New study makes strong case for natural gas garbage trucks - alternative fuels

Diesel Progress North American Edition, Nov, 2003 by Bill Siuru

Garbage trucks are among the oldest, least fuel-efficient and most polluting vehicles in the United States. Alternative fuels, primarily natural gas, are making significant inroads in urban bus applications. Similarly garbage trucks running on natural gas could significantly improve the environment, reduce health risks to both sanitation workers and bystanders and reduce the country's dependence on foreign oil. These are key conclusions in a recent study, Greening Garbage Trucks: New Technologies for Cleaner Air by INFORM Inc., a national environmental research organization.

The garbage truck sector has not been in the national spotlight because more than 80 percent are owned and operated by private companies and, thus, less closely monitored than other publicly funded fleets like transit buses. Converting garbage trucks to alternative fuels could bring even greater benefits than converting buses. There are more than twice as many garbage trucks in the United States as urban transit buses, about 179,000 trucks--136,000 refuse collection trucks, 12,000 transfer vehicles and 31,000 recycling vehicles versus 82,600 buses. More than 90 percent of all garbage trucks and more than 99 percent of heavy-duty ones are diesel powered.

Diesel garbage trucks are a major source of air pollutants. Forty-one percent of garbage trucks in use are more than 10 years old and nearing the end of their lifetime, typically 12 to 14 years, when they operate with reduced efficiency and increased emissions. Garbage trucks pose particular health risks to sanitation workers at the front, back and sides of the truck where they are exposed to emissions for extended periods daily. Garbage trucks operate in closer proximity to a larger number of people than most other diesel trucks while idling at the curb and traveling on neighborhood streets. Diesel garbage trucks are notoriously loud, up to 100 decibels, which can cause serious hearing damage to truck operators and those living along garbage truck routes.

They get the lowest fuel economy, 2.8 mpg, of any vehicle type. Transit buses, single-unit heavy-duty trucks and tractor-trailers get 2.9, 7.0 and 6.1 mpg, respectively. Garbage trucks move slowly at an average speed of just 10 mph, constanty stopping and starting to pick up waste, regularly compacting its load and idling for nearly 70 percent of the time. Thus, they use more fuel than any other type of vehicle--averaging 8600 gal. per year--except for tractor-trailers and transit buses, which use 11,500 gal. and 10,800 gal. on average per year, respectively. The bottom line--garbage trucks in the United States consume approximately 1 billion gal. of diesel fuel anually--about 3 percent of toad diesel fuel used.

This first comprehensive study of the nation's estimated 179,000 garbage trucks showed that this high-polluting fleet is slowly, but successfully, shifting from diesel to cleaner natural gas. Twenty-six waste collection agencies in 25 U.S. cities have begun to shift from diesel to natural gas, with nearly 700 natural gas trucks in operation today, displacing almost 6 million gal. of diesel fuel annually. Currently planned natural gas garbage truck purchases will increase this number to more than 2200 by 2010, which will replace nearly 20 million gal. of diesel fuel annually.

Much of the switching to natural gas is occurring in California, where regulations and incentives are driving the change. The South Coast Air Quality Management District in Southern California has put a ban on diesel garbage trucks. Of the 26 garbage truck fleets included in this study, 10 are operated by public agencies and 16 by private companies that operate under contract to the municipal governments. These contracts give governments a powerful tool for economic motivation and contractual obligations to use alternative-fuel vehicles.

Of the 692 natural gas trucks studied, 69 percent were powered by LNG and 31 percent by CNG. LNG was preferred when the route demand for fuel was expected to exceed onboard CNG capacity. CNG was often chosen because of the availability of an existing refueling infrastructure that could be shared with other fleet operators. Fortunately, garbage trucks typically are centrally fueled and travel short distances so a widespread refueling infrastructure is unnecessary. Waste Management Inc. is the U.S. industry leader in the use of natural gas trucks, currently operating a total of 380 natural gas garbage trucks in 14 fleets including 13 in California and one in Pennsylvania.

While most major truck and heavy-duty engine manufacturers offer natural gas models for garbage truck applications, the variety of natural gas garbage trucks available still lags far behind diesel trucks. Though some development of hybrid electric technology and alternative fuels is underway in the garbage truck sector, almost all innovative development involves the use of natural gas. The study noted that new emissions standards for heavy-duty diesel vehicles beginning in 2004 require the use of cleaner fuels and technologies like low-sulfur fuel, particulate filters and oxidation catalysts. Because of the unique operating environment, it is unclear whether garbage trucks will be able to take fill advantage of all the benefits they do offer. Likewise, biodiesel and synthetic diesel are now being tested in heavy-duty truck applications, the emissions benefits and toxicity reductions of these fuels are also still unclear.