March 4, 2010

Hydraulic Hybrid Pressed into Service in Refuse Collection

We want to take this opportunity to put this [hydraulic hybrid] technology into the field. Our investment will provide good field data that will support industry development. It's exciting to be part of shaping the technology for the future.      
Adam Lovato, Manager, Thornton Environmental Services

Thornton Environmental Services in Thornton, Colorado, is home to the second hybrid refuse hauler service in the state. The Bridgeport automated side loader collection body is built on a Peterbilt chassis and uses Eaton hybrid hydraulic launch assist (HLA) technology. When the HLA system is engaged, energy is captured and released during deceleration and acceleration, respectively. This makes the stop-and-go trash collection routes an excellent application for hybrids.

During braking, the vehicle's kinetic energy drives the pump/motor as a pump, transferring hydraulic fluid from the low-pressure reservoir to a high-pressure accumulator. The fluid compresses nitrogen gas in the accumulator and pressurizes the system. The regenerative braking captures about 70% of the kinetic energy produced during braking. During acceleration, fluid in the high-pressure accumulator is metered out to drive the pump/motor as a motor. The system propels the vehicle by transmitting torque to the driveshaft.

Adam Lovato, Thornton Environmental Services manager, explains that the Thornton City Council directed staff to take an active role in conservation efforts and alternative energy. "We want to take this opportunity to put this new technology into the field. Our investment will provide good field data that will support industry development," Lovato said. "It's exciting to be part of shaping the technology for the future."

The vehicle joins a fleet of 19 city-owned refuse/recycle collection vehicles. Thornton plans to replace two traditional powered trucks with hybrid models later this year. The city anticipates that each truck may get 25% better fuel economy than its non-hybrid counterparts which could mean an annual fuel reduction of about 1,400 gallons per truck.