Heavy-duty hybrid trucks deliver on fuel economy

Sep 12, 2012

A performance evaluation of Class 8 hybrid electric tractor trailers compared with similar conventional vehicles by the U.S. Department of Energy's (DOE's) National Renewable Energy Laboratory (NREL) shows significant improvements in fuel economy.

"During our 13-month study, the tractors demonstrated 13.7 percent higher fuel economy than the conventional tractors, resulting in a 12 percent reduction in fuel costs for the hybrids," NREL Senior Project Leader Michael Lammert said.

For the "Coca-Cola Refreshments Class 8 Diesel Electric Hybrid Tractor Evaluation: 13-Month Final Report," the NREL team collected and analyzed fuel economy, maintenance, and other vehicle performance data on five hybrid and five conventional Class 8 tractor trailers operated by Coca-Cola Refreshments (CCR) for delivery service in the Miami, Fla., area.

NREL has been tracking and evaluating new propulsion systems in transit buses and trucks for more than 10 years. These evaluations are part of the U.S. Department of Energy's Advanced Vehicle Testing Activity, which conducts comprehensive, unbiased evaluations of advanced technology vehicles operating in fleets across the nation.

In addition to field testing, the NREL team performed dynamometer testing at its Renewable Fuels and Lubricants (ReFUEL) Research Laboratory. During testing, the hybrids demonstrated up to a 30 percent improvement in fuel economy, depending on drive cycle, and up to a 32.1percent improvement in ton-miles-per-gallon. The comparable conventional tractors were approximately the same age and operated in similar conditions in the same facility.

"Our analysis identified key variables on trucking routes—such as idle time, kinetic intensity, and average speed—that, if taken into consideration, can help Coca-Cola Refreshments optimize the use of its hybrid vehicles on routes where they offer the greatest benefits," Lammert said.

The hybrid tractors featured hybrid propulsion systems with 44 kilowatt electric motors. The systems included regenerative braking and lithium-ion batteries that provided energy storage. Energy that is normally lost during braking is captured, stored in the batteries, and used to power the electric motor, which is helpful on a truck that can weigh as much as 55,000 pounds.

"We see cost as the number one barrier to companies using advanced technologies," Lammert said. "Testing likes this helps companies understand whether these vehicles are going to save them money over the long run."

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mysoulwanders
not rated yet Sep 12, 2012
For an even BETTER increase in MPG this guy in CT has built and proven a Class 8 tractor that brought it from the national average of 6.5 MPG to 13.4 MPG close to 88% increase in MPG. :)