Diesel’s not done

John Deere was among the first to introduce electric drivetrain technology in construction and quarry-sized wheeled loaders

Talk of electrification has taken center stage in recent years when it comes to equipment power options, but we can’t ignore the many positive attributes of the diesel engine, which has evolved rapidly and significantly from its humble beginnings.

Engine makers have been working to reduce diesel emissions for decades, and that trend continues even after Tier IV Final regulations were met several years ago. Europe’s Stage V regs, for example, were scheduled to go into effect in June of last year but have been postponed due to challenges related to the worldwide pandemic.

“We’re in an exciting time for diesel engine development,” said Michael Lefebvre, manager, global marketing support, John Deere Power Systems. “After years refining our technologies to meet subsequent levels of emissions regulations, we can now leverage those technologies in new ways to achieve impressive results.

“We’ve always focused on uptime and reliability for our products, and that will continue to be an area of emphasis as we develop upcoming engine offerings.”

In this era of heavy-duty engine design, there are a few main areas of opportunity, Lefebvre said, including leveraging virtual analysis and telematics data, using digital tools and advanced simulation, and streamlining overarching power systems in the vehicle.

“Engines will become smarter and more capable – not only in terms of lower emissions or higher power, but by being more reliable to run in the way applications demand,” he said.

How low can diesel emissions go?

Regarding lower emissions, much of the focus to date has been on reducing nitrogen oxide (NOx) and particulate matter (PM), but the reduction of CO2 will be of greater focus in the coming years, noted Christer Hedström, director, product planning industrial at Volvo Penta.

“At Volvo Penta, engine performance and reduced environmental impact go hand in hand,” he said. 

Steve Nendick, marketing communications director, off-highway, Cummins, pointed out that diesel engines have never been cleaner.

“Cummins Stage V Performance Series engines deliver a particulate matter (PM) reduction of near-99%, alongside 96% reduction in NOx, compared to engines at EU Stage 1,” he said. “These engines, ranging from 100 to 675 hp, meet both EPA Tier 4 Final and EU Stage V emissions regulations, the toughest emissions legislation globally.”

Cummins Performance Series delivers on average 10% more power and 20% more torque across the 100-430 hp range when compared to its predecessors, Nendick said, pointing to their increased power density that encourages the installation of smaller and lighter engines, with no loss in performance.

“Operators can also reduce emissions at the point of use without impacting productivity,” Nendick said.

Advanced aftertreatment for off-highway diesel engines

At Volvo Penta, Stage V engines feature an advanced exhaust aftertreatment system (EATS) which consists of a Diesel Oxidation Catalyst (DOC), Diesel Particulate Filter (DPF), AdBlue dosing system, Selective Catalytic Reduction (SCR) and Ammonia Slip Catalyst (ASC), Hedström explained.

Much of the focus to date has been on reducing NOx and PM, but the reduction of CO2 will be of greater focus in coming years

“This system is very efficient at reducing emissions and has good reliability across a variety of applications,” he said. “Stage V emission legislation requires off-road engines up to 560 kW to have a DPF which captures and stores soot.

“The soot needs to be burned off to regenerate the DPF and this is normally done while the machine is at a standstill, known as active regeneration.

“At Volvo Penta we have a ‘Regeneration Zero’ vision which means we’ve minimized the need for active regeneration as much as possible, reducing downtime and keeping customers’ machines operational and profitable.”

Diesel engines are here to stay

While the diesel engine is undoubtably cleaner and more powerful than ever before, there’s no denying the off-road

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industry is interested in electrification and OEMs and their customers can certainly see the benefits.

“We have already started to see electrification where the energy demand is relatively small and where there are good charging possibilities during a standard working day,” Hedström said.

“I think we’ll see electrification move into applications where there is an increased energy demand, but it will take some time before we’ll see it in the high-power, high-energy demanding applications.”

Lefebvre said diesel power has a long life ahead, even with the growing electrification market.

“The demands of the off-highway market will continue to remain the same – which requires the energy density that comes from diesel and is not currently available from fully electric solutions.

“The role of diesel use will likely evolve when smaller applications can meet the same off-highway performance requirements with alternative systems. However, diesel will likely continue to be the main energy source in heavy-duty applications.”

The feasibility of implementing alternative power systems in off-highway equipment will depend on being able to optimize an overall power solution – balancing mechanical, hydraulic and electric power systems and cost.

The cost of construction equipment electrification

As the trend for electrification continues to drive evolution in passenger transport, there is an opportunity for manufacturers to consider alternative power solutions for off-highway vehicles, said Nendick. Key to this will be ensuring any new power is efficient, reliable and can meet the duty cycles required of construction equipment.

“We’re committed to developing solutions that meet the market expectations of performance, uptime and running costs, while also meeting the need to reduce emissions,” he said. “We’re doing this with a variety of fuel sources including advanced diesel, hybridization, full electric and hydrogen fuel cell technology.

“Due to the economic challenges of alternative solutions, construction equipment will continue to rely on diesel for some time yet, particularly for machines with heavy-duty cycles, such as bulldozers and large excavators. While great advances have been made, no viable alternative has yet emerged that can match the workhorse credentials, energy efficiency, flexibility, reliability and durability of diesel power for heavier-duty construction equipment.”

JCB’s chief innovation and growth officer, Tim Burnhope explained that for large-scale excavators, for example, electric power is quite simply too costly both financially and environmentally. It would cost $208,000 for a lithium-ion battery large enough to power a 22-ton excavator for an eight-hour shift – not to mention the vast amount of carbon-dioxide produced in the battery’s manufacturing process.

“Diesel, on the other hand, contains more energy than petrol, natural gas, a variety of battery types and many other fuels or power sources,” he stated. “In fact, by mass, diesel contains around 54 times more energy than current lithium-ion batteries.

“Diesel is safe to be delivered to the site easily – even in remote locations,” he said. “Finally, with their high-torque nature and robustness, diesel engines are perfectly suited to heavy-duty applications, including use in construction equipment.”

The consensus seems to be that there are applications that have traditionally been powered by electricity and there are applications that never will be. Machinery that is working very remotely, where the energy supply – or the grid – is not readily available, that’s where the traditional internal combustion engine will remain irreplaceable for the foreseeable future.