end collisions and pile ups on the highways could be eliminated if the range distance between the car in front and the car in back could be computer monitored.
Not only would it prevent accidents, but a highway train of sorts would reduce drag and fuel consumption. People in Southern California routinely travel at 70+ mph with 3-4 car length gaps between them and the car in front. You might think you were on a race track.
This is not a good driving habit, because reaction time is 1/2 second at best and you are in the guy's trunk in a blink. You hear about these accidents everyday and I am amazed that there are not more of them.
With the range sensor computer, you could run at that speed and distance with a safety margin at the same time. Now on the freeways, if you allow 7-8 car lengths, somebody will just change lanes into that space. If we can save fuel and save lives at the same time, that might be a winning combination.
Posted by: sjc | Apr 17, 2008 9:49:20 PM
realarms: isn't gas in the US not at like $3.50 a USG or something like that? i think they'd start thinking more about their choices even at $4 or $5 a gallon
Posted by: Brad Godfrey | Apr 17, 2008 10:19:18 PM
It took them this long to figure it out.NASA Dryden had it figured out in the 1970's. It just took this long for people to get serious about it.
Posted by: Reality Czech | Apr 18, 2008 9:12:54 AM
So all the discussion says to me that the independent trucker pays the fuel, but has to haul someones fuel inefficient trailer. This is another example of do your own thing lack of coordination. Maybe truckers, shippers and government can come up with a way to share the costs for more efficiency. If you are an oil guy, the more you sell the more you make. If you are a citizen of the country, going to war for oil is not a good idea and working together makes more sense.
Posted by: sjc | Apr 18, 2008 10:09:52 AM
Robert Englar at Georgia Tech is the leading man in the world on this. Rounded top spoiler extension to top back of container. Front air dam on top of cab must be higher than trailer or its useless. Flexible bellows/ skirt between cab and trailer/ container. Easy, very low cost, very high fuel savings. Current trucks could hardly be less aerodynamic.
Posted by: Emphyrio | Apr 18, 2008 12:28:12 PM
It sounds a bit like the tenant landlord problem. The builder builds the house, but they do not pay the utility bills, so they put in the cheapest most inefficient appliances. Then the landlord buys the house and rents it. He does not have to pay the utility bills, so what does he care? Then the tenant moves in and has to pay the utility bills, would like to put in more efficient appliances, but it is not his house....and so it goes.
If the company owning the trailer does not have to buy the fuel, what do they care? They are not going to buy skirts and spoilers to save someone else money. The trucker will not buy them, he is cash strapped enough as it is....and so it goes. Selfishness overrides common sense in doing the right thing for all of us. Even if the trailer owners just care about themselves (and that is a good bet) then they should know that the costs for fuel are reflected in the fees that they are charged.
But maybe they can bid one trucker against another and find a Mexican trucker that will take less. Houses in Mexico cost less, so the money he sends home goes farther. If we continue with this national Walmartization and race to the bottom, that is exactly where we will end up...at the bottom and it will be very difficult to ever get up again. The Republicans believe that if everyone just minds their own business and takes care of themselves, then everything will be ok. Divide and conquer by pitting one against the other. No unity and team play because the team may talk with one another, figure out that they have been conned and taken and turn against the dividers.
Posted by: sjc | Apr 18, 2008 4:02:37 PM
I can find pictures of Walmart trailers with skirts but I've never seen any in the last 8 years and I'm on the road 100,000 miles a year. I wonder how something like this would work on a box truck.
Posted by: drivin98 | Apr 19, 2008 11:52:13 AM
I'd like to see how a 5% cut of 750 million liters could amount to 50 million tonnes of CO2 per year?!
With a density of approx. 0.9 kg/liter, they will be saving:
0.9*750*0.05 = 34 million kg diesel, which maybe equates to 50 million kg of CO2, but not tonnes. Makes a helluva difference...
Still, it's worth saving.
Posted by: Thomas Pedersen | Apr 19, 2008 2:23:04 PM
Electric car, the future but in the present.
www.blobject.es
Posted by: Jose Luis | Apr 20, 2008 4:29:34 PM
I seem to remember seeing a video where they reduced drag with a curtain that closed the gap between the tractor and the first trailor. This may have been 20 years ago.
Posted by: keith fuller | Apr 23, 2008 6:57:58 PM
This really sounds like a great idea, and one that should be implemented on all trucks possible. The only drawback I can see is who will pay for this. The big companies don't have to worry about the driver with his own tractor, and the Independents can hardly afford to pay their own bills, let alone beef up their trucks. Good luck and maybe someday?!
Posted by: Mary Leigh | Apr 24, 2008 6:05:48 AM
Sideskirts are well known in the UK but have peaks and troughs in popularity with distribution fleets.
Hatcher Components is a company that has been supplying aerodynamic kit for european trucks for around 30 years.
Website address is www.hatchercomp.co.uk
Posted by: Mike Barker | May 21, 2008 6:30:23 AM
I've heard there are ice build-up issues with side skirts. Does anybody have any information or experience regarding that issue?
Posted by: David | Jun 5, 2008 1:53:49 PM
"Within a few hours a PT- Boat pulled alongside and these officers came aboard the LCI. They pulled out this big map and informed us that tomorrow is going to be D- Day. Our outfit's orders are to assault a place on the French coast code- named Utah Beach. The attack was just a few hours away. / p "At five o'clock on the morning of June 6 the front of our transport went down and we were off. The ramp opened up 200 yards short of dry beach and we stepped out into shoulder- deep water. / p "I had just turned...
Posted by: bimini tops | Jun 26, 2008 12:09:56 PM
I have a novice question. I just returned from Europe where the trucks look very different than new trucks do in the U.S. Specifically I'm talking about port drayage trucks. I've seen photos of the new trucks they are bringing in at the ports of LA and Long Beach and they look like dinosaurs compared to the ones I saw at the Port of Hamburg. Are these just optics? Or is there some other reason? Does anyone know why? Which are more aerodynamic? Feel free to write me off line at mcsbjm@yahoo.com. Thanks!
Posted by: Barbara | Jul 14, 2008 10:49:31 AM
The problem with side skirts and boat tails are maintenance and liability costs. Driving over a steep rail road crossing or cutting over a curb can damage the skirt before it pays for itself. Any tail hanging on the back end of a trailer will easily get hit in a trailer parking lot due manuvering a long trailer in and out of tight places. To be any good, tails have to be rigid and if so, violate the DOT's trailer bumper strength requirements.
Posted by: Geoffrey | Jul 15, 2008 4:05:05 PM
Next your going to tell us that the same thing happened years before when you, a buddy and his brother in law (call them call them Tom and Wayne to protect the innocent) were fishing and Tom s pole fell off his lap.
Posted by: bimini tops | Aug 15, 2008 2:02:53 PM
