MOTORISTS could halve their greenhouse gas emissions by trading in their
petrol-fuelled cars for diesel-electric hybrids or cars powered by fuel cells,
according to a comprehensive study by the oil giant Shell.
鈥淎ccording to the calculations in our study, there is a considerable
greenhouse gas benefit by changing to hybrid or fuel cell vehicles in the near
future,鈥� Jurgen Louis told the Society of Automotive Engineers in Detroit last
week.
Louis, a Shell researcher based in Hamburg, and his colleagues in Britain
looked at all the greenhouse emissions involved in using different types of
fuel. This 鈥渨ell to wheel鈥� analysis included emissions produced during the
extraction, manufacture and distribution of the fuels, as well as from the cars
themselves.
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The study shows that some apparently clean technologies are not so pristine.
Using liquefied hydrogen would produce more greenhouse gas emissions than
conventional cars running on petrol. 鈥淟iquefying hydrogen is very energy
intensive. There are a lot of problems with that route,鈥� says team member Roger
Cracknell.
The car with the lowest emissions in the study was powered by a fuel cell
running on compressed natural gas. But a compressed hydrogen fuel cell would cut
emissions by nearly the same amount.
Hybrid cars, powered by a battery and an internal combustion engine, would be
good in the short term. But hydrogen would be better in the long term, Cracknell
points out, because it can easily be generated from renewable or sustainable
energy sources, which would have no effect on global warming.
The study was geared to look at the effects of an immediate switch, so all
the fuels were produced as they are today: electricity from a mix of fossil
fuels and nuclear power, and hydrogen from natural gas rather then electrolysis.
