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Greener Truck and Bus Fleets 

Particulate Filters

Several Pennsylvania school districts were chosen for funding under the Clean Buses for Kids Program to install diesel particulate filters and purchase ultra-low sulfur diesel. The program's funding came from an enforcement agreement with Toyota. This program was only open to school districts that owned and operated their own buses. The districts are: Bentworth School District and Charleroi Area School District in Washington County; Garnet Valley School District in Delaware County; Plum Borough School District Plum in Allegheny County, School District of Upper Moreland Township in Montgomery County; Unionville-Chadds Ford School District in Chester County, and the West Shore School District in Cumberland/York County.

Krapf Bus Companies, a family-owned company in Exton, Pennsylvania and the largest private school bus contractor in Pennsylvania, is retrofitting at least 10 school buses with particulate filters, which will also be fueled with ultra-low sulfur diesel fuel. The buses serve the West Chester School District, which maintains a population of approximately 11,600 students. Partners include the National School Transportation Association and Johnson Matthey, Inc.

The Philadelphia-area Asthma Bus, a double-decker bus serving as a mobile classroom for the AsthmaBusters asthma awareness and diagnosis program, is being retrofitted with either an oxidation catalyst or particulate filter and will use ultra-low sulfur diesel fuel. Partners include Philadelphia Diesel Difference, Engine Control Systems, Inc., and Sunoco. AsthmaBusters is a free club for children ages 7 to 14 with asthma.

Southeast Pennsylvania Transportation Authority (SEPTA), the major public transportation provider in the Philadelphia area, plans to install diesel particulate filters on a total of 635 buses. To date, they have installed 380 of 400 particulate filters on 1996 NABI 40' buses. The program also includes installing filters on an additional 235 buses, including 155 Neoplan 60' articulated buses and 80 Eldorado 30' buses, which operate throughout the five county service area. Partners include the Delaware Valley Regional Planning Commission's Congestion Mitigation and Air Quality Program and Engelhard. SEPTA is also operating four diesel/hybrid buses.

Wissahickon School District, a suburban district in Montgomery County serving about 4500 students, is purchasing ultra-low sulfur diesel fuel for its entire fleet and has retrofitted 27 buses with particulate filters and 14 with diesel oxidation catalysts. This district was Pennsylvania's first school bus retrofit project. Partners include Pennsylvania DEP, USEPA, 3M Company, Engine Control Systems and Sprague Energy.

Upper Darby School District, the largest school district in Delaware County, is installing particulate matter filters on 61 buses. Its entire fleet of 115 buses is to be fueled with cleaner diesel fuel. The district has received a grant from the US Environmental Protection Agency.

The Chester County Intermediate Unit in the Philadelphia area will install diesel particulate filters on 33 Ford Diesel privately contracted mini-buses. The Great Valley School District, also in the Philadelphia area, will install particulate filters on 33 privately contracted diesel school buses. Both received funding from EPA in 2006.

Diesel particulate filters are ceramic devices that collect PM in the exhaust stream, reducing it by as much as 90%. The high temperature of the exhaust heats the ceramic structure and allows the particles inside to break down into less harmful components. They must be used in conjunction with ultra-low sulfur diesel.

Oxidation and Fuel-Borne Catalysts

General McLane School District, a five-municipality rural district in Edinboro, Erie County, is retrofitting its fleet of 40 buses with diesel oxidation catalysts. The District serves Edinboro Borough, Franklin Township, McKean Borough, McKean Township and Washington Township. Partners include US Environmental Protection Agency.

North Allegheny School District, located twelve miles north of Pittsburgh and serving Bradford Woods Borough, Franklin Park Borough, Marshall Township and the Town of McCandless, is equipping about 100 buses with diesel oxidation catalysts. The district transports about 9,400 students. Partners include the US Environmental Protection Agency.

Penn Hills School District in Pittsburgh is retrofitting as many as 75 buses - the entire active fleet -- with diesel oxidation catalysts and purchasing ultra low sulfur diesel fuel. Partners include the Allegheny County Health Department.

The City of Philadelphia is retrofitting 29 of their diesel-powered vehicles with oxidation catalysts, which will also be fueled with ultra-low sulfur diesel fuel. This project is envisioned as the first step in an ongoing commitment to achieve further emission reductions from the municipality's diesel fleet of approximately 600 vehicles. Partners include Pennsylvania DEP, Lubrizol/Engine Control Systems, Sunoco, and the Philadelphia Diesel Difference.

North Penn School District in Lansdale, Montgomery County about 20 miles north of Philadelphia is purchasing ultra-low sulfur diesel fuel and retrofitting a portion of its school bus fleet with oxidation catalysts. This school district operates one of the largest school bus fleets in Pennsylvania and serves 12,000 students in Montgomery County. Partners include Pennsylvania DEP.

Coca-Cola Enterprises' distribution facility in the Harrisburg area is installing a specially treated fuel (fuel-borne catalyst) and retrofit device system on a fleet of medium heavy-duty deliver trucks. Coca-Cola Enterprises is partnering with Clean Diesel Technologies, Inc. on a multiple step approach to developing emission reduction strategies for its entire 20,000 vehicle national fleet and is a charter member of EPA's Smartway Transport Program. Partners for the Harrisburg project include Pennsylvania DEP and Clean Diesel Technologies, Inc.

Waste Management Incorporated, the largest refuse hauler in North America and Pennsylvania, is installing a specially treated fuel (fuel-borne catalyst) and retrofit device system on a fleet of trash collection trucks operating in Berks, Chester and Montgomery Counties. These are vehicles that operate in urban areas with frequent stop-and-go traffic, making them a very cost-effective target for retrofit. Partners include Pennsylvania DEP and Clean Diesel Technologies, Inc.

Diesel oxidation catalysts initiate a chemical reaction in the exhaust stream, oxidizing pollutants into water vapor and other gases, such as sulfur dioxide and carbon dioxide. DOCs provide 20 to 50 percent reductions in particulate matter, 60 to 90 percent reductions in hydrocarbons and reduce carbon monoxide by more than 90 percent.

Early Use of Ultra Low Sulfur Diesel

The City of Philadelphia, School District of Philadelphia, Wissahickon School District and all school districts using particulate filter retrofit technology made the switch to ultra low sulfur diesel before it was commonly available. The fuel provides some emission reductions on its own, increases the emission reduction capability of oxidation catalysts and is required for most particulate filter operation.

Early Replacement

J.W. Gleim, Inc., Cumberland County, an excavation business, is replacing older diesel engines in several large pieces of equipment it owns. The Gleim Company is replacing older diesel-powered engines in two 40-ton dump trucks, three 20-ton dump trucks and four scrapers, combination vehicles that both scoop and haul earth. The new engines will reduce particulate emissions by 24 percent and the opacity of smoke from the diesel engines by as much as 50 percent. A DEP Small Business Advantage grant will assist with the costs.

Ultra-low sulfur diesel contains sulfur at 15 parts per million or less. (Conventional highway diesel contains no more than 500 parts per million of sulfur.) The use of ULSD alone can reduce particulate emissions between five and nine percent. The primary purpose of ULSD is to enable or improve the performance of aftertreatment technologies such as a PM filter. ULSD will be available nationwide in October 2006.

Compressed Natural Gas (CNG)

Several Pennsylvania transit system are using CNG to reduce emissions and energy dependence funded by DEP's Alternative Fuel Incentive Grant Program.

Centre Area Transportation Authority (CATA) operates about 50 buses in State College, including the PennState campus. Almost all of their buses now run on compressed natural gas (CNG), refueled at a station operated by CATA and supplied by Columbia Gas. This station also supplies a nearby UniMart, making natural gas refueling available to the public.

Port Authority of Allegheny County, (PAT), one of the first transit authorities in the state to operate CNG transit buses, provides service to the greater Pittsburgh region. PAT has operated five CNG buses in its fleet and owns two refueling facilities supplied by Equitable Gas.

The Erie Metropolitan Transportation Authority (EMTA) provides service to the City of Erie and most of Erie County. EMTA operates 12 CNG buses and owns a refueling facility.

The Area Transportation Authority of North Central Pennsylvania (ATA) serves McKean, Potter, Elk, Bradford, Cameron, Jefferson, and Clearfield counties. ATA operates 16 CNG buses and has installed two CNG refueling facilities in its service area.

Indiana County Transit Authority (IndiGO) operates a CNG refueling station supplied by Peoples Natural Gas Company and five CNG-powered transit buses. The CNG buses loop through the Indiana University of Pennsylvania (IUP) campus six days a week. IndiGO is adding additional CNG buses over the next several years.

Rabbittransit is York County's public transportation system. Rabitttransit operates a CNG refueling station and operates 2 CNG transit buses, with plans to add more.

Lower Merion School District, Montgomery County, has committed to operate its entire school bus fleet on CNG. It operates over 60 CNG buses.

Berks Area Reading Transportation Authority (BARTA), which purchased its first compressed natural gas (CNG) powered transit bus in 1995, is currently operating 11 CNG buses in its service area. (Not an AFIG project)

Natural gas is a clean-burning, domestically produced fuel that can generates significantly fewer emissions than diesel. CNG is compressed to 2,400-3,600 pounds per square inch and stored on-board a vehicle in specially designed and constructed cylinders. Vehicles that run on CNG have engines and fuel systems that are optimized for gaseous fuel use. Heavy-duty fleets using CNG generally have constructed their own refueling stations; public and semi-public CNG stations are also available in some locations.


Fleets generally use a mixture of 20% biodiesel and 80% diesel fuel.

  • Valley Forge National Park: 14 vehicles
  • Pennsylvania Turnpike Commission, Philadelphia area: 315 vehicles
  • Willow Grove Naval Air Force Base, Montgomery County: 30 vehicles
  • USDA Eastern Regional Research Center, Wyndmoor: 2 vehicles
  • Great Valley School District, Malvern: pilot project with 1 bus
  • The first biodiesel fueling facility in Pennsylvania opened its d oors June 28 in Lancaster County. The Elm Wo-Go fueling station, owned by Worley and Obetz Inc., is the first in the state to offer biodiesel B5 (5 percent soybean oil and 95 percent diesel) to the public.
  • The Conewago Valley School District in Adams County will use about 4,000 gallons of bio-derived diesel fuel a year (5 percent soybean oil). The fuel was developed through the work of researchers at PennState Energy Institute and their partnership with the bio-diesel supplier, Ag Com, Inc.
  • Biodiesel, made from soybean oil or vegetable oils or animal fats. It can be blended at any level with petroleum diesel to create a biodiesel blend. It can be used in diesel engines with little or no modification. The most common blend is 20 percent biodiesel and 80 percent diesel. Its use reduces most pollutants.

Hybrid Vehicles

Jennings Transportation, a school bus company in Nazareth, was named in July 2006 as one of 15 organizations to participate in a demonstration of a hybrid electric school bus. IC Corporation will supply the buses. The competitive process was sponsored by Advanced Energy, a nonprofit association in North Carolina, and funding came from utility companies and the state of North Carolina. DEP provided funding to assist the company with its participation through the Alternative Fuel Incentive Grant program.