Good Math, Bad Math

Bad Math and Ethanol

One thing I’ve been hearing a lot lately is discussions about Ethanol, and it’s been
really pissing me off. Can ethanol be a serious replacement for oil as a source of energy? I don’t know. Because *both* sides are using really bad math to make their arguments.

There are two fundamental questions about ethanol as fuel where the bad math comes in:

1. How much energy does it cost to *produce* ethanol compared to the amount of
energy released by *consuming* ethanol?
2. How much pollution is generated by the process of producing ethanol?

There are numerous reports or studies from both sides of the political spectrum that quote the
supposed “fact” that ethanol product consumes more energy than can be produced by burning ethanol. But that fact dates back to a single study, which is at best misleading, and at worst, deliberately deceptive.

The classic bad argument about question one comes from the work of Profesor David Pimentel at Cornell. Professor Pimentel isn’t entirely to blame for this; while I believe that his work was intended to be deceptive, the way that it’s been used is even *more* deceptive than I think he intended.

Pimental studied the production cost of ethanol. What he was trying to determine was the *total* energy cost of producing ethanol. The end result of his study was that it costs approximately 1.3 gallons of gas to generate the energy needed to produce one gallon of ethanol. And since burining one gallon of gas produces as much energy as 1.5 gallons of ethanol, the effective energy cost of ethanol is close to twice the amount of energy yielded by burning it.

This is *very* frequently cited as an argument against Ethanol. For an example of just how widely this argument has spread, here’s an example of an [an environmentalist group using it to argue against ethanol.][env]


The problem is that the figure is calculated to produce the highest possible cost for ethanol. What would you guess would be included in the energy cost of producing ethanol? My off-the-top-of-my-head guess would be “growing and harvesting the crop, transporting it to the ethanol factory, operating the factory, transporting it from the factory to the user”. The Pimentel calculation includes all of those, but it doesn’t stop there. It also includes:

* The cost of producing and transporting fertilizer for the crops.
* The cost of producing and maintaining the farm equipment used in growing the crops.

Reasonable. I wouldn’t have thought of those, but it’s fair to include them. But it doesn’t stop there either. It also includes:

* The cost of producing the materials used to construct the ethanol factory (including
everything from the cost of mining the ores that are used to produce the steel for
girders used in the plant on up).

That’s starting to get silly. But it doesn’t stop there. He even goes so far as to include:

* transportation costs for the workers commuting to the farm and the ethanol plant.
* the energy consumed by the *workers* on the farm and in the ethanol plant in order
to do their work!

That’s just ludicrous. The idea that it’s *reasonable* in an assessment of the production costs of ethanol to include the *food* consumed by the workers is just crazy. But that’s what the most widely cited argument does.

To give you a sense of how much is wrong with this, we can just look at a Pimentel calculation
on the energy cost of oil. By Pimentel calculation, you’d conclude that *oil* is a net
*consumer* of energy. Including drilling, refinement, transportation, pumping, and the kinds
of associated worker and supply costs, *at best* you wind up with a computation that it takes
the amount of energy produced by 1.1 gallons of gas to produce 1 gallon of gas. [(And that’s
*Pimentel’s own calculation!)][pim]


But the other side isn’t any better. Ethanol promoters use calculations of the energy cost of producing ethanol that *omit* things like the energy costs associating with growing the
ethanol crops, the transportation costs, etc., and focus *only* on the cost of the
ethanol fermentation and refinement. That’s equivalent to computing the energy cost of
oil while omitting the costs of drilling for oil, and transporting it from the drilling site in the middle east to the refineries in the US.

Either way – including too many things to make it look bad, or omitting things to make it look good – either way, it’s faking numbers with bad math. And the end result is that it’s *very* difficult for anyone to figure out honestly what the costs and benefits of ethanol really are! Is ethanol production a good idea? Will it help us produce more energy without importing oil? It’s almost impossible for the general public to figure it out, because both sides are faking their numbers, and we simply don’t have access the information to figure out what the real, honest number is!

There’s also a similar kind of argument about carbon dioxide and ethanol. Various oil-industry
front groups have pushed the fact that an ethanol production factory produces an enormous
amount of carbon dioxide. And that’s [absolutely true.][co2] The fact that they neglect to
mention is that nearly all of the carbon dioxide produced by the factory, plus the carbon
dioxide produced burning the ethanol as fuel, is carbon dioxide that was *removed from the
atmosphere* by the plant. It’s a nasty little game of math: when they’re trying to show that
ethanol’s cost is high, you skew the numbers by including every conceivable cost from the farm
to the factory to the point of delivery. But when they’re trying to show that ethanol isn’t
better when it comes to pollution, suddenly the farm, the process of growing the crop for
producing ethanol just *poof*! disappears.

This is more clear cut. I can’t find *any* examples of ethanol promoters overstating the
carbon-fixing capacity of ethanol crops, whereas there are plenty of examples of ethanol opponents lying about the carbon dioxide produced by ethanol fermentation.



  1. #1 _Arthur
    December 6, 2006

    When ethanol prodution starts in earnest, the machinery in the ethanol plant, and the agricultural machinery, will use ethanol, they they’ll provide to themselves at cost; it just makes more sense that way.

    Corn is probably not the best crop to produce ethanol; it is too valuable as a grain. Crops where the whole biomass can be converted to ethanol (like sugar cane, but it doesn’t grow well i8n the USA –without heavy subsidies) are possibly the best choice. Prez GWB mentionned switchgrass, then proably cut finanacing in that area of research, if he runs true to form.

    I have seen mentionned, here in ScienceBlogs, that converting the whole US maize crop into ethanol and the whole soya crop into biodiesel would not suffice to meet US current fuel consumption. I’ll have to serach a little to find the reference.

    Cuba would probably gladly provide the US with huge quantities of relatively low cost ethanol, but for some prehistoric political reason, this is impossible.

  2. #2 Mark C. Chu-Carroll
    December 6, 2006


    The problem that I’m talking about is the fundamental question about whether or not ethanol is a viable fuel. *If* the real energy cost of producing ethanol is more than you can get from it, then you *can’t* run an ethanol factory from ethanol; that would mean that the ethanol plant would need *more* energy to operate than you could get by feeding all of the fuel it produces back into the operation of the plant.

    I doubt that that’s true. But what’s the real tradeoff? Is the energy cost of ethanol 10% of what you get from it? 50%? 80%? It’s almost impossible to figure out what that number really is given the amount of smoke and mirrors surrounding the question.

    You are right that corn is not the best crop for ethanol (which is another problem with the commonly cited study). Corn is relatively expensive to grow, in comparison to other crops which can be used for ethanol production. There are a number of woody grasses, like the sawgrass that you mention, which are less expensive to grow, and which produce more material suitable for fermentation into ethanol.

  3. #3 _Arthur
    December 6, 2006

    I agree, MCCC, I, as a layman, cannot determine if the energy output of corn ethanol is a net positive, from outside.
    My speculation is that the transformation is much less energy intensive than, say, oil cracking, since most of the work is done by … yeast.

    How much oil-derived, energy-intensive fertilizers, pesticides and whatnots it takes to bring in a modern crop is another, unpleasant, question.

  4. #4 _Arthur
    December 6, 2006

    Here’s the Pure Pedantry link,

    “The study showed that both corn grain ethanol and soybean biodiesel produce more energy than is needed to grow the crops and convert them into biofuels. This finding refutes other studies claiming that these biofuels require more energy to produce than they provide. The amount of energy each returns differs greatly, however. Soybean biodiesel returns 93 percent more energy than is used to produce it, while corn grain ethanol currently provides only 25 percent more energy.

    Still, the researchers caution that neither biofuel can come close to meeting the growing demand for alternatives to petroleum. Dedicating all current U.S. corn and soybean production to biofuels would meet only 12 percent of gasoline demand and 6 percent of diesel demand.”

  5. #5 JimK
    December 6, 2006

    The reason Seagram isn’t a producer of fuel ethanol today is because they did that calculation back in the 70’s when I worked for them.

    At the time, Seagram controlled the complete product from field to aged liquor. They owned or had controlling interest in farms (both grain like corn and sugar cane for Rum), grain elevators, rail lines, the (at the time) most efficient fermenters in the business, distilleries, warehouses, and trucking companies. Therefor, it was uniquely situated to calculate the true cost and energy efficiency of producing fuel ethanol.

    After months of work, the conclusion was simple….fuel alcohol from grain was a 20% – 25% net loser from a BTU standpoint. Fuel from sugar cane was better, but still a net loss. Note that the physical plant necessary was already in place, so none of those costs or the energy to build them were included.

    Financially it made sense if the subsidies proposed by President Carter held up….but none of us thought that the US Government would subsidize a losing proposition for long (obviously we were engineers and scientists, not politicians). ADM took the opposite tack, also building up a considerable political lobby, and today is the major fuel ethanol producer in the US instead of just supplying grain to companies like Seagram.

    As for Seagram, it should have pursued fuel ethanol….instead the name is now owned by a British firm, the distilleries mostly shut down or sold to others and the former owners (the Bronfman family) are out making miscief in the entertainment industry.

  6. #6 cooper
    December 6, 2006

    How much pollution is generated by the process of producing ethanol?

    Well, the answer to that is how much non-ethanol energy is consumed.

    Remember, while ethanol burns to CO2, the CO2 comes from carbon absorbed from the atmosphere in the growth of the stock plants.

    My problem is using even the GOOD numbers, it doesn’t represent a good enough source of energy to really be a “solution”

  7. #7 _Arthur
    December 6, 2006

    For back-of-the-enveloppe calculation, one kilo of corn (popcorn kernels) cost me $1.99 at the nearby grocery store, and gas is $1.00 a liter hereabouts.

    I’d take that as a very strong indication that it does NOT take 1 liter of gas to grow 1 kilo of corn, including fertilizer, pesticides, transportation, bagging and whatnot. If you guesstimate the grower profit margins, the distributor profit margins and the store profit margins on this bag of corn, you come to the conclusion that corn require much less than its weight in fuel to grow ….

  8. #8 _Arthur
    December 7, 2006

    JimK, ethanol was not price-competitive with oil in the 70s because oil was too damn cheap then. Oil cost much more then. Of course, if it is true that you need huge quantities of oil and energy to grow ethanol, it will always end up costing more than oil.

  9. #9 Ahcuah
    December 7, 2006

    Does it really matter if it does take 1.3 gallons of energy to make 1.0 gallons of ethanol?

    For instance, it takes way more energy to make a D battery than the energy I can get out of it. So, why the heck do we buy and use the things? Because they are a convenient, compact source.

    And isn’t that, to large extent, the point of gasoline and ethanol? They are nicely compact sources of energy that are very convenient for our transportation devices.

    If your ethanol plant was sitting next to a nuclear plant (or efficient solar farm) then it would be worth it even if the ethanol part of the equation was 2.0 or 3.0 gallons, as long as you made up the energy differential from some other source that was not transportation-friendly.

    Or am I just full of it?

  10. #10 Torbjörn Larsson
    December 7, 2006

    Interesting to see the different perspective.

    E85 ethanol cars are rapidly increasing in Sweden. But about 80 % of the fuel is still imported from Brazil. And winter starts gives a lot more emissions than usual even with cats.

    Best economy and cleaner city air comes with biogas cars which has had a stable growth. The gas is locally produced.

    The future though may be BTL (biomass to liquid) from wood, which apparently could cover 50 % of the current need with domestic production, and with fewer emissions than ethanol.

    Even in such a best case scenario the remaining gap needs other systems. Apparently a single longterm solution isn’t feasible for us.

  11. #11 bigTom
    December 7, 2006

    Well it is also likely that the ratio varies considerably with process, and farming methods. Presumably the cellulosic ethonal that we hear about -but if somewhere off in the future isn’t viable, until breeding produces suitable yeast. At least thats what I guess when I hear its not going to be ready for awhile. So even if the early subsidized production is too close to energy (or oil) breakeven to really be useful, future processes will likely do better in that regard.
    In any case much ado is made of Brazil’s ethanol (I don’t have the figures, but ethanol is roughly 40-50% of fuel). But total fuel consumption in Brazil is only 6% of the US, for nearly as large a country as the US. And forest clearing for fuel plantations is now the greatest consumer of rainforest.
    Bottom line. Improved technology will probably make bio-fuels viable alternatives to oil eventually, but the total amount of fuel produced per year will probably be less than out current oil consumption. This can still become a replacement for oil -but only if seriously improved fuel economy is part of the equation.

  12. #12 Jens Ayton
    December 7, 2006

    “Of course, if it is true that you need huge quantities of oil and energy to grow ethanol, it will always end up costing more than oil.”

    Recently, I heard the following: in the early 1950s, US grain farmers used roughly 1 mass unit of oil (as fuel and fertilizer) to produce 100 mass units of food. In 1970, it was 1:1. Now, it’s 100 units of oil per unit of food – an increase in fuel usage of 10,000x in 60 years. If oil usage in farming was reduced 10,000x it is reasonable to assume that production would drop significantly, but it’s definitely possible to use much less fuel and synthetic fertilizer in crop production. What’s lacking is an incentive – there is little economic pressure on eco-fuel producers to actually be environmentally friendly.

  13. #13 Alex
    December 7, 2006

    Pimentel is right in a trivial sense. Of course you need more than one gallon of ethanol’s worth of energy to make one gallon of ethanol – energy conversion is never 100 per cent efficient by definition. But, as Mark points out, that’s also true for oil or indeed anything.

    But the point is how much extra energy is needed, and more specifically, how much extra nonrenewable energy is needed. It is of no interest to anyone how much SOLAR energy is used to make a gallon of ethanol – it’s free, clean and won’t run out – nor how much food the workers eat, as they will eat whether they are working on ethanol or anything else.

    He needs to differentiate with respect to oil(or whatever), not total energy. Consider the situation when the farmer’s tractor runs on ethanol and the ethanol plant on part of its output – the question is, would this leave any to sell? To put it another way, the relevant efficiency is the ratio of solar energy in to the ethanol system to ethanol delivered to the customer.

  14. #14 Greco
    December 7, 2006

    And forest clearing for fuel plantations is now the greatest consumer of rainforest.

    Where, exactly? If you mean Brazil, then sugarcane production occurs either in areas that were cleared of forests centuries ago or in cerrado. The major crop in rainforest areas is soybean.

  15. #15 biofuelsimon
    December 7, 2006

    For what they’re worth, I’ve done some sums on the practicality of using wheat to produce ethanol in the US.

    You might also want to think about the effects on the water table of growing more corn or wheat to produce biofuels.
    Longer term, the more likely processes will be to use the cellulose in plants and either burn it or convert it into ethanol, or diesel.

  16. #16 Harald Korneliussen
    December 7, 2006

    JimK, that’s interesting, but my sympathy for Seagram and the family behind them is very, very limited. The particular numbers vary from place to place, and from where you draw the line at abuse, but almost no matter how one juggles those numbers the vast amount of profit from consumed ethanol comes from the very worst abusers.

    I don’t think anyone can make that much money from human misery and not be affected by it.

  17. #17 DouglasG
    December 7, 2006

    What I find ironic is that nobody is talking about the only solution that makes sense. The reason this is an issue is an attempt to keep the oil companies in business. The oil companies have spent a lot of money making and maintaining gas stations. Thus, the model for going somewhere to “fill up” is what is often discussed. IE. Biofuels or Fuel Cells or whatever. The real solution SHOULD be electric cars. Thus, it does not matter one bit how the electricity is generated. If the power plant wants burn ethanol it can or oil or natural gas or nuclear or … We are at the point where battery technology and electric motor technology can create a car with a 200 mile range and go 70 MPH. The debate over which fuel is better should be irrelevant…

  18. #18 John
    December 7, 2006

    Unfortunately I think the issue of energy is necessarily more political than science, which is why this debate is focused on the wrong things -> which is exactly what the ethanol and oil lobbies want to have happen through the propagation of their mis-used statistics. Ironically, both sides have turned this into an oil vs. ethanol debate taking the focus off the more important aspect of America being energy independent.

    Scientifically, energy in = energy out. And, since lots of energy escapes in the production process of both oil and ethanol (i.e. heat), according to the laws of physics, of course it takes more energy to produce both than we get out of the final products. Who cares if one’s energy balance is worse than the other? FOr instance, let’s say ethanol’s energy balance is worse -> since the feedstock is a replenishable, renewable resource that we can plant on our vast land, we can stay ahead of the inefficiencies. Whereas with oil, there is only a finite amount remaining and it isn’t replenishing itself.

    Geopolitically, it is difficult to calculate the dollar value of being energy independent. However, we spend about $225 billion per year in military spending protecting the flow of the 850 million barrels we get annually from the Persian Gulf -> this equates to about $260 per barrel, taking the “real” cost of middle eastern oil to about $320 per barrel. So we currently spend $450 billion per year on Middle East security and OPEC oil.

    The debate we should be having should be around the best ways to spend this money “at home” improving the energy yields of all our home-grown solutions like ethanol, solar, wind, nuclear, etc. Oil is a fantastic source of energy, but based on our usage, we can’t harvest enough domestically so we must consider other alternatives, even if they are less “energy efficient.”

    Taking the long-term view (50+years), relying on oil is clearly not a sustainable policy/approach for our country. Therefore, we must start doing something else. Our ingenuity will certainly close any energy balance gaps that may exist today.

  19. #19 _Arthur
    December 7, 2006

    Douglas, electric cars would certainly be nice, but so far the energy density of batteries doesn’t come close to the energy stored in chemical fuels, even when to take into account the disparity in the weight of motors (electric motors are just a few coils, and that’s it).
    People would have to settle for reduced-speed and reduced-range cars ….

    In another example of Bad Math, one European scientist computed that electric cars would pollute MORE than than conventional ones. His reasoning was that european electricity was generated from coal and oil, and that there were significant energy losses when charging batteries; so, with his numbers, you ended up burning more oil at the power station than you would have just filling your tank and stepping on the gas pedal.

    Of course, most of his numbers were dodgy, he didn’t take in account that power plants can and do have far better pollution controls than individual cars, that in France more than 60% of the electricity is produced by nuclear power plants (that do not pollute conventinally), or, for example, in Quebec more than 90% of the electric power is hydro generated, so electric cars WOULD pollute less, in those countries.

  20. #20 Jonathan Vos Post
    December 7, 2006

    Isn’t it a good idea to back up and calculate the costs and benefits of the “Hydrogen Economy”, solar power, wind power, ocean temperature gradient power and wave power, the fission reactor economy, and compare ethanol and gasoline to those?

    Biological or biochemically-based hydrogen production appears to have a bright future, whereas making hydrogen from petroleum seems to me to be something of a fraud.

    Coal is dirty to burn and deadly to mine, but has become cheaper to transport via coal slurry (coal dust in water) pipelines. “King Coal” — surely a mature industry — is still being tweaked to higher efficiency. Nuclear reactors have been made safer and cheaper, so that environmentalists have gritted their teeth and started recommending them.

    Solar cells of 40% efficiency have recently been demonstrated by the Department of Energy. 40% has been a holy grail for a long time.

    Multiple nations have comitted to ITER, and fusion power will likely be available in a generation.

    My work in the field focused on giant solar collectors — on the Moon! Made robotically from amorphous silicon lying about as lunar regolith. Power beamed to Earth by laser or microwave. 100% sunlight for two weeks at a time (no atmosphere, clouds, or lunar night in the interval). Very high efficency, no pollution on Earth (other than the rocket launches to the Moon Base and the collector fields). And now NASA has committed to a Moon Base!

    I’m going to dust off my old reports on Moon Base design and construction. Wild as it seems, they pencilled as commercially viable in the energy supply debates.

  21. #21 Jimk
    December 7, 2006

    Aurthur – In the late 70s, crude oil was nearly as expensive as it is now in constant dollars. In the early 80s, it was actually higher than current costs. That’s why fuel ethanol became interesting in that time frame.

    However, my point was that Seagram was so highly integrated that it was in a position to know exactly how much energy it took to go from bare ground to a gallon of ethanol delivered to a distribution point. No matter how rosy our assumptions of improvements in various parts of the process, the calculations always came out negative.

    One other thing I’m noticing on this thread is confusion between producing oil produts and producing ethanol. While the words are the same, the actions necessary aren’t. Producing oil products involves finding existing deposits (and some processing). Producing ethanol involves making ethanol, not finding it. Finding is much less energy intensive than making.

    That difference is the crux of our dilemma today. The current status quo is so cheap (both in dollars and in energy expenditure to deliver it) compared to all the alternatives that little investment in alternatives is done by anyone. The total worldwide research budget for energy alternatives probably wouldn’t run a single large refinery for a month. Since oil will run out some day (there’s a lot of controversy over how long so I won’t get into that), we can only hope that a viable alternative will be discovered by the time that happens.

  22. #22 Davi Ottenheimer
    December 7, 2006

    What about the problem with efficiency? You can buy a Chevy Tahoe today that runs on E85 and it will only get 10mpg instead of 18mpg on regular gasoline. What’s the point of that? Makes no sense if you can do basic math. Diesel engines, on the other hand, are vastly more efficient more powerful and the latest engines burn far more cleanly than gasoline. Perhaps ethanol is thus destined to be nothing more than an additive to produce biodiesel, in which case it makes no sense to do calculations on it as a sole-source energy for the future. Think of it as part of the new blend…

  23. #23 Bernhard
    December 7, 2006

    Ethanol has other costs associated with it as well. It requires enormous amounts of water to make ethanol. For example, see this report from my home town:

    So in making a choice to use ethanol you are also choosing where to allocate other valuable resources, such as water, and we tend to ignore this, food! Amerika has only recently started importing more food then it makes…do we really want to feed our cars instead of our bodies?

    Ethanol is a distraction. There are much better alternatives out there, which don’t compete with other more valuable resources.

  24. #24 Jonathan Vos Post
    December 7, 2006

    “In principle it should be possible to produce ready amounts of hydrogen using sea water and solar cells, giving the next generation of vehicles an inexhaustible supply of environmentally-friendly fuel.”

    Invention Could Solve ‘Bottleneck’ In Developing Pollution-free Cars

  25. #25 Joel
    December 7, 2006

    Some math you should look at is the comparison between the amount of energy humans consume and the amount taken in by all biomass on the planet. I remember hearing that human activity uses energy at 4 times the rate of biological activities. If this is true, then even if we turned everything from algae to bamboo to old-growth forests and hydrothermal sulphate-reducing bacteria into biofuels and starved out all other animals, we’d only cover about 1/4 of our current energy needs…and by that time, the exponential growth from India and China would have increased those needs by a factor of 2 or 10 or…

  26. #26 Winston Smith
    December 7, 2006

    I think the problem is the internal combustion engine. At approximately 20% thermal efficiency its a dinosaur. If we’re throwing away 80% of the stored energy in a gallon of fuel we need to be looking at fuel cell technology or something else entirely. The good thing about high energy prices is the kick start it gives to alternative technology research.

  27. #27 Geoff
    December 7, 2006

    I have to agree with Davi… I think that biodiesel is the medium-term solution (and I own a diesel car, so I’ve already made my bet… once the warranty expires, it’s going as close to B100 as I can afford/find).

  28. #28 Dave
    December 7, 2006
  29. #29 dan rather
    December 7, 2006

    We have to stop thinking with this one replacement attitude. Ethanol is good, hydrogen is good, less fuel in fuel is good, natural gas etc. One thing missing is modularizing our cars to use multiple energy sources. If the industry supports multiple energy sources for fuel then this will influence design in a good way and make energy markets more about pluggable designs. Ethanol is a good soution yes because it can be made from many other things than corn, its already 15% of all fuel (infrastructure is there already and being ramped up), it makes more money go to Iowa rather than Saudi Arabia and it encourages at least “felx” fuel cars. What we need it pluggable cars, technology in cars again challenging the current energy sources designs. Ethanol helps this, stop being so confused, its very good for every aspect of progression.

    Do IT systems run on a single powersource or server farm? Is the internet broken if one node goes down? Why woudl we only have ONE fuel source that is on teh market. It is horrible for design, competition, gouging and many other things (terrorism).

  30. #30 ytba
    December 7, 2006

    How ’bout a little solid experimental data, or at least basing the calculations on some.

    I occaisionally run into information of value in a Dr.’s waiting room, at least when they have something to read other than Newsweek or Time.

    “Crunching the numbers on alternative fuels.” — BY Mike Allen

    The Great Alt-Fuel Debate: It takes five barrels of crude oil to produce enough gasoline (nearly 97 gal.) to power a Honda Civic from New York to California. So how do the alternative fuels that may gradually reduce America’s dependence on foreign oil stack up against the mileage and convenience of the filling-station stalwart? Download our comparison chart and find out.

  31. #31 AJS
    December 8, 2006

    And forest clearing for fuel plantations is now the greatest consumer of rainforest.

    Where, exactly? If you mean Brazil, then sugarcane production occurs either in areas that were cleared of forests centuries ago or in cerrado. The major crop in rainforest areas is soybean.

    Interesting ….. the vegetarian / vegan / save the cute fluffy bunnies brigade over here seem to think much or all of that land is being used to raise cattle for McDonalds (who by turn claim to use all British b**f in their British outlets).

    Which takes us off on a pleasant tangent ….. I don’t think there’s any debate that growing crops to raise animals for m**t is less efficient than eating plant-based foods. But the human digestive tract is too short to derive nutritional value from many plant sources (i.e. you sh*t them out before you’ve abstracted as many kJ as you expended in chewing them), it’s possible to raise animals for food on land that would be unsuitable to grow crops for human consumption, and whatever it is that they do to soya beans to make them into vegeburgers must be using a fair bit of energy (and probably isn’t any less unpleasant to watch than a cow being slaughtered).

    The trouble is, nobody’s doing the research who hasn’t got an agenda to push, and governments are in the pockets of big corporations whose agenda is definitely for the short term.

  32. #32 Steve
    December 8, 2006

    AJS –

    That’s a common objection, but inaccurate; Meat animals can – and often are – raised on land that is not useful for plant food production. It’s really only particularly relevant when the system (as we have today) is poorly implemented. We take animals that are perfectly capable of eating scrub grass and other vegetation and feed them grains and plant foods that we’ve spent a lot of time, money, and water on. So one can certainly reasonably argue that a particular method of animal meat production uses more energy per kCalorie supplied, but it’s extremely difficult to support the categorical statement.

    Which leads me back on-topic, sort of. ALL of the energy debates are politicized beyond all rational analysis. There is one important point that should be noted – there is NO form of non-polluting energy when viewed in the context of our ever increasing demand for it. Every joule of sunlight redirected from its destined impact with the earth or plant is one that doesn’t perform the task it’s done throughout history in producing this environment. If we pump geothermal energy up to a processing plant, we will resitribute the heat in such a way as to alter the environment… Sure, on small scales it’s negligible, but when we start talking huge power production plants, the impact becomes significant.

    As has already been pointed out – if we reduced our energy requirements by 90%, this debate suddenly becomes long term and nearly academic… new technologies and improved efficiency is the only hopeful solution to these problems. Less hopeful are the global results of some future where energy production (in the form of oil) virtually halts and millions of people starve or die from other causes associated with the breakdown of the power infrastructure, or futures where the nightmarish predictions of the environmental alarmists are realized and population is reduced that way.

  33. #33 jpaulr
    December 9, 2006

    Slightly off-topic, but the geothermal comment by Steve reminded me of this –
    I saw a paper a little while back about how large scale wind-farming(read: Huge, Kansas sized, or maybe even a few midwest states combined, in total of course) would be able to pull enough energy out of the air to seriously effect climate. Kinda cool when you think about it, but it would only affect climate patterns and not global warming (the heat’s still stuck on Earth).

  34. #34 ytba
    December 10, 2006

    In response to my post above,
    there is the following comment…
    “And forest clearing for fuel plantations is now the greatest consumer of rainforest.”

    While I don’t know if the extent of consumption is that great, but it isn’t good…

    “Spring in Malaysia is even more silent than it was when I reported how the indigenous jungle is being destroyed to provide palm oil for the Soil Association’s “environmentally-friendly” pesticide soft soap. More great swathes of the eco-system are being replaced by oil palms to supply Europe with the biodiesel it must have by next year to comply with Directive 2003/30/EC requiring 5 per cent of road fuel to come from biological sources.

    there’s also this confirmation of that phenomena…


    Investors are pouring billions of dollars into “renewable” energy sources such as ethanol, biodiesel and solar power that promise to reduce the world’s reliance on petroleum. But exploiting these alternatives may produce unintended environmental and economic consequences — fallout that could offset many of the expected benefits.

    Here on the island of Borneo, a thick haze often encloses this city of 500,000 people. The cause: forest fires that have blazed across the island, some of which were set to clear land to produce palm oil — a key ingredient in biodiesel, a clean-burning diesel fuel alternative.

    Whenever we respond to a perceived problem in a knee-jerk fashion, we almost always create more of a problem than we solve. When there’s too much of politics, and not enough good science, the outcome is virtually never good.

  35. #35 ytba
    December 10, 2006

    (the heat’s still stuck on Earth). — jpaulr | December 9, 2006 12:15 AM

    Um, not exactly, if this is correct, and it sounds like it to me. In fact, it’s one of those, ‘Why didn’t I think of that’ pieces.

    “Sunday, December 10, 2006
    What is the maximum temperature of the Earth?

    To sum it up. There’s a point at which temp maxes out, and the earth’s history is a constant cycle from low to max to low, etc. AND we are right now very near the maximum, and even if humans have any input, it’s only in the frequency of the cycle, not it’s amplitude.

    i.e., global warming is a con-game that some power mongers are foisting on us for their benefit, not ours.

  36. #36 roystgnr
    December 10, 2006

    To sum it up. There’s a point at which temp maxes out, and the earth’s history is a constant cycle from low to max to low, etc. AND we are right now very near the maximum

    Your summary appears to be inaccurate, since the page you linked to says that the current average temperature is 3 Kelvin above their theoretical maximum. It seems likely that “Greenie Watch” has published their theory prematurely.

  37. #37 Gary Dikkers
    December 11, 2006

    Despite the disparate studies about whether making corn ethanol has a positive or negative return on energy invested, it’s actually quit easy to decide with a simple experiment.

    The “Connect the Output to the Input Test”

    Ever since the US Patent Office (USPO) has existed, it has received a steady stream of proposals for perpetual motion machines. (Machines that will generate more energy than they use.) Very early in their existence the USPO asked those petitioners to perform a simple test before they would issue a patent. The patent inspector would say something like this, “Please connect the output of your machine to the input and let’s see if it keeps running.”

    Of course as we all know, none of those machines have ever defied the Second Law of Thermodynamics and continued running, and the USPO has yet to issue a patent for a perpetual motion machine.

    That leads to a simple question: Why has no one ever asked the corn ethanol industry, “Please connect the output to the input and let’s see if it keeps running?”

    I would like to see Congress ask the corn ethanol and agribusiness to pass that test before sending any more tax credits and subsidies their way. Ask the corn ethanol industry to set up a demonstration where a corn farm and ethanol plant are powered SOLELY by the ethanol the plant make. Let’s see if the ethanol from that plant can supply enough energy to keep the system running.

    Of course the ethanol industry and agribusiness would never do that voluntarily — they would have too much to lose. Their world would be turned upside down if we saw that an ethanol production system actually lost energy and could not power itself with its output. But that doesn’t mean Congress and the American people shouldn’t ask them to pass that test.

    That would be the ultimate way to find out the truth about the net energy balance of making corn ethanol, and help us decide whether corn ethanol is actually leading us down a dead end road. If the “connect the output to the input test” failed, we could then spend our limited resources on research to find more lucrative renewable fuels that would actually solve our energy crisis.


    Gary Dikkers

  38. #38 Tracy W
    December 12, 2006

    While all these discussions are fascinating enough from a technical viewpoint, from a policy viewpoint they’re irrelevant.

    Remove the subsidies, tax the pollutants (eg carbon emissions, methane emissions), etc, and let people make their own choices about which fuels to use. If ethanol really uses more than one gallon of oil to produce a gallon of ethanol, then it will be inherently more expensive than oil and no one will buy it. If ethanol doesn’t, or there’s some technological change that means ethanol uses less, people will switch to ethanol.

    You may want to put some of the tax money into basic research into environmentally friendly energy sources, or energy efficiency, but there’s no reason for a government to subsidy particular technologies. Or at least, no environmental reason.

  39. #39 Aaron F.
    December 17, 2006

    But the human digestive tract is too short to derive nutritional value from many plant sources (i.e. you sh*t them out before you’ve abstracted as many kJ as you expended in chewing them).

    Human digestion of meat would have to be way more efficient than digestion of plant material in order to offset the energy lost in the conversion from plant to meat. If a meat animal, like a cow, stores S percent of the energy it consumeds, and humans turn Ep percent of plant energy and and Em percent of meat energy into useful work, then we would have to have Ep / Em < S for meat-eating to be more efficient overall. The most-commonly-cited estimate for S is around 10%, so meat digestion would have to be ten times as efficient as plant digestion to offset that cost. Since my general impression is that the human digestive tract seems fairly omnivorous, not optimized for the consumption of either meat or plants, such a large efficiency gap would surprise me.

  40. #40 Aaron F.
    December 17, 2006

    Aack! Sorry about the open tag… the preview button apparently turns &lt; into < in the original comment source… 🙁

    But the human digestive tract is too short to derive nutritional value from many plant sources (i.e. you sh*t them out before you’ve abstracted as many kJ as you expended in chewing them).

    Human digestion of meat would have to be way more efficient than digestion of plant material in order to offset the energy lost in the conversion from plant to meat. If a meat animal, like a cow, stores S percent of the energy it consumeds, and humans turn Ep percent of plant energy and and Em percent of meat energy into useful work, then we would have to have Ep / Em < S for meat-eating to be more efficient overall. The most-commonly-cited estimate for S is around 10%, so meat digestion would have to be ten times as efficient as plant digestion to offset that cost. Since my general impression is that the human digestive tract seems fairly omnivorous, not optimized for the consumption of either meat or plants, such a large efficiency gap would surprise me.

  41. #41 David Marjanović
    December 19, 2006

    To sum it up. There’s a point at which temp maxes out, and the earth’s history is a constant cycle from low to max to low, etc. AND we are right now very near the maximum, and even if humans have any input, it’s only in the frequency of the cycle, not it’s amplitude.

    This is either kookery or a simple straight-faced lie.

    I mean, look. We still have ice on Greenland — I’m not even talking about East Antarctica, I’m talking about GREENLAND, yes, I am shouting — and these f***ing morons claim we are “very near the maximum”?!?!?

    Just 50 million years ago there wasn’t any inland ice anywhere on this planet, and that was nowhere near the maximum of the last 200 million years.

    And 4.5 billion years ago, when we had carbon dioxide instead of oxygen in the air, the global average temperature is estimated at 70 °C…

    What next? Tyrannosaurus on Noah’s ark?

  42. #42 Ike Solem
    January 28, 2007

    One of the problems with analyzing these ‘energy cost estimates’ is that it’s that they are attempts to come up with complete life-cycle energy costs, rather then an energy cost for a single A -> B process.

    For example, let’s say you are firing up a boiler in order to distill ethanol and letting all the heat produced escape to the atmosphere; then you put in a turbine system that uses that heat/air flow to generate electricity that powers much of the plant’s electricity costs (lights, motors, etc.) – for that stage of the process, you might have improved efficiency by 50%, and it’s easy to figure out – just compare the plants electricity use before and after the heat capture system was put in.

    However, for ‘life cycle’ costs you might have a hundred steps, many of them linked to other energy and economic processes; say you use wind or solar power as the energy source for distillation – do you count the sunlight as an ‘energy cost?’ Also, if you look at corn kernels, they have protein, oil and sugars in them – and only the sugars go into ethanol; the corn protein can go to many uses, as can the corn oil – so do you assign the costs of initial corn treatment to oil production, protein production, or sugar production? You can go on and on like this, and depending on the result you want to see it is very easy to fudge the numbers in any direction.

    Thus, any decent ‘lifecycle energy cost’ estimate for ethanol should (as the author points out) apply the same methodology to gasoline production from crude oil, and should also have very clear diagrams indicating what goes into the lifecycle cost estimate, and should also produce a range of estimates – i.e. a variability estimate – for example, if you save 1% in energy at stage one, how does that change the final output, compared to a 1% savings at the final step – this kind of honest analysis also helps people decide where to focus their process engineering improvement efforts.

    I haven’t seen a single example of a decent energy estimate based on these principles – apparently, everyone who does this has some ulterior motive in mind.

  43. #43 j
    March 13, 2007

    60% of the corn is used in animal feed, the idea is to use the high carb byproduct of ethanol for animal feed instead of straight corn. This can actually be better for feed than high sugar corn.

    Many of the food uses for corn such as high fructose corn syrup do no digest correctly or work with our pancreases as they do with sugar. Honeybees are dying from corn syrup,etc. (If we were to evaluate the diabetes and weight impacts of some corn products for humans, ethanol would look like a better application and prices would stabilize. Though farmers honestly need to be able to make a living and their costs have gone up.)

    The dual output from ethanol processing needs to be factored in to your energy use calculations, as you will be generating feed and ethanol with the same expenditure of energy.

  44. #44 Steve
    October 8, 2007

    Every ethonal exagerates the carbon emissions of their product. I am a Mechanical Engineer, and recently discussed this with a colleage a Chemical Engineer. First we must know where all fuel gets it energy.
    CxHy + (O2+2.76N2)~ A*CO2 + B*H20 + N2 +(NOx + CO + MISC)
    This is from memory it may not be 100% correct but it will surfice. Basically the power comes from splitting the carbon and hydrogen. All fuels must do this, so greenhouse emissions per HP produced is the practically the same +/- 20%.
    Second, the assumption that since the crop absorbs CO2 that we do not have to count the CO2 emissions is bad, no horrible math! If you disagree answer these questions. If I burn off my field this fall, do I emit more green house gasses than if I just let it die out? Due wood burning stoves produce greenhouse gasses even if you plant a new tree? Of coarse burning it produces more greenhouse gasses. Technically if we use this logic and slowed our consuption gasoline would not be producing any carbon emissions since oil is being generated. So, unless you are cultivating a desert, the equation must read like this. Carbon burned by the car +carbon to produce ethonal-Carbon obsorbed by the plant – carbon absorbed by natural vegitation.
    Finally it takes 2 gallons of ethonal to produce 3 gallons. Lets assume corn absorbs 20% more carbon than natural vegitation, and ethonal produces 20% less greenhouse gasses than gasoline. Now lets do the calculation.
    .8 Carbon Gas + .8*2/3 Carbon Gas=1.336 Carbon Gas
    1.336*.8Carbon Gas will equal 1.07 Carbon Gas<1 so ethonal is worse.
    One more assuming everything is equal.
    1.67 Carbon Gas. I believe the best ethonal can do is equal the greenhouse emissions of gas.

  45. #45 Don
    December 30, 2008

    I have been involved in agriculture for over 40 years, and ethanol from grains is not and never will be a viable source of power. Ethanol has 66% of the energy of Gasoline. I also believe that any industry that needs a government subsidy is not a real industry. We have subsidized agriculture for 60 years and it is time to stop all subsidites including those to banks, auto industry and agriculture.

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