The engine and aftertreatment technology developed for engines in conjunction with the newer 15 ppm ultra low sulfur diesel (ULSD) fuel rules is reducing emissions, but how the mandates for 2010 will be met remains somewhat undecided.
"It's going to be tough to get there," said Ed Raniszewski of Freightliner LLC, speaking at the Dairy Distribution and Fleet Management Conference March 28-31 in San Antonio, Texas.
The Detroit Diesel Series 60, MBE 4000, and MBE 900 engines are equipped with a diesel particulate filter system that replaces former muffler systems. "They are huge and they are heavy," Raniszewski said. Some trucks with high horsepower ratings would need two systems. Exhaust heat is used to burn-off the particulate matter collected in the diesel particulate filter through a process called regeneration.
Diesel engines manufactured after December 31, 2006, are required to meet the new Environmental Protection Agency 2007 emissions standard that includes a reduction in nitrogen oxides (NOx) emissions by over 50 percent, as well as a reduction of particulate matter emissions by 90 percent. The exhaust gas recirculation system is optimized to meet the low NOx requirements. The particulate matter, which consists primarily of soot and ash, is reduced with the use of the aftertreatment system.
There is one way to meet the 2010 requirements and that would be by using a selective catalytic reduction technology as Mercedes-Benz is doing in Europe that would reduce nitrogen oxide gases, Raniszewski said. The reduction comes from using a non-toxic, aqueous reduction agent (such as AdBlue, a product used in Europe) that is a solution of urea in demineralised water. Supplied from a separate tank, the solution converts nitrogen oxides into harmless nitrogen and water. Mercedes-Benz supplies trucks with the systems in other parts of the world. Raniszewski said that the EPA is in the process of authorizing the system in the United States.
And then there are the hybrid trucks. "Testing is going on," Raniszewski said. "So far, the systems are working and we are seeing lower fuel use."
One example of the Freightliner hybrids is a medium-duty prototype utility truck introduced at the Great American Trucking Show August 24, 2006. A Class 7 Business Class M2 106, the truck is an example of how Freightliner LLC can integrate engine, powertrain, and other vehicle functions with environmentally responsible technology. The prototype is a full-parallel hybrid, similar to hybrid electric cars, with regenerative braking that recharges the batteries and electric launch functionality. It has an integrated electric motor in line with the engine and transmission, enabling operation with electric or diesel power, either separately or in combination. The truck launches with electric power and the diesel engine provides additional torque as required.
The prototype vehicle that was introduced at the show integrates the hybrid electric vehicle system with hydraulics for electric power takeoff (ePTO) operation. On a jobsite, the engine remains off for the majority of the operation with the hydraulics being run by batteries. When the batteries get low, the engine automatically turns on to recharge them. This takes approximately five minutes and, when the batteries are fully recharged, the engine automatically turns itself off. Because the batteries are charged by regenerative braking, brake shoes will receive less wear, extending their life and reducing maintenance costs.
Pending final results of tests currently underway with this proof-of-concept vehicle, Freightliner is considering implementing the hybrid system in a variety of medium-duty trucking segments, including beverage, school bus, and pick-up and delivery applications, the company said at the introduction.
Freightliner is collaborating with the Hybrid Business Unit of Eaton Corporation on this effort.