Clearing the Air With Hybrid Buses

The soot spewing from the exhaust pipes of diesel buses doesn’t just look dirty, it is dirty. Diesel exhaust accounts for 20 percent of U.S. air pollution, says the Natural Resources Defense Council. Some forward-thinking transit agencies are fighting back with hybrid diesel-electric buses. New York City Transit (NYCT), for example, took the lead and purchased 10 prototype hybrid buses in 1998, helping clear the air in a metropolis with very poor air quality.

Seattle's King County Transit has ordered 235 hybrid diesel buses, which cut carbon monoxide emissions by 97 percent.©KING COUNTY PHOTO BY NED AHRENS

A Department of Energy (DOE) study reports that hybrid buses, combining a diesel engine with an electric motor, outperform regular diesel buses in a variety of categories, offering 10 percent higher fuel economy, 19 percent lower carbon dioxide emissions and a 97 percent reduction in carbon monoxide emissions.

"The days of the dirty diesel bus are numbered," says Dan Becker, director of Sierra Club’s Global Warming and Energy Program. "The federal Clean Air Act requires states to reduce soot and smog emissions, and hybrids are a good way to do this."

Buoyed by the success of the prototypes, NYCT has ordered an additional 325 diesel-electric buses. Other states are following suit, including Washington, where Seattle’s King County Metropolitan Transit Authority recently purchased 235 diesel hybrid buses. New Jersey Transit, the nation’s largest statewide public transportation system, has used $8.5 million in federal funds to buy seven hybrid buses. Connecticut, Minnesota and Toronto, Canada are also buying hybrids.

"Like anything else, it takes time to get this new technology into the marketplace," explains John Powell, executive director of the Advanced Transportation Technology Institute. Powell sees the dual-fueled hybrids as the optimal choice with the most benefits. "Hybrids have an advantage over single-fueled vehicles," says Powell. "A good hybrid can provide economic benefits regardless of the fuel you’re using."

Transit passengers and environmental activists can get active to increase the number of cleaner buses on America’s roadways. "We need to pressure city councils and administrative agencies to purchase cleaner alternatives," says Becker. "Bus manufacturers aren’t falling over themselves to promote more eco-friendly buses."