Breathing near the California seaports at Long Beach and Los Angeles is probably a little easier now, two months after Daimler Trucks North America began delivering 232 natural gas-fueled day-cab tractors to customers working in and around the two busy cargo hubs.

All of the new units -intended to replace aging, much less environmentally-friendly ones -are Sterling L-113 flat-roof conventionals, powered by 8.9-litre Cummins Westport ISL G engines rated at 320 hp and 1,000 lbs./ft. of torque. More than half the total, 132 to be exact, went to California Cartage Company, a family-owned drayage and warehousing firm with operations across the US. The other 100 were destined for smaller carriers and owner/operators doing business with the ports.

These “green” trucks were not cheap. They sold for roughly US$160,000 a copy. Cal Cartage, however, was rewarded for being an “early adopter” under a local initiative called the Clean Trucks program, the goal of which is to reduce air pollution at the ports by more than 80% by 2012. As such, the company was able to score a significant discount on its purchase, thanks to a collaborative funding project between the US Environmental Protection Agency, California Air Resources Board and the South Coast Air Quality Management District. The agencies put together grants totalling nearly US$12 million, or about US$90,000 per truck, and another US$4.22 million in federal tax credits. The amount of governmental subsidies available for other buyers was unclear. Although assistance is certain -to be paid for by a levy on containers moving through the ports -it probably won’t be quite as generous.

Obviously, the cost of engines burning natural gas, whether compressed or liquefied, is much higher than that of comparably sized diesels. But truckers switching from the latter to the former do benefit somewhat from lower fuel prices -even though diesel offers better economy.

The chief advantage of natural gas is its effects, or lack thereof, on the environment. During a press event to publicize Sterling’s sizable sale at the ports, officials from Daimler Trucks North America referred to the Cummins Westport ISL G as a “near-zero emissions” engine. They said that it already met the EPA’s 2010 diesel exhaust mandate -without particulate filters or other aftertreatment devices. The engine uses an advanced combustion system, cooled exhaust-gas recirculation and a three-way catalyst to quell emissions. Nitrogen oxide emitted from the engine is at a CARB-compliant 0.20 gram per brake horsepower/hour; particulate matter is at 0.01 gram bhp/h. Greenhouse gasses are almost non-existent because natural gas contains little carbon.

DTNA president Chris Patterson, speaking at the event, pointed to yet another benefit of natural gas: It’s abundant throughout North America. “Each of these tractors will reduce the use of imported oil by 500 barrels per year,” he said. Multiplied by 232, the total reduction could be as much as 116,000 barrels annually.

Of course, the abundance of domestic sources doesn’t mean the fuel is readily available on the street, at least not yet. Bob Lively, vice-president of strategic planning for Cal Cartage, says the ports currently have just one publicly accessible LNG fueling station nearby, and it’s owned and operated by Southern Counties Express, another drayage fleet that’s begun using natural gas-powered vehicles. Until more are built, this could pose problems for newly-minted LNG truckers who might spend a lot of time waiting for their turn at the pump, especially because the trucks in question have an operational range of only 250 to 300 miles between 100-gallon fills. Lively says there are actually more CNG facilities in California, but few of those are set up for large trucks. Still, he’s bullish about the future of both types of natural gas, and he expects his company to continue buying trucks powered by those fuels.

That might be true, but it won’t be ordering many more with a Sterling nameplate. This fall, DTNA announced the brand’s discontinuation (scheduled for March) in an effort to cut costs during these lean economic times. Officials have chosen Freightliner’s M2-112 to replace Sterling’s L-113 as the designated medium- and heavy-duty natural gas vehicle.

Whatever body panels are used, executives said the environmental benefits of these new trucks will be considerable, noticeable and immediate. Cal Cartage president Bob Curry Sr. agreed, saying he was proud to be involved with an effort to improve the area’s air quality: “At our company, we want to be a part of the solution, not the problem.”