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Truckmaker MAN is abandoning its hydrogen research to focus on developing its heavy duty diesels. It aims to increase injection pressures to 2,500bar by 2013 and will improve aerodynamics and the efficiency of auxiliary systems.

MAN has been working on hydrogen since the early 1990s and has built four generations of internal combustion engines and fuel cells, but has decided that its low energy content and the difficulty of refilling high-pressure tanks makes it less likely than a Fischer-Tropsch derived diesel fuel for 2050.

Engineering director Dr Karl Viktor Schaller said: “Don't underestimate conventional technology. In the 70s Maglev trains with speeds of 400km/h looked like the future; today diesel trains run at 320km/h and Maglev’s benefit comes with too much risk. Similarly, in 30 years, conventional technology will do so much that the advantage of alternative fuels will disappear.”

It is often assumed that diesel injection pressures will level off at a little more than 2,000bars, but MAN is working towards diesel systems capable of 3,000bars for around 2016. MAN doesn’t have systems capable of 3,000 bars yet, but is trying tests with Denso and Bosch by overloading current systems and is getting good results with particulate emissions. “Every 100 bars helps,” said Schaller.

The efficiency of the pump is a problem, however. More and more power must come from the engine to drive it. “We’ll have to go to multi-stage systems,” said Schaller. “We’re working with Bosch and Denso and they’re making progress.”

At the same time MAN will have to increase exhaust gas recirculation rates to more than 30 per cent, which will mean the space needed for heat exchangers will increase from 0.9m2 to 1.3m2.

Trucks’ conventional chassis rail system will have to change. In the past, trucks had frame rails with the cooling system in the middle. Newer designs have frame rails and a front end design with cast parts that stretch out to the side to make more room for the cooler. These will have to get wider.

Packaging this and the greater aftertreatment will not compromise cab size, but improvements to trucks’ aerodynamics might, said Schaller. The cab always looks like a cube with round edges. With 0.55Cd the potential for improvements is tremendous.”

MAN is also addressing the efficiency of auxiliary devices using compressed air. The compressor is not needed when driving on motorways. At the end of the year it will produce a vehicle with a shut-off compressor that can save 0.5 litres of fuel per 100km.

Schaller is sure that hydrogen engines will not be in use before 2050 and said MAN will not focus on them any more. “If batteries become twice as good then hydrogen is no longer needed. In the future, biomass-to-liquid fuels will become more important,” said Schaller.

MAN so far has only one hybrid vehicle with a good business case, he said. By 2010 all the firm’s citybuses will be fitted with ultracapacitor-hybrids. Their constant stopping means they can achieve fuel savings of up to 20 per cent.