Closed-Loop Ethanol Plant in Mead, Neb, Dec 06 Eliminates Need for Fossil Fuel in ethanol production

[JohnWxy]

http://www.genengnews.com/news/bnitem.aspx?name=7808903&taxid=48

MEAD, Neb., Oct. 30 /PRNewswire/ -- Dennis Langley, Chairman and CEO of E3 BioFuels, announces the Genesis plant will begin production in December 2006 at Mead, Nebraska, as the first-ever closed-loop system for distilling commercial quantities of ethanol using methane gas recaptured from cow manure, instead of fossil fuels. This virtually eliminates the need for fossil fuels in the production of ethanol.

The closed-loop system -- derived from an exclusive patent co-owned by an affiliate of E3 BioFuels -- combines a 25-million-gallon ethanol refinery, beef cattle feedlot, and anaerobic digesters to maximize energy efficiencies unavailable to each component on a stand-alone basis. This system eliminates the potential for manure to pollute watersheds, and it enables the wet distillers grain from ethanol production to be fed on-site to cattle without energy-intensive drying and transportation costs.

~~
~~

"The Genesis plant at Mead will be the first to market ethanol produced from closed-loop, self-sustaining ethanol technology by at least a year or two, in comparison to any other competitors," Langley said. "This plant will make ethanol more than twice as energy-efficient as any other method of producing ethanol or gasoline."

(more)

Given the opportunity, engineers, chemists and technicians will make improvements in the efficiency of this technology.

(apologies to anyone who may have already posted this not so new news_JW)

[jpak]

1. The Devil's Alchemy!!!

:evilgrin:

[Cosby]

2. Seems they forgot...

The huge amount of fossil fuel needed to grow, harvest, process and transport the corn in the first place. They start out in a hole, stop digging for a while when they produce the ethanol, and then start digging again when they have to distribute it...

[jpak]

3. Organic agriculture and biofuels can eliminate that...

n/t

[NNadir]

4. And maybe they forgot about the corn that feeds the cows.

I recall reading some figure about how many barrels of oil each cow represents, but I think it's rather large.

[Chemical Bill]

6. Vegetarianism is a separate issue.

Cow manure is free for the taking at this point. When everybody in the US is a vegan, then figure in the corn used to produce the cow manure. Until then, cowpies for everybody!!

Bill

[jpak]

9. Some people (not you) can't grasp the concept of a closed loop system

The plant operators don't feed the cattle corn to produce manure - they use the distillery mash to feed them, then collect the manure for biogas production.

corn -> ethanol still -> cattle -> manure -> biogas -> ethanol still

Low input and organic agriculture can produce corn with minimal or no fossil fuel inputs (and farm equipment can use biodiesel or ethanol too).

[NNadir]

11. Why? Because you wish to pretend cowshit is free?

It isn't.

Neither is the issue of Vegatarianism in any way separate from the use of oil. I actually knew this like 30 years ago, which is why I stopped eating cows. It was in the beginning totally an environmental issue. Now I have other issues with meat, but that's where it began.

As always the cowshit arguement is clueless cowshit, a pretend shell game that seeks to avoid reality.

[JohnWxy]

12. You stopped eating cows and switched to cow-shit? That explains your posts!

Just kidding. You probably don't eat cow shit. ...Do you? Was that you I saw with your head jammed under my cow's tail.

Seriously though, the cow shit is not free. It costs something to get rid of it and treat it as waste. THis way it becomes something of greater value.


... and no, I don't want to borrow your toothpick.

[Name removed]

13. Deleted message

Message removed by moderator. Click here to review the message board rules.

[kestrel91316]

35. And of course we know that there's no OTHER shit in the world

that could be used.

Human waste just goes magically into nothingness when you flush, silly.

[JohnWxy]

32. Only the starch content of the corn is used to make alcohol. the protein is recovered

and sold as high quality animal feed - Dried Distillers Grains.

NO loss of food nutrients.

[NickB79]

38. Carbohydrates aren't food nutrients?

The bacteria digest sugars in the corn into alcohol, which is siphoned off for ethanol fuel production. The remaining mash most definitely has fewer calories, pound-for-pound, compared to the starting product. It's nice they can feed the leftovers to livestock, but you can't claim it is just as nutritious if you've removed a sizeable amount of carbohydrates from it.

[Chemical Bill]

5. >They start out in a hole

Actually, they don't:

Research studies from a variety of sources have found ethanol to have a positive net energy balance. The most recent, by the U.S. Department of Agriculture, shows that ethanol provides an average net energy gain of at least 77%.

http://www.ethanol.org/talkingpoints.html

So while it takes energy to grow and process ethanol, it doesn't take more that you get. The technology described in the OP means that they use even less energy from fossil fuel than before. Why is that a bad thing?

BTW, how much fossil fuel does it take to transport fossil fuel?

Bill

[4dsc]

7. energy balance is a farse

Dr Wang latest statements about energy balance besicaly states it is not a very good source when talking about EROEI or ethanol in general!! I would take any statement that talks about energy balance with a grain of salt!!

But we will see if this E3 ethanol plant hold any promise.. I believe it would take over 20,000 cattle to run the plant at optimal levels.. That's alot of crap!!

[JohnWxy]

10. It's interesting to note that the fossil fuelophiles kept talking Energy Balance all the time UNTIL

Wang showed that the energy balance for gasoline is actually negative (.81 : 1 ) i.e. for every 1 unit of energy you put into drilling for, transporting and refining the oil you get out .81 units of energy in the final product. For ethanol, the latest figures recorded in studies (2004 time frame) are 1.67 to 1 for a 67% gain (1.77 to 1 - for dry mill plants, which the majority of ethanol plants now being built are). And Wang has stated the latest ethanol plants are turning in numbers of over 1.9 to 1. So now some fossil fuelophiles don't want to talk about net energy balance anymore.

Actually, Dr. Wang has always said JUST using Net Energy Balance alone is not so useful as there are more aspects to the use of a fuel - such as GHG emmissions. Ethanol releases less GHGs than gasoline and as less fossil fuel is used in the farming and producion of ethanol this will only improve.

from a report by Michael Wang:

"Though self evaluation of ethanol’s energy balance is easy to understand, it may not be useful to fully understand true energy benefits of fuel ethanol. A more complete way is to compare fuel ethanol with the fuels to be displaced by ethanol (i.e., gasoline). GHG emissions were simply ignored in some debatable studies."

AND as ethanol production uses less and less fossil fuels the GHG reduction numbers for ethanol will keep improving. As farmers learn they can use less nitrogen fertilizer, the GHG numbers for ethanol will only improve (fossil fuel is used in making nitrogen fertilizers). Iowa farmers reduced their usage of Nitrogen fertilizer by 16% and maintained or improved their yields compared to neighboring states farmers.

Other current developments include the application of ultra-sound to the ethanol production process (ultra-sound applied to the corn slurry before the fermentation stage produces much smaller particle size) results in a 30% gain in alcohol yield. Future ethanol plants will incorporate this in there designs.

[4dsc]

16. Wang was proven wrong..

I have to admit johnywx, you like to present OLD news here although its been debunked to support your corporate ethanol interests!!

[JohnWxy]

17. You really have a lot of faith in the principle of the "BIG LIE" don't you? Keep repeating it and

some will think it must be true. Michael Wang's research into ethanol (and his conclusion as to it's positive net return of energy) is being demonstrated to be true every day.

Either that or you are an idiot. I don't really want to know. You live in a world your own. I guess it's an idiots delight.



From the article published in the journal Science, stating the conclusions of Alexander E. Farrell,1* Richard J. Plevin,1 Brian T. Turner,1,2 Andrew D. Jones,1 Michael O’Hare,2
Daniel M. Kammen1,2,3 of University of California, Berkeley. They reviewed six studies of the energy balance (net energy returns) of ethanol. Among these studies was that of Michael Wang, of the Argonne National Laboratory, - U.S. Department of Energy which showed along with all the other studies reviewed, except for those of Pimental and Patzek, that ethanol has a positive net energy balance. Wang is a redognized authority in the field of fuel research.

rael.berkeley.edu/ebamm/FarrellEthanolScience012706.pdf

"To better understand the energy and environmental
implications of ethanol, we surveyed the
published and gray literature and present a
comparison of six studies illustrating the range
of assumptions and data found for the case
of corn-based (Zea mays, or maize) ethanol
(11–16)."


" Two of the studies stand out from the others
because they report negative net energy values
and imply relatively high GHG emissions and
petroleum inputs (11, 12). The close evaluation
required to replicate the net energy results showed
that these two studies also stand apart from the
others by incorrectly assuming that ethanol
coproducts (materials inevitably generated when
ethanol is made, such as dried distiller grains with
solubles, corn gluten feed, and corn oil) should
not be credited with any of the input energy and
by including some input data that are old and
unrepresentative of current processes, or so
poorly documented that their quality cannot be
evaluated."

11. T. Patzek, Crit. Rev. Plant Sci. 23, 519 (2004).
12. D. Pimentel, T. Patzek, Nat. Resour. Res. 14, 65 (2005).
-------------------------------------------------------------------------------------------------------------


Wang is a recognized authority in fuel/energy research and developed the GREET Model used by researchers in government, industry and the academia.

www.transportation.anl.gov/software/GREET/publications.html

GREET in Action (3.11Mb pdf); Argonne's Standard-Setting GREET Tool Models Fuel-Cycle Energy and Emissions Performance (451kb pdf) ...

GREET Is “Gold Standard” for Well-to-Wheel Analyses of Vehicle/Fuel Systems
Government, industry, and academic researchers are developing advanced vehicle technologies and transportation fuels to help reduce the nation's dependence on oil, lower greenhouse gas emissions and urban air pollutants, and boost energy efficiency. To assist these efforts, Argonne National Laboratory's Dr. Michael Wang has created a transportation analysis tool that allows users to accurately evaluate the energy and environmental benefits of such technologies and fuels.

The GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) software model addresses the need for truly comparative full fuel cycle (or well-to-wheel) analyses. Developed in a user-friendly Microsoft® Excel platform with a graphical user interface, the model is available to the public free of charge.

The Society of Automotive Engineers maintains that GREET has become a "gold standard" for well-to-wheel analyses of vehicle/fuel systems.

Users that can benefit from GREET include government agencies, the auto industry, the energy industry, research institutes, universities, and public interest groups. Already, more than 2,000 GREET users in both the public and private sectors are registered throughout North America, Europe, and Asia.

To date, Argonne has used GREET to evaluate various engine and fuel systems for the U.S. Department of Energy (DOE), other government agencies, and industry (see publications list). Other organizations have used GREET to evaluate advanced vehicle technologies and new transportation fuels.

[4dsc]

23. Changing your tune?? What Mr Wang says now

I guess our ethanol corporate hack will never come up with the latest about ethanol so here is what Mr Wang is stating now about energy balance.

http://i-r-squared.blogspot.com/2006/09/postscript-with-wang-and-khosla.html


What has been debated about bioethanol is ENERGY BALANCE, not energy efficiency. Energy balance is defined as the energy in the fuel minus FOSSIL energy input to produce the fuel. Why only fossil energy? That is because to many, fossil is non-renewable. As long as we use it, it will be gone, and it takes millions of years to get it back, if ever. But anyway, we can debate whether energy balance is a right matrix to use for energy policy evaluations. I, together with Mr. Khosla and many others, maintain that energy balance is NOT a good matrix for energy policy debates. But energy balance for ethanol has been debated for more than 20 years and it seems that there is still no way near an ending of this debate.

[JohnWxy]

26. Wang hasn't changed anything in his position. He has maintained for over 10 yrs that energy balance

is an inadequate measure of a fuels efficacy. YOu seem to be unable to understand what he is saying. Here is an extract from a widely known presentation by Dr. Wang comparing ethanol production to gasoline.


Wang's presentation comparing ethanol to gasoline

----------------------------------------------------------------------------------------------------------------------
We believe a recent Argonne National Laboratory study (Michael Wang, Center for Transportation Research, Argonne National Laboratory) has laid to rest some long-held misunderstandings about ethanol and its important role in reducing America’s reliance on imported oil and our greenhouse gas emissions. In terms of key energy and environmental benefits, cornstarch ethanol comes out clearly ahead of petroleum based fuels, and tomorrow’s cellulosic-based ethanol would do even better.


This figure illustrates the energy inputs used to produce and deliver a million British Thermal Units (Btu) of ethanol (EtOH) and petroleum gasoline to a refueling station.

(could not reproduce chart_JW)

As you can see, the fossil energy input per unit of ethanol is lower—0.74 million Btu fossil energy consumed for each 1 million Btu of ethanol delivered,

- - compared to 1.23 million Btu of fossil energy consumed for each million Btu of gasoline delivered.

{NOW PAY VERY CLOSE ATTENTION TO THIS PARAGRAPH_JW)

Some of the confusion arises over the fact that some of the total (not fossil or petroleum) energy used in the production of ethanol is “free” solar energy used to grow the corn in the first place. Indeed, if you include the solar energy inputs, it is true that you “spend” between 1.5 and 2.0 Btu to produce a Btu of ethanol… but since the solar energy is free, renewable and environmentally benign, we shouldn’t care.
-----------------------------------------------------------------------------------------------------------------------------
Now Dr. Wang's wording here is less than perfect, specifically the use of the word "spend". We didn't 'spend' anything to put the solar energy into the plants. What we did spend was energy to plant and harvest the crop which, of course, Dr. Wang took account of (to arrive at the "0.74 million Btu fossil energy consumed for each 1 million Btu of ethanol delivered"). The solar energy in the plants, as he said, came 'free of charge' (we don't have to pay for sunlight) so when you compute the amount of energy in ethanol compared to the total energy contained in the plants plus the energy to produce the crop and the ethanol fuel you get a invalid figure in that we didn't pay for the energy gained from the sunlight. The plants performed the photosynthesis for us without charge.

So again, if you look at the energy consumed to produce the crop and process the plants material into ethanol you get

For ethanol you consume .74 million BTU's consumed to produce 1 Million BTUs in the ethanol.

For gasoline you consume 1.25 million BTUs to get 1 million BTUs in the gasoline.


There is nothing in the email you pasted that contadicts anything in the above presentation.


Since 1996 when Dr. Wang developed these data the efficiency of ethanol production has continually improved. Dr. Wang has recently stated in public forums that the newest ethanol plants are producing ethanol at better than 1.9 to 1 energy output (in the ethanol) vs energy consumed. further improvements are expected (e.g. In 2006, Iowa State University filed for patent protection on a process using ultra-sound (which reduces particle size of the corn slurry prior to fermentation) and thus increases alcohol yield by 30%).

[4dsc]

37. old report typical

The remarks I posted by Dr Wang are remarks made after the report you cited.. Thsu any discussion about energy balance and ethanol are a waste of time..

[NickB79]

19. Oil EROEI numbers

"Wang showed that the energy balance for gasoline is actually negative (.81 : 1 ) i.e. for every 1 unit of energy you put into drilling for, transporting and refining the oil you get out .81 units of energy in the final product."

If that's true, what keeps the system going? If we've been losing energy with every gallon of gasoline refined for the past century, what other energy source has been making up the difference?

While it is true that refining oil at the refinery into gasoline is a net energy loser, the initial EROEI of crude oil is something like 30:1; ie one barrel's worth of energy can pump 30 barrels worth from the ground. 0.8:1 is only for the refinery portion of oil-to-gasoline production, not the entire drilling-to-pumping-to-gas station chain of events. The extremely positive initial EROEI offsets the negative EROEI in the final few steps.

[JohnWxy]

21. THE REAL COST OF GAS - International Center for Technology Assessment (CTA):

http://www.iags.org/costofoil.html

go to bottom of page and click on:

International Center for Technology Assessment (CTA): The Real Price Of Gas
This is a very long article so I just pasted the summary value for the low estimate of the price of gasoline. Basicallly, we subsidize the oil industry with tax breaks and what's called program subsidies. This cost of gas doesn't show up on the pump at the station but it is covered in your taxes. Figure about $2 to $3.00 per gallon of gas you use (this is without figuring in the cost of the Iraq war (did you think we went to Iraq to bring democracy to the Iraqees, or to find WMDs, or catch al Kaedas or Osama?}.

THE REAL PRICE OF GASOLINE

Low estimate: $5.60/gallon
---------------------------------------------------------------------------------------------------------------------------
Some estimates of the true price of gas are higher than $5.60 a gallon.

NOte this estimate was done in 1997 when the nominal cost of gas at the pump was less than it is now. So the final figure, now would be above $5.60 a gallon. In Europe they pay a LOT more for gas than we do. That's because they do not subsidize gas production nearly as much as we do.

NOte that this estimate was done BEFORE we went into IRAQ (you don't think we'd be worried about Iraqee democracy if there was no huge oil deposits under it do you?). Iraq is going to cost north of $400 Billion and more than 3,000 lives lost before we are out of there.

More and more people are sick of buying oil from those who would cheerfully kill us (and do kill us), given the chance. For these people, even if there was no cost advantage to home grown, GHG reducing ethanol it would still be worth it. There is a national energy security issue involved here.

[NickB79]

22. Yet we still have wars

Yes, I realize that the true price of gasoline is far above what it is currently sold at when you factor in the cost of waging wars to secure oil reserves. However, if oil production yielded an EROEI of less than 1:1, such as the 0.81:1 you claim, we would be fighting wars on horseback, not in oil-fueled tanks and armored vehicles. The fact that oil is valuable enough to fight massive wars over to obtain and protect furthers my point that it's EROEI is far above 1:1; otherwise no nation on Earth would or could fight for it.

If the true price of gasoline is $5.60/gallon, that means the true value of oil is far above 1:1 EROEI, not below it.

[JohnWxy]

27. meet the puppet master

[NickB79]

28. Dick Cheney can violate the laws of thermodyamics?

He can keep the world running for the past century on a fuel you claim is energy-negative,ie 0.81:1 EREOI?

Wow, that Dick Cheney sure is something.

You never answered my previous question: if we use more energy to produce gasoline than we ultimately get from it (EROEI below 1:1), then what has kept the world economy going for the past century?

[JohnWxy]

29. very simple. We have been tapping an energy store - billions upon billions of barrels of it.

As long as you have more of it to take out of the earth you can operate your machinery on it even as you burn your way through your supply. as long as you have a large store of this fossil fuel source you can keep on doing this (well, leaving out the somewhat serious problem of Global Warming) even if your system isn't all that efficient.(e.g. 19% loss of enrgy value in conversion of crude petroleum to gasoline).

Look, the use of fossil fuels, as long as the oil was relatively easy to get to was the best game in town (if you didn't care about CO2 emissions to the atmosphere, which we only began to recognize about 40 years ago). But with Global Warming as an issue and the fact that oil is getting more expensive every year makes renewable fuels a critical technology to develop. The problem with fossil fuels is that once you use up a barrel of it, that barrel is gone, forever. With renewable fuels you just replant your crop the next season and make more fuel from the same land. The source of your energy is the sun which is made available to you in chemical form by the plants through photosynthesis.

YOu can operate on fossil fuel, even inefficiently, as long as you have sufficient stores of it to keep drawing on. That's what we have been doing. But, the cost of oil has become high enough that some renewables are now competitive and the GHG problem also demands our attention. Renewables offer a better way to go, in this matter too, than fossil fuels.

[NickB79]

30. EROEI isn't about efficiency, it's about energy in vs. energy out

And anything less than a 1:1 ratio EROEI means we're using MORE energy to extract than we get from the extracted material itself. Such a system would quickly grind to a halt

For an analogy, say you worked a job where it cost you $50/day to drive to work and back. But, you only made $40/day in income. You don't continue to work that job because you are spending more than you are making. Similarly, if a company or nation is drilling an oil well but using more oil to power your drilling rigs, trucks, and oil tankers than you extract from the well itself, it will quickly go broke.

"As long as you have more of it to take out of the earth you can operate your machinery on it even as you burn your way through your supply."

At anything below 1:1 EROEI, you will be required to not only burn SOME of your supply, but ALL of it and then import some additional supplies to keep the system running.

[BR_Parkway]

18. Article says 28,000 cattle will be in the feedlot, and they're feeding them

the grain after it's been processed, so plenty of mildly intoxicated cows shitting all over the place.

In the October edition of Wired Magazine, venture capitalist Vinod Khosla writes, "It may surprise you to learn that the most promising solution to our nation's energy crisis begins in the bowels of a waste trough, under the slotted concrete floor of a giant pen that holds 28,000 ... beef cattle."

[JohnWxy]

20. one of the biproducts of ethanol production is dried distillers grains. Only, in this case it's not

dried (hence more energy saved). It's used as a feed supplement for cattle. It does not have any alcohol in it. (of course if it did you'd have more jovial cows - just kidding.)

[4dsc]

24. Bad cattle food too..

Cows evolved to eat grass, not distillers grains from ethanol plants. They can survive on DG, but it's not an optimum food for them as it requires antibiotics an other supplementals to keep them from getting sick on DG.

The livestock industry is also learning there are problems feeding hogs and poultry on DG.

[JohnWxy]

25. Anti-biotics have been given to cattle and chickens for years because they are crammed together in

very close quarters. This is an environment conducive to infections rapidly taking over a whole heard or flock. That's why antibiotics as well as supplements are given to them.

DDG is actually a better nutritionally than corn and other feeds. It's better absorbed by the cattle. .. very high protein content.

You got any more disinformation?

[NNadir]

36. Would it be disinformation to suggest that this system is abysmally cruel?

I mean really, sticking 28,000 solidungates on a metal grid so closely packed that they need massive doses of antibiotics while standing over vast piles of their crude oil generated shit?

Only a person completely lacking in a sense of decency would applaud this situation.

[JohnWxy]

33. for those who just arrived from the land of nod - a realitay check - ethanol is energy efficient

http://www.ncga.com/ethanol/main/energy.htm




Ethanol Production: A Net Energy Winner

There is clearly no doubt that fuel ethanol contains more energy than it takes to produce.

In June 2004, the U.S. Department of Agriculture updated its 2002 analysis of the issue and determined that the net energy balance of ethanol production is 1.67 to 1. (For every 100 BTUs of energy used to make ethanol, 167 BTUs of ethanol is produced.) In 2002, USDA had concluded that the ratio was 1.35 to 1.

The USDA findings have been confirmed by additional studies conducted by the University of Nebraska and Argonne National Laboratory. In fact, since 1995, nine independent studies found ethanol has a positive net energy balance, while only one study – which used outdated data – found the energy balance to be negative.

A Michigan State University study (2002) found that ethanol produced from corn provided 56 percent more energy than is consumed during production (1.56 to 1). This study looked at producing ethanol from both dry and wet milling of corn—and included corn grain production, soybean products from soybean milling and urea production.

These studies take into account the entire life cycle of ethanol production—from the energy used to produce and transport corn to the energy used to produce ethanol to the energy used in the distribution of ethanol in gasoline.

[kestrel91316]

34. SO RIGHT!!! We all know what a waste this is, and how we all

will be so much better off if we just continue our total dependence on fossil fuels for everything!!!!!!!!!

You're so clever, Cosby!!!!!!1!!!!11!!!!

[silverweb]

8. Excellent.

Whether it's an "ultimate answer" or not, every single baby step in the right direction is to be welcomed and applauded.

[JohnWxy]

31. know how many beef cattle and dairy cows we have in the U.S.? - over 100 million.

www.ers.usda.gov/news/BSECoverage.htm

that number of cattle could supply a volume of methane many times that required to supply the entire ethanol industry. The surplus could generate electricity for farmers to be sold back to utilities.

To show the power of technologies working together. MIT Engineers have developed a Ethanol Direct Injection ICE, using turbo-charging to fully exploit the higher octane of ethanol vs gasoline (ethanol 105 - gas - 92-93 (high-test)). This engine reduces gas consumption by 30% while using only 5% ethanol and 95% gasoline. The MIT people have entered into an agreement with Ford to develop this engine for mass production by 2011.

what this means is if all the cars on the road were using this engine an amount of ethanol equallling only 5% of the total fuel supply would yield (with this engine) a 30% reduction in total gasoline usage! Now, we should reach ethanol production equalling 5% of the total fuel supply in a few years(probably less than 3 yrs). Ethanol production for 2006 was up 50% over 2005.

This is how continued work on technologies can sometimes yield surprising results.

Then or course, there is the MIT work on a modified form of yeast which produces 50% more alcohol in LESS time than regular yeast. It's more tolerant of alcohol, so it can go longer producing more alcohol without worry of it being killed off by the alcohol.

And... there is the applicaton of high intensity Ultra-sound to the ethanol production process, for which Iowa State University has filed a patent. It produces much smaller particle size in the corn slurry prior to the fermentation stage. This results in a 30% gain in alcohol yield (without using MIT's new yeast). The process also reduces the time and energy inputs to get the higher yield in alcohol.

..and there is more (check my earlier posts for "monster cane")

[amandabeech]

14. No indication of what happens to the manure after it goes

through the digester which harnesses the methane.

It's not like all that organic matter vanishes into the air.

What about recycling the NPK?

This is an interesting article, and clearly systems such as this will make the EROEI or net energy of ethanol somewhat better in locations very similar to that described.

However, the heart of the corn belt covers very little of the U.S. land surface.

This is a silver mini-bee-bee, not a silver naval artillery shell.

[JohnWxy]

15. So "the heart of the corn belt" is all that needs consideration?

I would say, without actually doing the numbers, that all the states where corn or soy beans or sugar cane, can be grown would equal more than a "very little of the U..S. land surface area.", whatever the significance of that is supposed to be. MOre to the point is the supply of animal waste. Generally speaking, wherever they are growing crops there is are also cattle and pigs being raised in some number.

In my view, anything that reduces fossil fuel use cost effectively (keep in mind a lot of money and no small amount of effort is being expended dealing with this waste anyway - and we're not getting anythng for it.) is worth pursuing and should not be minimized.

ONe point some have made, rather stridently, is the use of fossil fuel in the manufacture of ethanol. Just on this point alone, that fossil fuel can be greatly reduced or eliminated, makes this 'closed loop' technology a very significant development (especially to those who have raised the issue of fossil fuel use in ethanol production).

regarding what's left after anaerobic digestion:

http://en.wikipedia.org/wiki/Anaerobic_digestion

By-products of anaerobic digestion
There are three principal by-products of anaerobic digestion.

Biogas, a gaseous mixture comprising mostly of methane and carbon dioxide, but also containing a small amount hydrogen and occasionally trace levels of hydrogen sulfide. Biogas can be burned to produce electricity, usually with a reciprocating engine or microturbine. The gas is often used in a cogeneration arrangement, to generate electricity and use waste heat to warm the digesters or to heat buildings. Excess electricity can be sold to electricity suppliers. Electricity produced by anaerobic digesters is considered to be green energy and may attract subsidies such as Renewables Obligation Certificates.
Since the gas is not released directly into the atmosphere and the carbon dioxide comes from an organic source with a short carbon cycle biogas does not contribute to increasing atmospheric carbon dioxide concentrations; because of this, it is considered to be an environmentally friendly energy source. The production of biogas is not a steady stream; it is highest during the middle of the reaction. In the early stages of the reaction, little gas is produced because the number of bacteria is still small in size. Toward the end of the reaction, only the hardest to digest materials remain, leading to a decrease in the amount of biogas produced.

Acidogenic anaerobic digestateThe second by-product (acidogenic digestate) is a stable organic material comprised largely of lignin and chitin, but also of a variety of mineral components in a matrix of dead bacterial cells, some plastic may be present. This resembles domestic compost and can be used as compost or to make low grade building products such as fibreboard.
The third by-product is a liquid (methanogenic digestate) that is rich in nutrients and can be an excellent fertilizer dependent on the quality of the material being digested. If the digested materials include low levels of toxic heavy metals or synthetic organic materials such as pesticides or PCBs, the effect of digestion is to significantly concentrate such materials in the digester liquor. In such cases further treatment will be required in order to dispose of this liquid properly. In extreme cases, the disposal costs and the environmental risks posed by such materials can offset any environmental gains provided by the use of biogas. This is a significant risk when treating sewage from industrialised catchments.
Nearly all digestion plants have ancillary processes to treat and manage all of the by-products. The gas stream is dried and sometimes sweetened before storage and use. The sludge liquor mixture has to be separated by one of a variety of ways, the most common of which is filtration. Excess water is also sometimes treated in sequencing batch reactors (SBR) for discharge into sewers or for irrigation.