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Saving green to go green

Hybrid garbage trucks mean cleaner air, lower operating costs

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Saving green to go green

Municipal refuse worker Bill Kuhnlenz behind the wheel of Manteca’s hydraulic launch assist refuse collection truck that was the first of its kind of the West Coast.

Bulletin file photo/

POSTED February 21, 2012 11:58 p.m.

Manteca is now in the same league as New York City and Miami when it comes to cleaner burning garbage trucks.

 City leaders Tuesday blessed the purchase of two diesel-hydraulic hybrid side loaders for $886,321.96 from Western Truck Center. The trucks actually will cost the city $633,321 once a $242,500 grant from the San Joaquin Valley Air Pollution Control District and a $70,000 hybrid vehicle voucher from the state are taken into account.

The city had two trucks in its garbage truck fleet near the end of their useful life in 2011 and budgeted to replace them. But instead of doing so right away, city staff looked for various grants to allow them to essentially avoid paying extra for the hybrid technology that would further reduce air pollution and reduce operating costs.

Garbage trucks typically get low single digit miles per gallon with all of their strop-and-go driving. The state-of-the-art trucks nearly double mileage resulting in an annual fuel savings of $4,000 to $6,000 per truck. That is on top of extensive brake replacement savings. Typically a refuse truck needs its brakes replaced four times a year at a cost that can exceed $2,000 a pop. The hybrid system significantly whittles down the need for brake work to a little over a year plus between shop appointments.

A typical refuse truck travels 68 miles on a work day and gets an average of six miles per gallon of diesel. Saving four gallons a day would translate into $16 in reduced costs for one day, $90 for a week, $4,680 for a year, and $46,800 for a typical 10-year lifespan of a city refuse truck. And if diesel prices keep climbing so will the savings.

The hydraulic hybrid technology system works much like a gasoline-electric hybrid. It works by recovering a portion of the energy normally lost as heat when the vehicle’s brakes are engaged. Unlike gasoline hybrids such as a Toyota Prius, it doesn’t employ a battery pack. Instead the hydraulic system uses pistons to capture the wasted energy by compressing nitrogen gas stored in a tank. When the foot is taken off the pedal the wheels drive a hydraulic pump that sends hydraulic fluid to compress the nitrogen gas to slow the truck down. When the pedal is pushed down, the nitrogen expands to push a piston in a cylinder filled with hydraulic fluid to help the diesel engine turn the rear wheels.

The truck staff selected is also able to maximize the compaction of recyclables to reduce the number of trips needed to drop off collected recyclables.

The two trucks also will be equipped with a system that allows a wand to be passed over an onboard electronic database so California Highway Patrol officers can extract all maintenance details without having to go through written log books.

Councilman Vince Hernandez - a longtime advocate of employing alternative vehicle fuel systems to save the city money and reduce air pollution - praised staff’s efforts.

The air pollution control district is also picking up a $70,000 tab to have a consultant keep tabs on the operation, fuel efficiency, and pollution output of the two new trucks as well as Manteca’s existing fleet of garbage trucks. That’s because the technology is new to the San Joaquin Valley.

The city has three different hybrid vehicle vendors provide them with garbage trucks to try out before making their decision on which was  the best way to go. They also examined the trucks in New York City and Miami.

Councilman Steve DeBrum was not completely pleased with the process saying that it should have gone out to a competitive bid. He voted against the purchase because he felt the council needed to assure taxpayers that they got the absolutely lowest cost garbage truck for municipal needs.

The city historically has picked one manufacturer for specialized vehicle fleets such as garage trucks. That way it costs less to keep available parts in stock plus doesn’t require mechanics to secure training from more than one vendor or investment in duplicate equipment to diagnose vehicle problems.

Eventually all of the fleet’s 25 trucks will be converted to the HLA technology. The city is already one of a few agencies in the state that meets tougher new emission standards that must go into place over the next several years.

It is part of the city’s ongoing efforts to keep costs down.  Nineteen years ago, the city was using standard manual collection that allowed a drive to do 350 homes in one day. The city then switched to semi-automated that increased efficiency so one driver could collect from 750 homes a day. Now with the fully automated system a driver can pick up trash at as many as 975 homes per shift.

Manteca already has one hybrid garbage truck in its 25-truck fleet. It is a rear loader used for commercial collections.

The city is already one of a few agencies in the state that meets tougher new emission standards that must go into place over the next several years. That was accomplished by upgrading engines on all existing trucks.

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