The New York City Department of Sanitation collects more than 12,000 tons of residential and institutional refuse and recyclables each day

. This involves 7,899 uniformed sanitation workers, 2,041 civilian workers and about 5,700 vehicles, including collection trucks, street sweepers and front-end loaders. "Clean is the name of the game," says Rocco DiRico, deputy commissioner of support services for the department.

As a city that is constantly under public scrutiny and burns a lot of diesel fuel, New York strives to be a model of environmental pursuits - especially within its Department of Sanitation, where clean is part of the job description. "That's what we do," DiRico says.

So when the department had the opportunity to evaluate hybrid refuse trucks in its fleet and become the first municipality to use hybrid technology in a rear loader configuration, they jumped at the chance.

Buying hybrids

The city recently added four hybrid trucks, thanks to the help of the Hybrid Truck Users Forum's Refuse Truck Working Group, a program of Calstart. The Hybrid Truck Users Forum's goal is to speed the commercialization of medium- and heavy-duty hybrid and high-efficiency technologies.

Because hybrid truck technology is still in its infancy and has limited production levels, it is expensive - although there are various tax breaks and grants from federal and local sources. If hybrids catch on with the private sector, it will help drive the price down. DiRico says it's the chicken or the egg scenario. "No one wants to be the first," he says. "We thought we'd take the lead and get things going."

The department invested in a hybrid electric Mack TerraPro Low Entry model refuse truck, a Class 8 model with parallel architecture. The city also tapped two Crane Carrier refuse trucks, one installed with Bosch Rexroth's hydrostatic regenerative braking parallel hydraulic hybrid system, and another hybrid electric with series architecture. A fourth vehicle, the Kenworth T370, a 33,000-pound medium-duty truck with Eaton's hybrid system and a parallel architecture, will be used as a rack truck, delivering supplies and parts. The city has purchased four additional Crane Carrier refuse trucks that will arrive by the end of the year, including two hybrid electric and two hybrid hydraulic vehicles.

(A parallel hybrid has multiple propulsion systems that can be operated independently or together. In a series hybrid, both sources of energy go through a single propulsion device.)

With the exception of the Kenworth, all are preproduction prototypes. "These are the latest and greatest," DiRico says.

Testing, testing

Over the next year, the department will be testing each truck, looking at emissions and fuel economy. Also part of the evaluation are how well they operate on the streets collecting refuse, how the drivers like them, and how well they perform in the five boroughs and hold up as the seasons change. The refuse trucks will also be used to plow snow in the winter.

It will be particularly interesting to see how the technology copes with the stop-and-go aspect of refuse collection. In Queens, for example, the trucks will likely be stopping every 50 feet or so, DiRico says. In Manhattan, the cycle is similar to that of a bus, with stops every block. "If one can do it all, that's great. If all three can do it all, it's even better."

The Hybrid Truck Users Forum is working with the department to help with the data collection.

DiRico, who had the chance to test drive a truck, was pleasantly surprised by its braking capabilities. As a result of the regenerative process, he did not have to use the brake pedal as often because the vehicle decelerates on its own, causing less brake wear and reduced brake noise. According to DiRico, these advantages were mentioned by the truck makers but were not front and center. "That was the silent successes of what I saw," he says.

Other efforts

This is not the department's first attempt to make its fleet more environmentally friendly. A few years ago, New York switched to a 5-percent biodiesel blend. It is currently retrofitting all existing diesels with advanced diesel exhaust aftertreatment technology, such as diesel particulate filters. With ethanol fueling stations in every borough, the department also houses 200 to 300 light-duty ethanol-powered vehicles.

The department has also been testing Class 8 compressed natural gas trucks. In the Northeast, however, the CNG vehicles have had issues in terms of weather and range. The problems prompted the department to try hybrids. "Diesel has been good to us performance-wise," DiRico says. "The technology seems to be the best path to reduce fuel consumption."

"We do have other technologies on the horizon," DiRico says, including a CNG-powered hybrid hydraulic collection truck that's in the pipeline.

By this time next year, the department will add three more hybrid vehicles and hopes to have enough information as to what path to pursue. "If these trucks can work here, they can work anywhere," DiRico says.

From the July 2009 issue of Heavy Duty Trucking.