Fuels for the future
The climate-neutral further development of combustion technology is within reach
Reducing greenhouse gases is one of the major challenges in the off-highway industry. With the aim of achieving net-zero emissions in the future, exhibitors at Systems & Components are working on alternative drive concepts and pursuing an open technology approach that will also make established systems fit for the future. Looking at the innovations that will be presented at the exhibition centre in Hanover from 9 to 15 November, it is clear that the diesel engine will continue to have its place - but will no longer be the "all-rounder" for everything.
As different as the tasks of agricultural and construction machinery are, almost all of these vehicles have one thing in common: the diesel engine. It still has a share of over 80 per cent of the off-highway market. Its robustness, low operating costs and quick and easy refuelling are the basis for its appeal. Experts assume that by 2035, more than three quarters of vehicles over 56 kilowatts will still have a diesel engine.
For Petra Kaiser from the DLG (German Agricultural Society), there is therefore no question that combustion engines for heavy commercial vehicles are far from obsolete. But the Brand Manager of Systems & Components also knows: "The discussions about low-emission drive alternatives are not leaving the suppliers of mobile machinery cold. Even heavy-duty engines are increasingly becoming the focus of engineers in order to offer the required exhaust gas quality in every power range and reduce fuel consumption."
Classic combustion engines still necessary
The exhibitors at the exhibition centre in Hanover have made it their mission to shape the future of drive systems in a way that is open to all technologies. The concepts on show at Systems & Components are not based on an either-or, but a both-and approach: the engine platforms are compatible with a variety of current and future low-carbon and carbon-free fuels, including natural gas, synthetic fuels (e-fuels) and hydrogen, in order to ensure a smooth transition to the new technologies.
At the same time, existing diesel concepts are being specifically optimised for greater efficiency. "This applies in particular to key components in the area of exhaust gas aftertreatment, which enable cleaner engines," confirms Deutz CEO Dr Sebastian C. Schulte. One option is to run the combustion engine in lean-burn mode. This means that the engine runs with excess air and has lower emissions than a conventional diesel engine with comparable performance. Liebherr has developed an air booster to ensure that this operating mode does not impair the engine dynamics. It recovers hydraulic energy and uses it to drive a mechanical compressor when required. If power is required at short notice, the system is activated - and the compressor feeds additional air into the engine so that it can respond quickly to the power demand.
Heavy-duty sector relies on climate-neutral alternatives
The technology is also of interest for drives using alternative fuels - because the hydraulic air booster can help hydrogen engines to develop their power more quickly in order to keep up with diesel engines. Ammonia engines, which have good dynamic behaviour, could also benefit. By reducing the engine speed, efficiency increases and fuel consumption decreases. One thing is certain, however: further development of the diesel engine alone is not enough. Demands for climate neutrality and increasingly stringent limits are forcing engine manufacturers to look for alternatives beyond the diesel engine, which only fulfils EU Stage V standards with complex exhaust gas aftertreatment.
Against this backdrop, many operators are looking to make their existing fleet of mobile machinery powered by fossil fuels more climate-friendly - for example by using regeneratively produced HVO (Hydrotreated Vegetable Oil) or ethanol. Obtained from waste and residual materials, HVO fuels produce up to 90 per cent lessCO2 than fossil diesel. Both solutions are among the most promising options for agricultural and construction machinery manufacturers for short-term integration into commercial vehicles. As a fuel with a high octane rating, ethanol is particularly suitable for petrol engines in the upper power segment. John Deere has already presented its 9.0 L concept engine at AGRITECHNICA 2023, which can be used with renewable and alcohol-based fuels. Another example is the LH60M excavator from Liebherr, which can be fuelled with HVO100.
Green hydrogen drives decarbonisation forward
Hydrogen combustion engines continue to be one of the megatrends at Systems & Components. Due to their principle-based properties such as efficiency, robustness and low raw emissions, they are "a promising approach to accelerate the decarbonisation of off-road drives," says Mikael Lindner, Head of MAN Engines. Hydrogen engines are also a suitable complement to fuel cells and power-to-liquid processes (for e-fuels), as they require the same storage systems and infrastructure. Another advantage is that they can be brought to market comparatively quickly and can be installed in a variety of small series applications with different load profiles. "For the series production of our TCG 7.8 H2 hydrogen engine, which has already begun, only the test bench had to be adapted; the engines run off the same production line," emphasises Dr Petra Mayer, COO of Deutz AG. The six-cylinder engine, which with 220 kilowatts of power is not onlyCO2-neutral but also very quiet, is based on an existing Deutz engine concept.
The MAN H4576, which is based on the established MAN D3876 diesel engine, is also exemplary of current progress. It shares around 80 per cent of its components, such as the crankcase, shaft, connecting rod and cooling and oil circuit, including pumps and filters, with the hydrogen engine. The almost identical dimensions facilitate integration into existing vehicle concepts. Significant modifications have been made to the components for hydrogen supply and combustion, engine control and exhaust gas regulation. Compared to the diesel engine, new pistons and liners are also required, as the piston diameter has been increased to 145 millimetres. With the resulting higher displacement of 16.8 litres, a performance of 368 kilowatts (500 hp) is achieved, which corresponds to that of a diesel engine with a displacement of 12.4 litres.
Fuel flexibility is a must for modern engines
"More than 90 per cent of existing development and production technologies can be used for the hydrogen engine. This allows us to retain large parts of our value chain - which also applies to the spare parts market," says Jan-Oliver Röhrl, Executive Vice President Commercial Vehicles and Off-Road at Bosch. New injectors, such as the AFI-LP (Alternative Fuel Injector - Low Pressure) from Bosch, offer not only the direct injection of hydrogen but also the option of using other fuels such as methanol for both intake manifold and direct injection. This gives engine manufacturers the greatest possible flexibility on the road to an emission-free future. One of the company's latest innovations is an injector for direct hydrogen injection that requires no additional lubrication.
And yet another trend will be reflected at Systems & Components in Hanover from 9 to 15 November: multi-fuel and dual-fuel engines. They run on different fuels and gases or use energy sources that can only be ignited with a pilot. They offer customers a low-carbon interim solution until suitable emission-free alternatives become available. The MAN H4576 is also designed as a dual-fuel engine and can be used in combination with conventional diesel or HVO. A mock-up from Liebherr shows that ammonia engines are now also being developed. It is also based on a dual-fuel engine. While green ammonia supplies the main energy, either diesel or climate-neutral hydrogen provides the ignition.