Off-Highway Emissions Set to Get Stricter

Eaton director Dr. Mihai Dorobantu says regulators likely will push for “maximum reductions” in nitrogen oxides and carbon dioxide once the technology path is clear.

Relieving the turbocharger from the EGR management task with an EGR pump (above) allows for higher-efficiency turbos and the elimination of pumping losses. (Eaton)

Emissions regulators currently are largely focused on on-highway NOx and CO2 reductions, according to Dr. Mihai Dorobantu, director of Technology Planning and Government Affairs for Eaton Vehicle Group. But even more attention is about to be turned toward off-highway emissions, he added: “I think we are beginning the journey towards significantly more stringent off-road regulations.”

Cylinder deactivation is another technology that breaks the traditional trade-off between NOx or CO2 emissions reduction. (Eaton)

Dorobantu recently answered a range of emissions-related questions for SAE Mobility Media, and also briefly addressed the semiconductor shortage that continues to stymie supply chains across markets. While Eaton’s direct exposure to the chip crisis is limited, he said, it certainly affects its customers. “We are watching carefully and trying to manage through it,” he said, “but we also have no basis to assume it will get better any time soon.”

Are global emissions regulations for off-highway converging, or will regional differences continue?

By and large, regulators are now focused on on-road simultaneous NOx and CO2 reductions, but in all three major regions, they have begun activities to determine the scope of off-road emissions. The on-road regulations and technology packages, the extent to which those technologies or close-by variations are applicable to off-road, and political objectives will eventually shape the outcome. However, it is difficult to see how regulators will not push for maximum reductions once the technology path is clear, which is why in the next several years we believe we will see a push for an 80-90% reduction in NOx and a 5-10% reduction in CO2. From that perspective, regulations will converge.

Dr. Mihai Dorobantu, director of Technology Planning and Government Affairs for Eaton Vehicle Group. (Eaton)

Do you believe a global emissions standard is possible?

It is far less likely certification cycles will converge, given the different paradigms and legislative authorities of the various regulators. However, if the regulations will be the maximum in terms of stringency, the technology packages to satisfy them also will be quite similar, even if the regulatory test procedures will be different.

Can technology sharing between the off- and on-highway sectors become more commonplace?

The off-road segment is very different from on-road. The typical cycles run at significantly higher loads and they’re steeper and more often transients. Also, there is a significantly larger variation from one off-road application to another compared to the variability of on-road vehicles. All this means that the emissions-reduction technologies are very different between the segments, as is the potential bottom-line number in terms of CO2 and NOx. For this reason, we don’t quite see the opportunity for the alignment of regulations, or technologies, between the sectors. The fast and often transients [in off-highway] are a good example. Maximizing reductions requires massive amounts of aftertreatment heat that points to fuel burners rather than engine exhaust thermal management or a few kilowatts of electrically generated heat.

What technologies are best positioned to help satisfy ultra-low limits in NOx and CO2, seeing as these traditionally are competing targets?

We need to break the traditional trade-off. Relieving the turbocharger from the EGR [exhaust gas recirculation] management task with an EGR pump allows for high-efficiency turbos (better boost, thus better CO2), and the elimination of pumping losses by equalizing exhaust and intake pressures. Then EGR can be flowed with very little power to assist in lowering NOx and in fact flow massive EGR at idle where the aftertreatment is challenged for NOx conversion. This is an example where you simultaneously get better CO2 and better NOx control.

Cylinder deactivation is another one – at idle and low load it acts as a smaller displacement engine, which reduces CO2 through better combustion in the active cylinders and reduced friction, but at the same time increases exhaust temperature for better NOx conversion in the aftertreatment. Another one is 48V electric power that can be used to drive variable flow oil and water pumps for reduced parasitic loads, and allow for some brake regeneration – all CO2 plays – but [it] also can instantly power an electric heater in the aftertreatment system to get it at the right NOx conversion temperature faster, clearly a low-NOx play.

When will these emissions technologies be ready for widespread use? Any challenges to bringing them to market?

The technologies described are ready to use. They have been developed and deployed in other applications. What is new is the way they are being combined, applied and controlled. The technical challenge is in controls, especially as they require deep integration and share multiple functions. The other challenge is engineering costs. These technologies need to be deployed as the industry also needs to invest in electrification, fuel cells and autonomous driving features. All these are needed, and they compete for limited resources.

Electrification continues to gain steam, but the demise of diesel engines does not appear imminent. Can you provide your take on this interplay?

The off-road segment and the heavy-duty freight segment are by far the highest CO2 and NOx emitters – and also the hardest to electrify, given the vast amounts of energy they use (which is why they are high emitters in the first place). The geographical spread is an additional infrastructure challenge. From that perspective, we expect diesel to be the prime mover for a long time, a decade or two, in these segments.

Electrification is already taking off in more urban applications, and we expect that to grow quickly. Finally, there is an interplay between diesel and electrification. As electrical technologies develop, some are applicable to hybridizing diesels, and conversely, the diesel applications can give some electrical technologies scale faster than otherwise expected.