April 17, 2005
Is Corn Ethanol A Good Energy Source?

Mike Millikin of Green Car Congress reports on arguments about whether corn ethanol is a net producer of energy, of general harm to the environment, and of CO2 emissions.

To that list, on the con side, I would add a paper by Tad W Patzek. Patzek, a professor at UC Berkeley’s Department of Civil and Environmental Engineering, who had earlier authored a paper with Pimentel, one of the energy critics of ethanol, has recently updated (24 March 2005) a paper, Thermodynamics of the Corn-Ethanol Biofuel Cycle.

It’s an interesting and detailed paper, and in it he reviews and corrects the assumptions and calculations of both primary pro- and con- ethanol factions (including some of his earlier work), while making new calculations of his own. His conclusion is that corn ethanol is a net loss to the environment and in energy, and a net contributor of CO2. Nor is he particularly keen on biomass-based ethanol, as a paper published earlier this year (with Pimentel) details. Patzek would prefer the research money (and crop subsidies) flowing to ethanol and corn production go instead to solar and hybrid research.

Corn ethanol research is funded because the farmers are a powerful lobby, not because it makes sense to grow corn for energy. Though maybe some day a way will be found to take the left-over cornstalks and convert them into ethanol for less energy than it takes to do the conversion.

Nobel Prize winning physicist Steven Chu argues for biomass using cellulose.

The US already subsidizes farmers to grow corn to turn into ethanol, but $7bn in the past decade has been wasted because the process isn’t carbon-neutral. “From the point of view of the environment,” explains Chu, “it would be better if we just burnt oil.”

“But carbon-neutral energy sources are achievable. A world population of 9 billion, the predicted peak in population, could be fed with less than one third of the planet”s cultivable land area. Some of the rest could be dedicated to growing crops for energy. But the majority of all plant matter is cellulose—a solid, low-grade fuel about as futuristic as burning wood. If scientists can convert cellulose into liquid fuels like ethanol, the world’s energy supply and storage problems could both be solved at a stroke.“

Mike Milliken also reports on efforts to drive down the materials cost for corn ethanol conversion by development of cheaper enzymes.

Regarding the reference to a paper by Tad W Patzek with David Pimentel of Cornell University on whether corn ethanol is a net producer of energy: This debate has been raging for years. Michael Graboski of the Colorado School of Mines has taken the opposing position that corn ethanol is a net source of energy. I have not read their papers and can not comment on the question of which side is right. But be aware that it is not a settled question and that some sharp engineering minds think corn ethanol is both bad for the environment and a net energy drain.

Biomass has some other big downsides. The most obvious is that if it is produced by growing crops for biomass then it will increase the demand for cultivable farm land and water. In industrialized countries increases in productivity of farms have been decreasing the amount of land and water needed for farming. While some of that freed up land gets used for building residential and business areas a significant portion of farmland in the United States has reverted to nature. But biomass could easily reverse that trend in the United and speed the already problematic encroachment of human habitats on nature worldwide.

Cost effective biomass would also make food crops compete with fuel crops for cultivable land. This could have the effect of driving up food prices. This would be especially problematic in the poorest countries.

By contrast solar panels do not need cultivable land. When photovoltaics and other solar energy collection devices become cheap enough for widespread use most solar collectors will be attached to buildings and given enough advances in materials science photovoltaics could be built into roof shingles and siding. Solar panels that are installed on land can just as easily be placed in a desert that supports relatively less wildlife. The solar panels will not need to be watered or sprayed with insecticides. Therefore they will not deplete water tables, lead to the build-up of salt in soil, or cause pollution in the form of agricultural run-off.

Wind energy is similar to solar energy in that lends itself to dual uses of land. Wind towers can be build over food crop farm fields since the shadow that a tower would cast would move during the day and crop plants near towers would still get the bulk of the light that they would get in absence of the towers. But not all towers will be built on farmed lands. Operators of wind towers will tend to want to build them in mountainous areas with high winds and along shorelines and thereby ruin some beautiful scenic vistas.

Share |      Randall Parker, 2005 April 17 12:40 PM  Energy Biomass

gmoke said at April 17, 2005 1:35 PM:

"When photovoltaics and other solar energy collection devices become cheap enough for widespread use most solar collectors will be attached to buildings and given enough advances in materials science photovoltaics could be built into roof shingles and siding."

Uni-Solar 17W Photovoltaic Module Roofing Shingles. 1-Pack - $126.79 - BuilderDepot
Uni-Solar 17W Photovoltaic Module Roofing Shingles. 1-Pack - $126.79 - SHOP.COM

Solar roofing shingles have been available for a couple of years now commercially and GE, among others, was doing prototype work on them since at least the 70s. You might also want to check out the Japanese and German solar markets which tend to be much more advanced than the US (thank you, Ronald Reagan).

back40 said at April 17, 2005 1:51 PM:

There's another consideration for mixing wind farms and crop farms. Wind towers alter micro-climate by mixing atmospheric layers. Genrally, this means increasing heat at ground level. There are good points and bad points. Sometimes frost is a threat, such as to citrus orchards in winter, so warmer ground temperatures, especially at night, are good. Warmer temperatures in general increase water usage, which is a major factor for summer row crops such as maize and wheat. Rainfall is one of the primary determinants of yield and hot weather retards growth. It can be too cool as well, but that is rarer. Unfortunately the wind is often still at night, especially when frost is a threat, so wind farms may not deliver higher ground temps when most needed.

The idea of dual use isn't as simple as it sounds. The initial or primary use is degraded by the second use. We lack good data to quantify and evaluate the net benefits but it is certain that using crop areas for wind farms is not a cost free alternative to using scenic mountain and coast sites.

Dave said at April 17, 2005 2:00 PM:

Having been raised in northeastern Montana (though now in coastal Oregon) I must take exception to the following statement though I do recognize the qualifying aspect of "tend":

"Operators of wind towers will tend to want to build them in mountainous areas with high winds and along shorelines and thereby ruin some beautiful scenic vistas."

There have been plenty of wind studies (lots of sun too) done in Valley and the surrounding counties (Phillips, Daniels, etc.) to suggest that efficient wind and sun potential lies in areas not considered by most people to be scenic.

Existing 230kv lines come out of the generators at Fort Peck dam and are put into the nets that orient to Seattle and Chicago. While these lines are insufficient to handle excess power from wind or photovoltaic output the rights of way should be sufficient to handle much more power distribution should the Corps of Engineers permit further construction of power lines.

Literally tens of thousands of SQUARE MILES of Montana and North Dakota have consitent wind and sun to generate power and are on the path between major metro areas.

While most of us who grew up in that area (or still live there) might have some peculiar fascination with the area most
of you would find the country barren and ugly. Oh yeah - there is some coal and oil (dinosaur fossils too) there
also - but who's counting?

gustable said at April 17, 2005 3:06 PM:

It's sad to see that the United States, and specifically the Republican party are so backward and unwise as to not only elect a nincompoop like Geeorge W. but to allow the U.S. to regress under his leadership to where we are actully ending up a whole generation behind the Deutsch in energy. During Democratic days, we were the world leaders in solar and other alternative energies, but now of course we are reverting to an old technology (see the recent debate on nuclear power) that the Germans are in the process of leaving behind. With solar energy where it is today, the entire U.S. could be running on solar panels. Not every roof gets sunlight in the summer, but most do, and according to the above post, solar shingles are only twice as expensive as normal composition shingles. The sun is responsible for all of the energy here on earth including fossil fuels, but its our responsibility to harness it cleanly. Wind farms up north and gasified coal plants that inject their CO2 into the earth could keep us going through winter until synthetic hydrocarbon solar-systems allow us to overproduce with photovoltaics and store energy long-term.

There is no need to go nuclear again when so many clean and renewable resources are out there. Ethanol has long been known to be energy intensive to create. While photosynthesis to cellulose is a very efficient process...it is also very slow, and cellulose is of course a nigh-useless energy storage material. Not only that, the natural carbon sink afforded by plant life is crucial at this time, and the monocrop ag production systems we use not only deplete ever lessening water resources, but deplete the soils of their natural nutrients and gradually salt them as well with their chemical treatments. So in essence, using biomass on a large scale is like trying to build a hydrogen infrastructure...really stupid!

Recently I read about a farmer in Illinois who received temporary ATF permission to buld a solar still and had a small battle with the government over this issue. He has managed to build a machine that uses solar heat to turn his wheat crop into ethanol. This process is fairly efficient and entirely renewable...if he uses an ecologically sustainable growing practice, yet on a small scale it is really ideal. He produces enough fuel to last his farm all year long. (http://www.motherearthnews.com/library/1979_March_April/Mother_Is_Making__Fuel_)

In short, during this time of energy crisis, there are so many different sources of energy that we can look towards, but in the end, the fact is that all that energy originally came from the sun. That means that our real quest is to find the most efficient means of getting it.

Untrover said at April 17, 2005 4:27 PM:

The uninformed continually harp on solar and wind. I've installed several solar and wind systems myself. It's great for off-the-grid installations, and for places where you can count on them, or use them to supplement the grid. I've got a micro-hydro installation at my mountain property. It's fantastic.

But it's very stupid to assume they can replace nuclear, coal, gas, oil, or biomass if it becomes widely available. An energy source must be available all the time to meet variable loads. Academics don't know what the hell they're talking about when it comes to electrical load matching.

Randall Parker said at April 17, 2005 4:39 PM:


You have to separate what is possible today from what will be possible tomorrow. I do not see why it will always be impossible to build photovoltaics cheaply. I also do not see why batteries can not be made to be higher density and cheaper eventually. There are plenty of indications that advances can be made in both these areas to drive down costs. I've posted on this previously. See my Energy Tech archives.

With sufficient advances in storage technologies we will be able to use many energy sources which are not available all of the time. Cheap high capacity batteries will eventually be enabling technologies for solar and wind energy and would even increase the value of baseline energy generators like nuclear by allowing more of the demand to be shifted away from peak hours.

The problem holding back solar is the cost of photovoltaics. Come up with a cheap enough way to make photovoltaics and it could be used initially to reduce natural gas and coal burning for electricity during daylight hours. This is a solvable problem with a larger research effort. But eventually with better energy storage technologies photovoltaics could supply energy for around the clock use.

J. D. said at April 17, 2005 6:36 PM:

Political rantings and ravings aside renewables will not support the world's energy needs. Biomass in a large implementation is fruitless and wastefull. Until there is vast improvement in energy transmission and storage both solar/wind/wave are bit players. Clean coal is not very practicle either since fluid bed combustion is also low temperature and therefore more ineffecient combustion. As an example the great fanfare about the Alaska clean coal project in Healy Alaska died last year with little public comment due to the high cost, fragile nature of the equipment and just overall un-reliability.

Those who are support renewable only will not be convinced by anything I print as I will be totally un-moved by what they expouse. Twenty years from now we'll see who's right.

gmoke said at April 17, 2005 7:33 PM:

Every society and economy on this planet has always been solar powered and probably always will be. Each one of us human beings is solar powered. The amount of sunlight that goes into into growing only the food we eat (which is, after all, what powers a human body) is on the order of three times the US energy budget ( I checked my back of the envelope calculations with David Pimentel of Cornell a few years ago). The problem is that economists do not count the contributions of sunlight to our economy because we don't generally have to pay for it.

Randall Parker said at April 17, 2005 8:30 PM:

The amount of sunlight energy required to grow crops can be spun two ways: On one hand it can be argued that we harness huge amounts of solar energy. On the other hand the amount of energy we extract from those crops to power ourselves is a very small fraction of the amount of light that falls on the crops when they are growing. So it can be argued that the efficiency ratio of how that solar energy is used is very low.

Look at corn ethanol as an extreme example. It is debateable whether the energy usage efficiency is even positive. Certainly Pimentel and Patzek do not think so. If we make the efficiency usage ever so slightly positive and then start using it to power cars that would be nothing to brag about.

Engineer-Poet has posted on energy usage efficiency with all sorts of neat insights. If I understand him correctly he believes that if we could switch to pluggable electric vehicles and yet still burned oil to generate the electricty this would improve the efficiency of the use of the oil.

Patrick said at April 17, 2005 8:38 PM:

One thing that's never mentioned is Geothermal.

It's currently done in a couple of places where there is a natural source, but it could be done anywhere if you just drilled a hole deep enough.

There is currently a project north of Sydney to investigate a pilot plant. This is a geologically very normal area, but with the latest drilling tech the backers claim it will be cost competitive with coal. And coal in Australia is very cheap.

There was actually a similar scheme devised in the 1960s to use underground nuclear explosions to make vast underground cavities which would be filled with water, and provide steam power for decades. So fusion power can be used right now, if anyone was desperate enough.

Rob McMillin said at April 18, 2005 8:02 AM:

As to the reliability of wind: yes, at the earth's surface, it's very unreliable. However, at around 15,000 feet, wind is constant nearly everywhere in North America. As a result, tethered kite-like devices become an interesting way to generate electricity. As the Engineer-Poet pointed out in the comments of my blog entry above, "If you can get wind power with an 80% capacity factor, you can pretty much run everything but chemical synthesis on blowin' air."

Geothermal: for that to work, you have to have very good siting (i.e., the heat source has to be pretty shallow). It turns out that California has a number of good sites, as does much of the intermountain west.

gmoke said at April 18, 2005 2:30 PM:

"The amount of sunlight energy required to grow crops can be spun two ways: On one hand it can be argued that we harness huge amounts of solar energy. On the other hand the amount of energy we extract from those crops to power ourselves is a very small fraction of the amount of light that falls on the crops when they are growing. So it can be argued that the efficiency ratio of how that solar energy is used is very low."

We should count solar energy the same way we count other energy resources. We do not take efficiency into account when we total the amount of oil, gas, and coal we use. We just count quads. Yes, the efficiency of photosynthesis is small but the input is enormous and photosynthesis is not our largest and only input from the sun. An honest, full-cost accounting of energy flows in society would be a useful first step toward changing our relationship to energy and the inefficienct ways we use it. (Exergy, exergy, exergy...).

Randall Parker said at April 18, 2005 3:35 PM:


You need to read E-P's Ergosphere site. He really does energy efficiency calculations and has posted tables comparing energy sources on this basis. Read his post on solar versus wood biomass area needed to support a household. Also see his post from a few months back on a new kind of photovoltaic cell which includes some calculations on energy falling on areas humans have covered over.

Also, see his post on uses for wind power.

Also, check out his charts on where our energy currently comes from and note the efficiency column.

I wanted to find something of his about efficiency of power delivered to the wheel of a car but can't find what I was looking for. If he sees this does he know a good post of his on this or could he write one? He argues (if I understand him correctly) that power delivered from a fossil fuel burning electric generating plant to a car to batteries will be more efficiently used than fossil fuel burned in a car. I'd really like clarification on that.

Cory said at April 20, 2005 6:54 AM:

Great debate but in the end, powerful lobbyists for existing industries with infrastructure investments will dictate the future policy of renewable energy. The solar industry was set to take off in the late seventies only to be crushed by these interest groups. Tax breaks disappeared and companies on the forefront of research were swallowed up by competing big business and mothballed.

The recent research being conducted in China on pebble-bed nuclear reactors holds great promise for launching a hydrogen economy. Americans need to demonstrate the political will to change course and ween
themselves from dependence on the Middle East and fossil fuels. A phased approach of Hybrid dual-fuel autos, incentives for solar and wind investment, and a new look at safer nuclear power generation would help create jobs that we are losing to China and keep our dollars at home (and out of the hands of US-haters).

Bob Badour said at April 21, 2005 9:48 AM:


Why do you think a conspiracy that killed solar in the 1970's? Has it occured to you that market economics rightly killed it for lack of competitiveness?

After all, crude prices went back down instead of soaring to the prices predicted by the doomsayers at the time. Market interference and curbs on competition held crude prices high back then, and when the interference stopped (ie. when Saudi decided to opt out of the price fixing scheme) the price went down.

I suspect we now see crude prices increasing to the point where other energy sources become competitive. However, coal and natural gas remain more competitive than solar. As demand for energy increases to the point where it pressures the ability to supply natural gas and coal, the costs of those sources will increase as well. At that point, other sources of energy will become competitive. I have no idea whether the competitive sources at that time will include solar or wind instead of some other energy source.

Solar's day will come when it becomes competitive with all the other substitutions.

Cory said at April 21, 2005 12:13 PM:


Valid points but there have always, and will remain, early adopters who are willing to pay more for new technology.
These tend to be the "seeders" of inovation and change. Solar was embraced by early adopters and environmentalists who saw the future. When Congress eliminated tax credits for home systems, the rug was pulled out and the existing fossil fuel infrastructure let it die on the vine and/or bought up and shelved the promising technologies and research (to your point, less conspiracy than practical economics).

My point was that we Americans will complain about the high price of gas for our SUV's and 3000 sq.ft homes. We are all too willing to jump onto the political pundit bandwagon by buying into causes for our dependence on foreign oil (Iraq: blood for oil, Government collusion with oil producers, untried technological hurdles for extracting US oil, etc., etc.) but when push comes to shove, we don't have the backbone to drive a policy change. Even the "so-called" environmental lobby can't provide a coherent plan to rally around (decrying the use of nuclear energy for the waste issue while never questioning why a pre-WWII technology sponsored by the Navy for powering submarines continues to be our "best effort" at addressing cheap electricity.

Where is the advancement in more efficient fractional motors? Smart appliances? Fuel-cell powered electronics?
The lack of progress is directly proportional to consumer and government backing and will to convert. I guess I
expect a little vision from "Joe Budweiser". Unfortunately, he is on the couch, drunk and happy with the remote in hand.

gmoke said at April 22, 2005 1:41 PM:

"Why do you think a conspiracy that killed solar in the 1970's?"

Well, the Reagan administration came into power and closed down the Solar Energy Research Institute in such a way that researchers there reportedly felt like the message was "get out of this field and stay out." Reagan also cut the tax breaks for solar and reduced the monies available for research and for energy conservation. He took the solar panels off the White House that Carter had installed. His people tried to suppress the last report by Carter's Council on the Environment which called for 20% renewables by 2000....

Not a conspiracy but a set of policies and actions that was formulated to cut renewables off at the knees.

BTW, I have never seen a poll in which the support of renewables over the other alternatives is less than 70%. Not once since the first energy crisis under Nixon. There has always been a superduper majority for more investment in renewables and efficiency over coal, oil, gas, and nuclear and there has never been funding at commensurate levels. Once, I did a back of the envelope estimate of subsidies for renewables and fossil/nukes from 1950 to 1980. It came out to be about $6 billion for renewables as opposed to $60 billion for the "conventional" sources.

Last time I testified at a public hearing on energy policy, I asked the panel of experts whether any of them knew what the Paley Commission was and what its recommendations were. None of them knew. The Paley Commission was set up by Truman to examine the strategic materials and energy resources of the US and recommended that we lower our dependence on fossil fuels and switch to renewable resources like solar for energy. Circa 1952.

"Them that's got shall get, them that's not shall lose
So the Bible says and it still is news.
Mama may have
Papa may have
But God bless the child that's got it's own."

Not conspiracy but policy. Wake up and smell the crude, dude.

Douglas Hvistendahl said at July 3, 2005 12:28 PM:

Some technologies make sense right now - if one is willing to input the work needed to install them. For example: look at www.annualizedgeosolar.com. This method of heating/cooling a low-rise can be added to an existing house, using conventional materials. I'm doing it here - estimate is about three years spare time activity and probable heat bill near zero. Not bad for North Dakota! As for ethanol - I'm using it not because it is the best possible, but because businesses tend to pay more attention than politicians, if we vote with our dollars.

Stephen Brubaker said at September 15, 2006 5:00 AM:

Thanks for posting Patzek's paper! It strikes me as being a very well-considered view on the topics of corn ethanol and sustainability. We really need more work like his to inform public opinion. Too many academics appear to have traded common sense and interest in a common good for chasing the latest sexy research idea and getting the next research grant.

I completely agree that conservation itself is not the whole solution; but progress on more efficieint energy utilization has several great benefits
1) It buys us precious time
2) It places lower burdens on alternative fuels when they finally become available.
3) It begins paying out immediately.

While I understanc Chu's motivation in arguing for biomass - namely as a solution to the global warming problem - I have spent just a little time looking at the issue and I see a number of serious the problems with it.
1) existing waste streams would provide less than ten percent of needed fuels
2) the conversion efficiency of sunlight to sugars tops out at about 6 percent. Transforming these into ethanol uses perhaps 30-50% of the balance. The locations suitable for 'growing fuel' are all pretty much committed to 'growing food.' This alone would be bad enough but
3) we are already 'mining' soil. We extract more from it than it can produce. And we make up the difference with fertilizers - which are derived from oil. When the oil is gone, we will need to add MORE BIOMASS to the soil than we do now. If we are to have anything to eat.
4) food production is not really very far from being maxxed out ( without changing diet in unfavorable ways.) There is hope for a new "green revolution" by inventing grains that fix their own nitrogen, but it takes about five sugar molecules to make one molecule of nitrogen, so crops that fix their own nitrogen - while they are beneficial - will probably come in with lower yield.
5) solar technologies, by comparison, have higher conversion efficiencies than photosynthesis. And they can be installed where they do not displace plants - namely in places where it is too dry and sunny. ( When I worked in that industry fifteen years ago I discovered that at 8% conversion efficiency and 20 year life, a pv panel may never deliver the total energy required for its manufacture, so efficiency and manufacturing technologies have to improve...)

If there is a biogenic solution - and I hope there will be - then it will be something akin to using algae to generate hydrogen and harvesting that. And the solution will be implemented in flat, dry places like the Australian outback and eastern Montana.

America made a great mistake, IMO, by not pursuing nuclear. By all rational criteria a breeder reactor program with very stringent control of fuel would go far in bridging the gap to other sustainable power sources. It avoids CO2 emissions, it is ideally suited for 'baseline' use without storage. It is more cost effective than fossil fuels (will be soon.) The Japanese and the French are doing it, so it is not a matter of a lack of technology. If we seriously imagine what it would be like without energy, and then we compare the fallout from Chernobyl to the fallout of having insufficient energy, I think it is easy to prove that, until all our promising renewable sources stop promising and start delivering, we need this source to bridge the gap.

Energy is, literally, the lifeblood of civilization. Anyone who has read Jared Diamond's Collapse will agree that without adequate resources civilization will collapse. Others have argued that it was when the Easter Islanders, the Greenlanders, the Anasazi, and the Maya ran out of fuel that their civilizations collapsed. We might do well to learn from their mistakes.

shidoobyshattered said at April 11, 2008 4:27 PM:

The idea that "[solar and wind] can replace nuclear, coal, gas, oil, or biomass if it becomes widely available." is rooted in the idea that coal, gas and oil aren't forms of solar energy.

I'm with you the nuclear part, but in the end the rest is an inaccurate statement. Pumping out the gooey corpses of dead dinosaurs and ancient plants - that which people so commonly call "coal, gas and oil" - is just a very inefficient form of solar energy.

Those plants, eons ago, grew from the sun. Those dinos and bacteria ate the plants (and ate other dinos who ate plants). This stuff is almost 100% solar power. The melting blobs of gooey corpses are effectively just "batteries" which store the ancient remnants of that solar power, in their own form of untapped energy (until we go through the very dirty and inefficient process of tapping the resource). It is just a very dirty, very inefficient form of solar power. Just because a nasty form of "quick fix" energy is located underground somewhere, doesn't mean we're compelled to use it. There are cleaner ways to get energy from the sun, without setting fire to a bunch of gooey corpses.

So its like this: "Hey! I found some batteries buried in my back yard! They're very inefficient, they ooze toxic waste, they belch poisonous smoke, and they're not capable of being replenished ... how about I power my house with them! How about we power our whole society with them! We'll just dig them up and keep finding them, oozing with toxic waste, and soon our whole society will depend on them. Yay!"

What a bad set of choices. But luckily, we can back away from this crummy choice we mistakenly made (this was decided back during a time when people thought sticking leeches on their bodies would cure just about anything).

If the molten goo of inefficient corpse-based energy is so great, then ... what next? Maybe when the old corpses run out, we can start burning more recent corpses? Maybe try to melt grandma down, and pour her into the gas tank? Some folks would seem to say "If its feasible, why not?"

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