# Poop powered lights



## fishhead (Jul 19, 2006)

http://www.reuters.com/article/newsOne/idUSN0937395520080909

"SAN ANTONIO (Reuters) - San Antonio unveiled a deal on Tuesday that will make it the first U.S. city to harvest methane gas from human waste on a commercial scale and turn it into clean-burning fuel."

"The city approved a deal where Massachusetts-based Ameresco Inc will convert the city's biosolids into natural gas, which could generate about 1.5 million cubic feet per day, he said."


My only question is why has it taken so long. And why aren't we doing this with feedlot waste too instead of letting it turn into an environmental hazzard?


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## Cabin Fever (May 10, 2002)

The majority of large and medium size wastewater treatment plants use anaerobic digestion to process their biosolids. The closest one to you is probably St. Cloud. The anaerobic digestion process requires heat (about 95ÂºF) and produces biogas. The biogas generated by Minnesota wastewater plants is used to heat the digestors and the wastewater plant buildings. This has been done for decades. 

BTW, the process whether using biosolids and manure, still has a by-product that is typically land applied. It doesn't disappear.


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## benevolance (Aug 10, 2008)

No the left over byproduct does not disappear... but if the digestor is built correctly and the temputures are regulated 99.9% of any nasty pathogen or unwanted bacteria is removed and what you are left with is a great all natural fertilizer rich in trace metals notorgen and ammonia...which are essential for healthy plants...

The bio digestors that use Animal manure generate a slurry that is a direct fertilizer and possibly the best fertilizer known to man... beats chemical based petroleum fertilizer hands down.

In asia they are using the by product from digestors that process human waste as fertilizer for feedstock crops I believe. So the byproduct of converting waste into clean bio fuel need not be useless by any means.


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## rambler (Jan 20, 2004)

It's been done on farms since the 1980's. In general, the digesters are terribly fragil & create a nightmare of problems, and the whole thing is forgotten about in about 3 years.

I keep reading about them in the farm papers, every time there is a blip of energy crisis, yet another 'new' manure digester is written about, how it makes electricity & composted manure from waste.

And, if you follow up on them about 3 years later, you find it is a rusting pice of machinery no longer being used because it was too fussy, cost too much to operate for what it returned. Happens over & over.....

The manure just as it is is worth more as fertilizer than to have it sitting around for a year, the methane produced does not equal the repairs & time spent on keeping the digester going. And it all falls apart once the govt seed money dries up. Just not practical.

Perhaps on a city-wide scale it will work better, hope so for the taxpayers involved!

--->Paul


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## fishhead (Jul 19, 2006)

There's a dairy in Elk River MN that produces electricity from a methane digester. I think they said the minimum number of animals needed was 1,600.

It just doesn't make sense to not recover the most of the nutrients that the farmer bought and put into his animals. My plan for my fish farm did that and was designed to produce a product at every step of the process before the cleaned water was reused.


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## Jack Parr (Sep 23, 2005)

rambler said:


> It's been done on farms since the 1980's. In general, the digesters are terribly fragil & create a nightmare of problems, and the whole thing is forgotten about in about 3 years.
> 
> I keep reading about them in the farm papers, every time there is a blip of energy crisis, yet another 'new' manure digester is written about, how it makes electricity & composted manure from waste.
> 
> ...


The problem with the above mentioned digester or methane gas generator is that they are designed to be not "labor intensive" I'm thinking. I have not seen one.

When I was in Vietnam during 1971 a member of my unit was assigned to do some civic action projects working and helping the locals. He was assigned to help a pig farmer and that involved constructing a methane gas generator.

I did not see this gas generator but my fellow soldier explained how it worked. 
It was simply a concrete box built into the ground with a sealable and removable metal cover light enough that it could be handled by hand. The pig manure was dumped into the concrete tank, cover installed and nature did the rest. The cover had a pipe fitting installed, a rubber? tube was attached to it and the gas was piped to a room to heat the pig food cookers and for the farmers own cooking needs.

I don't recall how long it took for the digestion and gas generation took before gas could be retrieved from a given batch of manure. I also don't know or remember how long the manure generated gas before depletion. I know that all the work of loading and cleaning out the box of manure was by hand. Maybe with the use of a wheelbarrow? and shovels.:rock: The removed processed/de-gassed manure was used as a fertilizer. 

To this day I regret not making more of an effort to accompany the guy who was working on the project to see it. 

I did see the pig farm from the air since I flew helicopters in RVN. It was a fairly large operation by their standards. 

I thinking that the equipment discussed as ineffective in the quote above is because it's designed to be used free of "manual" labor and automatic? I have seen images of gas processing equipment associated with landfill methane gas extraction and it's looks as complicated as a natural gas "from down below" plant does. Methane gas from any source is a natural process. 

I also think about what could have happened to the pig farmer once the country was taken over by the Commies. Probably he was considered a capitalist and made to suffer? Then again since he was into food production he may have been allowed to continue although without making a "profit".

Just to satisfy my curiosity I'm going to do some searching on methane gas generators.

Jack


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## mdharris68 (Sep 28, 2006)

I have been reading about Jean Pain Composting http://journeytoforever.org/biofuel_library/methane_pain.html in which he was producing methane gas quite a while back, but he was also compressing it. Does anyone know how or what equipment can safely compress a flammable gas? I would like to try it on a small scale with my goat manure pile, but am unsure of the process to store it. One of our local manufacturing plants has thier own watewater treatment plant, and they have a flame burning off the methane and it has been burning for at least 15 years if not more as I recall.


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## Windy in Kansas (Jun 16, 2002)

mdharris68 said:


> Does anyone know how or what equipment can safely compress a flammable gas?


For seven heating seasons I hauled LP gas (propane) for a dealer. It was only the last few that a liquid pump was used instead of a vapor compressor. 

The compressor simply removed vapor pressure from the truck being loaded and added it back into the nurse tank. That allowed the liquid to flow to the vessel with the least pressure.

The compressor looked much like any other but instead of sucking air to compress it was a closed loop system and the cylinder sucked in vapor. Of course the electric motor powering the compressor was one of the explosion proof units like are also used around grain handling facilities where dust explosions are a threat.

I don't know if there are any LP vapor compressors still around or not. Liquid pumps were much faster for transfer.
============
"It just doesn't make sense to not recover the most of the nutrients that the farmer bought and put into his animals."

Even without digesting the manure can be spread and will still retain all of the input save for some weather loss and some other. 
-------
Gasses are very corrosive (hydrogen sulfide) and for some uses need to be scrubbed or cleaned before use. As an example an engine would deteriorate quickly with constant highly corrosive gas going through it. 

Cheap homemade scrubbers which only partially work and can be something as simple as running the gas through iron filings/shavings or attempting to dry the fuel by running it though wood shavings.

One major consideration is the number of BTUs per cubic foot of methane versus other gasses. It is very very low in comparison. This chart show it with only about 1/5th that of propane. Methane 530. Propane 2500+ http://www.steamonline.com/btu.html 

When Mother Earth News interviewed a methane producer in India decades ago the producer told that the MIXTURE had to be stirred for 20 minutes each day. Kind of labor intensive unless energy other than human is used which kind of defeats the purpose.

The producer did state that the digesting process locked in nitrogen and tests revealed the digester wastes were higher in nitrogen somehow than undigested manure.


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## fishhead (Jul 19, 2006)

I read that methane is harder to compress into a liquid compared to propane. It takes more pressure.

The chinese people in rural areas have pits where they throw waste to turn into methane. A pipe runs to the kitchen stove for cooking.


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## fishhead (Jul 19, 2006)

I read that methane is harder to compress into a liquid compared to propane. It takes more pressure.

The chinese people in rural areas have pits where they throw waste to turn into methane. A pipe runs to the kitchen stove for cooking.


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## fordson major (Jul 12, 2003)

this the one windy?http://journeytoforever.org/biofuel_library/MENintvus/singhintvu.html
problem with waste water plant supernate is that it has been weakened by immersion in water, also imurities in the water eg. detergent in quantity, oils, stuff that should not go in your body should not go down the drain! usually happens at 2 AM! (here at least!)


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