saving the world and other fun stuff...

Digester design and construction info

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Bob
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Postby Bob » Tue Oct 15, 2002 9:29 am

Well, anaerobic digestion itself, as a metabolic process, is exothermic.

But I'm not sure that's what you're asking.
There are different groups of bacteria, which only live within very specific range of temperatures. If the heat loss from the reactor vessel is greater than the heat generated by metabolism of the organisms within, then, for all practical purposes, I suppose you could consider the overall process to be endothermic.

Kind of like, human metabolism is an exothermic process, but you still have to heat your house in the winter.

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nathan_lamothe
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Postby nathan_lamothe » Sat Nov 02, 2002 11:23 am

Sorry this is so long in coming. I am so regularly at Brainstorms I forget that we are conversing here as well.

You answered my question re:endothermic reaction. I kept reading that AD's had to be heated, and that didn't make sense to me as I was envisioning the strongly exothermic aerobic digestion process which is self heating, and can melt the snow off around here even in the dead of winter.

I just read your reply to Laurel about seeding and methanogens, and thought that developing cultures of methanogens for this project would become important, as it is the methanogens rather than the system that will need to be modified for each different mix of feedstock.

Developing a GM methanoge that can effectively decompose wood fiber would greatly increase the number of usefull applications / industries for whom this project would be a significant progress.

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Re: saving the world and other fun stuff...

Postby nathan_lamothe » Wed Nov 19, 2008 11:06 am

Just went through the original post, and most of the links are broken. Going to take some time soon to rework them all...

worried especially about the McLeod Harvester, as it was a fairly small company, and its website is now showing up as a malware thing or something. Not good.

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Re: saving the world and other fun stuff...

Postby Bob » Wed Nov 19, 2008 12:14 pm

Good deal!

How goes your world?

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nathan_lamothe
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Re: saving the world and other fun stuff...

Postby nathan_lamothe » Thu Nov 20, 2008 11:09 am

My world is well. I am living off the largess of the government (well... I've paid for it already, but still, it seems nice) My wife and daughter are both doing well. (Natalie has a cold, but we live in the north and she is an elementary school principal - it comes with the paycheck).

Brainstorms just scored me a $35 dollar article for free... which has in its citations nearly everything I want to read about AD of agricultural waste.

Quick skim shows the conversion rate for wheat straw to CH4 at nearly 0.4m^3 / Kg of VS

So now I need to go find new sources for all my other numbers again, and recheck the math.

You? Big plans for Costa Rica?

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Bob
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Re: saving the world and other fun stuff...

Postby Bob » Thu Nov 20, 2008 2:18 pm

Glad to see you able to pick this back up, Nathan. I'll look forward to seeing what new information you find. And I would love to see it move forward -- like find some funding to build a prototype, test feasibility?

For myself, I'm spread a mile wide and an inch deep. Too many projects, just trying to keep up. One that I've taken forward since our last conversation about it is the lab scale digester and an automated data collection system. Are you still able to log onto the R&D forum? I'll update it with recent developments.

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nathan_lamothe
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Re: saving the world and other fun stuff...

Postby nathan_lamothe » Thu Nov 20, 2008 4:44 pm

Yup, I can still get to the private forums. You fixed that for me just before you went south.

I'm not giving it a lot of time, but hope to be able to steal an hour or so a day for reading etc. Dishes, laundry and house cleaning all provide lots of time for the digestion/planning/headgames.

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nathan_lamothe
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Re: saving the world and other fun stuff...

Postby nathan_lamothe » Fri Nov 21, 2008 12:16 pm

http://engrwww.usask.ca/oldsite/societi ... /c0556.pdf has a summary of the straw from cereal grains available in the Prairie Provinces. After deducting 1t/ha for preventing wind/water erosion, and the amounts necessary for livestock feed and bedding the three prairie provinces produce between 2.313 and 27.622 Mt of straw for potential industrial use. (The average was 15.021Mt).

That average - works out to 450 kg per year for every person in Canada. When you add in the farms elsewhere, and the non-cereal crop residue (canola, carrots sunflower, sugar beet, etc...) there must be a lot of crop to utilize.

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nathan_lamothe
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Re: saving the world and other fun stuff...

Postby nathan_lamothe » Thu Nov 27, 2008 9:51 pm

There is a lot of new information available. Found this tonight:
http://www1.agric.gov.ab.ca/$Department ... agdex11397

So it seems to me that the AD process is gaining traction.
here's hoping.

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Re: saving the world and other fun stuff...

Postby Bob » Fri Nov 28, 2008 11:03 am

Did you see the stuff I added to the R&D Forum?

davidwillis
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Re: saving the world and other fun stuff...

Postby davidwillis » Tue Jan 13, 2009 10:32 am

I am very interested in this (on a small scale). I would like to read what is in the R&D. How Do you get access to that?

Thanks
David


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