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Biofuels more harmful to humans than petrol and diesel, warn
scientists 2 Feb 09
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|Corn-based bioethanol has higher burden
on environment and human health, says US study.
Some biofuels cause more health problems than petrol and diesel,
according to scientists who have calculated the health costs
associated with different types of fuel.
The study shows that corn-based bioethanol, which is produced
extensively in the US, has a higher combined environmental and
health burden than conventional fuels. However, there are high hopes
for the next generation of biofuels, which can be made from organic
waste or plants grown on marginal land that is not used to grow
foods. They have less than half the combined health and
environmental costs of standard gasoline and a third of current
The work adds to an increasing body of research raising concerns
about the impact of modern corn-based biofuels.
Several studies last year showed that growing corn to make ethanol
biofuels was pushing up the price of food. Environmentalists have
highlighted other problems such deforestation to clear land for
growing crops to make the fuels. The UK government's renewable fuels
advisors recommended slowing down the adoption of biofuels until
better controls were in place to prevent inadvertent climate
Using computer models developed by the US Environmental Protection
Agency, the researchers found the total environmental and health
costs of gasoline are about 71 cents (50p) per gallon, while an
equivalent amount of corn-ethanol fuel has associated costs of 72
cents to $1.45, depending on how it is produced.
The next generation of so-called cellulosic bioethanol fuels costs
19 cents to 32 cents, depending on the technology and type of raw
materials used. These are experimental fuels made from woody crops
that typically do not compete with conventional agriculture. The
results are published online today in the Proceedings of the
National Academy of Sciences.
"The dialogue so far on biofuels has been pretty much focused on
greenhouse gases alone," said David Tilman, a professor at the
department of ecology, evolution and behaviour at the University of
Minnesota. "And yet we felt there were many other impacts that were
positive or negative not being included. We wanted to expand the
analysis from greenhouse gases to at least one other item and we
chose health impacts."
The health problems caused by conventional fuels are well studied
and stem from soot particles and other pollution produced when they
are burned. With biofuels, the problems are caused by particles
given off during their growth and manufacture.
"Corn requires nitrogen fertilisers and some of that comes on as
ammonia, which is volatilised into the air," said Tilman. "The
ammonia particles are charged and they attract fine dust particles.
They stick together and form particles of the size of 2.5 micron and
that has significant health impacts. Some of this gets blown by
prevailing winds into areas of higher population density – that's
where you have the large number of people having the health impact
which raises the cost."
Health problems from biofuels and gasoline include increased cases
of heart disease, respiratory symptoms, asthma, chronic bronchitis
or premature death. The team has calculated the economic costs
associated with these. "For the economy, it's the loss of good,
productive workers who might otherwise have been able to
contribute," said team member Jason Hill, an economist at the
University of Minnesota's Institute on the Environment.
"These costs are not paid for by those who produce, sell and buy
gasoline or ethanol. The public pays these costs," said Dr Stephen
Polasky, an economist at the University of Minnesota, also part of
A report published last year by Ed Gallagher, the head of the
government's Renewable Fuels Agency, suggested that the introduction
of biofuels to the UK should be slowed until more effective controls
were in place to prevent the inadvertent rise in greenhouse gas
emissions caused by, for example, the clearance of forests to make
way for their production.
His report said that if the displacements were left unchecked,
current targets for biofuel production could cause a global rise in
greenhouse gas emissions and an increase in poverty in the poorest
countries by 2020.
Gallagher also suggested the government should introduce incentives
to promote the production of next-generation biofuels of the type
studied by the Minnesota researchers. So-called cellulosic ethanol
can be made from plants such as switchgrass or jatropha that can
grow with very little fertiliser on poor land, but the technology to
convert these plants into fuels is in its early stages.
Tilman said society needed to make the transition away from
corn-based ethanol as soon as possible.
"We've gone one step further than the work that only looked at
greenhouse gases and found some surprisingly large effects. Before
we dedicate major resources to new biofuels, we should be trying to
quantify other likely impacts to society – water quality,
biodiversity and so on – and put all of those into our analysis." He
hopes this will encourage society to make "a long-term commitment to
the right biofuel".
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