Hydraulic hybrid garbage trucks save Miami fuel and money

As Miami has been tightening its fiscal belt over the last few years, city leaders have been scrutinizing ways to save money. They recently replaced a few traditional diesel garbage collection trucks with hydraulic hybrid models, and as a result, they expect to save nearly $70,000 in fuel annually.

To reduce the amount of money the city spends on fuel for its solid waste fleet, General Services Administration Fleet Superintendent Jose Davila began investigating alternatives to traditional diesel-powered garbage trucks. In September 2010, Davila began testing a refuse truck from Autocar equipped with the Parker RunWise Advanced Series Hybrid Drive System. The hybrid equipment replaces a refuse truck’s conventional drive train with a series hydraulic hybrid drive system, which captures energy when the vehicle brakes and stores it in compressed hydraulic fluid. The compressed fluid propels the vehicle from a stop when the driver steps on the accelerator pedal, and then the diesel engine is used at higher speeds.

Miami used part of a $731,850 grant from the National Clean Diesel Funding Assistance Program B to purchase four of the hybrid garbage trucks, and it purchased two more of the trucks with city funds. By late summer 2012, all six trucks will be operating regular routes collecting garbage from residents throughout the city.

Each truck is consuming 400 fewer gallons of diesel fuel per month than a non-hybrid garbage truck, according to Davila. That is 51 percent less diesel fuel for each truck and a collective savings of 19,200 gallons of diesel per year.

Maintenance schedules also are improved. Because the brakes do not contact the drums until the truck slows to about 2 miles per hour, brake shoe life is extended significantly. Normal brake replacement occurs at four- to five-month intervals for rear axles on typical garbage trucks, but Miami projects that the brakes on the hybrid trucks will need changing only once every six years. Tire tread life is similarly affected, with less heat from friction going to the wheels.