Making Trucks More Aerodynamic
One of the biggest reasons for trucks' low efficiency is drag problems, which become worse with higher speed. Accordingly, researchers have focused on reducing drag effects on trucks, and in the last few years several have announced breakthroughs.
The square back of trailers is a big contributor to inefficiency. At high speeds, the square edges of the truck begin to generate a vortex which acts opposite to the direction of motion. This vortex increases the energy required from the truck engine, and drags down fuel efficiency. Engineers at a Georgia Tech institute, who have been studying this problem since the early 1990's, are in the late stages of testing a retrofit design which they say will fix the vortex issue.
Controlling Vortex Formation and Directing Airflow
This design works to prevent drag in two ways. First, rounded panels are added to the back of the truck to prevent vortex formation. Secondly, a system blows compressed air over the edges of the truck. This step is necessary to redirect the airflow and prevent it from collapsing into a vortex. The compressed air may be provided from a variety of sources, such as exhaust gas, air off the truck's turbocharger, or an onboard air compressor.
This gas could also be directed to slow the truck during braking, which would save energy and help make trucks safer.
Real world tests demonstrate that this system reduced drag by 35%, which translates into a 12% increase in fuel efficiency. The technology is working, and a 12% fuel savings is more than enough to prompt the trucking industry to adapt the technology.
The fact that the Georgia Tech design is a fairly simple retrofit bodes well for the technology's future adoption. It can be added to trucks quickly and cheaply, and won't necessitate buying a whole fleet of expensive trucks to replace today's models. Though researchers haven't provided a price point yet, installation of the system would likely pay for itself in fuel savings fairly quickly; this will be especially true if some sort of government subsidy or tax break is introduced.
Pictured: Old NASA-designed fuel efficient truck.
Image: NASA - E-38096