There’s a big push to increase the fuel efficiency of our country’s – our WORLD’S – passenger cars. All of the major automakers are working on more fuel-efficient engines, hybridization, electrification, lightweighting, idle-reduction, and other technology pathways in an effort to meet more stringent CAFE standards in America and compete in the new, greener automotive landscape.
But what about trucks? No, I don’t mean the pickup in your neighbor’s driveway. I mean the big, 18-wheeled, freight-haulin’, diesel-drinkin’, noise-makin’ semis that move approximately two-thirds of our nation’s freight around, accounting for around 7 TRILLION dollars annually – a substantial portion of our economy. These trucks get, on average, around 6 miles per gallon. Horrible, right? (Well, consider that these trucks, when fully loaded, weigh up to around 80,000 pounds – about the same as 20 passenger cars. If you assume the cars get 25 mpg each, then the group as a whole gets the equivalent of 1.25 mpg. In that respect, the semi ain’t so bad…)
…Which brings me to my point. When talking about fuel efficiency in the trucking industry, FREIGHT efficiency is the proper metric. (Units of freight-ton-miles-per-gallon are most often talked about.) And despite the fact that not much effort has been put forth historically into improving the freight efficiency of long-haul trucks, that trend is certainly changing. The US Department of Energy recently announced awardees under the SuperTruck program – funded in part by the American Recovery & Reinvestment Act of 2009 (i.e., the Stimulus Bill) – to improve the freight-fuel-efficiency of Class 8 trucks by 50%.
And how is this being accomplished? Although the impacts of hybridization in long-haul trucks may be modest, electrification can have a LARGE impact in idle-reduction at truck-stops. (Today, when truck drivers take their mandatory rests at truck-stops, they must let their engines idle to maintain the heating, cooling, and other ancillary functions within their cab. Having an auxiliary power unit – whether battery or fuel cell – could eliminate this need.) Aerodynamics plays a HUGE role as well. Think about it – semi-trucks today are a bit like a brick – an extremely large brick – blasting down the freeway at 70 mph. Aerodynamic improvements are the low-hanging fruit. Even simple add-ons that address the gap between the cab and the trailer, the space between the trailer and the road, and the flow-field immediately behind the trailer can have significant impacts.
Beyond this, truck OEMs are working on improvements with more efficient engines through downsizing and downspeeding combined with improvements in the transmission and controls. The use of waste heat recovery systems is being investigated to capture some of the heat energy that is released through the exhaust system, converting it to electricity to power accessories. Even driver aids, such as eco-feedback to provide information about the fuel-economy impacts of driving habits, and intelligent route mapping that considers traffic and topography in plotting the most optimum course for shipment, are being considered. Super-insulated cabs to reduce the heating/cooling load, and super-wide low-rolling-resistance tires are also being developed. The list goes on and on!
Why is this important? By some estimations, the emissions (of pollutants AND greenhouse gases) from passenger vehicles in the U.S. could flatten out as our vehicles become more efficient, combined with the (slight) potential for mass-transit as our population increases. (In developing countries however, that might not be the case, unless you’re an eternal optimist and believe that China/India/Brazil will seize the opportunity and grow more smartly than we did.) Freight, on the other hand, will continue to grow with our population, magnified by the globalization of trade. Basically, if we don’t do something now, the problem could be huge.
Plus, freight companies are businesses. Businesses make money (or fail). Rising and uncertain fuel costs wreak havoc with their operating expenses. More freight-efficient transport translates into more stable profits for freight companies, and more stable prices for the consumer.
Of course, we haven’t even begun to discuss rail-freight yet. But that’s a topic for another day…