Alternatives to Diesel Buses Gain Momentum
It often begins with one bus.
Such was the case in the Naperville Community School District outside Chicago two years ago, after fleet-maintenance manager Thomas A. Pelletier got a note from a parent asking what the district was doing to reduce toxic emissions from its diesel-fueled vehicles.
|See the accompanying table, "Routes to a Cleaner School Bus."||
Mr. Pelletier didn’t have an answer at the time, so he set out to educate himself on the ill effects of diesel—a fuel he’d long worked with but never given much thought. What he learned inspired him to transform a typical 1990s diesel-powered school bus into a clean machine.
With stricter federal standards for diesel engines imminent and numerous studies linking their emissions with rising rates of respiratory illness, efforts to clean up the iconic yellow school bus are under way across the country.
From a national standpoint, it’s a big job.
Roughly 450,000 public school buses operate in the United States, 390,000 of which are powered by diesel fuel, according to the U.S. Environmental Protection Agency. The 33 percent of buses in use that were manufactured before 1990 are the heaviest polluters.
But long-lasting diesel buses are hard for districts to scrap, and replacing them with cleaner models equipped with the latest pollution- control technology can cost $100,000 or more per vehicle.
"Improving school buses has been an uphill battle," said Rochelle R. Tafolla, the director of the Clean Diesel Campaign for the American Lung Association of Metropolitan Chicago. "It’s not that school districts don’t want to put students and students’ health first. It’s that they’re cash-strapped."
To help ease the burden, President Bush has proposed a big funding increase for the EPA’s Clean School Bus USA grants, from $5 million this year to $65 million in fiscal 2005. Legislation moving through Congress would provide $300 million.
A number of states and cities already have similar programs, making it possible for many schools to test solutions at virtually no cost of their own.
As Naperville’s Mr. Pelletier learned, the big problem with diesel vehicles is the smelly, black exhaust they spew from their tailpipes.
A combination of carbon monoxide, hydrocarbons, and nitrous oxides, that "particulate matter" can reach the deepest regions of the lungs. Health effects include asthma, difficult or painful breathing, and chronic bronchitis.
Children are particularly vulnerable because they breathe more air than adults and their respiratory systems are still developing.
Alarmed by those facts, Mr. Pelletier decided to experiment. He pulled one vehicle from the district’s 136-bus fleet and outfitted it with a particulate-matter filter, or trap. He also started fueling the bus with ultra- low-sulfur diesel. Those approaches have been shown to reduce harmful emissions by 60 percent to 90 percent.
"When I first heard that claim, my reaction was ‘bull,’ " Mr. Pelletier said. "Then I saw a demonstration where a guy held a white handkerchief over the tailpipe [of a running bus] retrofitted with a trap and running on the cleaner diesel. When he pulled [the cloth] away, it was clean."
Rather than retrofit diesel buses, a handful of districts have switched to buses that run on compressed natural gas.
Under pressure from the community to clean up its bus pollution, the 8,500-student Lower Merion district in the Philadelphia suburb of Ardmore started its experiment with natural gas in the mid-1990s with a single bus "to get our feet wet," said Michael E. Andre, the district transportation supervisor.
Now, after spending nearly $1.2 million, mostly in government grants, the district owns 72 buses and three utility trucks that run on compressed natural gas. It also operates two special fueling sites for the vehicles, which have logged a combined 5.5 million miles.
Though compressed natural gas has the benefit of being far cleaner than diesel fuel and is domestically produced, it is an alternative with drawbacks.
Natural- gas buses cost about $30,000 more than the typical $75,000 diesel bus, Mr. Andre said, and the infrastructure needed to support them is also pricey.
Plus, long trips can be difficult because compressed natural gas isn’t as readily available as diesel.
"In theory," Mr. Andre said, "you could go coast to coast in a natural-gas bus, but you’re going to have to take an awfully jagged path."
One of most common methods of cutting emissions, and the cheapest, is the enactment of anti-idling policies.
The 7,500-student Portland, Maine, schools "don’t allow buses to idle at all anywhere," said Transportation Director Kevin J. Mallory. "We were one of the first districts in the state to go anti-idling, and we have a very strict policy.
"There’s no cost," he added, "and we’re getting a half-gallon a mile more per bus as a result."
In the past five years, the Portland district has also been replacing its diesel vehicles with newer, cleaner buses and practicing "route management" to assign the cleanest buses to the longest trips.
This summer, Mr. Mallory plans to retrofit his diesel buses with oxidation catalysts to cut toxic emissions by 40 percent, as well as purchase a few compressed-natural- gas buses.
The next step, he said, is to get the entire community on board with the district’s clean-air efforts because school buses are just one part of the pollution problem.
"We want to encourage carpooling, encourage kids to ride bikes to school, and create pollution-free school zones where parents can’t sit and idle their cars either," Mr. Mallory said. "More than 500 of our children have asthma. You can see [poor air quality] is a problem, and we have to do something."
Vol. 23, Issue 36, Page 5