“We will need all technologies”

Werner Kübler is the Head of Development at MAN Engines. In the future, he sees room for a wide range of different drive types – tailored to the respective application.

Climate protection is a hot topic and in the public debate battery-electric drives are often seen as the only sustainable solution. Why won't you only offer these drives in the future?

Because battery-electric solutions are currently not suitable for all applications. Let me give you an example: a combine harvester is only used four weeks a year, but for these four weeks it operates around the clock. It also requires a very high output of around 1,000 kilowatts. This is no problem with diesel because the tank can easily hold the daily fuel volume and be refilled quickly if necessary, for example using a mobile tanker in the field. If you wanted to power the combine harvester electrically, the batteries for ten hours of electric operation would currently weigh 15 tonnes. Recharging is not possible because it would take far too much time. So you would need to have a spare battery or two on hand, which would be far too expensive and impractical. Operation with hydrogen is also not possible in this example because the combine harvester would need to hold 5,000 litres in pressure tanks. There simply is not enough space for that.

Tractor operated with climate-neutral HVO, B100 or eFuels

Diesel alternative: with HVO, B100 or eFuels, farm vehicles can be operated in a climate-neutral manner.

A colourful mix

In the future, many sustainable drive technologies will be used in parallel.

So will diesel drives stick around?

Yes, for the time being. However, after all, the CO₂ does not come from the engine, but from the fuel. If we use alternative fuels such as B100, HVO or eFuels instead of fossil diesel, we will be able to operate the large fleet of farm vehicles with zero local emissions in the future, and that’s ultimately what matters. Although these new fuels are currently more expensive than diesel, there are already plans for large production plants. As a result, prices should drop significantly in the future.

Commercial vehicles from MAN Truck & Bus with battery-electric drives

A pioneer: MAN Truck & Bus relies on battery-electric drives for its commercial vehicles.

The low efficiency level of the production process is often used as an argument against synthetic fuels. What are your thoughts on this?

The efficiency level of battery-electric drives is certainly higher. That is why we mainly use battery-electric solutions for the trucks and buses at MAN Truck & Bus. However, there are also applications for which these solutions are not practical or even feasible. These may be vehicles and machines used by authorities and organisations with security tasks or bulky, heavy transport. This is the area where I see opportunities for such fuels, particularly in the high-performance range.

So battery-electric drives do not stand a chance in high-performance applications?

Further improvements are being made all the time, of course. However, I do not foresee any leaps in the next five to ten years of the magnitude we would need for a combine harvester or other types of farm and construction machinery with high power requirements. Furthermore, we at MAN Engines must consider the fact that other regions of the world are not becoming electrified as quickly as we are. There will be a demand for combustion engines in those areas for a long time to come, but ideally in combination with climate-friendly fuels, so that they too can operate drives with reduced CO₂ emissions.

Biogases and sewage gases are also climate-friendly. What do you offer your customers in this respect?

We have already constructed lots of biogas and sewage gas engines that are in operation around the world. Incidentally, synthetic methane would be another more climate-friendly fuel that could be easily burned in our gas engines – even with added hydrogen – and thus extend their operating time. We should never forget that the natural gas network is the largest store of energy in Germany and can supply energy for four months without replenishment.

Where are hybrid drives particularly useful?

In the marine sector, for example. You can move in and out of the harbour electrically without making much noise. In addition, the battery supplies electricity quietly at night in “hotel mode”, meaning that the on-board unit can remain switched off. The combination of diesel and electric engine also has advantages when moving. The two diesel engines on board are usually operated at part load, which impairs efficiency. With a hybrid drive, you can switch off one engine and run the other at full load. It then provides power for the second propeller.

Boat with hybrid drive anchors with no emissions or vibrations

Maximum efficiency: zero-emission and vibration-free anchoring with the hybrid drive.

Alternative drive: hydrogen injection on the dual-fuel engine of the “Hydrocat 48” workboat.

Where does MAN Engines stand when it comes to hydrogen drives for off-road or marine applications?

With regard to engine construction, hydrogen is not a problem for us, and we are currently working hard on new products. Stationary hydrogen engines can be used, for example, to convert regeneratively produced hydrogen back into electricity. Thanks to combined heat and power (CHP), usable heat is also generated during this process, so the overall efficiency of these plants is very high – with significantly reduced CO₂ emissions. In addition, we can also equip snow groomers with a hydrogen engine because they have enough space for the pressure tanks. Dual-fuel solutions are also interesting. For example, a mobile crane could be operated with 20 to 80 percent hydrogen, depending on the current performance requirements. If only the crane or the rope needs to be moved, up to 80 percent hydrogen is possible. When driving on a steep uphill road, on the other hand, the diesel proportion will need to be increased considerably. In addition, we need the diesel in the hydrogen dual-fuel engine to ignite the mixture. However, this could also be possible with HVO in the future.

We have now explored many possible drive technologies. What is your conclusion?

It's quite simple really: we must not write off any possible solution if we want to reduce CO₂ emissions, because we will need all technologies – from synthetic fuels to battery-electric drives. Synthetic fuels will become indispensable purely because there are around 1.5 billion vehicles and roughly 700 million fossil-fuelled machines in existence around the world. We must also consider the growing global population and the rising standard of living, which will continue driving the demand for energy. If we want to achieve our climate goals under these circumstances, we will need a colourful mix of different drives in the future.