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11/12/03 by Staff Writer
School buses are a natural for carrying the air quality banner, as far as Anne Tasewell is concerned.
“School buses are a good place to begin with solving our air quality problems,” says Tasewell, the Clean Cities coordinator for the Triangle J Council of Governments. She notes that young children are typically more vulnerable to air pollution and its health-related risks. In fact, they breathe 50 percent more air per pound of body weight than do adults, making them more susceptible to respiratory illnesses.
The Environmental Protection Agency is more specific. Its literature states that exposure to diesel exhaust can cause lung damage and respiratory problems. Diesel exhaust also aggravates asthma and existing allergies. Studies indicate that long-term exposure can even increase the risk of lung cancer.
Two areas – Durham and the western North Carolina counties of Buncombe, Madison, Haywood and Transylvania – have recently taken steps to make their bus emissions cleaner. The Durham school system was the first in the state to use biodiesel in its school buses. The system was able to make the switch in March 2003, thanks to a grant from the Triangle J Council of Governments. The funds were provided from the N.C. Department of Transportation through a federal Congestion and Mitigation Air Quality grant.
Biodiesel is a fuel that can be produced from renewable sources like soybean oil, animal fats or even recycled cooking grease. While 100 percent biodiesel is usable, its most common use is known as B20, which is 20 percent biodiesel and 80 percent conventional diesel. This has a host of benefits. It results in significantly lower emissions of particulate matter, carbon monoxide, toxic contaminants, sulfur dioxide, hydrocarbons.
“Biodiesel is stellar on most everything except for NOx (nitrogen oxide), which is a ground-level ozone precursor,” Tasewell says.
The Triangle Clean Cities Coalition biodiesel fact sheet lists a 2 percent elevation in NOx with biodiesel, which Tasewell calls “statistically insignificant.”
One of the reasons biodiesel is often considered the fuel of choice is that it doesn’t require any engine modification. “We call it ‘pour-and-go’ technology,” Tasewell says. “It definitely is the easiest alternative fuel.”
It is also a cleaner burning fuel. “It actually cleans out your fuel line so if you have older vehicles, you need to change the fuel filters initially after the first tank or two of biodiesel,” Tasewell says. Since it is a lubricant, it also reduces wear and tear on the engine, which reduces maintenance costs.
The fuel is available through a state purchasing contract for any government purchaser, including public and private schools. “One of the reasons we have seen such growth in North Carolina is that the Department of Transportation started experimenting with biodiesel in 1997,” Tazewell says. “They used almost two million gallons of B20 just this past year.”
It does, however, cost more. The Durham school system is paying 20 cents per gallon more than it would for conventional diesel.
WESTERN NORTH CAROLINA
Buncombe, Haywood, Madison and Transylvania counties have taken a different tack in their efforts to clean up the air. The Western North Carolina Regional Air Quality Agency will retrofit more than 320 school buses in those counties with diesel oxidation catalysts by the beginning of the next school year. The result will be a decrease of 40 percent in carbon monoxide emissions; a decrease of 20 percent in particulate matter, which has been linked to serious health problems; and a decrease of 50 percent in hydrocarbons, which contain toxic substances and contribute to ground-level ozone.
The EPA funded the $275,000 project through its Clean School Bus USA program.
Justin Greuel, an air quality engineer with the Western N.C. Regional Air Quality Agency, notes that diesel oxidation catalysts, which are like catalytic converters on cars, were the obvious choice for the four counties. “Other emission devices require ultra low sulfur diesel,” he says, “and that is not currently available in this region.”
The fixed amount of funding also played a role in the decision as did the life of the devices. “We were told we’ll probably see the vehicles wear out before we see the oxidation catalysts wear out,” Greuel says, noting that North Carolina typically runs its school buses 200,000 miles or 20 years.
Clean Air Initiative – Schools in Durham, Buncombe Area Vow to Clean Up the Air
Harold Laflin with Buncombe County Schools notes that it is a proven technology and EPA certified. “We feel that it is a move in the right direction,” he says. “We want to do anything we can to provide a cleaner environment for all the citizens of our area.”