Seeking More Efficient Trucks: By Technology and By Design

November 12, 2006 – Vol. 11 No. 34

SEEKING MORE EFFICIENT TRUCKS: BY TECHNOLOGY AND BY DESIGN.

According to the Truck Manufacturers Association (TMA) and the US Department of Energy (DOE), America could save more than 1 billion gallons of diesel fuel annually if tractor trailers were more aerodynamic.

The results of a two-year joint study showed that gap enclosures (filling the gap between the tractor and the trailer to smooth the air flow), adding side skirts ( to reduce airflow under the trailer), adding boat tails (aerodynamic extensions to the trailer to minimize wake) and installing aerodynamic mirrors resulted in 23 percent less drag for tractor trailers.

For every two percent improvement in drag, they concluded, there was a one percent improvement in fuel economy - about 10 percent in the study. Ten percent fuel economy improvement means that average fuel economy for large trucks would increase from 5.5 miles per gallon to 6.05 miles per gallon.

Sound like nothing? As of 2002, according to the US Census, there were 750,000 tractor/van semi-trailer combination-unit trucks in operation traveling 60,101 million miles. That ten percent improvement in fuel economy nationally and fleet-wide would mean a savings of 993.4 million gallons per year.

(That ,plus four years of more tractor trailers added to the nation’s highways, is where the one billion gallons per year savings came from. Of course every truck in the nation’s fleet would have to become aerodynamically slick to see those diesel fuel savings.)

Yet there’s more the truck industry could do to save fuel. Build hybrid electric heavy trucks for long hauls and begin selling electric trucks for urban use.

Maxwell Technologies has announced it now has 125-volt ultracapactior modules developed specifically for use in for heavy hybrid, electric vehicles, heavy duty industrial applications, even electric rail vehicles. The modules can be linked together for up to 1,500 volts of power that can be used for torque assist systems, that is helping out with acceleration and overcoming inertia: trucks moving from rest. The bank of ultracapacitors would capture the normally lost energy of braking and put it to work.

Enova Systems has announced that it will supply a 120-kilowatt electric drive to Tanfield’s Smith Electric Vehicles of the UK on a trial basis. Smith Electric is the world's oldest electric vehicle manufacturer and the world's largest producer of road-going commercial electric vehicles. Their road-going vehicles, largely urban delivery and industrial vehicles, can achieve ranges of more than 100 miles between battery charges and speeds of 50 mph.

Surprisingly, Smith has been around since 1920 and now has a client base of 500 world wide. What better way to deliver goods around city streets than clean, quiet electric trucks?

Finally BAE Systems, best known for its hybrid bus drivetrains, has been selected by the US Federal Transit Administration to integrate a hydrogen fuel cell into a diesel fueled hybrid electric transit bus.

Under the $5.35 million award BAE will incorporate a fuel cell that will be used as a generator to power accessories such as air conditioning, air compressors, power steering, cooling fans and pumps, and a 28-volt electric power generator.

Having the fuel cell generator on board will allow the bus’s diesel engine to shut off at traffic lights and bus stops, adding to overall fuel efficiency. The challenge will be cost-benefit of the fuel cell compared with diesel fuel savings.

Hydrogenics will supply the fuel cell, DaimlerChrysler an Orion bus, and WestStart-CALSTART will divvy out the cash over four years. The bus will be in revenue service in San Francisco.

Visit Maxwell at http://www.maxwell.com/ , Enova Systems at http://www.enovasystems.com/ ,Smiths Electric Vehicles at http://www.smithelectricvehicles.com/ and BAE Systems North America at http://www.na.baesystems.com/