United Kingdom
September 21, 2007
Source:
Chemistry World,
magazine of the Royal Society of
Chemistry (RSC)
Growing and burning many biofuel crops may actually raise,
rather than lower, greenhouse gas emissions. That’s the
conclusion of a new study led by Nobel prize-winning chemist
Paul Crutzen, best known for his work on the ozone layer.
He and his colleagues have calculated that growing some of the
most commonly used biofuel crops releases around twice the
amount of the potent greenhouse gas nitrous oxide (N2O, also
known as ‘laughing gas’) than previously thought – wiping out
any benefits from not using fossil fuels and, worse, probably
contributing to global warming.
‘The significance of it is that the supposed benefits of
biofuels are even more disputable than had been thought
hitherto,’ Keith Smith, a co-author on the paper and atmospheric
scientist from the University of Edinburgh, told Chemistry World
magazine. ‘What we are saying is that [growing many biofuels] is
probably of no benefit and in fact is actually making the
climate issue worse.’
The work is currently subject to open review in the journal
Atmospheric Chemistry and Physics, and Crutzen himself has
declined to comment until that process is completed. But the
paper suggests that microbes convert much more of the nitrogen
in fertilizer to nitrous oxide than previously thought – 3 to 5
per cent, which is twice the widely accepted figure of 2 per
cent used by the International Panel on Climate Change (IPCC) to
calculate the impact of fertilizers on climate change.
For rapeseed biodiesel, which accounts for about 80 per cent of
the biofuel production in Europe, the relative warming due to
nitrous oxide emissions is estimated at 1 to 1.7 times larger
than the relative cooling effect due to saved fossil CO2
emissions. For corn bioethanol, dominant in the US, the figure
is 0.9 to 1.5. Only cane sugar bioethanol – with a relative
warming of 0.5 to 0.9 – looks like a better alternative to
conventional fuels.
In the wake of the findings comes a recent report prepared by
the OECD for a recent Round Table on Sustainable Development,
which questioned the benefits of first generation biofuels and
concluded that governments should scrap mandatory targets.
Richard Doornbosch, the report’s author, says both the report
and Crutzen’s work highlights the importance of establishing
correct full life-cycle assessments for biofuels. ‘Without them,
government policies can't distinguish between one biofuel and
another – risking making problems worse,’ he said.
Full text of this Chemistry World exclusive:
http://www.rsc.org/chemistryworld/News/2007/September/21090701.asp
Abstract and full research paper:
http://www.atmos-chem-phys-discuss.net/7/11191/2007/acpd-7-11191-2007.html
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