While diesel is expected to remain the dominant fuel typeused in commercial vehicles for the foreseeable future, truck and enginemanufacturers are actively exploring alternative fuels that offer enhanced fuelefficiency, can be used to help reduce greenhouse gas emissions and lowerdependence on non-renewable energy sources.
One example of this activity was an August 2007demonstration by the Volvo Group, the parent company of Mack Trucks and VolvoTrucks North America. Displaying seven trucks, each powered by a differentnon-carbon dioxide emitting renewable fuel, the company showcased alternativesthat could be used by North American fleets in the future.
On that list were the following fuel types:
• Biodiesel produced from vegetable oils
• Biogas comprised of hydrocarboned methane that can beextracted in sewage treatment works, at garbage dumps and other sites
• Biogas + Biodiesel combined in separate tanks andinjection systems
• DME (Dimethyl ether) gas that is produced through thegasification of biomass, including that originating in paper manufacturing
• Ethanol/Methanol (methanol is produced through thegasification of biomass and ethanol through the fermentation of crops rich insugar and starch) blended together
• Synthetic Diesel, a mixture of synthetically manufacturedhydrocarbon produced through the gasification of biomass mixed withconventional diesel fuel
• Hydrogen Gas + Biogas, a mixture of hydrogen gas withcompressed biogas
Already in use powering truck engines are compressed naturalgas (CNG), liquid natural gas (LNG) and liquid propane gas (LPG). CNG is storedon vehicles in a tube-shaped compressed gas cylinder. LNG, natural gas cooledinto a liquid form that takes up less space to transport and store, is oftenused for longer-range applications. LPG, a bi-product of natural gas processingand petroleum refining, is also used because it liquifies at relatively lowpressures.
Cummins Westport Inc., a joint venture between Cummins andWestport Innovations, offers natural gas engines for medium- and heavy-dutytrucks and buses. The engines, which meet U.S. Environmental Protection Agency(EPA) and California Air Resources Board (CARB) emissions standards, are in useby over 75 city fleets where they have provided millions of miles of service.
The Cummins Westport offerings include the 8.9-L ISL G, which is available in 250, 260, 280, 300, and 320 HPratings. The ISL G is capable of operating on CNG or LNG, as well as biomethanethat meets fuel specifications. Common applications are heavy-duty refuse anddump, medium-duty trucks, and urban buses. The ISL G will replace the L GasPlus and C Gas Plus natural gas engines in North America.
The B Gas Plus Cummins Westport engine is a 5.9-Lsix-cylinder natural gas engine that will be available in North America through2009. Certified to EPA and CARB 2007 standards, the engine delivers up to 230HP for use in shuttle buses and medium-duty trucks. The company also offers the195-HP B LPG plus 5.9-L six-cylinder propane engine for pickup and delivery trucks,step vans, street sweepers and other medium-duty applications.
Coming of age
Hybrid technology for heavy-duty trucks is now coming ofage. Recently, ArvinMeritor announced that Wal-Mart Stores is operating aprototype heavy-duty truck equipped with the first Meritor diesel-electricdrivetrain. Wal-Mart will test and evaluate the vehicle in regular linehaulservice throughout 2009.
The Meritor dual-mode hybrid drivetrain, developed incollaboration with Navistar and Cummins, is comprised of a motor/generatorunit, high capacity lithium-ion batteries and a power-management system. Under48 MPH, vehicle propulsion is delivered entirely through the battery-poweredelectric motor. The batteries are recharged through regenerative braking and/oran engine-driven generator. As the vehicle approaches highway speed, thedrivetrain phases to a diesel-powered system with the electric motor providingpower only as required.
A key differentiator of the Meritor system, according to thecompany, is its ability for zero-emissions over a wide range of vehicle drivingconditions. This allows the truck to operate in places where emissions arerestricted, like ports or urban areas. Additionally, the batteries providecontinuous power for hotel loads during overnight rest periods, eliminating theneed for engine idling.
Mack Trucks recently delivered its fifth diesel-electrichybrid refuse truck to the U.S. Air Force (USAF) Advanced Power TechnologyOffice (APTO). The TerraPro Low Entry refuse model is equipped with a 325 HP2007-compliant Mack MP7 engine. The Mack hybrid electric powertrain features anintegrated starter, alternator and motor that assists the MP7 in providingtorque to the wheels and regenerates energy during braking. The energy capturedduring braking (stored as electricity in lithium-ion batteries) is then used inplace of diesel to help launch the truck from stops.
The Mack TerraPro hybrid truck has undergone extensivetesting including several thousand accumulated miles of operation. After APTOreviews and tests the truck, they will provide it to the City of Macon, Ga.,for continued testing in its municipal waste collection operation.
The Volvo Group is introducing its fourth-generation hybridsolution for use in trucks. The OEM has been testing various types of hybridsolutions since the 1980s and first unveiled a commercial system for heavyvehicles in 2006. Volvo’s solution is based on a concept known as I-SAM(Integrated Starter, Alternator Motor) that employs an electric motor and adiesel engine in parallel so either system can be used in the areas where it ismost effective.
The Eaton hybrid system is already widely available for manymedium-duty trucks. Commercial vehicle fleets with Eaton hybrid systems haveaccumulated more than 12 million miles of service. Delivery vehicles with theEaton system are being used by companies such as
Fed Ex, UPS, Coca-Cola and Pepsi, to name a few. Work truckswith Eaton hybrid power are also in service at dozens of utility and telecomcompanies across North America.
Models from Freightliner, International, Kenworth andPeterbilt are offered with the Eaton hybrid system. Included are FreightlinerBusiness Class M2e and M2 106 Hybrid drop frame trucks, the InternationalDuraStar Hybrid, Kenworth T270 and T370 models, and Peterbilt Model 330 andModel 335 hybrid electrics.
The impetus to operate alternatively powered commercialvehicles is growing. Recently, under the EPA’s Diesel Emission Reduction Act(DERA), $156 million in grants was made available for diesel hybrid trucks. Thefunding for up to 25% of the cost of a new hybrid truck came from the AmericanRecovery and Reinvestment Act (ARRA) that allowed fleets to purchase multipletrucks as long as an existing diesel truck was taken out of service for each newhybrid.
Combining DERA funding with an IRS tax credit and the fueland operating savings of a hybrid versus a conventional diesel truck, the costof a new diesel hybrid truck is estimated by EPA as about the same as aconventional new truck over a five-year period. For more information about theEPA’s DERA program, visit www.epa.gov/cleandiesel.
RydeGreen
Ryder’s approach to improving fleet fuel efficiency andhelping reduce the carbon footprint of trucks and tractor-trailers is thecompany’s RydeGreen program. One of the vehicles offered is the DuraStar hybridfrom International that employs diesel-electric hybrid engine technology. Itsrange of applications includes beverage and refrigerated food distribution,package pick-up and delivery, local and regional government transportation, andutility operations. The RydeGeen program also includes Freightlinersleeper-equipped Columbia and Century tractors equipped with a host of fuelsaving technologies, and several “green” trailers with a variety of options toincrease fuel savings.
RETROFIT ALTERNATIVES
Available to fleets in the fourth quarter of 2009, theSyngas DPF (Diesel Particulate Filter) emission control system from NxtGen isdesigned for intra-city medium-duty trucks where daily regeneration ofparticulate filters is impeded by low operating temperatures. Syngas technologyutilizes a non-catalytic generator to produce syngas for use in activelyregenerating diesel particulate filters.
The use of syngas, the company says, is superior to diesel fuelfor DPF regeneration because it is highly reactive and combusts at a lowertemperature, which translates into reduced fuel consumption. Syngas DPF can beretrofitted with no change to engines or controls. Field trials are takingplace on medium-duty trucks in several fleets in 2009.
NxtGen will also be offering Syngas LNT (Lean NOx Trap) as aretrofit diesel emission control system. The system, the company says,eliminates the complexity and cost of SCR by not requiring urea, on-boardstorage tanks, heaters or injectors. A combined system, Syngas DPF+LNT, is alsounder development and recently completed engine test cell trials. Field trialsare set to begin in the third quarter of 2009 and the system will be availablein 2010.
