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Old 11-10-2013, 02:59 PM
 
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I was reading up on biogas, which is gas produced from the methane and carbon dioxide (primarily) from anaerobic digestion of waste, in the wikipedia article on it. What a great idea! With such a thriving beef industry in the US, it seems a no-brainer for biogas conversion plants to be installed, or however it works. Just an idea I thought I should shed some light on. I'll share these snippets from the Wikipedia article that are quite enlightening:

"Normally, manure that is left to decompose releases two main gases that cause global climate change: nitrogen dioxide and methane. Nitrogen dioxide (NO
2) warms the atmosphere 310 times more than carbon dioxide and methane 21 times more than carbon dioxide.

By converting cow manure into methane biogas via anaerobic digestion, the millions of cattle in the United States would be able to produce 100 billion kilowatt hours of electricity, enough to power millions of homes across the United States. In fact, one cow can produce enough manure in one day to generate 3 kilowatt hours of electricity; only 2.4 kilowatt hours of electricity are needed to power a single 100-watt light bulb for one day.[15] Furthermore, by converting cattle manure into methane biogas instead of letting it decompose, global warming gases could be reduced by 99 million metric tons or 4%.[16]"

See: http://en.wikipedia.org/wiki/Biogas

My question is, when the methane is combusted, as in the case of biogas, can it still trap heat in the atmosphere or what?
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Old 11-10-2013, 03:22 PM
 
Location: Volcano
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Quote:
Originally Posted by juliaanne View Post
I was reading up on biogas, which is gas produced from the methane and carbon dioxide (primarily) from anaerobic digestion of waste, in the wikipedia article on it. What a great idea! With such a thriving beef industry in the US, it seems a no-brainer for biogas conversion plants to be installed, or however it works.
There already are a number of large livestock operations... dairies and pig farms among them... which capture and burn methane gas to generate electricity. It doesn't even require advanced technology, just commitment.

Here in Hawai'i, two islands are doing that with wastewater treatment plants and household garbage as well. Besides producing energy, it reduces water pollution and solid waste disposal.

Quote:
My question is, when the methane is combusted, as in the case of biogas, can it still trap heat in the atmosphere or what?
Methane is the main ingredient in natural gas, and its main byproducts are water and CO2. Yes, the CO2 is a greenhouse gas, but it is far less so than methane is, so there's a net improvement in converting waste dump gas into power.
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Old 11-10-2013, 05:12 PM
 
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Originally Posted by OpenD View Post
There already are a number of large livestock operations... dairies and pig farms among them... which capture and burn methane gas to generate electricity. It doesn't even require advanced technology, just commitment.

Here in Hawai'i, two islands are doing that with wastewater treatment plants and household garbage as well. Besides producing energy, it reduces water pollution and solid waste disposal.



Methane is the main ingredient in natural gas, and its main byproducts are water and CO2. Yes, the CO2 is a greenhouse gas, but it is far less so than methane is, so there's a net improvement in converting waste dump gas into power.
They are using methane gas emitted by wastewater? Huh, I never really thought of grey water as having the potential to emit methane...it's always the landfills and dung brought to light.

Ah okay, I suppose that's good because carbon dioxide has 21x less the warming potential than methane, however its lifetime in the atmosphere is 30–95 years, longer than that of methane which is about 10 years. Plus, water vapor accounts for the largest percentage of the greenhouse effect, though the average time a water molecule spends in the atmosphere is 9 days (all these numbers taken from Wiki articles). So even still, biogas capture and combustion doesn't seem a remarkable improvement for the environment.
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Old 11-10-2013, 08:24 PM
 
Location: Volcano
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Originally Posted by juliaanne View Post
They are using methane gas emitted by wastewater? Huh, I never really thought of grey water as having the potential to emit methane...it's always the landfills and dung brought to light.
Sorry I was not clear. I wasn't talking about greywater, I was talking about blackwater. IOW, human manure.

Indeed, there's yet another technology now being explored in pilot projects here and in other places, to replace septic systems (anaerobic decomposition) with algae ponds, which combine solar energy with biological digestion to grow biomass that can be readily converted into biodiesel fuel, which can directly displace the fossil fuel equivalent.

Quote:
Ah okay, I suppose that's good because carbon dioxide has 21x less the warming potential than methane, however its lifetime in the atmosphere is 30–95 years, longer than that of methane which is about 10 years. Plus, water vapor accounts for the largest percentage of the greenhouse effect, though the average time a water molecule spends in the atmosphere is 9 days (all these numbers taken from Wiki articles). So even still, biogas capture and combustion doesn't seem a remarkable improvement for the environment.
Significant improvement is often incremental, just as the problems we face were created incrementally. To the extent that methane is going to be produced anyways by natural processes, capturing that methane for energy production AND conversion of the gas to byproducts that are less ecologically damaging is pretty much a no-brainer. As I said, the key element to utilizing that resource is simply making the commitment to do so.

And though the CO2 level in the atmosphere continues to trend upward, it IS a natural component of the planet's life cycle, being used and sequestered by photosynthesis, continuously recycling through. Using that recently captured captured carbon for part of our energy needs is much healthier than continuing to use the carbon that was so captured millions of years ago, which has added huge quantities of CO2 to our atmosphere since the Industrial Revolution. Fortunately our oceans are taking CO2 out of the air at unprecedented rates as well. The thing we need to focus on is to stop adding more to the current systems.

And we also need to to pay attention to the ecological tipping point that some experts predict could be fast approaching... when the arctic warms sufficiently that permafrost begins to melt, huge quantities of methane will be released, and it could become an irreversible chain reaction. And for that reason, pursuing every incremental improvement in the release of greenhouse gases we can right now is important.

Last edited by OpenD; 11-10-2013 at 08:36 PM..
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Old 11-10-2013, 11:37 PM
 
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Quote:
Originally Posted by OpenD View Post
Sorry I was not clear. I wasn't talking about greywater, I was talking about blackwater. IOW, human manure.

Indeed, there's yet another technology now being explored in pilot projects here and in other places, to replace septic systems (anaerobic decomposition) with algae ponds, which combine solar energy with biological digestion to grow biomass that can be readily converted into biodiesel fuel, which can directly displace the fossil fuel equivalent.



Significant improvement is often incremental, just as the problems we face were created incrementally. To the extent that methane is going to be produced anyways by natural processes, capturing that methane for energy production AND conversion of the gas to byproducts that are less ecologically damaging is pretty much a no-brainer. As I said, the key element to utilizing that resource is simply making the commitment to do so.

And though the CO2 level in the atmosphere continues to trend upward, it IS a natural component of the planet's life cycle, being used and sequestered by photosynthesis, continuously recycling through. Using that recently captured captured carbon for part of our energy needs is much healthier than continuing to use the carbon that was so captured millions of years ago, which has added huge quantities of CO2 to our atmosphere since the Industrial Revolution. Fortunately our oceans are taking CO2 out of the air at unprecedented rates as well. The thing we need to focus on is to stop adding more to the current systems.

And we also need to to pay attention to the ecological tipping point that some experts predict could be fast approaching... when the arctic warms sufficiently that permafrost begins to melt, huge quantities of methane will be released, and it could become an irreversible chain reaction. And for that reason, pursuing every incremental improvement in the release of greenhouse gases we can right now is important.
You mean, transporting the human sewage to open pits to become ponds? Ooh, that sounds pretty smelly if so. That probably wouldn't bode well with the general public--I wouldn't want to live near that. It reminds me of the compost toilets, in which the poop from an outhouse is converted into compost which people can use for their garden. Human poop manure just sounds a little more off-putting than that of cows, doesn't it?

I see what you're saying -- the biogas burns methane that's being released to the atmosphere anyway, whereas extracting fossil fuel from deep underground means combusting carbon dioxide that has already been sequestered, if I'm understanding correctly. Good point.

Yes, I did a paper on methane clathrates--it sure is chilling. It's being released from deep in the ocean as well, not just the Arctic, as it warms. There are corporations that are looking into and planning to actually EXTRACT the methane from those clathrates, making into natural gas, and at the same time, sequestering carbon dioxide--by injecting carbon dioxide into the clathrates, the extraction of the methane is made easier, if I remember correctly. This seems crazy--I think the clathrates should not be messed with.

When methane is combusted, it turns into carbon dioxide and water, right? This is another thing that confuses me. If this is so, then sequestering CO2 into hydrates while releasing methane for use as a natural gas doesn't make sense to me.

The oceans absorb most of CO2, but it is slowing. And more acidic, as well as warmer water cannot absorb as much.

I think the best solution is algal biodiesel. Unlike ethanol, it doesn't use up corn that could contribute significantly to ending world hunger.

I've heard that the ocean conveyor belt shutting down could also contribute to the lower carbon dioxide storage potential.

This is a bit of a tangent, but I know the conveyor belt/thermohaline circulation could shut down because more warming in the Arctic would mean the icebergs and caps, which are 100% fresh water, could melt and make the water too fresh to produce the dense, cold waters form into deep water currents, moving toward the equator. But a few things confuse me about this...when the polar areas grow warmer, there is more evaporation, which leaves salt behind. Also, warmer air can hold more water vapor, which means there would be greater potential for snow to form. It's complicated, sigh.
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Old 11-11-2013, 12:37 AM
 
Location: Volcano
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Quote:
Originally Posted by juliaanne View Post
You mean, transporting the human sewage to open pits to become ponds? Ooh, that sounds pretty smelly if so. That probably wouldn't bode well with the general public--I wouldn't want to live near that.
That's typical and normal, but it's a fundamental human need to take care of, and water based sewage systems are very wasteful of water resources, which in some areas is becoming increasingly problematic. And here in Hawai'i the septic tank systems that are so common in rural areas in other parts of the country are more difficult to dig and more expensive, because the underlying lava rock is so near the surface in so many areas, so many areas have to depend on cesspools anyway. So the algae pool system, which is surprisingly unsmelly, would actually be an upgrade for many.

Quote:
It reminds me of the compost toilets, in which the poop from an outhouse is converted into compost which people can use for their garden. Human poop manure just sounds a little more off-putting than that of cows, doesn't it?
Properly manufactured composting toilets are quite refined, with no more smell than a water closet, and are not only permitted here but actually preferred to cesspools by the County Government. And the relatively odorless compost that results is great fro flower beds, yes. Ed Begley Jr, the actor, has composting toilets installed in his Beverly Hills California mansion, and uses the byproducts to grow his prize winning roses, but that a whole separate topic completely.

Quote:
I see what you're saying -- the biogas burns methane that's being released to the atmosphere anyway, whereas extracting fossil fuel from deep underground means combusting carbon dioxide that has already been sequestered, if I'm understanding correctly. Good point.
Combusting methane and releasing CO2 from fossil fuels, yes. Burning fossil fuels increases the total amounts newly released to the atmosphere, whereas burning biomass or biogas simply recirculates what is already in the atmosphere.

Quote:
Yes, I did a paper on methane clathrates...
I'm sure it was great... I haven't studied this area at all.
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Old 11-11-2013, 05:14 AM
 
Location: Minnysoda
8,590 posts, read 8,502,979 times
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Old technology really...If I recall correctly it takes about 900 animal units to make 840 Kw.. A animal unit is 1000lbs

some light reading on the subject...
http://www.nrel.gov/docs/fy11osti/49629.pdf
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Old 11-15-2013, 08:03 PM
 
Location: East Side Milwaukee
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In my city, a business was opened that creates electricity from food waste. Waste not, want not.

BizTimes: Milwaukee and Southeastern Wisconsin Business News | BizTimes
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Old 11-18-2013, 10:56 PM
 
Location: WA
4,246 posts, read 7,825,861 times
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Quote:
Originally Posted by juliaanne View Post
They are using methane gas emitted by wastewater? Huh, I never really thought of grey water as having the potential to emit methane...it's always the landfills and dung brought to light.
At my wastewater treatment plant, they don't get methane from the wastewater itself, but from the "sludge" (biosolids) that settle to the bottom. They move this sludge to a huge digester and let it ferment for a while, collect the methane and use it to fuel the entire plant (and even sell some back to the utility). Then they mix the sludge with some sand and sell it to gardeners.
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Old 11-18-2013, 11:43 PM
 
Location: Volcano
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When I lived near Seattle I bought composted manure from the zoo, which they call Zoo Doo. I particularly liked the stuff from the cages of the big cats, because I got the biggest, nicest roses by generous applications of that Zoo Doo. I don't actually know how good a fertilizer it was, but the carnivorous predator odors embedded in the product definitely kept the deer from eating all the leaves and rose buds off my bushes, so they finally had a chance to bloom.
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