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New papers from Science on biofuels and
Use of
Timothy Searchinger,1* Ralph
Heimlich,2 R. A. Houghton,3 Fengxia
Dong,4 Amani Elobeid,4 Jacinto
Fabiosa,4 Simla Tokgoz,4 Dermot
Hayes,4 Tun-Hsiang Yu4 1Woodrow
Wilson School, Princeton University, German Marshall Fund of the U.S.,
Georgetown Environmental Law and Policy Institute. 2Agricultural
Conservation Economics, 3Woods
Most prior studies have found that substituting biofuels for
gasoline will reduce greenhouse gasses because biofuels sequester carbon
through the growth of the feedstock. These analyses have failed to count the
carbon emissions that occur as farmers worldwide respond to higher prices and
convert forest and grassland to new cropland to replace the grain (or cropland)
diverted to biofuels. Using a worldwide agricultural model to estimate
emissions from land use change, we found that corn-based ethanol, instead of
producing a 20% savings, nearly doubles greenhouse emissions over 30 years and
increases greenhouse gasses for 167 years. Biofuels from switchgrass, if grown
on U.S. corn lands, increase emissions by 50%. This result raises concerns
about large biofuel mandates and highlights the value of using waste products.
10.1126/science.1151861
Supporting Online Material : http://www.sciencemag.org/cgi/data/1151861/DC1/1
Land Clearing and
the Biofuel Carbon Debt
Joseph Fargione,1 Jason Hill,2,3 David Tilman,2* Stephen Polasky,2,3 Peter Hawthorne2
1The Nature
Conservancy,
Evolution, and Behavior,
of
Increasing energy
use, climate change, and carbon dioxide
(CO2) emissions from
fossil fuels make switching to lowcarbon
fuels a high
priority. Biofuels are a potential lowcarbon
energy source,
but whether biofuels offer carbon
savings depends
on how they are produced. Converting
rainforests,
peatlands, savannas, or grasslands to produce
food-based
biofuels in
17 to 420 times
more CO2 than the annual greenhouse gas
(GHG) reductions
these biofuels provide by displacing
fossil fuels. In
contrast, biofuels made from waste biomass
or from biomass
grown on abandoned agricultural lands
planted with
perennials incur little or no carbon debt and
offer immediate
and sustained GHG advantages.
10.1126/science.1152747
Supporting Online
Material : http://www.sciencemag.org/cgi/data/1152747/DC1/1
http://www.independent.co.uk/environment/climate-change/biofuels-make-climate-change-worse-scientific-study-concludes-779811.html
Biofuels
make climate change worse, scientific study concludes
JAY DIRECTO/AFP/Getty Images
Workers load harvested sugarcane onto a truck in the central Philippine
By
Steve Connor, Science Editor
Friday, 8 February 2008
Growing crops to make biofuels results in vast amounts
of carbon dioxide being released into the atmosphere and does nothing to stop
climate change or global warming, according to the first thorough scientific
audit of a biofuel's carbon budget.
Scientists
have produced damning evidence to suggest that biofuels could be one of the
biggest environmental con-tricks because they actually make global warming
worse by adding to the man-made emissions of carbon dioxide that they are
supposed to curb. Two separate studies published in the journal Science show
that a range of biofuel crops now being grown to produce "green"
alternatives to oil-based fossil fuels release far more carbon dioxide into the
air than can be absorbed by the growing plants.
The
scientists found that, in the case of some crops, it would take several
centuries of growing them to pay off the "carbon debt" caused by
their initial cultivation. Those environmental costs do not take into account
any extra destruction to the environment, for instance the loss of biodiversity
caused by clearing tracts of pristine rainforest.
"All
the biofuels we use now cause habitat destruction, either directly or
indirectly. Global agriculture is already producing food for six billion
people. Producing food-based biofuel, too, will require that still more land be
converted to agriculture," said Joe Fargioine of the US Nature Conservancy
who was the lead scientist in one of the studies.
The
scientists carried out the sort of analysis that has been missing in the rush
to grow biofuels, encouraged by policies in the
Both
studies looked at how much carbon dioxide is released when a piece of land is
converted into a biofuel crop. They found that when peat lands in
The next
worse case was when forested land in the Amazon is cut down to convert into
soybean fields. The scientists found that it would take 319 years of making
biodiesel from the soybeans to pay of the carbon debt caused by chopping down
the trees in the first place.
Such
conversions of land to grow corn (maize) and sugarcane for biodiesel, or palm
oil and soybean for bioethanol, release between 17 and 420 times more carbon
than the annual savings from replacing fossil fuels, the scientists calculated.
"This
research examines the conversion of land for biofuels and asks the question 'is
it worth it?' Does the carbon you lose by converting forests, grasslands and
peat lands outweigh the carbon you 'save' by using biofuels instead of fossil
fuels?" Dr Fargione said.
"And
surprisingly the answer is 'no'. These natural areas store a lot of carbon, so
converting them to croplands results in tons of carbon emitted into the
atmosphere," he said.
The
demand for biofuels is destroying the environment in other ways. American
farmers for instance used to rotate between soybean and corn crops but the
demand for biofuel has meant that they are growing corn only. As a result,
Brazilian farmers are cutting down forests to grow soybean to meet the
shortfall in production.
"In
finding solutions to climate change, we must ensure that the cure is not worse
than the disease," said Jimmie Powell, a member of the scientific team at
the Nature Conservancy.
"We
cannot afford to ignore the consequences of converting land for biofuels. Doing
so means we might unintentionally promote fuel alternatives that are worse than
the fossil fuels they are designed to replace. These findings should be
incorporated into carbon emission policy going forward," Dr Powell said
yesterday.
The
European Union is already having second thoughts about its policy aimed at
stimulating the production of biofuel. Stavros Dimas, the EU environment
commissioner, admitted last month that the EU did not foresee the scale of the
environmental problems raised by
Professor
John Pickett, chair of the recent study on biofuels commissioned by the Royal
Society, said that although biofuels may play an important role in cutting
greenhouse gases from transport, it is important to remember that one biofuel
is not the same as another.
"The
greenhouse gas savings that a biofuel can provide are dependent on how crops
are grown and converted and how the fuel is used," Professor Pickett said.
"Given that biofuels are already entering global markets, it will be vital
to apply carbon certification and sustainability criteria to the assessment of
biofuels to promote those that are good for people and the environment. This
must happen at an international level so that we do not just transfer any
potentially negative effects of these fuels from one place to another."
Professor
Stephen Polasky of the
"We don't have the proper incentives in place
because landowners are rewarded for producing palm oil and other products but
not rewarded for carbon management. This creates incentives for excessive land
clearing and can result in large increases in carbon emissions," Professor
Polasky said.
http://www.guardian.co.uk/science/2008/feb/08/scienceofclimatechange.biofuels
Biofuel
farms make CO2 emissions worse
· Land conversion
increases greenhouse gases - study
· Carbon
debt may take centuries to pay off
This article appeared in the Guardian on Friday February 08
2008 on p14 of the UK
news section. It was last updated at 00:14 on February 08 2008.
Transforming
ecosystems into farms for biofuel crops will increase global warming and result
in net increases in carbon emissions, according to a study.
Scientists
have found that converting rainforests, peatlands and grasslands can outweigh
the carbon savings made from biofuels and produce "carbon debts"
which could take centuries to pay off.
The study
will add to concerns about the ability of biofuels to replace fossil fuels. The
EU is reviewing its pledge that biofuels such as bioethanol and biodiesel
should make up 10% of transport fuel by 2020.
In the
study, US researchers calculated that converting natural ecosystems to grow
corn or sugarcane to produce ethanol, or palms or soybeans for biodiesel, could
release between 17 and 420 times more carbon than the annual savings from
replacing fossil fuels.
This is
due to the carbon contained in the original plants and soils which is released
as CO2 when the vegetation rots after it is cleared. The researchers said this
carbon debt must be paid before biofuels produced on the land could count
towards reducing greenhouse gas emissions.
"This
research examines the conversion of land for biofuels and asks the question 'Is
it worth it?'" said Joe Fargione, a scientist for the environmental group
The Nature Conservancy. "Does the carbon you lose by converting forests,
grasslands and peatlands outweigh the carbon you 'save' by using biofuels
instead of fossil fuels? And surprisingly, the answer is no."
In
Stephen
Polasky of the
Fargione
said all biofuels now in use destroyed habitats. "Producing food-based
biofuel will require that still more land be converted to agriculture," he
said. The team also identified biofuels which did not contribute to global
warming, including agricultural waste and grasses grown on land not suitable
for crops.
"Biofuels made on perennial crops grown on
degraded land that is no longer useful for growing food crops may actually help
us fight global warming," said Jason Hill of the
Other
Press coverage:
|
Destroying Native Ecosystems For Biofuel Crops
Worsens Global Warming |
|
Are Biofuels Bad for the Environment? |
|
Full Text |
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