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Hairyloon
Joined: 20 Nov 2008
Posts: 15372
Location: Today I are mostly being in Yorkshire.
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dpack
Joined: 02 Jul 2005
Posts: 35938
Location: yes
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 Posted: Thu Dec 10, 15 5:24 pm Post subject: |
 
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that might be a load of bullocks to fit with bags and what about static sparks? a herd doing a hindenberg impersonation would be horrible.
considering what i was just reading about tar sand oil extraction and super scale strip mining for coal i recon moo gas is a fairly minor issue. |
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Rob R
Joined: 28 Oct 2004
Posts: 31902
Location: York
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| Posted: Thu Dec 10, 15 6:26 pm Post subject: |
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One issue for the free ranging cattle might be lack of production but it's always bugged me why, with so many animals kept indoors (allegedly) are we not collecting the gas as it leaves through the ventilation systems? Perhaps for exactly the same reason. |
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Ty Gwyn
Joined: 22 Sep 2010
Posts: 4293
Location: Lampeter
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| Posted: Thu Dec 10, 15 7:06 pm Post subject: |
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Be interesting to hear from Slim on the thinking of his French counterpart on this subject. |
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Slim
Joined: 05 Mar 2006
Posts: 5485
Location: New England (In the US of A)
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| Posted: Thu Dec 10, 15 7:20 pm Post subject: |
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| Ty Gwyn wrote: |
| Be interesting to hear from Slim on the thinking of his French counterpart on this subject. |
The short answer is: It's complicated.
I don't know enough about the methane end of things to want to risk saying anything that could be off-base. (I know what I don't know in this case). I have seen folks link polyunsaturated fatty acid (PUFA) rich feeds with methane reduction, but haven't read into much yet. I think that a lot of conventional folks like to say that they generate less methane per amount of product produced with high corn diets, but I am guessing that is over-simplifying things as well (ignoring carbon budgeting of growing corn versus grazing and haying)
I will say that contrary to the article, it isn't as simple as "just adding some linseed" for those farmers that are using primarily corn silage. Firstly the linseed must be process for the PUFA to be available, and secondly they easily run the risk of milk fat depression because they probably have their herd on the verge of ruminal acidosis as it is, and a slug of PUFA might push them into milk fat depression, which can be enough of an income loss to warrant not caring about your methane.
More info: https://ecommons.cornell.edu/bitstream/handle/1813/39200/4Harvatine_manu.pdf?sequence=2
It's a different story with grass/alfalfa feeding, as that is a lot less likely to verge on acidotic rumen conditions anyway. |
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Ty Gwyn
Joined: 22 Sep 2010
Posts: 4293
Location: Lampeter
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| Posted: Thu Dec 10, 15 8:05 pm Post subject: |
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Fully agree with you on the Acidosis angle,
It was the mention of an increase in grass diet to combat methane release i was interested in your point of view? |
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Hairyloon
Joined: 20 Nov 2008
Posts: 15372
Location: Today I are mostly being in Yorkshire.
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| Posted: Thu Dec 10, 15 8:27 pm Post subject: |
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| Rob R wrote: |
| it's always bugged me why, with so many animals kept indoors (allegedly) are we not collecting the gas as it leaves through the ventilation systems? |
It will be very dilute by then and I think it is not easy to refine.
If somehow you ventilated less, so that gas built up to a level that would be useful, then there would be risk of explosion. |
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Mistress Rose
Joined: 21 Jul 2011
Posts: 11156
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| Posted: Fri Dec 11, 15 7:45 am Post subject: |
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The same problem with decomposing rubbish. We have several of them round Portsmouth, often with ventilators attached. In fact the highest point of Portsmouth is a man made rubbish heap which has been nicely grassed and planted with trees, and must be sinking at an appreciable rate.
As we have discussed elsewhere, the amount of fossil fuel/greenhouse gas involved in producing grain or other arable crops on unsuitable land that is better grazed by cattle is probably worse than the amount that cows produce. |
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Rob R
Joined: 28 Oct 2004
Posts: 31902
Location: York
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| Posted: Fri Dec 11, 15 11:03 am Post subject: |
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| Hairyloon wrote: |
| Rob R wrote: |
| it's always bugged me why, with so many animals kept indoors (allegedly) are we not collecting the gas as it leaves through the ventilation systems? |
It will be very dilute by then and I think it is not easy to refine.
If somehow you ventilated less, so that gas built up to a level that would be useful, then there would be risk of explosion. |
By my reckoning it'd be in the region of 0.036% when combined with the air exiting a cow, versus 0.00018% in the atmosphere. They're already looking at technology to capture methane from the atmosphere so I would have thought that starting with a concentration of 200 times that of air would be more logical. I'm not a chemist though, so perhaps it becomes more problematic to extract higher concentrations.
Stopping it coming out to increase the energy balance in cattle is likely to be the more beneficial route to take though, and I expect we'll see more of that in the coming years. |
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Behemoth
Joined: 01 Dec 2004
Posts: 19023
Location: Leeds
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| Posted: Fri Dec 11, 15 11:35 am Post subject: |
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Assuming the could collect and contain it as HL says you're then in a world of moving pressurised explosive gases and a hatful of regs. Not impossible though. A more effective way to generate gas may be through digesting the slurry. |
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dpack
Joined: 02 Jul 2005
Posts: 35938
Location: yes
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| Posted: Fri Dec 11, 15 11:40 am Post subject: |
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from a dilute amount in air the major problem i can see would be the energy in/energy out equation.
getting the methane out could be fairly simple either chemically or using physical properties and fractionally distilling liquid air but both ways it would be an expense rather than a profit/energy supply.
re the minor amounts involved the effort might be better put to battery tech and renewable/low impact energy sources except perhaps in the case of landfill methane capture |
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Hairyloon
Joined: 20 Nov 2008
Posts: 15372
Location: Today I are mostly being in Yorkshire.
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| Posted: Fri Dec 11, 15 1:57 pm Post subject: |
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If you consider the thermodynamics of a distillation, the overall net energy transfer is zero.
It is almost certainly nigh on impossible to actually run one that way, but it may be possible to get relatively close...
Just in case anyone here wants to start thinking about it any, the boiling point of methane is -161°C at 1.013 bar and, Critical temperature is -82.59 °C... |
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Slim
Joined: 05 Mar 2006
Posts: 5485
Location: New England (In the US of A)
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| Posted: Fri Dec 11, 15 2:39 pm Post subject: |
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| Behemoth wrote: |
| Assuming the could collect and contain it as HL says you're then in a world of moving pressurised explosive gases and a hatful of regs. Not impossible though. A more effective way to generate gas may be through digesting the slurry. |
Methane digesters are very common around here:
http://www.greenmountainpower.com/innovative/cow/ |
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Mistress Rose
Joined: 21 Jul 2011
Posts: 11156
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| Posted: Sat Dec 12, 15 7:53 am Post subject: |
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I think the only sensible way of extracting methane is by digesters. I have been thinking for years that they were the way to go for organic rubbish, and they are now reasonably common on farms.
Hairyloon, you have to put a lot of energy into compressing/cooling the gas before you can distil out all the different gases. |
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Hairyloon
Joined: 20 Nov 2008
Posts: 15372
Location: Today I are mostly being in Yorkshire.
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| Posted: Sat Dec 12, 15 11:17 am Post subject: |
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| Mistress Rose wrote: |
| Hairyloon, you have to put a lot of energy into compressing/cooling the gas before you can distil out all the different gases. |
You do, but you can use some of that energy to compress/cool the next lot of gas. |
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