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Clean Bus, Clean Air

By Joshua Brown Article published February 21, 2007

CNG
UVM bus driver Bob Comeau had 78 students aboard the first regular service trip for two new compressed natural gas buses now in operation on campus. (Photo: Sally McCay)

A sleek new bus eases around the snowbank and into its stop at the University of Vermont's Royall Tyler Theater. Every 21 minutes, this Redstone Route shuttle stops here to pick up students on its loop around campus. But unlike buses in most cities around the world, this is not a noisy vehicle spewing a black cloud of diesel smoke.

It sounds quiet and there is no smell from the tailpipe. Its secret? The bus runs on compressed natural gas, one of two CNG vehicles purchased by the university for its Campus Area Transportation System and put into regular service, Tuesday, Feb. 20.

The natural gas fleet will grow to six vehicles by fall 2008, the product of a partnership between UVM, the City of Burlington, Vermont Gas Systems Inc., and the Federal Transit Administration to improve air quality and develop Vermont’s first “fast-fill” natural gas refueling station.

Sen. Patrick Leahy provided key leadership on the project, securing a $2.4 million appropriation through the federal Clean Cities Program.

It’s an investment in public health. Motor vehicles are the largest source of toxic and cancer-causing air pollutants in Vermont. “Particulate pollution on these CNG buses should be about 100 times lower than what you get from typical buses,” says UVM engineering professor Britt Holmen, an expert on vehicle emissions.

And, compared to petroleum diesel, compressed natural gas emits about 50 percent fewer nitrogen oxides (sometimes called “NOx”), a major contributor to smog, greenhouse gas formation and, like particulate pollution, a cause of respiratory health problems. As an added benefit, natural gas engines reduce noise pollution; they are about 15 decibels lower than diesel.

Maiden voyage
Tom Abdelnour ’10 is looking forward to the ride. “This will be my maiden voyage on one of these buses,” he says, standing in the cold outside the theatre as he waits with a few other would-be passengers. “I’m taking a ridiculous round trip to my dorm. It would be faster to walk, but at least the bus is powered by clean natural gas.”

The new CNG refueling station at the city’s department of public works will allow each bus to fill its rooftop tanks in just a few minutes. After the university's fleet has been serviced, excess capacity in the system can be used in new, heavy-duty natural gas vehicles the city plans to put into service, such as street sweepers and recycling trucks.

Although the city has been running a few vans on natural gas for several years, they take hours to refill from a low-pressure tank; the new fueling station is suited to rapid refill of large vehicles and is the first of its kind in Vermont.

Supplementing the funds secured by Leahy are matching funds from UVM, the city and other partners, which “bring the total project costs to about $3 million,” says Dan Bradley, transportation planner for the city.

The new CNG buses are part of a long-term commitment by UVM to use environmentally friendly alternative fuels in its campus area transportation (CATS) fleet. For several years, the university has been running its buses on B20, a mix of 20 percent biodiesel, a cleaner, vegetable-based fuel, and 80 percent petroleum diesel.

“Our use of biodiesel was pioneering when very few other universities were making this step to a cleaner fuel. Now CNG is the next logical step in UVM’s commitment to reducing emissions. It will be a good complement to the biodiesel that will continue to fuel some of our smaller buses,” says Gioia Thompson, UVM’s environmental coordinator.

And all new buses, diesel and CNG, are built with cleaner engines than what was available a decade ago. “If you go from a 1998 model year to a 2007, you’ve already improved by an order of magnitude the emissions standards for that vehicle,” Holmen said.

Natural gas vehicles date back at least into the 1930s, and today natural gas is well established as safe transportation fuel, having been on the road in California, Colorado, and many other states and foreign countries for years. “There are now hybrid electric engines available,” says Bradley, “that are also a good alternative to diesel, but they are not as well-tested and there are fewer options than with natural gas.”

“CNG is a mature fuel,” he said, noting that natural gas has an established distribution network, is less expensive than diesel, and that numerous types of heavy equipment, like the new trucks and vehicles the city will use, are available with natural gas engines.

Local loyalty
In addition to their cleaner, safer emissions, CNG buses offer other advantages.

The new buses help reduce dependence on imported oil; more than 99 percent of natural gas consumed in the United States is produced in North America, according to the California Energy Commission.

The building of compressed gas delivery systems – like the new tanks and equipment at the city’s public works building – could support clean-burning hydrogen vehicles in the future. In the near term, blends of hydrogen and natural gas could be available, and as the technological problems that hydrogen now faces are overcome, the CNG equipment could be converted for use in a straight hydrogen delivery system.

The new vehicles and fueling station also fuel the regional economy. The 41-foot buses — air-conditioned, handicapped accessible, and with 20 percent more seating capacity than UVM’s current buses — are built by the Orion bus company in Oriskany, N.Y. The new fueling station at 645 Pine Street was built by Smalley Contractors of Rutland.

For both the university and the city, the long-term goal is to run cost-effective vehicles that produce zero emissions fueled from renewable energy sources, such as solar and wind power. But that appears to be years away and, in the meantime, ground-level air pollution — with buses and other heavy diesel vehicles being major culprits — is a leading cause of respiratory and other health problems. CNG buses reduce this problem today.

“Natural gas is a bridge technology,” says Katherine Decarreau, director of UVM’s transportation and parking services. “They’re a great choice for now, and when they need to be replaced, we’ll have a clearer sense of what the next best technology will be.”