ISIS Report 28/02/06
Biofuels for Oil Addicts
Cure Worse than The Addiction
Bioethanol and biodiesel from energy crops compete for land that grows food
and return less energy than the fossil fuel energy squandered in producing them;
they are also damaging to the environment and disastrous for the economy. Dr.
Mae-Wan Ho
A longer, fully referenced version of this article is posted on ISIS
members’ website. Details here.
“We must break our addiction
to oil”, President George W. Bush said in his State of the Union address;
but he wasn’t advising people to give up their cars or to use less oil, say
by improving the gas mileage of cars. Instead, he launched the “Advanced Energy
Initiative” that would increase federal budget by 22 percent for research
into clean fuel technologies; including biofuels derived from plants as substitutes
for oil (see Box) to power the country’s cars.
Successive US
presidents have promoted ethanol from corn as a subsidised fuel additive.
President Bush said US scientists are now working out how to make ethanol
from wood chips, stalks, or switch grass “practical and competitive within
six years”, which would replace more than 70 percent of oil imports from “unstable
parts of the world” - the Middle East - by 2025. Currently 60 percent of the
oil consumed in the US is imported, up from 53 percent since George W. Bush
came to power.
What are biofuels?
Biofuels are fuels derived
from crop plants, and include biomass that’s directly burned, biodiesel
from plant seed-oil, and ethanol (or methanol) from fermenting grain, grass,
straw or wood. Biofuels have gained favour with environmental groups as
renewable energy sources that are “carbon neutral”, in that they do not
add any greenhouse gas into the atmosphere; burning them simply returns
to the atmosphere the carbon dioxide that the plants take out when they
were growing in the field.
However, they take up valuable land that should be used for growing food, especially
in poor Third World countries. Realistic estimates show that making biofuels
from energy crops require more fossil fuel energy than they yield, and do not
substantially reduce greenhouse gas emissions when all the inputs are accounted
for. Furthermore, they cause irreparable damages to the soil and the environment
(see main text).
Biofuels can also be produced from wood chips, crop residues and other agricultural
and industrial wastes, which do not compete for land with food crops, but the
environmental impacts are still substantial.
Biofuels cannot substitute for current fossil fuel use
Biofuels from energy crops
cannot substitute for current fossil fuel use. The major constraints are land
surface available for growing the crops, crop yield, and energy conversion
efficiency, although economics also plays a large role.
Growing crops for
burning – biomass - should be the cheapest kind of biofuel both in energy
and financial terms, as it requires minimum processing after harvest.
Crop
scientists at Virginia Tech, David Parrish and John Fike, reviewed the biology
and agronomy of switchgrass, the most researched and favoured biofuel crop.
Switchgrass is a perennial native to the USA, and has been extensively
grown for fodder soon after the Europeans arrived. It is prolific, does not
require much nitrogen fertilizer, and is considered the most sustainable,
or the least environmentally damaging biofuel crop. But the review concluded
that, “even at maximum output, such systems could not provide the energy currently
being derived from fossil fuels.”
Substituting
switchgrass for coal is estimated to reduce greenhouse gas emissions by about
1.7 t CO2 per t switchgrass. The prices that growers
must receive for biomass, however, must be sufficiently favourable. Thus,
about 8 m ha would be available if the price reached $ 33 per t at the farm
gate, increasing to about 17 m ha at $44 per t. The market price paid for
woodchip biomass in Virginia in 2004 averaged about $33 per t delivered, and the price for hay (all kinds)
is about $95 per t.
One estimate placed the
delivery costs of switchgrass at $63 per t. Adding the costs of processing,
such as pressing into pellets or cubes for handling within a power plant,
would bring the user’s costs to about $83 per t. One t of switchgrass produces
17-18 GJ of energy when burned, compared with 27-30 GJ for coal; and coal
prices are $55 per t.
Switchgrass
for energy is not at all economically competitive, unless substantial subsidy
is available. The same applies, perforce,
to other energy crops.
David Pimentel, a professor
of crops science at Cornell University New York and Tad Patzek, a professor
of chemical engineering at University of California Berkeley, reviewed the
energy balance and economics of producing biomass, ethanol or biodiesel from
corn, switchgrass, wood, soybeans and sunflower using the now generally accepted
life-cycle analysis. Although there is much controversy over the energy balance
of ethanol and biodiesel, the energy balance of biomass yield is generally
less subject to dispute, and is therefore a useful starting point.
It turns
out that switchgrass has the most favourable output/input energy ratio of
14.52, followed by wheat at 12.88, and oilseed rape at 9.21, if the straw
is included. Switchgrass is hence the most promising energy crop, whether
as biomass for burning or to make other fuels downstream, such as ethanol.
A quick
calculation showed that even if all the farmland in the United
States were converted to growing switchgrass, it would not produce enough
ethanol for the country’s fossil fuel use. Switchgrass takes several years
to mature. The yield ranges from 0 for complete failure of the crop to take
hold to 20 t or more per ha, a lot depending on the rainfall. A yield of 15
t /ha is optimistic; and would provide some 250 GJ/ha of raw chemical energy
a year. If that energy could be converted with 70 percent efficiency into
electricity, ethanol, methanol etc., it would take about 460 m ha to produce
the 80EJ (ExaJoule = 1018J)
fossil fuel energy used in the USA each year. The total farmland in the USA
is 380 m ha, of which 175 m ha is harvested cropland.
Clearly, energy crops are a bad option, and may become
obsolete as ethanol can now be made from wood chips, crop residues and other
agricultural wastes, and industrial wastes, though even that is not sustainable
(“Ethanol from wood biomass not sustainable”, this series).
Do you get more energy out of biofuel than the fossil fuel energy you put
in?
There is a huge debate
over the energy balance of making ethanol or biodiesel out of energy crops,
with David Pimentel and Tad Patzek presenting negative energy balance for
all crops based on current processing
methods, i.e., it takes more fossil energy input to produce the equivalent
energy in biofuel. Thus for each unit of energy spent in fossil fuel, the
return is 0.778 unit of energy in maize ethanol, 0.688 unit in switchgrass
ethanol, 0.636 unit in wood ethanol, and worst of all, 0.534 unit in soybean
biodiesel.
Their
paper has provoked a strong riposte from several US government departments,
accusing Pimentel and Patzek of using obsolete figures, of not counting the
energy content of by-products such as the seedcake (residue left after oil
is extracted) that can be used as animal feed, and of including energy used
for building processing plants, farm machinery, and labour, not usually included
in such assessments.
For their
part, Pimentel and Patzek, along with many other scientists like me, are critical
of estimates that produce positive energy balance precisely because they leave
out necessary energy investments. In fact, neither Pimentel and Patzek nor
their critics have included the costs of waste treatment and disposal or the
environmental impacts of intensive bioenergy crop cultivation such as depletion
of soil and environmental pollution from fertilizers and pesticides.
To apportion
processing-energy to coproducts according to their bulk composition in the
seed may appear unexceptionable. Only 18 percent of the soybean is oil that
makes biodiesel, while the rest is soybean cake used as animal feed. However,
as the seedcake is produced as soon as the oil is extracted, it is simply
creative accounting to attribute 82 percent of the downstream processing energy
for biodiesel - which is quite substantial - to the animal feed.
Energy balance of ethanol from corn
Sure enough, a new study
comparing six estimates of energy balance of corn ethanol did find that “net
energy calculations are most sensitive to assumptions about coproduct allocation”.
The new
study, carried out by researchers at the University of California
Berkeley, published in the journal Science,
evaluated six analyses of corn-ethanol production, including those of Pimentel
and Patzek. The researchers developed a ‘model’ to allow them to compare the
data and assumptions across the analyses. Pimentel and Patzek’s negative energy
balance stood out in including energy used for building processing plants,
farm machinery, and labour, and for not giving credit for co-products. Removing
those “incommensurate” factors nevertheless resulted in only a modest positive
energy balance of just over 3 MJ/litre to 8 MJ/litre ethanol in the analyses
that gave positive energy balance, which translates to 1.13 to 1.34 for energy
output/energy input (there being 23.4MJ in one litre of ethanol), while the
reduction in greenhouse gas emissions averaged about 13 percent.
The researchers
have devised a way of presenting energy balance in terms of “petroleum input”
- expressed as MJ petrol/MJ ethanol – that puts a very positive gloss on the
figures and is very misleading. It essentially adds one hundred percent energy
credit to the ethanol because it assumes that the ethanol substitutes 100
percent for fossil fuel use.
The researchers
then used the “best data” from the six analyses to “create” three cases with
their model (hence all hypothetical): Ethanol Today, that claims to include typical values for the
current US corn ethanol industry; CO2 Intensive, based on plans to ship Nebraska corn
to a lignite-powered ethanol plant in North Dakota, and Cellulosic, which assumes that production
of ethanol from switchgrass cellulose becomes economic, an admitted “preliminary
estimate of a rapidly evolving technology”.
he three cases, the researchers found a positive energy balance: a whopping
23 MJ/litre ethanol for Cellulosic, 5 MJ/litre for Ethanol Today,
and 1.2 MJ/litre for CO2 Intensive; the corresponding
output/input energy ratios are 1.98, 1.21, and 1.05 respectively. Cellulosic
is the clear winner in terms of energy balance, and also by a long shot in net
greenhouse gas emission saved, which is 89 percent; the corresponding values for
Ethanol Today and CO2 Intensive are 17
percent and about 2 percent respectively.
These analyses show that current production methods, represented by Ethanol
Today and CO2 Intensive, offer but a small positive
energy balance and little if any savings in greenhouse gas emissions, even
with the most favourable assumptions built in.
Bad economics of ethanol from corn
Ethanol constitute 99 percent of all biofuels in the
United States; 3.4 billion gallons of ethanol were produced in 2004 and blended
into gasoline, amounting to about 2 percent of all gasoline sold by volume
and 1.3 percent of its energy content.
Ethanol use is set to expand as the federal government has introduced a 0.51
tax credit per gallon of ethanol and issued a new mandate for 7.5 billion gallons
of “renewable fuel” to be used in gasoline by 2012, which is included in the
recently passed Energy Policy Act (EPACT 2005).
Pimentel and Patzek have shown not only that the energy return is substantially
negative, the economics is worse. About 50 percent of the cost of producing
ethanol is for the corn feedstock itself ($0.28/litre). Ethanol costs a lot
more to produce than it is worth on the market, and without federal and state
subsidies amounting to some $3 billion per year, corn ethanol production in
the US would cease. Senator McCain reports that total ethanol subsidies amount
to $0.79/ litre; adding the production costs would bring the cost to $1.24/litre.
Ethanol has only 66 percent as much energy per litre as gasoline; so corn ethanol
costs $1.88 per litre- or $7.12 per gallon- equivalent of gasoline, compared
to the current cost of producing gasoline, which is $.33/litre.
Federal and state
subsidies for ethanol production that total $0.79/litre mainly end up in the
pocket of large corporations, with a maximum of $0.02 per bushel, or 0.2 cent/litre
ethanol going to the farmer.
The total costs to
the consumer in subsidizing ethanol and corn production is estimated at $8.4
billion/yr, because producing the required corn feedstock increases corn prices.
One estimate is that ethanol production adds more than $1 billion to the cost
of beef production.
Clearly ethanol from
corn is neither sustainable nor economical, and a lot of effort has been devoted
to finding alternative feedstock.
Worse energy yields as accounting gets more realistic
In a detailed rebuttal to
the Science paper showing a
positive energy balance in ethanol production from corn, Patzek exposed the
major flaws in energy accounting used, which greatly inflated the energy return.
These include:
- Failure to account for the energy in corn grains as energy input
- Assuming an impossibly
high yield of corn ethanol at variance with real data available
- Assigning away undue
energy costs in ethanol production, in particular, distillation, to coproducts
such as fermentation residues that have nothing to do with ethanol production.
In addition, the ethanol industry routinely inflates the ethanol yield by counting
as ethanol the 5 percent of gasoline added to corn ethanol as denaturant; by
taking the amount of fermentable starch to be the total extractable starch,
although not all of the latter is fermentable; and by taking the weight of wet
corn (average 18 percent moisture) as dry corn.
When the energy accounting
done by different authors is reanalysed on the same set of realistic data,
energy yields come out remarkably uniform. The output/input ratio varies between
0.245 and 0.310. In other words, the energy balance is strongly negative: for every unit used
in making corn ethanol, one gets at most 0.3 unit of energy back. It takes at least
9 times more fossil fuel energy to produce ethanol from corn at the refinery
gate than gasoline or diesel fuel from crude oil.
As Patzek points out, the 7.5 billion gallons of ethanol mandated by the 2005
Energy Bill by 2012 could be compensated by an increase of car mileage by just
one mile per gallon, excluding gas-guzzling SUVs and light trucks.
The economic consequences of excessive corn production have been devastating.
The price of corn in Iowa, the largest corn producer, declined 10-fold between
1949 and 2005 as corn yields have tripled. Today, Iowa farmers earn a third
for the corn they sell compared to 1949, while their production costs increased
manifold, because they burn methane and diesel to produce corn. The price of
methane has increased several-fold in the last three years. “Corn crop subsidies
supplemented the market corn price by up to 50 percent between 1995 and 2004.”
Patzek writes, predicting more concentration of industrial corn production in
gigantic farms operated by large agribusiness corporations, and real farmers
will only rent the land.
An industrial raw material at rock-bottom price can now be processed into ethanol
at a significant profit, further enhanced by a federal subsidy of 50 cents per
gallon ethanol, plus state and local community subsidies.
Patzek concludes: “the United States has already wasted a lot of time, money,
and natural resources…..pursuing a mirage of an energy scheme that cannot possibly
replace fossil fuels…The only real solution is to limit the rate of use of these
fossil fuels. Everything else will lead to an eventual national disaster.”
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