Car makers exploring many options for fuel of the future

By Thomas Geiger Dec 7, 2011, 4:06 GMT

Berlin - With the earth's oil resources declining, car makers are exploring numerous options for a fuel of the future despite the current hype on electric vehicles and fuel-efficient combustion engines.

Ethanol is seen as one alternative but the production of maize or sugar cane for these so-called bio-fuels is taking precious agricultural land from food production and destroying rainforests. Researchers are thus concentrating on a second generation of bio-fuels.

Sweden has an experimental plant producing ethanol from garbage. The German company Choren, which produced a so-called biomass-to-liquid (BTL) fuel from wood chips, declared bankruptcy earlier this year. However Volkswagen's head of research Juergen Leohold believes BTL 'is one of the key technologies to reduce carbon dioxide emissions in the transportation sector.'

Natural gas is seen as another alternative to petrol and diesel. It burns cleaner and has significantly less CO2 emissions. Several car makers at the recent Frankfurt Motor Show offered natural gas versions of their vehicles.

Alternative fuels only make sense if they come from renewable sources. Audi has for instance acquired a wind farm which converts green energy into methane which is chemically identical to natural gas. It will be used for both households and in motor vehicles.

The installation will in future produce 1,000 tons of methane which Audi calls e-gas. The fuel is enough to power 1,500 vehicles for 15,000 kilometres annually such as the A3 TCNG which Audi plans to launch in 2013. That is the equivalent of saving 2,800 tons of carbon dioxide annually.

Hydrogen fuel in its pure form is however favoured by several car makers as the fuel of the future for fuel cell cars powered with electric motors. The technology has been successfully tested by Mercedes, Ford, Opel, Honda and Toyota.

Hydrogen, however, has one major drawback: it lacks the necessary infrastructure. 'It is difficult to transport, you can't fill up with it anywhere and you need expensive and heavy special fuel tanks in the car,' says researcher Wolfgang Arlt from the University of Nuremberg-Erlangen in Germany. Apart from that the tanks need to withstand temperatures of minus 200 degrees Celsius and enormous pressure.

Arlt believes the problem can be solved with a new fuel which could become the driving force of the hydrogen age called Carbazol. The fluid can be enriched with hydrogen that is again withdrawn in a further chemical reaction in the vehicle, generating energy in the fuel cell that drives the electric motor. Or thermal energy produced by combustion is transformed into motion energy. 'In both variations the only emission is water vapour,' Arlt says.

Energy suppliers could use the available infrastructure but as yet Carbazol is still at an early stage of development and could still be years away from being sold at the pump station.

Karin Retzlaff from the German oil industry association (MWV) argues that 'none of the current alternative fuels is competitive. The transportation sector will remain dependent on fossil fuels for some time,' she says.