A lead-in to 2010 begins this year, with targets of 1.2 g/bhp-hr NO_x and the same PM target.

Given an average 3-year timeline to take a new product into production, all the manufacturers have made their basic technology decisions—albeit not yet announced—on 2010 technology, although some room for tuning remains. All the panelists were in agreement that, once the 2010 products are in development, they can turn more of their focus to what comes next.

This is the first time in many years, as Dr. Wayne Eckerle, Executive Director of Research and Technology at Cummins said, that the manufacturers “don’t have an impending legislative limit that we need to meet that I’m not sure how to meet.”

For the manufacturers, that expanded focus includes on-going improvements in reliability and operational efficiency of the 2010 products currently under development. An example would be meeting emissions requirements in increasingly efficient ways—for example, meeting NO_x limits via advanced combustion and without aftertreatment systems.

On that topic specifically, Alan Karkkainen, Director, Future Technologies, Engine Engineering for International Truck & Engine, noted “Will we get to 2010 by 2010 [with only advanced combustion]? Probably not. By 2012 or 2014, probably.”

Related to that focus on increasing efficiency of emissions management will be a much greater focus on fuel efficiency, especially related to reducing greenhouse gas emissions. Meeting anticipated, but as yet undefined, climate change regulations is on everyone’s radar screens.

When people like these [the scientists of the IPCC] say [climate change] is a real issue, policy will follow shortly thereafter. The next decade will see unprecedented pressure to reduce CO₂.

—Dr. Michael Readey, Applied Technology Development Manager, Caterpillar

In addition to those two key areas, the manufacturers will begin to focus more on safety systems, as well as driver comfort and convenience.

Tony Greszler, VP Engineering at Volvo Powertrain and the moderator of the panel, laid out a basic technology menu for 2010 that included:

• Diesel particulate filters.

• NO_x aftertreatment systems.

• Advanced combustion, including a range of advanced system components (such as two-stage boosting, injection systems, and variable valve management among others).

• Control systems and on-board diagnostics (OBD). Dr. Readey from Caterpillar said that in his opinion, OBD poses more of a risk issue than emissions.

• Hybrids.

• Waste heat recovery, including the possibility of thermo-electric recovery.

• Fuels (biofuels and eventually synthetics).

The Diesel particulate Filter is already becoming common on heavy-duty platforms to meet the 2007 limits. As the manufacturers head into 2010, they all see a need for some form of NO_x aftertreatment. Greszler said “I’m not aware of anybody that will attempt to meet 2010 NO_x without some kind of aftertreatment.”

Although urea-based SCR is the odds-on favorite at this point, with its greater than 80% conversion efficiencies, it is not the only choice nor is it without concerns, related to infrastructure, operational convenience, and vehicle layout.

While the extra tank and injector required for a urea-based system is likely not a problem on a long-haul Class 8 truck, Karkkainen noted, “The truck is only part of the tool in a medium-duty application. With a mobile crane, for example, there is no room under the body [for the urea system].”

There is also some worry that, given potential technology developments, urea SCR could become a stranded technology several years after its implementation.

Another option for NO_x control is a lean NO_x adsorber (trap). Such LNTs offer excellent NO_x reduction when new, but have some issues with cost, durability and engine management during desulfation. Some see it as likely on lighter duty applications, but questionable on the heaviest duty vehicles.

Cummins earlier this year paired its new 6.7-liter turbodiesel with an advanced aftertreatment system including a close-coupled diesel oxidation catalyst, a NO_x adsorber catalyst and a combined diesel oxidation/particulate filter to deliver the first 2010-compliant diesel powertrain on the market.

An option that some are exploring is a hybrid aftertreatment system—a combination of lean NO_x traps with Selective Catalytic Reduction—to meet NO_x limits without having to go to urea.

Eaton Aftertreatment System. Click to enlarge.

Tom Stover, Engineering Manager, Technology, from Eaton, discussed the Eaton Aftertreatment System (EAS), announced last year. (Earlier post.) The EAS combines a fuel reformer catalyst with doser, LNT and SCR technology to create an exhaust aftertreatment system capable of meeting 2010 EPA diesel emissions requirements without the need for a urea storage and injection system.

The hydrocarbon doser feeds the reformer, producing hydrogen and CO—ideal for use in regenerating the LNT. The LNT produces ammonia in significant amounts, according to Stover. In fact, Eaton optimized the system to produce more ammonia than usual. That ammonia becomes the reductant for the second stage SCR catalyst.

Eaton acquired the reformer technology with its acquisition of Catalytica in 2006. (Earlier post.)

Hino is also exploring non-urea approaches with NO_x reduction for 2010, according to Masatoshi Shimoda. Hino is using combustion work (high cooled Exhaust Gas Recirculation ration of 29%, high boost and 200 MPa (2,000 bar) injection) to reduce engine-out NO_x to 0.75 g/bhp-hr (when hot), then is looking to a variety of aftertreatment systems for the additional required 82% reduction.

Hino is testing a number of non-urea systems, including a single system adsorber, a 2-leg adsorber system, a fuel reformer system, a plasma reformer system as well as a urea system. In early testing, the company had its best results with the urea system and the plasma reformer, although Shimoda said that the 2-leg system has room for improvement. The company begins feasibility studies in March 2007.

On the combustion front, there is a wide variety of work underway in exploring the use of increased injection pressure, higher boosting and higher cooled EGR ratios in addition to work with HCCI and Partial HCCI combustion regimes.

In a separate presentation at the conference, Per Andersson, a Technical Specialist from Ricardo, characterized HCCI combustion as “like balancing on a knife’s edge—the combustion can’t be too rich nor too lean, and at a temperature not too high to form NO_x, but not too low to misfire.”

These engines are sensitive to virtually everything... a change in environment, fuel, the engine has to take care of it.

—Per Andersson

Challenges at low load and high load are quite different for HCCI combustion, especially on a heavy duty vehicle. Among the technologies being explored are different injection systems (such as dual-mode injectors) and strategies, variable valve management on a per-cylinder basis, variable compression ratio engines, further development of EGR and boosting systems,and mixed-mode strategies.

Making all that work requires significant development of sensors and control systems. The focus on engine work will result in a need for increased base engine strength to handle higher cylinder pressure and injection loading, and especially more sophisticated controls and On-Board Diagnostics.

Hybridization is seen almost as a given beyond 2010 in the current environment. Volvo, Hino and International all have heavy-duty hybrid vehicles and Eaton is about to begin production of its medium-duty hybrid drivetrain (earlier post) and is further developing its heavy-duty hybrid drivetrain. Cummins is working on hybrids, and Caterpillar is working on both on-road and off-road hybrids.

Eckerle from Cummins noted that “as we start heading to hybrids, we want to make sure we optimize the power density in the engines.”

One regulatory issue outstanding in this area is that there as yet no provision to certify a hybrid cycle. Manufacturers thus need to certify the hybrid vehicle on the base engine, noted Greszler, thereby limiting the opportunity for optimizing the hybrid cycle.

Waste heat recovery is seeing a big emphasis as a means to pushing up the overall brake thermal efficiency of the systems to 50% or better from the current low 40s, and Cummins is actively developing Rankin cycle conversion of EGR heat to electric power.

Eckerle said that Cummins has recovered about 57 hp from its Rankine cycle waste heat recovery system. The question, he said, is making it cost-effective. He sketched out a series of steps that could push BTE over 50%. Starting at a current base of 42% BTE, Cummins thinks it can deliver:

• 5 percentage points in improvement with combustion and air handling;

• 1.5 percentage points with EGR Loop

• 1.5 percentage points with optimized controls and calibration

• 1.5 percentage points with improving PM aftertreatment—reducing the time required for thermal management on the engine, as well as active regeneration;

• 5 percentage points with waste heat recovery and electric accessories.

The biofuel currently at the forefront of the heavy-duty industry is biodiesel. All the manufacturers are taking that also as a given, but note that more work needs to be done on quality—including on the blending side—as well as on understanding the emissions impact.

We’re working with EPA to understand what is the impact of biodiesel on emissions. It’s too early to say what is happening with post 07 technology. It’s not just the engines, its also the aftertreatment systems with their injection systems...but this [biodiesel use] is happening, and we will need to modify whatever aftertreatment systems we need to to work with the fuels, provided the fuel is quality.

—Dr. Readey

Cummins, which will shortly announced B20 compatibility for its 2007 engines, is actively working with the refineries to get away from splash blending, which can have variable results.

We'd like to get away from splash blending. We need a national approach, so we all have the same fuels.

—Dr. Eckerle

The major alternative fuel for heavy duty vehicles currently is natural gas, and Graham Williams, Director Global Heavy Duty Programs for Westport Innovations, a major provider of gas engine technology, noted that in terms of 2010 technology, his company “will likely follow what the diesel industry gives us and for good reasons.”

The diesel industry will make it, natural gas will follow, but we will retain where possible the characteristics of well-developed diesel products.

—Graham Williams

Westport takes two combustion approaches with natural gas: otto cycle (spark ignited) and diesel cycle (with diesel pilot).

Westport’s joint venture with Cummins (Cummins Westport) will introduce a spark-ignited, 2010-compliant gas engine in June. This is evolutionary technology, and reflects the overall improvement in natural gas engines over the past few years in terms of efficiency.

The engine goes to stoichiometric rather than lean burn and, with addition of EGR, can handle emissions with a simple three-way catalyst. (Earlier post.) The direct-injected, pilot-ignited system (High Pressure Direct Injection—HPDI) changes as little as possible with the diesel engine.

Although natural gas engines are inherently about 50% cleaner than diesel with respect to NO_x, there originally was a sizeable efficiency gap due to immaturity and lack of optimization.

Over the last few years, we have dramatically improved the efficiency and retained the emissions reduction compared to diesel, so in 2007 we have a gas engine as efficient as a diesel.

However, meeting the 2010 target with a gas engine on a diesel cycle will be difficult, Williams noted, and for that reason it is likely they’ll follow “what the diesel industry gives us.” Combining HCCI with HPDI is a promising approach.

In terms of greenhouse gas reduction, Williams noted that landfill gas and biogas are both very compatible with Westport’s technology.