Cos more methane from mouth or dung?
March 7, 2008 10:22 AM Subscribe
Is it possible to say whether more methane is produced from cow feces or their mouths? How political is this topic?
I thought I read in the NY Times about some studies in Australia/NZ that methane emission from cow dung may not be nearly as significant as the methane released from their mouths. I mentioned this to someone trying to harness the methane from fecal lagoons for energy and it has started a bit of a jovial debate. Apparently my friend spoke to the cow caca methane guru and is gleefully waiting to send some proof that this is not true (the guru apparently also had not nice words to say about "people like me"). Harumph to him too. Well, people like me can be hard-headed so now I am curious. I know these issues can be deeply politicized and statistics work wonders in all kinds of ways so what's the scoop on methane from poop versus mouth? Any good respected, neutral info/studies/reports out there you can point me to?
Thanks!
I thought I read in the NY Times about some studies in Australia/NZ that methane emission from cow dung may not be nearly as significant as the methane released from their mouths. I mentioned this to someone trying to harness the methane from fecal lagoons for energy and it has started a bit of a jovial debate. Apparently my friend spoke to the cow caca methane guru and is gleefully waiting to send some proof that this is not true (the guru apparently also had not nice words to say about "people like me"). Harumph to him too. Well, people like me can be hard-headed so now I am curious. I know these issues can be deeply politicized and statistics work wonders in all kinds of ways so what's the scoop on methane from poop versus mouth? Any good respected, neutral info/studies/reports out there you can point me to?
Thanks!
There are a number of installations in Vermont, generating significant amounts of power, running on methane from cow manure. So, there's a lot of methane in the manure, ie., it is certainly "significant".
It certainly could be that they belch even more methane, but you could not capture it very easily to turn it into energy.
posted by beagle at 10:33 AM on March 7, 2008
It certainly could be that they belch even more methane, but you could not capture it very easily to turn it into energy.
posted by beagle at 10:33 AM on March 7, 2008
In this Digg comment, the guy says eructations (belches) are a bigger problem than flatulence, but he's not considering dung. (And he has a financial interest.) You might try skimming through this report.
posted by salvia at 10:34 AM on March 7, 2008
posted by salvia at 10:34 AM on March 7, 2008
What would also be useful to know is the difference between grass fed and grain fed animals. If there is a difference.
posted by Toekneesan at 10:53 AM on March 7, 2008
posted by Toekneesan at 10:53 AM on March 7, 2008
Cows that are fed grain tend to suffer from indigestion since grain is not normally a part of a cow's diet; I would imagine cows that are grass-fed don't have as much a problem with indigestion, and therefore, produce less methane than their grain-eating counterparts.
posted by chan.caro at 11:09 AM on March 7, 2008
posted by chan.caro at 11:09 AM on March 7, 2008
Excuse the pun
It has become a politicized issue: the government here tried to impose a 'fart tax' on ruminants as part of an ecological policy and the resulting protests reinforce every pastoral-hick stereotype (that's the former leader of the opposition on the tractor). The point was made then that ows produce much more methane from the mouth than from the other end.
posted by Paragon at 11:41 AM on March 7, 2008
It has become a politicized issue: the government here tried to impose a 'fart tax' on ruminants as part of an ecological policy and the resulting protests reinforce every pastoral-hick stereotype (that's the former leader of the opposition on the tractor). The point was made then that ows produce much more methane from the mouth than from the other end.
posted by Paragon at 11:41 AM on March 7, 2008
Here's a good listen from a recent Quirks and Quarks podcast: Dr. Athol Klieve, a researcher with the Department of Primary Industries & Fisheries in Queensland, Australia, is studying the gut bacteria of certain species of kangaroo, in the hope that they can be transfered into the digestive system of cattle; and, in doing so, significantly cut back the amount of greenhouse gas they produce. Interview (mp3).
posted by jaimev at 11:56 AM on March 7, 2008
posted by jaimev at 11:56 AM on March 7, 2008
I don't think the question is really answered. We have two newspaper articles saying that 95% of the methane comes from the front end of the cow. Neither story provides a source for that statement, and as we well know, plenty of canards get repeated until they are accepted as truth, when they have no foundation whatever in actual research. ("You need to drink 8 glasses of water a day" for example.)
Besides burps and farts, there's also the methane exuded by the cow dung, as mentioned by the OP. So there are three sources from one cow. The methane that comes from the manure is a product of continued bacterial activity after the manure leaves the cow. This happens, and the methane is released, whether the manure is spread on a field or put into an anearobic composting unit to generate electricity.
So in any event, allow me to restate the question:
Cite a credible scientific study that quantifies the amounts of methane exuded over a period of time by one cow (a) as eructative exhalation, (b) as flatulent emissions, and (c) from the manure produced by cow as it biodegrades through bacterial action.
Extra credit for providing the same information on other ruminants.
posted by beagle at 2:24 PM on March 7, 2008
Besides burps and farts, there's also the methane exuded by the cow dung, as mentioned by the OP. So there are three sources from one cow. The methane that comes from the manure is a product of continued bacterial activity after the manure leaves the cow. This happens, and the methane is released, whether the manure is spread on a field or put into an anearobic composting unit to generate electricity.
So in any event, allow me to restate the question:
Cite a credible scientific study that quantifies the amounts of methane exuded over a period of time by one cow (a) as eructative exhalation, (b) as flatulent emissions, and (c) from the manure produced by cow as it biodegrades through bacterial action.
Extra credit for providing the same information on other ruminants.
posted by beagle at 2:24 PM on March 7, 2008
beagle, instead of complaining about the other answers, why don't you start googling? The report I cited above comes pretty close to answering the question, and that was like the third google result for "methane eructation" or "carbon emissions eructation flatulence" or something like that.
posted by salvia at 3:01 PM on March 7, 2008
posted by salvia at 3:01 PM on March 7, 2008
...the methane is released, whether the manure is spread on a field or put into an anearobic composting unit...
Not so, and that assumption might be the cause of the whole disagreement. It is possible to get more or less methane from dung depending on how you handle it. "Spread on a field" is pretty much the opposite of "anaerobic composting".
posted by Canard de Vasco at 3:39 PM on March 7, 2008
Not so, and that assumption might be the cause of the whole disagreement. It is possible to get more or less methane from dung depending on how you handle it. "Spread on a field" is pretty much the opposite of "anaerobic composting".
posted by Canard de Vasco at 3:39 PM on March 7, 2008
Salvia: I'm interested in the question, and I've been googling. I'm not complaining about other answers, but I'm saying they don't answer the question posed by the OP, which asks for "proof", and "neutral info/studies/reports. I did "skim" the report you linked to, but if it "comes close", it doesn't answer the question. Neither of the words "eructation" or "flatulence" appear in it, by the way.
Canard de Vasco: I'll stand corrected if anaerobic composting doesn't happen on the meadow, although I've seen my farmer neighbor spread it so thick that only anaerobic processes could be happening down underneath. But if spreading the manure releases less methane, can you cite a study?
posted by beagle at 7:07 PM on March 7, 2008
Canard de Vasco: I'll stand corrected if anaerobic composting doesn't happen on the meadow, although I've seen my farmer neighbor spread it so thick that only anaerobic processes could be happening down underneath. But if spreading the manure releases less methane, can you cite a study?
posted by beagle at 7:07 PM on March 7, 2008
beagle, are we talking about the same report? Did you click anything? For example, if you click on the methane section, Chapter 7, it contains this sentence:
Murray et al (1976) showed in sheep fed 800 g lucerne chaff per day, that while 87% of methane was produced in the rumen and 13% in the lower digestive tract, >98% was excreted via the mouth and about 2% in the flatus.
It's talking about both the location where the methane was generated, and the location where it was expelled. It goes into emissions from effluent ponds, what difference different feed makes, etc.
posted by salvia at 11:51 PM on March 7, 2008
Murray et al (1976) showed in sheep fed 800 g lucerne chaff per day, that while 87% of methane was produced in the rumen and 13% in the lower digestive tract, >98% was excreted via the mouth and about 2% in the flatus.
It's talking about both the location where the methane was generated, and the location where it was expelled. It goes into emissions from effluent ponds, what difference different feed makes, etc.
posted by salvia at 11:51 PM on March 7, 2008
When I said "spread" I was thinking of the NZ context, where it's actually more like "sprayed", not too deep, and even then only involves the manure dropped during the small part of the day that dairy cows spend in their milking shed. New Zealand's Ministry for the Environment says that in New Zealand enteric fermentation produces around 30 times more CO2 equivalent emissions than "manure management", but that wouldn't carry across to countries that use feedlots rather than pasture because:
posted by Canard de Vasco at 12:38 AM on March 8, 2008
In New Zealand only dairy cows have a fraction (5 percent) of the excreta stored in an anaerobic lagoon waste system. The remaining 95 percent of excreta from dairy cattle is deposited directly on pasture. All other ruminant species (sheep, beef cattle, deer and goats) deposit all faecal material directly onto pastures.So
I've seen my farmer neighbor spread it so thick that only anaerobic processes could be happening down underneathIn Australia or New Zealand you would never see that.
posted by Canard de Vasco at 12:38 AM on March 8, 2008
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posted by carabiner at 10:32 AM on March 7, 2008