Brown Power

The NY Times is really starting to get the complexities of examining potential alternative energy projects. Despite the obvious toilet humor potential of the subject, they had a serious editorial today about converting manure to power:

As a livestock farmer and environmental lawyer, I've paid particular attention to discussion about using manure as "green power." The idea sounds appealing, but power from manure turns out to be a poor source of energy. Unlike solar or wind, it can create more environmental problems than it solves. And it ends up subsidizing large agribusiness. That's why energy from manure should really be considered a form of "brown power."
The article goes on to say that subsidizing manure to energy projects may artificially increase the size of livestock farms, which has all sorts of impacts on energy consumption and the local environment of those farms. Indeed, subsidies continue to skew all analyses of different project's true value.

I couldn't agree more with the last paragraph of the article:

Using manure as power sounds like a good idea, but it's not. The energy that can be generated from manure is not worth the expense. And by lowering industrial animal operations' cost of production, subsidizing manure power pushes family farms further toward the brink of extinction. Our money would be better spent investing in truly sustainable, sensible ways of producing energy and food.

As I mentioned before which was picked up by the local political blog - Gotham Gazette, we need a common understanding of the boundaries/terminology of a proper EROI analysis of alternative fuels to decide where to invest our resources. At least if everyone can agreed on the terms of the debate we might actually have one!

The price of hog manure has increased 50% in two years.  

The 1,000 gallons of hog manure that was worth $20 just a couple of years ago is now valued at $30, he said.

The increase coincides with the increase in commercial fertilizer prices, pushed up by the costs of natural gas, which is used to make commercial nitrogen fertilizer, Brenneman said.

I suspect fertilizer is the better use for it.

Yeah, that makes a lot more sense.
Anaerobic digestion does not consume or reduce the nutrient content of manure and organic products. On the contrary, it concentrates it while killing pathogenic organisms present in the manure. Normally, feedlot manure that is used for fertiliser must be stabilised, or aerobically composted, to kill off pathogenic organisms. Open or semi enclosed manure ponds are aerated to break down organic material, yeilding CO2 while leaving nutrients in the manure which is then spread as fertiliser. A big downside of this technique is that odours are pretty substantial and offensive. Aeration is also imperfect and these ponds can produce significant amounts of free methane to contributing to atmosperic GHGs. Solving odour problems is in itself a strong enough argument for livestok operators to move to anaerobic digestion. This goes a long way to addressing NIMBY concerns by neighbours and nearby towns. Anaerobic digestion achieves manure better, faster manure treatment, minimises and contains odours while recovering very useable biogas. At the very least this gas can be flared. A better scenario is that it is used to power and heat the digestor system at least. Gas can be rather cheaply stored (compressors can run on biogas) for use when a farmer needs heat or generator fuel. The material product of digestion, often called "liquor" is a highly potent fertiliser. It requires less storage space, is more easily transported, more easily spread on fields and has very low probability of carrying infectious bacteria/amoebi. Farm based biogas recovery is a local solution for a local problem. It is not for every context and not always advantageous. Chinese farmers have long used a very simple approach with human and animal wastes to produce cooking gas. This practice is spreading as energy prices and technological knowhow increases. To make generalised statements whether biogas recovery from farm wastes is good or bad does . Context is king when discussing renewable energy systems so we should never rush to either condemn or endorse a particular technique. Biogas recovery is no exception.
Dinaz - You are right that context is important. But I think it's more a matter of what your starting assumptions are:

A. There needs to be large scale livestock farms so we might as well collect the waste and convert it to local energy.


B. The best model is sustainable organic agriculture where crops and livestock co-exist or livestock is raised free range.

I prefer B. In that context, manure is not concentrated enough to make it's collection worthwhile.

The real world situation is not A or B. Its AAA and AAa and Aaa and Aab and so on. Use this technology on every level where it makes sense.

My advice is to dont bother if A or B is best but make the equipment movable and recycleable if the site it was used on ends up being outcompeted.

Sure Magnus, I know there's a huge grey area. As John Darnell (R. Barlett's advisor) said in his lecture at the NYC PO Conference in Oct. "We need to envision the world that is sustainable and work our way backward on how we get there." I don't think large scale livestock farms are part of that sustainable future so efforts to prop it up seem like a waste of time and energy to me. It's really the idea of subsidizing them that gets to me.
I don't think large scale livestock farms are part of that sustainable future so efforts to prop it up seem like a waste of time and energy to me.

I suspect you are right.  The two most petroleum-dependent industries are transportation and agriculture.  People seem willing to accept that  transportation is going to have to change fundamentally, but not many think the same about agriculture.  

Or maybe it's

C. The best model is to size farms such that energy from manure and other byproducts can be captured and the nutrients recycled.  The actual division between grazing/feeding hay in barns is part of the determination of optimum size.

I'm from Alberta where we have far more cattle than people and a good portion of these cattle are partially if not fully housed for a portion of winter. When combined with some sort of stationary winter feeding lot, collection of manure is not only useful - it is required. Manure is best when deposited on the field, I do not dispute this. What I have a problem with is the idea that AD should somehow be ignored as an energy option because it makes industrial farming more economical and viable. Is it then better to allow slaughterhouse and feedlot operators to NOT better use the masses of manure and entrails they have? Is it better for them to let it settle in open ponds, burp methane into the atmosphere and offend people for fifty miles in every direction? How about spreading it on fields after insuficient aeration treatment? I'm not so sure. Call it green, call it brown. Either way, AD is an effective means of extracting highly useable gas from an organic wastestream. I'm convinced that it is as useful at small scales as it is for large scales. The Chinese peasant will back me up. Even when it helps big agribusiness conglomerates continue to produce cheap, abundant, if somewhat morally and ecologically disruptive food to fill our fat bellies. Panning AD as an energy system because we dissaprove of a particular industries practices isn't particularly constructive. Industries will change as energy availability evolves - but AD will remain possible, feasible and desirable. Instead of worrying that AD will make the bad guys rich, why not support its development as we would a more efficient car. When a higher standard in CAFE is announced are we to complain that this will just perpetuate the problem?
I agree that AD may have a place, particularly in colder climates, but it should not be subsidized over wind and solar which are more sustainable. And it should not be touted as something that will supply power beyond the farm. At best this should be viewed as a slight improvement in efficiency on these farms (sort of like a hybrid recapturing lost energy in braking), not as a primary source of power. Overall though cutting the amount of meat consumption slightly would be a better use of scarce resources. I think the market will start to incentivize this, but not if economic subsidies skew this incentive.
dinaz wrote: "Anaerobic digestion does not consume or reduce the nutrient content of manure and organic products. On the contrary, it concentrates it while killing pathogenic organisms present in the manure."

I beg to differ a bit. The die-off of pathogenic organisms depends on the HRT (hyrdraulic retention time) and temperature of digester operation. The most common are plug flow mesophilic systems operating at about 100F and pathogen reduction is only several logs. The thermophilic systems, operating at 140F or higher, essentially produce a sterile product.

With respect to reduction of nutrient content, the most important impact may be the potential reduction of soil carbon, which has an adverse impact on both soil productivity and atmospheric CO2 level. The impact on soil health and productivity is likely a major weak point of all non-food energy production schemes; some refer to these as "dirt burning".

Take a look at:

Building Soils for Better Crops (in print and on-line)

The Soil Biology Primer

Glomalin: Hiding Place for a Third of the World's Stored Soil Carbon

Soil Carbon Center

Which one of those references has test results for soil carbon in those soils fertilized with raw manure vs. liquid digester effluent?  That is what we are debating, after all.
None here or elsewhere that I am aware of (with the caveat that I'm not a soil scientist), which is part of my point. Most of the work in this area is looking at the effects on constituents such as NPK. The relationships between soil arbuscular mycorrhizal fungi, glomalin, SOM (Soil Organic Matter), soil microbial diversity and soil management (tillage practices, fertilizer application, crop residues) are very complex and dynamic. This  is a very active research area. Glomalin was only recognized in the late 90's and it appears that there is still considerable controversy on the best techniques to measure SOM. With all the negative connotations of dirt, soil is a very complex but critical environment. Thus we are again perturbing a very complex system, potentially adversely, that we don't yet understand (IMO) sufficiently. Hence the word "may" in my original comment.

Several blogs that cover topics in this area are Muck and Mystery and Transect Points

In India cows are sacred, there are many of them, and they are the chief source of fuel for poor people. Little kids gather cow pats, slap them up against sunny walls to dry, and there is your cooking fuel.

Sure beats cutting down your forests to brew tea.

Especially if you don't have any forests.
If our REAL objective is to create methane, we'd be better off just killing the cows and throwing their carcasses into the biodigester. OR, better yet, not raising them at all, and using the land that was used to feed them to grow grass and such to throw into the biodigester. Much more efficient.

However, in a systems economy, we are then have energy as the sole output, and are lacking in milk, cheese, steak, and dogfood.

As Ive said - its all going to come down to tradeoffs.

Yes, exactly. Once you put an animal into the equation, you are losing efficiency no matter what. Either use the grass directly or just put up solar panels and wind turbines.

I think the real questions should be what is the best use of different types of land to sustain human life as best as possible.

I agree.

Though a philosopher might transpose your question to 'what is the best use of different types of humans to sustain land life as best as possible'

I think  a little clarification is in order here. First, it is one thing to install and operate an anaerobic digester as a means of stabilizing and reducing the volume of the waste, thereby making it more fit for land application, and then using the methane generated for on-site usage as a means of defraying overall operating cost.  It is entirely another thing to view energy from manure as a stand-alone alternative energy source that would be economically competive from a purely business sense.  

A thread that seems to go through the author's argument is that small private farms can't afford to install digesters or other energy recovery means, that they only make sense for large factory farms, so promoting digesters only encourages the large factory farms. Well, I would think that the large factory farms (some call them animal concentration camps) aren't going to go out of existence any time soon, so why not at least have them recover some of the energy content of the manure? The evils of large factory farms do not in and of themselves negate the benefits of performing some energy recovery.

It should also be pointed out that anaerobic digestion for the purpose of stabilizing waste and generating methane is hardly a new technology and is currently being practiced at probably thousands of sewage treatment plants and feedlots around the world. There is not much that is untried and ground-breaking here.

The burning of manure in an energy-recovery incinerator or in a power plant through the mixing of the manure with other fuel is a whole other matter. As I see it, one of the big drawbacks to this route is that all manure has a rather high nitrogen content, which causes the stack gases from such combustion to be high in nitrogen oxides, a major contributor to photo-chemical smog. This is a non-trivial air pollution issue.

The modern mega livestock feedlot is a perfect example of a serious dislocation between sources and sinks. Huge quantities of feed are grown elsewhere and then imported to the feedlot. This feed is converted into animal mass, carbon dioxide, and manure. The animal mass is exported from the feedlot, but the manure remains. It is  usually not economically feasible to return the manure (and hence its fertilizer value) back to the producers of the feed. So, nitrogen is leaving one agricultural area and piling up in another. The former is depleted of nitrogen, so synthetic fertilizers have to be used, while the latter has a surplus of nitrogen and hence a serious disposal problem.

A thread that seems to go through the author's argument is that small private farms can't afford to install digesters or other energy recovery means, that they only make sense for large factory farms, so promoting digesters only encourages the large factory farms.

Bogus argument. Nothing stops several small farms from cooperating with running a methane plant. It gives more transportation but a giant farm anyway has a long way to get all the manure out on the fields.

Agreed. Farmers could also maximize their yield of methane by using solar collectors to heat the manure. Not sunny today?  Not a big problem for a local operation. The methane will presumably be buffered in tanks anyway.
Well, I would think that the large factory farms (some call them animal concentration camps) aren't going to go out of existence any time soon

I'm not so sure about that myself.  Not because I have any delusions about agribusiness, but because the economics will change as oil prices rise.  I think the Green Revolution that swallowed so many family farms may unwind, as fuel, fertilizer, and pesticide prices keep rising.  Plus there may be a lot more labor available as the economy tanks.  

Plants need water, nutrients and oxygen. The oxygen gets there  during dry cycles, in soil that is not too compacted. Manures are  very good soil conditioners, needed for the oxygen to get to the roots; especially true if not plowing/tilling. Manure is lower in nutrients than is usually assumed, but adequate for most plants.Transporting manure is very energy consuming in any large scale operation whatever the purpose.  Heat from composting manures( necessary sometimes for certain plants/manures) is useful for starting plants, livestock,etc. But this is hardly any energy source in the usual sense.  Right on NYT.  I may start subscribing.

O.K. folks, let's talk.  creg says, in the post I am replying to, <Plants need water, nutrients and oxygen>
He left out something pretty important there:  Sun, or at least light.  Essentially, a manure to methane digester is getting the power of the sun in plants, using an animal as the intermediary. Big deal, you say, but it actually is, because nature has provided one of the few workable ways to convert sunlight, along with the above mentioned ingredients, into a vapor or liquid fuel...something man has difficulty doing by technical means (the only way I know of doing is by electrolysis of water to hydrogen with solar power).
Now, we are taking as for the granted the following:
>Humans will keep eating meat, cheese, eggs, drinking milk, and wearing leather for some time to come. So the need for the plants to feed these animals is a given.  The water consumption is a given.  The oxygen intake which is converted to carbon dioxide release of the animal is a given.
We will live with those either way.  What is not a given is that we will recapture some of the solar power in the animal.  This can only be done by (a) working the animal as a beast of burden (don't laugh, it worked for a few thousand years before John Deere was ever born), or, methane capture from the animals waste.  Now, it would be different if the methane was not going to be produced anyway.  It would be a poor conversion, we all agree, to raise cows as solar converters.  But, if we are going to have livestock anyway, the methane recapture is purely that, a recapture of energy (methane) as solar energy in gas or vapor form, ala artificial natural gas, made by solar power.
By the way, despite the media's love of giving the Japanese credit for inventing everything, including the sun itself if they thought the reader would buy it,  this technology is already well under way in the U.S.

Also gaining in acceptance is systems to use methane gas from sewer systems (because we assume humans are going to keep converting food into...uh, you know...let's call it recoverable human solar power! :-)

Another promising area is of course waste landfill gas, which allows the possible recapture of some of our wasteful ways.  AGAIN, wasting to produce fuel won't make sense, but if the waste is already there....

Let me close with something of a philosophical point that is troubling to me.

TOD is a fascinating place, I drop by every day.  The folks here are bright and well read, educated often in the broadest sense.  
Very troubling however is the drumbeat of defeatism.  The motto here seems to be "All worship the gods of crude oil and natural gas, and have no other gods before them, because any alternative is doomed to defeat."

Let us try to recall that mankind developed a high degree of cultural sophistication, art, government, education, religion and philosophy MANY CENTURIES before the first oil well was drilled, and sustained the said culture for centuries before the age of fossil fuel.

OIL AND GAS ARE GOOD AT PROVIDING AFFORDABLE, PORTABLE, COMPACT ENERGY.  We admit that, we admire that.  But the planet Earth is AWASH in a sea of energy, from the sun, the wind, internal geology, the surge of the waves, biotic processes that occur EVERY SECOND on land, under the sea, and even in the dirt beneath our feet....oil and gas are good, on an EROEI basis, but they are just not that dammed good.

It is amazing that if some incorporates a few used 55 gallon drums from a junk pile and some copper tubing to recapture waste gas, it has to be billed pound for pound, jot for jot, into the EROEI equation to prove that the steel in the drums in the junkyard HAD to have consumed energy when they were made sometime back in the 1960's, proving the EROEI balance JUST WON'T WORK FOR ALTERNATIVES....but no one tries to balance the 3 nuclear powered aircraft carriers in the Persian Gulf, complete with their extreme high tech aircraft, support and defense cruisers, and patrol planes, all running at full steam 24 hours a day against the EROEI equation used to get that dammd crude oil  (and what about the ship that will carry the oil, the tractor trailer that will deliver it, and the concrete white lit 24 hour a day convenience store to sell it....the EROEI ON CRUDE OIL IS NOT NEARLY AS GOOD AS IT APPEARS IF YOU COUNT EVERY OUNCE OF FUEL TO GET IT TO AGAINST IT, which is only fair, it's the way the alternatives are counted to dissuade anyone from even trying them.

As the quakers like to say, this Friend speaks my mind! Thanks,Thats.
BTW, where do I go to talk about solutions?
I think TOD is as good a place as any to talk about solutions. The Big Problem (BP) as I see it is that most workable solutions are politically incorrect or politically unacceptable. For example, societies have known for thousands of years how to stabilize population without birth control: What you do is to practice female infanticide, which is still widely done in rural China. Well, now the idea that soon we will be able to artificially select the gender of our unborn children is a scandalous idea, and the thought police are out there telling us not to think about it.

Well, think about it. If most babies are male, then females become relatively scarce and their status and value rises. This would be a bad thing????????

Another form of traditional population control is social stratification. Lower classes traditionally have had much higher death rates than higher social classes--e.g. in early Victorian England. Currently it is an Article of Faith that all citizens (and maybe resident aliens and maybe illegal immigrants) should have all technologically available medical care always and regardless of costs.

If current trends continue, all economic resources would be consumed by medical care in a relatively short period of time, roughly fifty years, depending on which society you look at. I have news: Current trends are not going to continue, but find me a politician brave enough in the U.S. to face up to the necessity for rationing medical care . . . and I'll vote for him or her.

Those who deny reality strike ice bergs and sink.

The problems( pop.,energy depletion,social response to such- increase in wars) are of such scale and orders of magnitude  compared to the solutions that the solutions, unless carefully thought thru  will become part of the problem.  I know for me on a couple of acres getting started ,I /we will become vegan to get in the ballpark with the scale of the food problem I think we will be dealing with.  The chickens we have will likely be gone due to risk of  bird flu.
Right.  So let's string a thread of solutions.  No whining, snivelling or giveupitis allowed.  Especially excuses by way of political correctness- Streng Verboten!

I have been politically incorrect all my life,and won way more than I lost.  Being NPC does not require being a world class jerk (WCJ)--- like Larry Summers, like.

Sailorman:  Good points.  I like your philosophy.  I have sent a copy of your post to some of the members of the Socrate's Cafe disscussion group that I attend.  I think it will spark some lively discussion.
I know many people, most women and sometimes my wife among them, who thinks Sailorman has it backwards: male infanticide would be less costly. My own view is that infanticide (not to be equated with abortion) is barbaric and has no moral or ethical justification.  
Both Aristotle and I agree with you.

My point is that certain truths are unpleasant to face, such as that if the ratio of males to females is say, three to two, there will be much less potential for population increase than with an equal number of males and females.

Do you then approve of abortion as a means to select gender of offspring? This technique is widely used today in India.

I am female, I don't think there's any denying that female infanticide is the classic way to deal with overpopulation.  Farmers do the opposite: kill the males.  Because they want to increase the size of the herd.  The number of females controls the fertility of a populaiton.  

Indeed, many anthropologists argue that this why males are considered superior to females in most cultures.  It justifies female infanticide.  You can't just tell people they should preferentially kill female infants and expect them to do it.  The next generation, when females are scarce and valuable, people are naturally going to start preferring female babies over male - unless they believe that females are inherently less valuable than males.  

This is one reason I fear the progress we have made in population control will be rolled back.  Available birth control and female empowerment are two factors that have slowed the population growth rate, and I'm not sure they will survive peak oil.  

Societies with surplus males tend to suffer higher rates of crime and violence. Idle hands and frustration.

The traditional solution to surplus males is warfare. What's going on in China and India is not going to end well.

That's true, too.  There are already a lot of angry young men in China who have no chance of marrying.  Some have taken to kidnapping young women and girls.
I will express some views on pluses of conerting manure to methane.  I have worked on manure to methane for 35 years, and want to address what I think are misconceptions in the NYT article (which I get) and some of the comments.  (I posted comments on this on the oil drum before).  

The conversion of manures to methane or "biogas" where it can be done, has several positive things going for it.  

  1.  We are going to grow animals. We need to deal with the manure.  The capture of methane (biogas from manure) for energy kees methane, a potent climate active gas from entering the atmosphere, and puts it to beneficial use. In addition, the methane energy use, electric or other, offsets fossil energy consumption which would otherwise be used and thus gives "greenhouse benefit" by offsetting fossil CO2 as well.  The US EPA has its AgStar program to encourage controlled digestion of methane to biogas for just these reasons.  

  2.  Contrary to comments, the digestion to methane of organics does not remove the fertilizer nutrient valuem-- manure nitrogen, phosphorus, potassium, etc.   Digestion to biogas removes only the organic material.  The organic material is not used by the plant anyhow, and is useless to the plant. The fertilizer value of the methane is still avilable and can be land applied.

  3.  Operators would certainly not increase animal husbandry and raising animals "for the methane".  The methane to biogas can only be an adjuct that can add environmental benefits  and renewable energy benefits to animal operations that would take place`anyhow.  Manure biogas energy is, incidentally, being embraced across the European Union.  The EU treats it as a significant energy resource.

So, having worked in this area for a long time I and regulators regard the "environmental balance sheet" of animal manure digestion to methane energy as being quite positive.  One barrier, until recently, has been cost  But rising energy costs are rendering more and more manure to methane operations economic.  Electricity for onsite use (net metering) and resale of the excess power to the grid has generally been the most practical use of the methane.  A current problem is the exhaust emissions, particularly NOx, of piston engines that are otherwise the best perfomers on manure biogas from efficiency and cost standpoints,  Exhaust gas catalytic converters can address this but at some cost.  

It should be emphasized that the US Environmental Protection Agency, California Energy Commission, European Union countries, and many US farm state agencies and utilities selling "green power" are strongly suportive of manure biogas for the renewable energy and environmental benefits.

Don Augenstein

During my travels in India quite a while ago, trying to sell stirling engines, I found the Indians were all in favor of biogas generators, since they provided a clean cooking method without all the stink and work for cow pats and twigs.  The villagers all considered the stirling a miricle machine, but the money bags people ignored them because they already had a diesel.  So no go.  I also tried to sell cheap plastic solar concentrators for cooking, but nobody wanted them because they didn't want to be out in the sun.  An obvious problem I hadn't thought of, being from the cold dark gloomy side of the world.
Not all Indians are resistant to solar cookers; one village has adopted them wholesale.

Maybe improvements like cheap clockwork sun-trackers (to avoid the need to stay out in the sun while food cooks) would increase acceptance.  Pendulums and escapements are very low-tech.

trying to sell stirling engines,

Start shiupping 'em at a reasonable price.   A atirling would work with biogas sue to the creation of Sulferic acid and Nitric acid during the burning process, because the heat exchange head can be replaced.  (The burning by-products is why bio-gas isn't as popular as it could be.)

(And no, really.   Get 'em to ship.  Because I've been wanting to buy a reasonally priced Stirling.)

Thanks for your comments Don. I completely agree that if you do try manure to power, it should be to offset onsite energy needs. My concern is that the gov't subsidies are skewing the economic incentives to overconsume energy in just the wrong place. Livestock farms consume vast amounts of energy directly and indirect through the feed they consume. The main goal should be to make farms as self sufficient and internally efficient as possible and I don't think we should be subsidizing these vast energy consumers.

But here's the real issue, I see the cost of meat prices going much higher in the future since they are much more energy intensive than grain, fruit and vegetables. Demand for meat is price/income elastic. That means a lot less meat consumption. I expect a lot of these big livestock farms are sensing this and looking around for energy subsidies to cover their increasing onsite feed, energy  and transportation costs. We should be trying to encourage people to consume less meat, not more.

For more on the energy inputs to meat, read this article at Go Veg.


the BBC main evening news in the UK  had an item on this very subject last night. The Chinese Govt are getting serious about encouraging brown power out in the country as a means of combating deforestation and desertification.

They are encouraging/subsidising the installation of small scale anaerobic digesters on family farms in order to produce methane for cooking. The output from half a dozen or so pigs being adequate to power a single ring burner which is all the featured peasant family seemed to need - something to heat a wok for stir fry or boil up a pot of noodles. The mother of the familly was very enthusiastic as she no longer did the daily schlep halfway up the nearest mountain to collect firewood from the forest (none left in the valley where the farms are) and consequently now had a bit of spare time to gossip with her pals!

other initiatives shown briefly at the end of the report inclused state subsidised solar water heating for small farmers.... there was something else but Ive forgotten what it was...bugger..

I think that those who have been involved with the anaerobic digestion of manure generally agree that while methane generation is (usually) a positive thing, it should be viewed more as a means of recovering some energy from waste that is going to be produced anyway rather than as a primary energy source. It's more in the nature of byproduct recovery to offset total operating energy requirements and hence total cost.

And the previous poster is entirely correct: it does absolutely nothing to reduce the amount of nitrogen and phosphorus in the waste stream.

One thing to remember with all of this is that we are dealing with a high-volume, low-value material, so there are very real constraints regarding handling and transportation. The waste generated by large feedlots (mixture of manure and the water used to flush it) has typically well less than 1% by weight nitrogen and even less phosphorus. Compare that to over 80% nitrogen for pure ammonia. Thus, handling and transportation costs greatly limit the practical radius of use.

Some further perspective on the scale of energy production might be useful. Mind you, these are just very rough rule-of-thumb numbers, but they will put us more or less in the ballpark.

A typical feeder cow generates about 1 cubic foot of wet waste per day per 1,000 lbs liveweight.

That waste contains about 6 dry lbs of organic material.

A well-operated anaerobic digester will convert about 75% of that organic material to digester gas (mostly methane plus carbon dioxide). Thus, 4 lbs of the organic material is converted to digester gas.

Roughly 14 cubic feet of digester gas is generated per lb of organic matter converted. Thus, our 1,000 lbs of liveweight will generate 56 cubic feet per day.

A feeder cow weighs about 800 lbs. So each cow generates about 44 cubic feet per day of digester gas.

A feedlot housing 5,000 cattle will thus generate 220,000 cubic feet per day of digester gas.

Because digester gas is mixture of methane and carbon dioxide, it only has a heating value of approximately 600 BTU/cubic foot (vs over 900 BTU/cubic foot for natural gas) Thus, our example feedlot generates the equivalent of roughly 150,000 cubic feet per day of natural gas equivalent.

For optimal methane generation, the digester must be kept warm ( 85 to 120 degrees F), so  a large fraction, probably at least a third, of that gas must be used to heat the digester (at least part of the year). Thus, we are left with 100,000 cubic feet of natural gas equivalent to do what we want with.  

Considering the size of a 5,000-cow feedlot, that is not a whole hell of a lot of energy.  While it can offset the considerable energy usage of a feedlot, it is not something that is going to be all too readily exported from the feedlot into the grid. And I have probably even been a bit too generous in some of these assumptions.

1,000 liters of water for a kilo of potato
40,000 + liters of water for a kilo of beef

and no one has mentioned farting

cows farts are very important, one cow farts 200 litres of methane a day
100million head of cattle...

I remember a story from years ago of a tribe of native indians in america deliberatly killing bison with the europeans to invoke the great "cow gods" fury.

And there was me thinking americans were reaping the cow karma with heart attacks and a variety of cancers, guess I can add dieing of thirst and climate change to the list.

I say, turn the Great Plains back to the bison and the Native Americans. Let the Native Americans harvest the bison in their traditional ways and sell us that excellent grass-fed meat, far leaner and tastier and better in every way than the disgusting and unhealthy corn-fed result of inhumanely treated cattle.

We should all reread (or read for the first time) "The Jungle" by Upton Sinclair.

I am not a vegetarian, but I do believe (along with Immanual Kant) that we have duties to animals, and our meat industry is a huge and horrible and largely hidden violation of those duties. If people knew how their meat and poultry were raised and "processed," I truly believe they would not eat it.

We cannot pretend to treat humans ethically if we ignore our duties to mammals, and (to a lesser extent) the lower animals as well. Native Americans and other hunting and gathering peoples understand this vital point far better than do most people in modern societies.

That's why I became a vegetarian.

But turning back the plains to the Bison won't satisfy the market's demand for $2 hamburgers.

Natural gas is actually a bit over 1000 BTU/ft^3, so your example would produce the equivalent of about 130,000 ft^3/day of natural gas.

That's a fair amount of energy, over 130 GJ.  If you ran an engine on it and it achieved 25% thermal efficiency, you'd get  over 300 kW.  The waste heat from the generator would be more than sufficient to heat the digester.

This looks like it would scale down well.  If you had 200 head, you'd get 8800 ft^3/day; @ 600 BTU/ft^3 that's 5.28 million BTU/day, or about 64.4 kW thermal.  If you can get 25% of that, it would make about 16 kW of electricity.  That's not half bad; a 4-cylinder engine built in the style of a Lister diesel should be able to handle that, and they run decades without major service.

Sure, that's fine for running your own operation, but as a primary source of energy it's not going to spread very far.

Mind you, these numbers are probably more of a best-case scenario.  Now, I've got nothing against anaerobic digestion for methane generation, but it's got to be put into the proper perspective. Waste is waste, and by that very fact it doesn't have all that much value. If it did, it wouldn't be waste in the first place.

As to your correction, I said that natural gas was over 900 BTU/cubic foot, so using a number of 1,000 BTU/cubic foot changes my 100,000 cubic feet 'energy to spare' natural gas equivalent more to 90,000 cubic feet, rather than your 130,000 cubic feet.

Yes, it's a good thing to do, but don't expect it to be feeding a significant amount of power into the grid for general use.

I was using your numbers (44 ft^3/head/day, 600 BTU/ft^3); for 5000 head, you get my results.  If you have corrections to make to your own figures, do so.
don't expect it to be feeding a significant amount of power into the grid for general use.
Did I ever state that it would?  On the other hand, a ready supply of methane would work well along with some wind power; the two of them combined could allow excess methane to be used for motor fuel, rendering the farm petroleum-independent.

Then there's the matter of the non-methane digester gas and the cogenerator exhaust.  It turns out that this might be converted to product also.  I think this is a very interesting development.

Cow farting is indeed a major source of methane, an even more potent greenhouse gas than CO2.

This in itself is a not-insignficant source of energy. What's the solution? How about giant 3-feet diameter inflatable condoms that are strapped around the cow, collect all the flatulent gases,  and emptied into a storage tank once or twice a day?

Hey, this is no crazier than a lot of alternative energy schemes I've been seeing of late.

It's disturbing to realize that there is several times more cow, pig, and chicken flesh alive in this country than human flesh. And that these cows, pig, and chickens, accordingly, produce far more feces and urine than the entire human population of the US. We treat human sewage fairly well, but the treatment and disposition of these massive amounts of ag wastes are an order of magnitude behind the times.  As to why ....... dare I bring up the power of the ag lobby in this country?

Something I'd like to see in this context is Thermal Depolymerisation. Are the tests not cutting it?

I'd especially like to see boidigestion and the above in the context of city sewage treatment. We have to treat it anyway.

So far, thermal depolymerization is not working as planned.  The plant was supposed to cost 5 million dollars, and ended up costing 40 million.  It was supposed to produce oil for $15 a barrel, but struggled to produce it at $80/barrel.  And it produced terrible smells that in the end forced it closed.  They were hoping the smell would improve when it got colder, but it didn't, so the governor ordered the plant shut down in December.  The other plants they were planning to build are now on hold.

The anaerobic digestion of sewage treatment plant sludge has been in use since at least the 1930s. Those digesters that produce methane largely use the methane to power machinery in the sewage treatment plant and to heat the digeesters. However, in many areas sludge digestion has gone out of favor and has been replaced by sludge incineration and other processes. As landfill have gotten more and more expensive, the goal has been to reduce the sludge volume as much as possible.
What can Brown do for you?

Ignoring HOW one has masses of manue you have to process (and why it won't be an issue with the end of cheap oil), the biggest issues are:

  1. Sodium.  The urine mixed with the fecal material adds sodium...material you don't want to add back to the soil.

  2. Phosporus.  Urine has the most of that too.  Factory farming moves the phosperous in the feed to the feed lot, and is put into the urine stream that gets mostly ignored.

You CAN convert fecal mater back into feed.  
Via The Maggot Pit!  (Some of the salt gets addressed)

Now, if anyone has a good idea/plan for binding up the Sodium in a urine stream - please post it.

Yes, you are correct: salt build-up is a problem, particularly if the feedlot is in an arid climate.

As I said in my earlier post, the major displacement of sources and sinks for nitrogen really messes things up. Though I didn't mention it (to keep my post short), the same is true for phosphorus, sodium (and don't forget potassium).

It is not good.

The graphic at the top of this article has a republican-elephant symbol that suggests that Republican shit can be used to generate electricity.  What is the BTU output of a Rove?  How many miles per Bush does you Hummer get?  Can we convince Iran to not pursue nuclear technology by giving them a Cheney?  I'd like to power my home with a Chertoff, but I'm concerned about reliability during storms.