What a long, strange, clean air trip it's been.

No longer do commercial trucks belch black smoke, nor leave behind the thick cloying stench of diesel fuel in their wake. No longer does the distinctive “bark” of the diesel engine create a jarring, clattering sound to the human ear.

Indeed, as 2010-compliant commercial trucks start to roll off production lines this year, an amazing transformation is now complete — one many even within the industry doubted could ever be accomplished. Today's diesel-powered trucks are cleaner and quieter than ever before — even, in the case of a smog-enclouded metropolis like Los Angeles — acting as “clean air agents” of a sort, scrubbing the air free of pollutants such as particulate matter (PM) and oxides of nitrogen (NOx).

“Diesel engines in vehicles have a hard-earned reputation for being dependable, for being powerful, for being energy-efficient, and they last forever,” explains Gina McCarthy, assistant administrator-air and radiation for the Environmental Protection Agency (EPA).

“But that used to be both an opportunity and a challenge, because diesels also had the reputation of not being the cleanest engines around,” she adds. “But we're changing that reality and the perception of what the diesel engine can deliver for us here in the U.S.”

McCarthy believes the ongoing partnership between the trucking industry, manufacturers, advocacy groups and the EPA allowed for the crafting of standards that brought “clean diesel” technology and fuels to the fore, without sacrificing their capability or performance as the workhorses of industry.

“Engineers have worked very hard over a long period of time to reduce emissions while preserving the efficiencies and advantages of the diesel engine,” notes John Wall, vp and chief technical officer for Cummins.

But none of this comes without cost. For example, about $1,800 to $3,000 was added to the base cost of a Class 8 truck in 2002 to meet the first round of emissions regulations. For 2007, an extra $5,000 to $10,000 got tacked on to Class 8 sticker prices, followed by another $6,700 to $10,000 extra in 2010 to meet the final round of emissions mandates.

Higher maintenance costs followed sticker price increases as well to cover all this extra emissions-related equipment, including all the new computer controls and wiring harnesses. Engine maker Detroit Diesel Corp. (DDC) estimates that fleets fork over an average of $367 extra per truck, per year just for the 2007-related upgrades alone.

Since 2007, commercial trucks have come equipped with diesel particulate filters (DPFs) to remove PM from the exhaust stream — and they need to be cleaned out when a truck reaches anywhere from 150,000 to 400,000 mi. on its odometer. The cost to clean them out has a pretty broad price range, too, from $150 (cited by Volvo Trucks North America) to between $300 and $500 per transaction, according to DDC.

Truckers also use new ultra-low sulfur diesel (ULSD) fuel as part of the emissions reduction equation. ULSD is a fuel with a sulfur content of just 15 parts per million (ppm) compared to the 500-ppm level in on-road diesels prior to October 2006. According to research by the American Trucking Assns. (ATA), that 15-ppm blend added between 5¢ and 13¢ per gallon to the price of diesel at the pump.

Despite all of these higher costs, the core competencies have been preserved, notes Allen Schaeffer, executive director of the Diesel Technology Forum.

“Diesel powers key sectors of the U.S. economy, yet it's important to note diesel technology is evolving to meet the future needs and will play a vital role in our energy and environmental strategy for the future,” he explains.

“A new generation of clean diesel technology is already in place that uses a combination of ultra-low sulfur diesel fuel, more fuel-efficient diesel engines, and highly effective emissions control devices,” he says. “Diesel's unsurpassed energy efficiency enhances America's energy security by reducing our reliance on oil imports as more ‘clean diesel’ vehicles are added to the nation's fleets.”

A LOOK BACK

The effort to clean up truck exhaust is a long one, stretching back decades. At its heart is an initiative launched by the EPA back in 1985 under then-administrator Lee Thomas. After two years of studies, the agency announced it would embark on a “national strategy” to reduce the risks from toxic air pollutants.

This effort represented the regulatory result of Congressional efforts to improve the air quality of the U.S. via the Clean Air Act of 1972. EPA's formal effort to meet the legislative requirements laid down in 1972 focused on five chemicals that were determined to be candidates for federal regulation under the hazardous air pollution control provisions of the Clean Air Act.

“EPA believes that air toxics are a serious problem,” Thomas said at the time. “But we believe they can be dealt with in a responsible and effective manner.”

Along with focusing on emissions of single pollutants from major industrial point sources, EPA began evaluating air toxin problems by source category — factories, wood-burning stoves, cars and, of course, trucks. The agency's strategy aimed to reduce public exposure to hazardous air chemicals by targeting widespread sources, especially motor vehicles and fuels.

At the time, EPA's efforts meant setting standards for lead in gasoline, evaporative hydrocarbons from trucks, and particulate emissions from both cars and trucks. Later, the agency went on to completely ban lead in gasoline and set new standards for fuel volatility and diesel fuel quality. Part of that effort reduced the level of sulfur in diesel fuel from 3,000 ppm to 500 ppm by 1992.

TARGETING TRUCKS

The EPA targeted trucking early on in its 1985 manifesto, pointing to a collection of hazardous chemicals in diesel truck exhaust such as PM, NOx, black carbon, sulfur dioxides, and some 40 others officially classified as “hazardous air pollutants” under the Clean Air Act. And while diesel-powered trucks made up only 2% of vehicles in the U.S., their exhaust was responsible for more than 60% of all particulates and nearly half of all nitrogen oxides, the agency concluded.

By the early 1990s, Congress added amendments to the Clean Air Act called, appropriately, the Clean Air Act Amendments (CAAA). As part of that updating process, new targets were set to further reduce truck exhaust emissions in phases between 2004 and 2010. In 1997, however, those reductions were “pulled forward” as part of a deal engine manufacturers cut with the EPA and the Dept. of Justice over what were termed “defeat devices.”

The EPA claimed these devices turned off the emissions controls on truck engines in certain situations, such as driving up a hill under load, so engine power wouldn't be restricted. Rather than fight a losing battle, the engine manufacturers agreed to move up the deadlines for emissions regulations put forth by the CAAA — starting the emissions technology timetable in 2002, as opposed to 2004, and wrapping those changes up in two additional phases in 2007 and 2010.

Seven diesel engine makers were also forced to pay $83.4 million in civil penalties and collectively spend more than $850 million to develop these new, cleaner engines and rebuild older engines to cleaner levels.

The EPA also created a specific “step-down” path to follow in terms of staged reductions in emissions, measured in grams per horsepower-hour (g/hp-hr). In 2002, the levels were set at 2.4 g/hp-hr for NOx and 0.1 g/hp-hr for PM levels mandated by EPA; in 2007, NOx dropped again before taking a final step down to 0.20 g/hp-hr this year, while the PM level has remained unchanged.

A LOOK AHEAD

Yet even as the industry reached the final stage of its long emissions control journey this year, the EPA began looking down a new — and some say far more complicated — path.

Late last year, the agency officially designated greenhouse gases (GHGs) a threat to the public health and welfare of the American people, pointedly noting that GHG emissions from on-road vehicles contribute to that threat.

EPA Administrator Lisa P. Jackson said her agency's endangerment final finding is a response to a 2007 U.S. Supreme Court decision that said GHGs fit within the Clean Air Act definition of air pollutants and covers six key gases: carbon dioxide (CO2), methane, nitrous oxide, hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride.

“This endangerment finding provides the legal foundation for finalizing the recently proposed clean cars program, [which] contains the nation's first-ever limits on greenhouse gas emissions from American vehicles,” Jackson states. “Starting next spring, large emitting facilities will be required to incorporate the best available methods for controlling greenhouse gas emissions when they plan to construct or expand.”

Jackson stressed that, though the EPA's findings do not in and of themselves impose any emissions reduction requirements, they allow the agency to finalize the first-ever federal GHG tailpipe standards for new light-duty vehicles. Those were proposed on Sept. 15 last year as part of the joint rulemaking with the Dept. of Transportation. Those rules are expected to be finalized by March of this year.

“These are reasonable, common-sense steps that will allow us to do what the Clean Air Act does best: reduce emissions for better health, drive technology innovation for a better economy, and protect the environment for a better future,” Jackson says.

“On-road vehicles contribute more than 23% of total U.S. GHG emissions,” she adds. “EPA's proposed GHG standards for light-duty vehicles, a subset of on-road vehicles, would reduce GHG emissions by nearly 950 million metric tons and conserve 1.8-billion barrels of oil over the lifetime of model year 2012-2016 vehicles.“

“The release of the endangerment finding is seen as an effort to focus more attention on pending federal climate change legislation, but it does not include any proposed regulations,” says Glen Kedzie, ATA vp and environmental counsel. “[But] it's unclear at this time how the EPA's endangerment finding will affect the trucking industry.”

Trucking is indeed in the EPA's sights when it comes to controlling GHGs, notes Kedzie. The agency is currently developing metrics to measure carbon outputs from trucking — while climate change bills being debated in Congress contain provisions for the EPA to take the lead in establishing regulations to limit GHGs from medium- and heavy-duty trucks.

FOCUS ON GHGs

Yet the agency's recent Final GHG Inventory Rule does not include reporting requirements for trucking fleets. That means — at least for now — the ultimate impact of EPA's GHG reduction efforts on trucking operations remains vague at best. “There are no specifics known at this time as to what the finding may mean for the trucking industry,” Kedzie stresses.

DTF's Schaeffer adds that the National Academy of Sciences is set to release a report this March that will highlight a path towards establishing a heavy-duty truck fuel economy standard, a key metric to controlling CO2 emissions, one of the leading GHGs cited in EPA's latest emissions broadside.

“This pursuit of higher engine efficiency and lower carbon dioxide, without slipping on any of the environmental accomplishments, will create unprecedented challenges in the industry [and] have the potential to make the emissions standards milestones look comparatively easy,” Schaeffer stresses.

“Getting diesel clean was a huge undertaking and expenditure from all the companies investing in all the emissions control technology optimization, combustion improvements, etc.,” he notes. “To reach these new levels of HDT efficiency of the total vehicle requires a lot of new basic engineering science work, algorithms for determining how to measure fuel economy and the effects of the many different variables and materials science research. This next challenge to make heavy-duty trucks substantially more fuel-efficient will be a doozy.”

EPA emissions regs:
A history of heavy-duty diesel truck and bus limits

Nitrogen Oxides Particulate Matter
1984 10.7 g/hp-hr* 0.60 g/hp-hr
1991 5.0 g/hp-hr 0.25 g/hp-hr
1994 5.0 g/hp-hr 0.10 g/hp-hr
1998 4.0 g/hp-hr 0.10 g/hp-hr
2002-4 2.4 g/hp-hr ** 0.10 g/hp-hr
2007 1.2-2.4 g/hp-hr ** 0.01 g/hp-hr
2010 0.2 g/hp-hr*** 0.01 g/hp-hr

NOx and non-methane hydrocarbons of 0.2 are phased in together between 2007 and 2010 based on a percentage of sales: 50% from 2007 to 2009 and 100% by 2010.

* grams per brake horsepower hour

** includes non-methane hydrocarbons

*** includes separate limit of 0.14 g/hp-hr for non-methane hydrocarbons