Washington Way: Revolutionary Or Evolutionary? Changes To Heavy-Duty Engines Are On The Way
Will restrictive new standards lead to alternative-fueled diesel engine designs?
By Mike Conlon
Revolution! The very word suggests radical change, violence, upheaval and catastrophic damage. We most often associate revolutions with politics, in which one group or one locality takes action to separate itself from another.
But revolution also refers to events or activities that by their very nature change the way we live, think or act. For example, we refer to the beginning of the machine age as the Industrial Revolution. The advent of electricity, computers and motor vehicles were no less "revolutionary" in their effect on our daily lives as well.
Heavy-duty diesel engines are now facing their own revolution. Stimulated by new government mandates to make our air even cleaner, both federal and state legislatures are moving quickly in ways which will either radically change the heavy duty diesel engine or make it obsolete.
Despite major efforts since the early ‘70s to control the causes of air pollution, the emissions from heavy-duty engines largely went unregulated. Their emissions were not overlooked, but partly due to the perceived difficulties in cleaning up these engines without losing power or performance, and partly because automobiles and stationary sources were much larger contributors to dirty air and easier to clean up, no major program was proposed to reduce heavy-duty emissions.
No more. Most of the economical or even possible emissions reductions from these other sources have already been achieved. As a result, emissions from heavy-duty vehicles now constitute a majority of the remaining emissions, especially of NOx and particulate matter. For this reason, environmentalists and regulators have the heavy-duty diesel engine squarely in their sights.
The Environmental Protection Agency (EPA) is concentrating its new clean-up efforts on heavy-duty vehicles. In 1997, EPA set stringent new emissions standards for heavy-duty vehicles, which will take effect in 2004. However, most engine manufacturers will be required to meet these standards by 2002 under a consent decree signed with EPA last year to settle a lawsuit. The suit arose because the manufacturers programmed their electronic engine controls to have engines meet emissions standards during test cycles, but to then change engine performance to increase emissions under normal driving conditions. This apparent attempt to circumvent the law was exposed by EPA and, as a result, the stricter requirements were advanced.
In addition, later this year, EPA is expected to finalize even lower emissions standards for 2007 and later model year vehicles. Under these new rules, heavy-duty vehicles will be required to meet the stricter standards, not only under test conditions or even normal operating conditions, as is the requirement now. The standards will become a cap, which cannot be exceeded under any conditions, including driving at high altitudes or in extreme heat.
At the same time, both EPA and the State of California are investigating whether diesel exhaust is a human carcinogen. California has already reached that conclusion, and under its laws, the California EPA is now adopting regulations to limit exposure to diesel exhaust, especially in areas where it is most likely to collect, such as around fleet terminals and repair facilities.
As a first step, it has passed a rule to require transit companies over the next several years to clean up their fleets by either purchasing "clean" diesel engines or alternative fuel vehicles. EPA is still studying the toxicity of diesel exhaust, but is expected to reach a conclusion similar to California’s and then to initiate its own control measures.
Mandates to require the use of alternative fuel vehicles are also arising. In mid-June officials of the California South Coast Air Quality Management District, which covers the Los Angeles area, adopted tough new diesel standards. These new standards apply to government vehicles, transit buses, truck haulers and other heavy-duty vehicles. The new rules require a reduction of 71% in particulate matter and 54% in NOx. Many believe that these standards may be impossible for diesel fuel to meet under any circumstances. In fact, trucking interests in the Los Angeles area contend that the rules were designed so that only alternate fuels, particularly compressed natural gas, can meet them.
Truckers are expected to challenge the new rules in court, but the rules are already having an effect. The Los Angeles Metropolitan Transit Agency recently announced plans to purchase 370 natural gas-fueled buses instead of new diesel ones, a decision directly related to the new rule.
And, the state of California is moving in other ways against diesel emissions. In July, the California Air Resources Board (CARB) proposed a plan to reduce diesel emissions by requiring particulate matter or soot traps on all new heavy-duty trucks and buses, as well as farm, construction and other off-road vehicles. Moreover, because of the long life of most heavy-duty vehicles, the program will also require most existing engines to be retrofitted with these devices. At the same time, CARB announced its intention to work toward standards that would reduce diesel emissions from the more than 1.25 million diesel vehicles in the state by up to 90%. While installing particulate traps and other emissions-reducing devices may provide immediate work for rebuilders, CARB’s ultimate reduction goal may hinge less on modifying diesel engines and more on replacing them with alternate fueled engines.
Simultaneously, federal and state incentive and grant programs are spurring research into innovative engine types, such as fuel cells and diesel/electric hybrids, as well as other alternative fuel technologies. These are all considered possible replacements for diesel engines. Ironically, some of these same research projects are actually focusing on diesel as a replacement for gasoline in automobiles because of the higher mileage achievable by diesels. Even the presidential candidates are getting involved. Vice President Al Gore has proposed a federal tax credit of up to $18,000 for purchasers of new technology, i.e., alternatively fueled, eighteen-wheelers.
As a result of these initiatives, many changes are occurring under the heavy-duty hood. To meet emissions and toxicity requirements many manufacturers are researching ways to reduce emissions. Short term, most are trying to adapt devices currently used on automobiles to reduce emissions, such as catalysts and exhaust gas recirculation (EGR) technologies. New emissions reduction technologies such as the aforementioned particulate traps are also being tested.
Indeed, the major manufacturers of both highway and off-road vehicles have established a cooperative research venture under government oversight to study such exotic technologies as direct injection homogeneous charge compression ignition, variable valve actuation, a second generation of cycle-resolved water injection, the effect of water emulsion on post-combustion exhaust emission reduction devices, and others. Fortunately, because these technologies should have little or no effect on the diesel engine itself, they could reduce a large part of the emissions without significant impact on the rebuilding industry.
However, almost all of these emissions reduction technologies require a change in diesel fuel to sharply reduce its sulfur content because sulfur can drastically reduce the long term performance of these devices. Diesel fuel now contains up to 500 parts per million (ppm) of sulfur. EPA is proposing reducing this to 15 ppm, a 97% reduction. However, such a large reduction may not be technologically feasible and in any event will be expensive.
Engine manufacturers are supporting the proposed reduction, but fuel companies are saying that it can’t be done and are pushing for a reduction to no less than 50 ppm. Rebuilders should be supporting the greatest possible reduction because it would increase the number of usable retrofit technologies and their durability.
The advent of these technologies has caused EPA to undertake a pilot program to retrofit up to 10,000 heavy-duty diesel engines to emit lower emissions than when they were new. Assuming that the program is successful, it seems likely that it will be expanded to an even larger number of vehicles.
California and the New England states are also considering similar retrofit programs. If, in fact, these programs use retrofit technologies that are available to everyone to achieve their results, and do not rely upon engine replacement or use of a manufacturer’s proprietary technology, these programs could be short-term boons to independent engine rebuilders.
Is this a revolution? It seems to be. But if lower sulfur fuel and exhaust type emissions reduction devices are successful it may only be a necessary evolution. Only time will tell. One thing is certain. The heavy-duty diesel engine systems of 2010 will be very different than their counterparts in 2000.