Biodiesel School Bus Cuts Down on Children's Pollution Exposure
Instead of motoring around on pure diesel, the 19-passenger bus that transports district children to the Media area is relying on a mixture that is 20 percent processed soybean oil.
Nancy Ziegler, the district’s just-retired transportation supervisor, said that the bus emits fewer hydrocarbons, less carbon monoxide, as well as less nitrous oxide, which typically increases, according to the U.S. Environmental Protection Agency
"It’s very exciting for me. The thought that we can actually be helping the environment and make the air cleaner for the children is wonderful," said Ziegler, who was behind the initiative, and who retired Dec. 23 after 20 years with the district.
The district had hoped to start fueling its contracted 54-bus fleet with biodiesel in January through the EPA’s Clean School Bus USA grant program that Ziegler suggested last fall the district pursue. Only 17 of 120 applicants were awarded money and Great Valley was not among them.
Still, the district plans to continue filling the Bus 40 tank with the B20 biodiesel fuel, an energy source that is 20 percent vegetable oil and animal fat and 80 percent petroleum diesel. Another bus may join Bus 40, and district officials hope to initiate discussions with its bus contractor and the Chester County Intermediate Unit to consider expanding the initiative to reduce the per-gallon cost while further decreasing pollution emissions, said Rita Jones, superintendent of the district.
"I was very excited about the possibilities that this offers," Jones said. "We will continue to explore it."
Biodiesel fuel costs more than pure petroleum diesel, but the increased cost is lessened when the fuel is bought in bulk.
For instance, Great Valley paid 60 cents per gallon more for 500 gallons of B20 biodiesel fuel -- which is 80 percent petroleum diesel and 20 percent vegetable oils and animal fats -- than it would have paid for pure petroleum diesel, Ziegler said. But that per-gallon cost would drop to between 19 and 24 cents if the district purchased enough oil to supply all 54 buses throughout the school year. Total, it would cost less than an additional $30,000 to use the B20 fuel, Ziegler said.
Jones said that the county’s intermediate unit already purchases fuel in bulk for the benefit of local districts and that Great Valley hopes to initiate discussions with IU officials about the possibility of it purchasing biodiesel fuel.
Ziegler said that the Greater Philadelphia Clean Cities Program is submitting the district’s proposal to the Pennsylvania Department of Environmental Protection to apply for grant money to fund bus pollution emission reduction programs.
The EPA says that B20 biodiesel fuel reduces diesel particulate matter -- a suspected carcinogen -- by 10 percent. Pure biodiesel -- which is 100 percent vegetable oils and animal fats -- reduces particulate matter by 40 percent.
Children are particularly susceptible to particulate matter because their inhalation rate is greater than adults’, said Kathleen Anderson, an environmental scientist with the EPA’s Philadelphia office.
"You do however get an increase in (nitrous oxide) emissions, which is also a health problem," Anderson said. Studies have shown that B20 increases nitrous oxide emissions -- a contributor to smog, which can cause respiratory failure -- by 2 percent.
But Ziegler said that the measurements taken of Bus 40 before and after using B20 biodiesel show a reduction in nitrous oxide. It fell from 381 parts per million in mid-August to 316 parts per million in mid-November, she said. She said she reported the finding to World Energy, which is a biodiesel supplier.
The Bus 40 emissions measurements -- taken by Brogan’s Service Center in East Whiteland -- also showed that hydrocarbons fell from 27 parts per million to zero, and that carbon monoxide fell from .06 percent to .03 percent of emissions, Ziegler said.
Bonnie Smith, spokeswoman for the EPA office based in Philadelphia, said that using biodiesel fuel is one in a list of EPA-approved technologies to reduce pollution.
The EPA has supported other initiatives to reduce air pollution from buses and trucks.
Initiatives encouraged in its grant program include installing effective emission control systems on newer buses, replacing the oldest buses with new buses, including buses powered by clean diesel or compressed natural gas, and implementing policies to eliminate unnecessary engine idling.
In three years, a new law will also significantly reduce another health hazardous pollutant, sulfur. In 1997, new diesel-engine buses and trucks purchased must run on ultra low sulfur diesel fuel, which reduce that pollutant from 500 to 15 parts per million. "It’s substantial," said Anderson, of the EPA.
Ziegler, who was transportation supervisor for the last dozen years, said one nice feature of the biodiesel fuels is that they can be used without making modifications to the buses.
"The thing with this, it’s simple," Ziegler said. "They don’t have to do anything with the bus."
She said that she first learned of the friendlier energy source two years ago when her daughter began using it to fuel her diesel-engine car. Ziegler then started to look into B20 fuel and was prepared to propose Great Valley use the energy source when the EPA asked for grant applications.
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