As mandated by federal regulations, new trucks will soon feature a less-polluting diesel engine. Meanwhile, other environmentally friendly diesel engine options are also in development.

A new generation of diesel engines will enter the market in a few months. These environmentally friendly engines emit less nitrogen oxide and thus conform to new federal standards taking effect in October that mandate a reduction in nitrogen oxide emissions, which help produce ozone and smog. These recirculating engines, which send exhaust gases back through the combustion chamber to cut down the amount of oxides emitted, are so far the only engines that have been certified to comply with new regulations.

The limited testing this new technology has undergone, however, worries many trucking companies. Trucking officials complain that these recirculating engines have been rushed to market. They say that these new engines are more costly, heavier, consume more fuel, and demand more maintenance. Some fleet operators are avoiding having to purchase these new engines by buying current truck models before the October deadline. For example, Tennessee-based US Xpress Enterprises Inc., the fifth largest publicly traded trucking company, has already placed an order for 1,200 new trucks this year and plans to prolong usage of each vehicle from three years to four or more, says its chief executive Max Fuller. “The economics in this thing are so upside down it’s not worth the gamble. Usually when you adopt new technology you’re looking for a payback,” Fuller says.

The new recirculating engines will likely add $3,000 to $5,000 to the $12,000- to $25,000-pricetag of a heavy diesel truck engine. Furthermore, trucking companies anticipate more oil changes and a 3-5% loss in fuel efficiency. These extra costs will further strain the already tight profit margins of the trucking industry, whose revenues exceeded $600 billion in 2000, the most current year that totals are available. The new federal standards’ promise to reduce truck pollution by more than 90% by 2010 is doing little to assuage some trucking executives. “I’m for clean air, but I think there’s a right way to do it and a wrong way to do it,” says Fuller. “This one feels like it’s being slammed down the industry’s throat right now.”

Trucking companies will soon have alternatives to recirculating engines. Dual-fuel diesel engines are currently in development. Along with conventional diesel fuel, these engines consume natural gas, which produces no sulfur oxides or particulates. In addition, compared to consuming liquid petroleum fuels, burning natural gas generates less carbon dioxide and fewer nitrogen oxides, which can exacerbate asthma and cause respiratory problems. Caterpillar Inc. of Peoria, Illinois—which, along with Cummins Inc. of Columbus, Indiana, claims half of the heavy truck engine market—currently sells dual-fuel diesel engines while forgoing the production of recirculating engines altogether. Ranging from 190 to 410 horsepower, its dual-fuel engines feature electronically controlled injectors that allow the consumption of both diesel fuel and a variable mix of natural gas. Caterpillar says, in some systems, more than 85% of the fuel used can be natural gas, which can be contained in compressed or liquefied form. In addition, the engines can rely solely on diesel fuel if they run out of natural gas on the road.

Vancouver-based Cummins Westport Inc.—a joint venture of Cummins Inc. and Westport Innovations Inc. of Vancouver—hopes to have a model of its 400-horsepower natural-gas-burning diesel engine on the market late next year. Still being tested, this 15-liter engine compresses air, not combined with fuel, like a standard diesel engine. Diesel fuel is introduced as a pilot followed by natural gas, which is regulated by electronic controls. According to Cummins Westport, natural gas will account for 95% of fuel consumption over a duty cycle. The engine’s fuel economy is similar to that of a conventional diesel engine, a company spokesman says, an amazing capability considering that to equal the energy contained in a gallon of diesel fuel, 1.7 gallons of liquefied natural gas (LNG) is needed. Most trucks testing this new engine are owned by Norcal Waste Systems Inc., which runs them in California’s Bay Area. In March, Norcal built an LNG fueling station in San Francisco and has already ordered nine more LNG-fueled trucks to add to its current 14.

These natural-gas-burning diesel engines may soon surpass federal regulations. For now, with only one approved choice—the recirculating engines—trucking companies may resist purchasing trucks after October.

Sources: Truck Fleets Scramble to Place Orders
Justin Bachman
Associated Press, May 30, 2002
http://story.news.yahoo.com/news?tmpl=story&u=/ap/20020530/ap_on_bi_ge/rushed_truck_orders_2

Heavy-Duty LNG
Harry Hutchinson
Mechanical Engineering, May 2002
http://www.memagazine.org/contents/current/features/heavylng/heavylng.html