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Limits to Substitutability: BioFuels

by DeAnander Thu Jul 14th, 2005 at 07:58:33 PM EST

At Cornell, a skeptical voice is raised about optimism wrt fuel substitutability:

Turning plants such as corn, soybeans and sunflowers into fuel uses much more energy than the resulting ethanol or biodiesel generates, according to a new Cornell University and University of California-Berkeley study.

"There is just no energy benefit to using plant biomass for liquid fuel," says David Pimentel, professor of ecology and agriculture at Cornell. "These strategies are not sustainable."

[Full Text]

at Cornell, a skeptical voice is raised about optimism wrt substitutability:

Turning plants such as corn, soybeans and sunflowers into fuel uses much more energy than the resulting ethanol or biodiesel generates, according to a new Cornell University and University of California-Berkeley study.

"There is just no energy benefit to using plant biomass for liquid fuel," says David Pimentel, professor of ecology and agriculture at Cornell. "These strategies are not sustainable."

[...]"The government spends more than $3 billion a year to subsidize ethanol production when it does not provide a net energy balance or gain, is not a renewable energy source or an economical fuel. Further, its production and use contribute to air, water and soil pollution and global warming," Pimentel says. He points out that the vast majority of the subsidies do not go to farmers but to large ethanol-producing corporations.

Pimentel's work is discussed again here

Neither increases in government subsidies to corn-based ethanol fuel nor hikes in the price of petroleum can overcome what one Cornell University agricultural scientist calls it a fundamental input-yield problem: It takes more energy to make ethanol from grain than the combustion of ethanol produces.

At a time when ethanol-gasoline mixtures (gasohol) are touted as the American answer to fossil fuel shortages by corn producers, food processors and some lawmakers, Cornell's David Pimentel has taken a longer range view. He laments growing of corn for an energy-inefficient process that yields low-grade automobile fuel amounts to unsustainable, subsidized food burning as abuse of precious croplands. Pimentel, who chaired a U.S. Department of Energy panel that investigated the energetic, economics and environmental aspects of ethanol production several years ago, subsequently conducted a detailed analysis of the corn-to-car fuel process.

According to him, an acre of U.S. corn yields about 7,110 pounds of corn for processing into 328 gallons of ethanol. But planting, growing and harvesting that much corn requires about 140 gallons of fossil fuels and costs $347 per acre. Thus, even before corn is converted to ethanol, the feedstock costs $1.05 per gallon of ethanol.

The energy economics get worse at the processing plants, where the grain is crushed and fermented. As many as three distillations steps are needed to separate the 8 percent ethanol from the 92 percent water. Additional treatment and energy are required to produce the 99.8 percent pure ethanol for mixing with gasoline. Adding up the energy costs of corn production and its conversion to ethanol, 131,000 BTUs are needed to make 1 gallon of ethanol.

One gallon of ethanol has an energy value of only 77,000 BTU. About 70 percent more energy is required to produce ethanol than the energy that actually is in ethanol. In making 1 gallon of ethanol, there is a net energy loss of 54,000 BTU. Ethanol from corn costs about $1.74 per gallon to produce, compared with about 95 cents to produce a gallon of gasoline. Therefore, why fossil fuels, not corn are generally used to produce ethanol.

Most economic analyses of corn-to-ethanol production overlook the costs of environmental damages, which should add another 23 cents per gallon. Corn production in the U.S. erodes soil about 12 times faster than the soil can be reformed, and irrigating corn mines groundwater 25 percent faster than the natural recharge rate of ground water. The environmental system in which corn is being produced is being rapidly degraded. Corn should not be considered a renewable resource for ethanol energy production, especially when human food is being converted into ethanol.

The approximately $1 billion a year in current federal and state subsidies (mainly to large corporations) for ethanol production are not the only costs to consumers, subsidized corn results in higher prices for meat, milk and eggs because about 70 percent of corn grain is fed to livestock and poultry in the United States Increasing ethanol production would further inflate corn prices. In addition to paying tax dollars for ethanol subsidies, consumers would be paying significantly higher food prices in the market place." Apart from this, if all the automobiles in the United States were fueled with 100 percent ethanol, a total of about 97 percent of U.S. land area would be needed to grow the corn feedstock. Corn would cover nearly the total land area of the United States.

I would offer one caveat:  Pimentel's study is based on the assumption of current insanely petro-intensive farming practise.  The study does not mention what the energy math would look like using sustainable agricultural methods, nor does it examine canola as opposed to soya oil or corn ethanol. He also skips any analysis of non-corn ethanol -- sugar cane or beet ethanol for example.  Less fossil-intensive farming methods might yield better payback rates, but nothing -- even in rosy scenarios -- solves the fundamental problem of a psychotically inefficient transport paradigm.

Here is some quantitative chitchat from the carfree list back in 2001:

The following webpage provides a table which estimates oil yield per agricultural land  area:


From that table, Canoloa (rapeseed) a dryland crop may be estimated as yielding upwards of 127 gallons per US acre.

Petroleum Diesel has an energy content of approximately 138,000 Btu/gal. Gasoline has 124,300 Btu/gal. LP gas has 92,300 Btu/gal, when stored at 4.25 lbm/gal.  Cold pressed, not converted to biodiesel, Canola oil has 121,904 Btu/gal. Thus the same Canola cooking oil as is found in many kitchens has 12% less energy per volume than Petroleum Diesel, 2% less energy per volume than gasoline, and approximately 25% more energy content per unit volume than LP gas.

My very rough estimate based on petroleum fuel use per acre in dryland wheat farming suggests that agricultural machinery could consume less than 20 gallons of Canola oil to plant and harvest enough seed to extract 127 gallons of oil. Ethanol from grain crops doesn't even come close to exhibiting the same favorable production use to product yield ratio.

Used as a utility bicyclist's food vegetable oils such as from Canola or Olive pits have sufficient calories per volume to suggest a "fuel" consumption rate from 900 miles per gallon to over 2,000 miles per gallon, depending on the bicycle's and cyclist's performance characteristics. This frugal resource utilization is primarily a direct consequence of a bicycle's mass which is scaled in proportion to the rider and use.  [John Snyder]

Taking Snyder's figures for the moment at face value, he claims a profit of 107 gallons per acre in canola oil.  If we subtract 12 percent for the energy density difference between canola and petrodiesel we get a diesel equivalent of 94 gallons/acre.  How does that compare with current agricultural acreage and current fuel consumption for transport?

The EPA estimates over 1 billion gallons of petrodiesel consumed per annum in idling alone.  This (PDF!) paper offers 1999 fuel consumption figures for the US vehicle fleet of 125 billion gallons of gasoline and 35.7 billion gallons of diesel.  If we believe the somewhat optimistic canola scenario above, we would need about 379,787,250 acres (380 million acres) under canola to meet our diesel habit alone.

How many acres do we actually have in the US under various crops?  Answers can be found at the fascinating ag statistics sites.  I find these maps really interesting, but the real numbers are in another blasted PDF file.  In 2004:  81 million acres under corn, 75 million acres under soya, 60 million acres under wheat, 14 million acres under cotton.  For a total of only 230 million acres.  In other words we could replace all agricultural activity in the US in corn, soya, wheat and cotton with canola plantings, and still not reap enough canola to replace only the diesel component of our transport fuel consumption.

Please, check my numbers!

But my point is that unless I am off by a couple of orders of magnitude, there is no way -- even at a net energy gain which the Cornell study suggests is unlikely -- that the US vehicle fleet and transport model in its current form [defended recently by asdf as a "good standard of living" indicator in which people will resist any cutbacks] cannot possibly be fueled by the amount of arable land available in the US.  All food production would have to cease and agricultural activity be dedicated solely to feeding the transport model.

One reason for this energy gluttony is the gross oversizing of ICE vehicles for the job they do, and unreasonable, spoilt-aristo expectations of "performance" (i.e. moving that enormous mass quickly off the mark and defying aerodynamics to shove high-profile boxy vehicles along the roads in excess of 45 mph).  The difference in fuel efficiency between a worst-case Hummer H2 and a best-case cyclist could be a factor of 100. Surely it makes more sense to grow human food to feed cyclists at 100x the efficiency than to grow fuel-optimised crops to feed Hummer H2s...

Anyway, some more numbers to ponder.

Is fossil fuel substitutable?
. no problem, hydrogen will save us 0%
. no, we'll have to drive smaller cars fewer miles with fuel and/or carbon rationing 30%
. no, the private automobile is about to become obsolete, along with jet travel and strawberries in December 40%
. no problem, all we have to do is kill 90 percent of the other people on earth and dedicate their farmland to fueling our cars 20%
. biofuels are a crock, we will power our cars with nuclear/electric systems 10%

Votes: 10
Results | Other Polls
Thanks De

I have usually refrained from commenting on the various renewable energy threads when people bring up biofuels, because I always felt that such biofuels could not possibly be energy-efficient on a grand scale, and that the main problem of energy being the overall lack of price transparency, bringing in the ag sector, the most distorted of all, in the balance, would certainly not be a good solution.

Now i have some hard numbers to back that up.

Price transparency, in my view, is a wider requirement than simple energy balance, as it includes the other inputs. It requires that all physical and economic distorsions be taken out to make a real assessment. The advantage of price transparency is that it seeps through the whole economy and brings that harsh light on all economic activity, which is what we need today.

In the long run, we're all dead. John Maynard Keynes

by Jerome a Paris (etg@eurotrib.com) on Fri Jul 15th, 2005 at 05:31:51 AM EST
Excellent article - and good catch! Critical studies of biofuel appear only seldom and seem to vanish in a New York minute.

Here in Germany, canola is the biggest biofuel candidate, specifically biodiesel (although I suspect that trade regulations will soon cause that to change to sugar beets), so I went looking to see if I could substantiate Snyder's energy yield figures, and found this (some points pertain to biofuels in general):

The production of biodiesel entails extensive land consumption. To meet the German demand for diesel fuel with biodiesel, it would be necessary to cultivate rapeseed in an area far exeeding the entire agriculturally used land in Germany.


Biodiesel without environmental benefit
The freedom of this fuel from sulfur, previously touted as an ecological advantage, no longer represents an advantage over conventional diesel fuel, as the German petroleum industry has been selling only sulfur-free fuels since the start of 2003... Lower particle emissions are no longer guaranteed, particularly with modern motor variants. The only remaining advantage is the reduction of CO2 emissions by 0.22%. On the other hand, this offset by several environmental burden:

  • Cultivation, harvest, processing and transport consume 60% of the energy yield of biodiesel

  • Fertilizers and pesticides used in cultivation pollute soil and water

  • Fertilization causes emissions of dinitrogen monoxide with a high greenhouse potential (290 times greater than CO2 )

  • Approx. 8 % greater consumption due to lower energy content compared to conventional diesel fuel

  • Greater aldehyde and nitrogen oxide emissions.

(xlation my own)

The source is Esso Deutschland, but the Naturschutzbund Deutschland essentially confirms these points.

The fact is that what we're experiencing right now is a top-down disaster. -Paul Krugman

by dvx (dvx.clt št gmail dotcom) on Fri Jul 15th, 2005 at 05:42:47 AM EST
Let's burn our food so we can drive! Yes!
by asdf on Fri Jul 15th, 2005 at 08:52:25 AM EST
My only understanding of these issues comes from reading here and on DKos, so please excuse my ignorance, but has has anybody run the numbers using industrial hemp? I ask this because I have read in the past that hemp doesn't require the fertilizer/persticide input that adds to pollution and energy use to the equation. Plus it may yield more biomass per acre than other plants.

Another question- since diesel engines get better mileage than gas engines, shouldn't the numbers for US fleet consumption be adjusted to take into account a change-over to the use of biodiesel?

Thanks to everyone who posts knowledgeably on these topics, I'm getting a great education and appreciate the energy (pun intended) you folks put into collecting info and sharing same.

by US Blues on Fri Jul 15th, 2005 at 10:25:22 AM EST
[ Parent ]
Hemp is MJ is bad. Didn't you learn anything from "Reefer Madness?"  :-)

Diesel cars get better mileage because of two reasons. First the Diesel cycle is more efficient in the thermodyanamic sense because it uses higher pressure. In modern high speed diesel engines the differentiation between the Diesel and Otto cycles is blurred, so this is not as strong an effect as it might be.

Second, diesel fuel contains more energy than the same amount of gasoline. So you need more crude oil to make it, and the Miles Per Gallon (or Liters Per Kilometer) metric is misleading. You need to de-rate diesel fuel economy numbers by about 20% to do a good comparison of the two fuels on an energy basis.

Really what should happen is that government standards, and all discussions, should be held in terms of energy use rather than miles per gallon. Doing so would make it possible to make sensible comparisons between electric cars, gasoline and diesel internal combusion engine cars, steam (external combusion) cars, hydrogen, fuel cell, etc.

by asdf on Fri Jul 15th, 2005 at 01:13:46 PM EST
[ Parent ]
Brazil produces lots of ethanol from sugar canel, but I haven't seen an energy balance analysis.  Apparently production costs are much less than corn based ethanol.
by corncam on Fri Jul 15th, 2005 at 10:39:05 AM EST
Very interesting. Considering that biodiesel seems to be net positive it makes sense to continue pursuing it as a partial solution. Clearly, we are going to need to become more efficient in our use. The increased use of trains, bicycles, and walking; plus higher mpg standards might allow us to produce 25% of vehicle fuels from crops (number is based on the obvious conclusion that 100% is ridiculous, and 50% still seems too optimistic).

On the other hand, the US has whole regions of South America growing cut flowers for out dinner tables. Up to this point we have shown no qualms about completely changing a regions agricultural system to suit our desires. Assuming that the system does not collapse before then, it is fairly likely that before we take harsh cuts to our fuel habits we will have the entire third world growing sugar cane, canola, and hemp to fuel us.

by toad on Fri Jul 15th, 2005 at 12:28:01 PM EST
Thanks for this.  It confirms what I have suspected: that the purpose of ethanol is totally political.

Reality is not always happy-making but paying attention to it has a lot of survival value.

by Plan9 on Fri Jul 15th, 2005 at 02:39:58 PM EST
I seem to recall reading something about conflicts in Brazil over the diversion of cropland to sugar cane for ethanol -- probably the traditional Enclosure mechanism, displacement of diversified subsistence/market agriculture with monocrop industrial farming, reduction of local food self-sufficiency, dumping of low-grade US corporate factory food on the population at below-market costs to drive local farmers out of biz, yada yada.  The usual suspects.  I'll try to track down the story.

Yes I believe hemp, like other weedy species (Paulownia trees, bamboo), produces more biomass per acre per season for the same water/soil inputs than slower-growing fibre or oil crops.  Hemp is a pretty nifty plant actually (practically a Wompom if you know your Flanders and Swann), and imho the whole US anti-marijuana hysteria has set back the US sustainable materials sector by decades.  I have often thought that Hawai'i's ruined sugar farming sector could easily be converted to hemp production;  but the local covert marijuana farmers hate the idea, as the low-quality hemp pollen would contaminate their expensive high-quality recreational crop.

I'll see if I can run some numbers on hemp.  Makes nice rope, and wonderful fabric too.  A hemp/silk blend is tough as nails and washes to a very pleasant texture.

Obviously I don't share asdf's enthusiasm for further expensive, corporate/industrial technofixes :-)  So far I know of no GMO crop trial which has actually produced improved yields per acre, only increased revenues for the patent-holding corporation (and for legions of trained attack-lawyers used to harass farmers like P Schmeiser).  I know of no GMO crop trial which has actually shown real promise of addressing nutritional deficits (the Golden Rice scam was just that:  a well-spun PR scam).  But we can tackle the GMO issues in another diary.  At least we can agree on the windmills :-)  and I'd like to see some tidal generation projects too.

But as asdf says in a comment w/which I could not more heartily agree, it makes little sense to burn our food so we can drive our cars.  At the heart of the problem is DEMAND REDUCTION.  There are only two ways to achieve this.  One is by voluntary or regulated reduction of consumption;  the other is by forcible extermination of large numbers of people to allow the remaining elite to go on hogging what remains.  Historically, collapsing cultures have consistently chosen Option B (which is why they collapse, so I guess that was tautological, sorry).  Tikopia is one instance of a culture choosing Option A... there may be other instances.

BTW if anyone is interested in a radical critique of Jared Diamond's "Collapse" book I have found one, worth a read I thought.  Certainly reinforces some of my own misgivings about bits of his text, though I still think the book as a whole is a good read and quite an achievement.
Part 1
Part 2
Part 3
Part 4
At same site, an interesting account of Soviet environmentalism and its destruction by Stalinism...

And J, sorry to be terrifying, but I have that same "stuck in a fast American gas-hog-mobile with a drunken teenage boy driver and already into the spinout" feeling.  I wake up scared, and if you ask me, more people should.  We're looking straight at the oncoming brick wall and trying to pretend it ain't there.  Scares the bejeezus out of me:  the level of denial and blind faith in the "They" who are going to come up with some miracle technology to make it all just peachy again, in our "advanced" cultures, is astounding.  Truly we have elevated "Science" to some kind of religious icon, a golden calf or an airplane made of bamboo; people now think of it as an institution into one side of which you pour credulous faith, and out of the other side comes infinite abundance and entertainment.  Ironic.

To tell the truth sometimes I think this whole GWOT scam and its use by the ruling classes to enact more and more repressive laws, the discarding of posse comitatus in the US etc, tightening of borders, ID cards, surveillance, RFID tagging, all this 1984esque stuff... is planned and thoughtful preparation by our elite masters, against the day when various shortages (food, water, oil) start to be felt and the population "needs to be controlled".  It's just a bad feeling I have sometimes.  But hey, in a pinch that tinfoil hat can be reworked into a primitive solar oven...

The difference between theory and practise in practise ...

by DeAnander (de_at_daclarke_dot_org) on Fri Jul 15th, 2005 at 04:47:05 PM EST
I found this article about biodiesel research from the University of New Hampshire. I had read it a couple of weeks ago on a link from DKos, and thought these folks had an interesting take.
by US Blues on Sat Jul 16th, 2005 at 09:04:56 AM EST
[ Parent ]
Yee hah -- Pimentel is not ignoring total energy efficiency issues for corporate ag vs sustainable ag.  He pops up again here:
Organic farming produces the same yields of corn and soybeans as does conventional farming, but uses 30 percent less energy, less water and no pesticides, a review of a 22-year farming trial study concludes.

    David Pimentel, a Cornell University professor of ecology and agriculture, concludes, "Organic farming offers real advantages for such crops as corn and soybeans." Pimentel is the lead author of a study that is published in the July issue of Bioscience (Vol. 55:7) analyzing the environmental, energy and economic costs and benefits of growing soybeans and corn organically versus conventionally. The study is a review of the Rodale Institute Farming Systems Trial, the longest running comparison of organic vs. conventional farming in the United States.

    "Organic farming approaches for these crops not only use an average of 30 percent less fossil energy but also conserve more water in the soil, induce less erosion, maintain soil quality and conserve more biological resources than conventional farming does," Pimentel added.

    The study compared a conventional farm that used recommended fertilizer and pesticide applications with an organic animal-based farm (where manure was applied) and an organic legume-based farm (that used a three-year rotation of hairy vetch/corn and rye/soybeans and wheat). The two organic systems received no chemical fertilizers or pesticides.

    Inter-institutional collaboration included Rodale Institute agronomists Paul Hepperly and Rita Seidel, U.S. Department of Agriculture's Agricultural Research Service research microbiologist David Douds Jr. and University of Maryland agricultural economist James Hanson. The research compared soil fungi activity, crop yields, energy efficiency, costs, organic matter changes over time, nitrogen accumulation and nitrate leaching across organic and conventional agricultural systems.

    "First and foremost, we found that corn and soybean yields were the same across the three systems," said Pimentel, who noted that although organic corn yields were about one-third lower during the first four years of the study, over time the organic systems produced higher yields, especially under drought conditions. The reason was that wind and water erosion degraded the soil on the conventional farm while the soil on the organic farms steadily improved in organic matter, moisture, microbial activity and other soil quality indicators. [emphasis mine]

Now what I want to say here is, can we please just get over this whole antiquated "Green Revolution" mythos, that good ag productivity is only possible with massive petro inputs?  I hear this assertion repeatedly, that "if we have to revert to organic agriculture we will all starve because yields will drop."  This is BS, end of story.  Not only will yields drop only temporarily, the most essential yield of all will go from extremely negative to positive.

That yield is soil quality.  The most important crop any farmer raises is good soil -- soil itself is a crop, a living system, an ecology in its own right.  With petro-intensive over-irrigated hypermechanised factory ag, we not only pour precious petroleum resources into the farm, by doing so we degrade and destroy soil quality -- a double loss.  With properly implemented sustainable methods we not only conserve both water and fossil fuel, we improve soil quality, thus making a profit on all counts -- rather than an ostensible short-term yield boost for the market crop taken out of the hide of the more essential crop, the soil itself.  When we destroy soil by means of petro-intensive practises we render ourselves more and more dependent on fossil inputs in a vicious downward spiral of diminishing returns and escalating costs.  When we maintain and improve the soil in the process of farming, our core investment and legacy is preserved and there is no diminishing return, only a gradual improvement tapering off to steady productivity.

And now a rhetorical interlude.  Fossil-fueled agriculture is a credit card binge (I repeat an analogy already aired on another thread) -- a form of "get rich quick with easy credit" which actually undermines our real capital.  Or to try out another analogy, its claim of miracle results and instant returns is like those of any patent medicine.  Sure it may make you feel all-powerful for a few hours, but the hangover's wicked bad and the long term health effects may be fatal.  The Green Revolution hasn't happened yet.  What we had was the Sticky Black Crude Revolution, which is just about over.  The real GR is yet to come...

The difference between theory and practise in practise ...

by DeAnander (de_at_daclarke_dot_org) on Fri Jul 15th, 2005 at 07:03:02 PM EST
More on Corn and US Ag
Corn is already American's most heavily subsidized crop, sucking up about $10 billion a year (according to OXFAM) along with all that water and fertilizer. About 13 percent of the corn crop is now devoted to ethanol production, but that would increase dramatically if the Energy Policy Act of 2005, now in a House-Senate conference committee, were to pass. The Senate version of the energy bill would require US ethanol production to more than double - from 3.3 billion gallons in 2004 to 8 billion gallons by 2012.

    Subsidies hide the true monetary cost of production, but the big accounting scandal here is the energy accounting. A study by Cornell ecologist David Pimentel and UC Berkeley engineer Tad Patzek found that when all the inputs to farming and ethanol production are accounted for, ethanol uses 29 percent more fossil fuel energy to produce than it yields in your gas tank.

There's more.  Worth a read.

The difference between theory and practise in practise ...

by DeAnander (de_at_daclarke_dot_org) on Wed Jul 20th, 2005 at 07:13:46 PM EST

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