STORY Industrial

The internal combustion engine will be around for a long time yet

Posted on November 08, 2019 by Roman Engeler

The editorial team of mtu Report spoke to Holger Bottlang, Head of Agriculture Application Engineering, and Peter Riegger, Head of Research & Technology, about future drive systems.

mtu Report:  Rolls-Royce is an mtu-engine manufacturer that also equips agricultural vehicles. Which manufacturers do you supply, and in which power classes?

Holger Bottlang: We supply engines for agricultural vehicles in the 115 to 480 kW (156 to 653 hp) power range. Our customers include well-known manufacturers such as Claas (large tractors, combine harvesters and forage harvesters), Krone (forage harvesters), Fendt (forage harvesters), Holmer (construction vehicles and beet harvesters) Ropa (moving loaders), Same Deutz-Fahr (combine harvesters) and Grimme (potato and beet harvesters).

Holger Bottlang: “Market demand among our agricultural machinery customers for electric drive systems is still very restrained at present."

Are the requirements made of these engines the same as for other diesel-powered vehicles?

Essentially, the same exhaust emission requirements apply as for all other off-highway engines. Our customers demand reliable engines with low fuel consumption and low maintenance costs.

But are there also differences?

We use the basic configuration engines from Daimler's large-scale truck series, which have been tested accordingly and are reliable. The mtu engines have been developed further by Rolls-Royce in collaboration with Daimler to meet the special requirements made of them. For example, components such as special flywheels, pipes and oil pans have been used. In addition, speed-based electronic engine control units are used to optimize fuel consumption. The load requirement profile is higher in continuous operation in agriculture settings than in on-highway applications.

As an engine manufacturer, where do you see the specific challenges when it comes to agricultural vehicles?

Agriculture requires particularly reliable engines, because the vehicles are exposed to harsh environmental conditions – dust and dirt in particular. Then comes the installation scenario which is very cramped and varies from vehicle to vehicle. Since agricultural vehicles are often used in tight timeframes (harvesting times), minimum downtime is of crucial importance to the customer. When a fault does occur that puts the vehicle out of action, you need a powerful service network to get it back up and running really quickly.

The implementation of Stage 5 exhaust emissions is a milestone. When can “Level 6” be expected?

It's currently under discussion with a view to implementation in 2026. The regulations for Level 6 are expected to be published by the authorities in 2023.

What other approaches can be taken to reduce emissions?

The main drivers will be “real drive emissions” (compliance with emission limits not only during certification, but in daily operation), along similar lines to the “6D” standard for trucks, and further reductions in NOx figures.

Zero emissions would then probably be the final step. Electric motors are the future – a mantra we hear everywhere. When is Rolls-Royce's last internal mtu combustion engine going to roll off the production line?

Peter Riegger: It will be a long time before that happens. There's no doubt in my mind that the internal combustion engine still has a long future ahead of it – albeit not as the sole source of power, but as part of a system approach. We're going to be supplying more and more of our engines in combination with electrical components. For example, under our Green & High Tech initiative we have developed – and are in the process of developing – products such as hybrid drives and microgrids. But in the vast majority of cases there will be no getting around the combustion engine, because whereas trains can tap into overhead power lines, combine harvesters and tractors cannot. Now and in the foreseeable future, the power density of batteries is nowhere near high enough to be able to do without an internal combustion engine.  

Peter Riegger: “Due to its high power density, the diesel engine will continue to feature prominently in our systems for a long time to come.”

Experts are predicting that, thanks to electrification, the best days of the internal combustion engine are still ahead of it. Can you sign up to that?

I certainly can. When it comes to development, electrification is opening up a whole raft of possibilities we simply haven't had before. Just look at our emergency power gensets. These generating sets have to start up at the drop of a hat, something we do a huge amount of development work to achieve. It's also possible to add a small electric motor and battery, and then simplify the engine design. Electrification means we no longer have to design our engines to cover the entire span of requirements, but rather it gives us much more freedom to make our combustion engines more robust, more efficient and more economical.

What kind of drive systems are hybrids suited to?

Hybrids really come into their own where you have a highly intermittent load profile, with frequent shifts between low and peak loads. The classic example is the hybrid rail drive, with trains entering and leaving stations under electric power, then using a combination of diesel engines and electric motors to accelerate, running economically on level track sections under diesel-only, and converting braking energy into battery power. The electric motor can also be brought on-stream when peak power is required. But, in my opinion, yachts are also perfect candidates for hybrid propulsion, albeit for reasons of comfort rather than economy, allowing skippers to turn off their diesels – say in scenic coves or anchorages – and maneuver quietly under electrical power. The battery can also be used to cover the high electrical power draw which a modern yacht has.

And what about agricultural machinery?

There'll be a time lag, but all the technology I've mentioned will come into play here too. In agri applications, electrical power can be shared very simply among various consumers. I'm thinking here of large combine-harvesters, for example, which have a multitude of hydraulic systems that – bit by bit – are going to be electrified. But this market is much more cost-intensive than rail or marine, and for that reason this trend will take a while to get going.

Will Rolls-Royce be supplying a fully mtu hybrid system?

Our hybrid design efforts are currently focused on marine propulsion, rail traction and electrical power supply systems. You'll see the first trains with the production-ready mtu Hybrid PowerPacks and a yacht with the first production hybrid propulsion system starting in 2020. We will then apply the experience gained along the way to the agricultural sector as well. We are currently working on preliminary studies and can see potential applications, for example in combine harvesters, machinery and vehicles for port facilities and in the underground mining sector.

Hybrid vehicles have been a feature of the automotive industry for some time now. Why are hybrids still so few and far between in off-highway applications?

It's true, hybrid cars and buses have been around for a long time now. Indeed, we started delving into this as early as 2006, and we first put a hybrid train on the tracks in a pilot back in 2012. The first ships are already being powered by mtu hybrid systems from rolls-Royce. However, until now, economy and ecology have not been great bedfellows, but we're slowly getting to the point where hybrids are paying real dividends. Battery storage capacity is coming down in price all the time, and – as developers – we've learnt a lot in recent years and are now in a position where we're able to offer customers a truly winning proposition.

What's the number one challenge in getting hybrids into full production?

Interestingly, it's not the tech that's our greatest challenge – a diesel engine is far more complex to develop than a hybrid system – but most of our time recently has been spent getting to grips with how customers want to use our systems, with a view to packaging together all the features and functionality they need. We are now in a position to give them total solutions that are both reliable and smart. Now, it's all about putting ourselves on the radar with reference installations, and convincing customers of the benefits these solutions offer.

Hybrid systems will also find their way into agricultural engineering,” say Holger Bottlang (l.) and Peter Riegger, although the development work will take some time because the market involves much more cost that other segments. Pictures: zvg

Rolls-Royce has been designing mtu combustion engines for over 100 years now, but can you 'go electric' at the drop of a hat?

It's not as if the whole e-issue has hit us out of the blue. We've been doing grid connection calculations for gensets for a long time now – something that calls for considerable electrical engineering skills – and diesel-electric drives have been part of our proposition for a long time in the form of mtu PowerPacks, which are underfloor railcar engines complete with generators and power transmission technology. And we've been fitting hybrid systems to yachts as well.

There's still some way to go there?

Of course there is. The trick will be to modularize our existing hybrid systems, making them easier to integrate. We want to cater for a wide range of variants, load profiles and operating conditions while minimizing the effort involved. That is not to say we're going to have a single standard product. Far from it – our aim is to develop an entire modular family which allows us to meet even special customer requirements simply and economically. Ideally, our sales engineer is going to click his way through the configurator software – I can even see a customer doing this on an app – putting together a power delivery system which triggers the corresponding production order. That is the goal we're not going to lose sight of.

So where does digitalization come into this?

Electrification offers us a vast array of new possibilities. However, to master these possibilities we have to understand how customers are going to use our new systems. Not everything can be simulated. To make our systems even more efficient, we have to collect data and focus our expertise on analyzing it properly.  

Any illustrative examples of this?

Let's take battery life. We can design systems with big batteries to reduce wear and tear on the cells and make them last longer. But that's a pretty expensive option. It's more economical to use a smaller battery and make it work harder – but this lowers its lifetime. Sure, we can run simulations to see which option is preferable, but detailed operational experience is a huge help in areas like this. Analyzing past data, and using present-day knowledge to predict what's going to happen in the future – I think that's going to be the great benefit of digitalization.

Where does the diesel come into this system approach?

A system is only as good as its components, and given the power density of diesel, these engines are going to play a key part in our systems for a long time to come. We're going to continue refining our diesels, keeping them at the forefront of technology. One major part of the development work we are doing involves designing the engine proficiently into the overall system.

Is hybrid technology a stepping stone to all-electric off-highway mobility – or is it here to stay?

The term “stepping stone” is sometimes used misleadingly. It's true that a stepping stone connects two places – in this case the conventional with the electric. My prediction is that hybrids will only be a stepping stone for a few applications – a one-way bridge to all-electric power systems – for example in ferry operations. We're already seeing the first all-electric ferries in Norway. They have large battery banks and comparatively low power draws because of the short routes, and their timetables take account of the time required to charge the batteries, or swap them over. This is no longer an engineering challenge – it's more a commercial one. In practically all other applications, its feasibility is fairly borderline. Some day, we might see trains bridging unelectrified track sections using on-board electrical power only, but that will still be no general replacement for the internal combustion engine in railcars. That said, we're going to be keeping a weather eye on all the factors involved, to see if they develop along the lines we're predicting – and to see whether, perhaps, any totally different emerging technology comes along to change the ballgame.

We've been talking a lot about electrified propulsion and drive systems. What other tech do you see coming over the horizon?

There are some big developments we've got our sights on. One is alternative fuels, which are set to gradually replace diesel fossil fuel. Natural gas is just one of these, and we're also looking at synthetic fuels. They jury's still out on which one is going to win the day – be it methanol or so-called OME fuels, or maybe even something completely different. The production of such fuels – thinking of “Power-to-X” – is one issue we're looking into.

Of interest to agriculture are fuels from renewable energies, which could possibly be obtained by growing one's own. What opportunities can you see there?

We're doing studies on this. Since 2018, we have been leading the way in the government-sponsored “MethQuest” project where we are looking into producing gas, including hydrogen, from renewable energies, and using this in our engines.

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