Deere Gas Engine's Clean and Quiet
Prototype natural gas-powered M2 was costly, but makes business and clean-air sense, says PG&E.
Tom Berg
Senior Equipment Editor
Wonder what the 2007 engines will look and drive like? Anyone able to use natural gas instead of diesel fuel can find out by looking under the hood of this Freightliner Business Class M2, then taking it for a spin, as many potential customers in California are now doing. And they might be pleased by its performance as well as its economics.
While it may look like a standard public utility dump truck that supports construction and maintenance work on a power grid, under its hood is a decidedly non-standard John Deere engine that burns compressed natural gas, and behind the cab there's a compartment with several gas tanks and associated controls. These are not factory options – they were custom installed – and it wasn't cheap.
Installing the engine and fuel system in this M2 cost a whopping $80,000. This according to Brian Pepper, the senior project manager who oversees this and other clean-air programs for Pacific Gas & Electric Co., the San Francisco-based public utility that owns the truck and is demonstrating it.
But he emphasized that this is a prototype; a production vehicle would cost far less, and much of the extra cost of engines and fueling stations can be paid for through government grants and tax credits.
Pepper listed several advantages for natural gas: clean exhaust, the geopolitical fuel situation, and favorable economics. The gas-fired engine emits almost nothing, easily meeting government air quality regulations, including California's; natural gas is readily available domestically and from friendly countries; the cost of diesel engines is climbing steeply as more apparatus is added to meet upcoming emissions limits; and natural gas costs about a third less than the equivalent amount of diesel fuel.
As any informed citizen knows, much of our petroleum comes from regions that are politically shaky, and its prices are at all-time highs. Pump prices for diesel continually fluctuate, making it hard for fleet managers to budget for it, Pepper said. Locking in gas in long-term contracts, as PG&E and other companies do, brings stability that adds further desirability to the concept, he contends.
As for clean-burn technology, the Deere 8.1-liter spark-ignition engine pretty much brings the future into the present. It needs no cooled exhaust-gas recirculation, like most diesels do, and it will meet the federal EPA's '07 limits without a particulate filter, which all diesels will have. This fall Deere will introduce an even cleaner version for California, and is readying a nine-liter variant to meet the EPA's 2010 limits, according to Don McCaw, business manager for the engine. He said about 2,500 of the 8.1-liter gas engines are now running – mostly in transit buses, but some in trucks like this. PG&E has 41 in older Freightliner FL70 chassis, and all were custom installed like this one.
Driving the Deere-powered M2 was a gas, as we used to say in the '70s. That was back when diesels needed nothing to be emissions legal and gasoline engines needed only slight EGRing and an air injection pump.
Don Allison, sales manager for Complete Coach Works in Riverside, which installed the Deere in this M2, tracked down the truck in Santa Monica, where the city fleet was trying it out. I drove it around narrow streets and up the Pacific Coast Highway toward Malibu, well aware of its special status and being careful not to bang it up.
The engine is quiet except at idle, when it makes a deep bawww sound. Above idle it quiets down, and at highway speeds you can't hear it at all. There's a slight whining, probably from the transmission, and some general road and wind noise. But there's no diesel rattle or rumble, and you'd think you were driving a gasoline engine. In a sense you are, as the Deere uses spark plugs to ignite the natural gas, stored compressed on this truck.
The vehicle is as wide as most medium- and heavy duty trucks, but is relatively short, and its 180-inch wheelbase makes it easy to turn. The six-speed Allison 3000 RDS automatic takes care of shifting. With no load, the 250-hp, 800-lbs.-ft. engine provided brisk acceleration. As with any M2, outward visibility is excellent and the steel cabinet behind the cab is about the same width as the Heil dump body, presenting no sight obstacle.
The cabinet holds three 18-by 78-inch cylindrical tanks for the compressed natural gas. The tanks are made of aluminum wrapped in glass and carbon fibers. Below them is the fuel panel with a regulator, filters, gauges and the filler. Each of the tanks holds 18.66 diesel-equivalent gallons, for a total of 56.
That supplies enough range and operating time for a locally operated truck.
