Future’s power plant

Those who like to gaze into the future of the automobile tend to enthuse about alternative propulsion systems such as fuel cells and hydrogen.

And faced with the current debate on climate change and the prospect of fossil fuels running out, manufacturers are also keen to show their credentials when it comes to reducing dependence on petrol and diesel.
At the same time, it is impossible to say when these alternative power plants will be mature enough to go into series production. For the next few decades at least, cars will be powered by traditional technology albeit using components honed by years of development.
“The combustion engine is set to remain the power plant of the future”, said Michael Bargende who heads the Stuttgart-based FKFS research centre for motor vehicle and engine technology, summing up the view of many experts.
This means that engines driven by petrol or diesel will continue to dominate for another 25 years, mainly because the alternative systems still display teething troubles, are too expensive or because other sources of energy are simply not available in sufficient quantity.
“There is no way around this problem because cars have such a lengthy life cycle and new propulsion concepts have to be nurtured for a relatively long time before they are ready”, said Eric Heymann, an analyst with a leading bank.
Engineers in the research and development departments of the carmakers are moving ahead just one small step at a time.
Experts are agreed, for instance, that the petrol-driven engine has much greater scope for fuel-saving than the diesel motor.
A saving of some 15 per cent is achievable using petrol as fuel compared to eight per cent for the diesel, said Andrea Gaertner. She works as a technician with a motoring club. In the case of diesels the focus is on boosting the pressure in fuel-injection systems.
This can mean that the combustion chambers receive fuel directly from the injectors and handle the entire combustion process instead of the pre chambers used at present which can lead to heat and throttle losses.
Meanwhile, the petrol power unit offers scope for a whole range of modifications such as a reduction in cylinder capacity or the ability to close down one or more cylinders during light running, especially relevant in the case of larger engines.
The measures aimed at boosting economy are not restricted to the power plants alone. Gearboxes with a higher ratio span, energy from recuperative braking or the use of tyres with a much lower rolling resistance, can all help to reduce emissions.
Several leading industry pundits say manufacturers are pinning their hopes on weight reduction.
Customer demand for more comfort and extras such as air-conditioning and all manner of power-assisted functions has made cars much heavier than they used to be.
The current Volkswagen Golf, for example, weighs 1.5 metric tons, nearly twice as much as the equivalent vehicle 30 years ago. Around a half a litre of fuel is needed in order to propel 100kg of vehicle weight.
“That offers plenty of fuel-saving potential”, said Mr Bargende.
Even though the conventional combustion engine seems to have a fairly long future ahead of it, hybrids will become much more common on the roads. The combination of an auxiliary electric motor with a conventional combustion engine makes good sense in an urban environment.
Many experts believe, however, that the significance of the hybrid as a solution to vanishing resources has been overestimated:
“Everyone is talking about hybrids, but this is not entirely justified in view of the relatively high cost involved, drawbacks when it comes to motorway driving and above all, because demand is currently so low,” said Mr Heymann.
In the end, the availability of energy will determine which alternative propulsion technologies find most favour.
“The issue is not the engines themselves but rather whether there will sufficient sustainable or regenerated energy sources out there to drive them”, said Ulrich Hoepfner, who heads an institute for energy and environmental research.
Not only is there a shortage of vehicles capable of running on hydrogen, there is not enough hydrogen in usable form to go around either. “In order to produce hydrogen in a green manner you need an excess of electrical power from sources which do not impact on the environment. We don’t yet have that”, said Mr Hoepfner.
The outlook for fuel cells is equally uncertain. “The fuel cell will only achieve the maturity needed for series production when the technical problems have been solved such as refuelling and maintaining performance over long periods”, said Wolfgang Meinig of the Automotive Industry Research Unit at Bamberg University. Quite apart from that fuel cell-powered vehicles still “cost a small fortune to buy”, he added.

By Marion Trimborn