Semi-trailers suck. Literally. As these boxy shapes barrel down the freeway, they leave a vacuum in the air behind them, and this area of turbulence and low pressure generates suction that accounts for at least a quarter of all aerodynamic drag on a tractor-trailer rig. If you could do something to disrupt the vacuum and reduce the drag, then the truck engine wouldn’t have to work as hard to maintain highway speed, and you’d save a lot of diesel fuel.
Those are the facts of physics, anyway. Whether the facts can be translated into a real business is the question that ATDynamics is now testing. The South San Francisco, CA, startup, which was born as part of a business plan competition at Dartmouth’s Tuck School of Business in 2006, sells a collapsible tail for semi-trailers that’s designed to smooth out the air flow behind a trailer, reducing drag and improving fuel efficiency by 6 to 7 percent.
ATDynamics founder and CEO Andrew Smith says rigs with the $2,000 “TrailerTail” burn 8 gallons less fuel for every 1,000 miles driven. Suppose diesel costs you $3.75 per gallon at the pump-you’d only have to drive your TrailerTail-equipped trailer about 66,000 miles to earn your money back. “If you’re driving over 25,000 miles a year, this becomes a no-brainer,” says Smith. (For a different take on making trucking more efficient, see this story today by my San Diego colleague Bruce Bigelow.)
So far ATDynamics has sold more than 5,000 TrailerTails—mostly to commercial fleets, but a few to individual owner-operators. This month, Smith set a goal of shipping another 50,000 tails by 2014. While that’s an ambitious target, it would still represent only a 2.5 percent penetration rate, given that there are 2 million semi-trailers on U.S. roads.
The trucking industry is notoriously slow to adopt new technologies. But with fuel prices unlikely to come down, and with more companies demanding that their shippers use green technology to reduce carbon emissions, Smith reasons that the economic incentives to trucking fleets to install TrailerTails and their close cousins, trailer skirts, will become irresistible.
“Four years ago, I went and sat down with the senior vice president of engineering at one of the top U.S. trailer manufacturers,” he recounts. “I presented all this stuff about rear-drag aerodynamics, and he responded that they had been building square boxes for 50 years and they planned to build them for another 50 years, and that was the end of the meeting. But in the last two years, the market for trailer skirting has taken off—from a couple thousand units in 2009 to 60,000 or 70,000 this year—and trucking companies now get that trailers can be modified to be more fuel-efficient. I would be shocked if in the next five years, the majority of fleets don’t have rear-drag technology.”
Here’s a 24-second video showing how the TrailerTail works; story continues below video.
So how did we end up with two million semi-trailers in the form of giant boxes—“the least aerodynamic shape” possible, in Smith’s words? When semi-trailers were invented at mid-century, the Interstate system wasn’t finished yet, trucks couldn’t drive very fast, and the price of diesel fuel was low, Smith notes. But “now we have a world where
