A Natural Transition

A Natural Transition

Sacramento, Calif., embraces liquid natural gas in its collection fleet.

The city of Sacramento, Calif., presently exceeds the federal standards for ozone emissions during the summer. Officials across northern California have mandated the reduction of ozone emissions and have encouraged the selection of lower-emission refuse collection trucks. Sacramento's most recent purchase of refuse collection trucks included 15 Wayne Engineering Curbtender bodies on new liquid natural gas (LNG) Condor chassis from American LaFrance.

According to Rowie Sizemore, operations general supervisor for the city, the new trucks are used to collect refuse, recycling and green waste. The total fleet now includes 72 side-loaders, 30 to 35 rear-loaders, seven front-loaders, 25 to 30 front-loaders with claws for picking up yard waste, and three roll-off trucks. Approximately 70 units are fueled by LNG. The city is considering expanding its LNG fleet pending budget approval and grant funding. Sacramento's trucks are scheduled to collect 900 to 1,200 cans of refuse per day and up to 1,200 cans of recyclables, though typically only 40 to 50 percent of residents set out their cans every week.

The new trucks were put into service in March of 2009. Years of experience working with LNG trucks allow Sacramento to offer some lessons about running a LNG refuse truck fleet.

“LNG is cleaner than diesel,” says Sizemore. “The trucks we've just purchased are 2010 EPA certified. They are significantly cleaner than the 2007 diesels. Also, LNG was very competitive when fuel prices were high because it was about half the cost.”

LNG trucks are not a panacea, however. As Sizemore points out, “It took two or three months to work out the LNG fuel system problems on the truck. For one thing, the engines were shutting down along the route.” It turned out that the economizer valve in the fuel tank was not suitable for the rich-burning Cummins engines. This resulted in less-than-adequate fuel pressure in the tank. The engines were essentially starving for fuel. Changing the valve helped. Adding pressure to the LNG storage tanks also allowed increased pressure to the vehicle fuel tanks.

Sizemore suggests that other LNG truck users would be well-served to outfit each unit with a material safety data sheet to ensure compliance with U.S. Occupational Safety & Health Administration guidelines and inform fire rescue personnel how to react in the event of an LNG vehicle emergency.

To ensure a steady supply of fuel, Sacramento installed its own LNG infrastructure. Storage tanks require a building permit, and since building departments are not always familiar with LNG, Sizemore recommends talking with them first before starting the process.

From his experience, Sizemore recommends that garages be equipped with methane detectors and air exchangers, use only direct-fired furnaces and keep open flame heaters turned off in the shop. These recommendations all are in addition to safety precautions that need to be taken with diesel fuel.

Jackie Couillard is an industry consultant with Pyramid Creative Group, Kaukauna, Wisc.

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