Barley (Image: National Non-Food Crops Centre)
The researchers question whether biofuel can cut carbon emissions
The EU target of ensuring 10% of petrol and diesel comes from renewable
sources by 2020 is not an effective way to curb carbon emissions,
A team of UK-based scientists suggested that reforestation and habitat
protection was a better option.
Writing in Science, they said forests could absorb up to nine times more
CO2 than the production of biofuels could achieve on the same area of land.
The growth of biofuels was also leading to more deforestation, they added.
"The prime reason for the renewables obligation was to mitigate carbon
dioxide (CO2) emissions," said Renton Righelato, one of the study's
"In our view this is a mistaken policy because it is less effective than
reforesting," he told BBC News.
Dr Righelato, chairman of the World Land Trust, added that the policy
could actually lead to more deforestation as nations turned to countries
outside of the EU to meet the growing demand for biofuels.
The study compared the amount of carbon absorbed by a forested area with
the total of "avoid emissions" by using biofuels instead of fossil fuels.
The researchers examined arable land that could either be used for
growing crops to produce biofuels, or replanted with trees.
"We looked at the amount of biofuels produced per hectare," Dr Righelato
explained. "From that figure, we were able to calculate the amount of
fossil fuels that could be replaced by biofuels.
"That gave a figure for avoided emissions, but then we had to subtract
from that the carbon emissions generated during the production of the
He said this calculation provided them with the "net avoided carbon
"This is the key factor, that is the amount of CO2 that is saved from
being released into the atmosphere by using the biofuel."
The researchers then compared the net avoided carbon emissions with the
amount of CO2 that would have been absorbed if forests were
re-established on the land.
"In all cases, the amount of CO2 sequestered (by forests) over a 30-year
period is considerably greater than the amount of emissions avoided by
using biofuels," Dr Righelato revealed.
The researchers also examined the impact of clearing forests in order to
convert land to grow crops used to make biofuels.
Dr Righelato said forest clearances had a large and immediate impact on
the carbon cycle.
"Forest carbon stocks are in the region of 100-300 tonnes per hectare.
Three-quarters of that is lost over the first year during clearing and
burning," he said.
"It would take - in all the cases we examined - between 50 to 100 years
to recover this carbon through the production of biofuels."
However, he said that so-called second generation biofuels, which used
feedstocks such as straw, grasses and wood (lignocellulosic material)
rather than grains or palm oil, offered a much better opportunity.
Biofuels: the next batch
"It was the one route that seemed to offer some possibilities in terms
of CO2 mitigation.
"If you can extract lignocellulosic materials sustainably from forests
without destroying the soil and maintain a way that forests can rapidly
regrow, it is quite possible you can have your cake and eat it, as it were."
A number of nations, including Germany, the UK and US, are developing
second generation biofuels, but the capital costs needed to build
commercial "biorefineries" have been seen as a major barrier.
But two US researchers, writing in the Biofuels, Bioproducts and
Biorefining journal, say that rising grain prices could make the
technology commercially competitive sooner rather than later.
Mark Wright and Robert Brown, from Iowa State University, US, said that
a second generation biorefinery cost four to five times as much as a
bio-ethanol plant that used grains, such as corn.
However, the overall cost of producing second generation biofuels would
be similar to biofuels produced from food crops when corn prices exceed
$3 (£1.50) per bushel, they explained.
The adoption of second generation biofuels would be welcomed by
environmental groups and food agencies, who view first generation fuels
Experts at the World Water Week conference in Stockholm have voiced
concern that growing food crops to be used to make biofuels could
jeopardise water supplies.
"When governments and companies are discussing biofuel solutions, I
think water issues are not addressed enough," Johan Kuylenstierna,
director of the annual conference, told AFP.
Check for earlier Pacific Biofuel posts: http://pacbiofuel.blogspot.com/