Although commercial vehicles such as transit buses, postal trucks and taxicabs increasingly are using natural gas, refuse collection fleets have been slow to embrace the trend. Yet the sprawling city of Los Angeles is taking the lead by fueling its waste fleet with natural gas.
The city has ordered 120 refuse trucks from Peterbilt, Denton, Texas, that are powered by low-emission engines from Caterpillar, Peoria, Ill. The engines are equipped with San Diego-based Clean Air Partners' Dual-Fuel natural gas systems. Currently, approximately 50 side-loading trucks run the city's trash routes, and approximately three more trucks are added every week.
“The air quality situation in Los Angeles is serious. [Because] we have to run our trucks every day to provide trash service to such a large area, it is critical that our emissions output is as low as possible,” says Jim Bonnville, city director of fleet services. “The [system] cuts emissions considerably, but it also provides an extended driving range with the same torque and horsepower as full diesel, which fits our needs.”
The Natural Gas Vehicle Coalition, Washington, D.C., estimates that diesel exhaust includes more than 40 substances that are listed by the U.S. Environmental Protection Agency, Washington, D.C., as hazardous air pollutants and by the California Air Resources Board (CARB), Sacramento, as toxic air contaminants. By contrast, natural gas vehicles reduce emissions such as carbon monoxide, carbon dioxide, and nitrous oxide (NOx). Almost 130,000 natural gas vehicles now are operating in the United States, with more than 2 million worldwide.
The Diamond Bar, Calif.-based South Coast Air Quality Management District, which governs emissions requirements for Los Angeles, recently enacted a rule requiring local public and private refuse fleets to use truck engines that run on alternate fuel, such as natural gas. According to the district, heavy-duty trucks and buses traditionally have been responsible for 20 percent of the total NOx emissions in the South Coast Air Basin. Low-emission natural gas engines produce approximately half the NOx emissions of their diesel counterparts. The Dual-Fuel engine and truck combination, in particular, reduces NOx emissions by more than 40 percent and particulate emissions by more than 90 percent, according to the manufacturer.
Los Angeles officials tested the Dual-Fuel trucks for two years before placing the final order. The engines use diesel fuel as the ignition source only, then switch to natural gas once the engine has started. More than 85 percent of total fuel use is natural gas, but the trucks have similar power to a diesel engine. And in an emergency, if the natural gas fuel supply is interrupted, the engine will continue to operate on diesel so that a truck can safely return to its fueling site.
“We're in an area with earthquakes,” Bonnville says. “The Dual-Fuel engine gives us an option, [if an earthquake damages the fueling site] and we need to run on diesel. It becomes a health and safety issue.”
In addition to lowering emissions, a key benefit of the Dual-Fuel engines is that they have sufficient horsepower and torque to carry heavy refuse loads. Los Angeles has steep grades, and natural gas engines would have difficulty navigating some of the hills.
The Dual-Fuel trucks have 305 horsepower, 1,050 foot-pounds of torque, three axles and can load 51,000 pounds in the state of California, according to Bob Wood, Peterbilt environmental sales manager.
So far, the trucks have required more maintenance and training for drivers and mechanics who are new to the natural gas systems, in addition to the normal tweaking required with new trucks, Bonnville says. However, as the entire fleet is replaced, workers likely will become more familiar with the systems. The city is looking to double its initial order of 120 trucks, which was funded through the city's Sanitation Equipment Charge, part of the refuse collection fee, as well as grant money from the South Coast district and CARB. The trucks cost $206,000 each.
Bonnville adds that the city is studying natural gas systems for other service vehicles, from street sweepers to heavy-duty trucks. Meantime, the city also has begun to retrofit its entire diesel truck fleet with particulate traps and already has converted to low-sulfur diesel fuel.
A key benefit to the Dual-Fuel system might even improve how residents view trash trucks, Wood says. “Think about how people might [perceive] a diesel truck, a truck that is running down residential neighborhoods all day long,” he explains. “There is a whole different attitude toward these trucks. I see it in terms of being a leader, a pioneer.”