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Home Forums General Discussion Methane digesters

This topic contains 6 replies, has 4 voices, and was last updated by  elnav 5 years, 11 months ago.

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  • #36651

    elnav
    Member

    Although this topic is not applicable to people living in urban areas or in RV, caravans or other temporary digs, generating methane is a very viable method to become self sufficient in an off-grid rural situation.

    Methane is naturally made by the decomposition of manure and rotting vegetation. The equipment involved can be as simple as a drum or as complicated as you like. If you do a Google search you will find a huge number of hits that cover the whole range from a55 gallon drums to huge industrial installations. As a child in Europe I remember seeing the huge gas filled storage tanks that rose and fell as the gas filled or was used up but I have not seen such installations in all my travels in North America.

    Somehow the public got seduced into using petroleum fuel for nearly everything.

    Large industrial farms raising pigs, dairy herds or chicken and turkeys have a huge disposal and environmental problem with their manure. There have been several successful test projects to demonstrate how to mitigate the smell and greenhouse gas emissions from these farms. The beneficial by product has been the capture of the naturally forming methane gas which in most cases is then used to power generators or in compressed form as fuel for the farm vehicles. These are not hair brained DIY projects but fully funded and scientifically documented test projects run by university or industry groups. In addition the methods and technology is scalable.Meaning it can be done on a small subsistence homestead as easily as it can be done on a 1000 head dairy farm. I did a Google search for ‘Methane digester’ and found so much material to look at I had to stop reading after several hours and I never got past the first page. I viewed videos of running operations that literally spanned the world. Many of them in foreign languages indicating this is a wide spread activity not a few isolated experimental cases. The point of this post is not to provide a detailed explanation of how its done, but to inform people who may not have heard about it before hand. Those Who are interested can then delve into it with a Google search.

    #41530

    caverdude
    Participant

    I have an article Home Energy Production Fuel where I talk a small bit about Methane production and storage. The 1970’s book “Producing your own power” Has some nice information, tables, diagrams etc. about this. They show you what you can expect from different types of manures.

    #41533

    elnav
    Member

    For real solid information on methane production there is a book written by L John Fry. It runs about 12 chapters including the reference section chapter. Published in 1975 it is now in the public domain and can be found for downloading on several websites. This is not light reading. It has tables of so many cubic feet of gas produced per tons of feed stock. This is a serious book for DIY engineers. Where I used to live they built a large digester that now feeds utility grade gas right into the naturql gas pipeline and it has been so sucessful a second unit is being built by the next farm over. North America is way behind Europe on this. ther are over 25,000 registered methane producing farms over there. Several companies sell all the required equipment of the shelf and provides the engineering if you need it.

    The best thing about methane digesters is the fact it is a scalable technology. you can build one sized to supply one house hold or a big one to supply power to 1000 homes like they did wher I used to live.

    Almost 2 decades ago there were seveal mid west pilot projects for dairy farms and CAFO meat producers. All of these projects resulted in energy self sufficient farms and in several cases they produced enough energy to also supply adjacent farms. There are also several pilot projects in the western half of the continent ranging from Washington state to California all of which have recieved limited media coverage. The common denominator being all of them are cost effective. They use a feed stock which otherwise would be a nuisance waste product and produce energy at a rate competitive with normal utility power.

    For an example of something slightly differrent look up Jean Paine piles or just the person. He developed a CHP installation that is worthy of emulating.

    #41544

    chowan
    Participant

    I have built 2 digesters so far and i am sold they are by far a better investment than solar panels or wind IF you have the feedstock and IF

    you are prepared to do the extra maintainance required.

    I also believe they are suitable anywhere including urban areas

    urban areas have a large amount of digestable material in the form of grass clippings,human poo and doggie poo just to name a few add in a few city rabbits or chickens and you are good to go.

    also with very small amounts of investment we could be feeding back into a

    “naturall gas grid” like we now do with solar.

    I have run engines off the stuff and they run great and run cleaner than

    gasoline.

    add to this we are cleaning up wast products and saving expensive dumping

    and sewrage charges and its a win win.

    I honestly believe they have ignored methane and natural gas investment in

    favor of more high tech examples like hydrogen because your average back yard

    mechanic could be fueling his house and cars with home brew methane and paying

    no fuel costs,fuel taxes or wast dumping costs.

    #41546

    Dustoffer
    Participant

    Very good!! After all the methane from waste is removed, is the rest compost or compostable for soil building/enrichment??

    #41547

    caverdude
    Participant

    Yes what is leftover after making methane is an enhanced fertilizer.

    http://larrydgray.net

    http://larrydgray.wordpress.com

    #41555

    elnav
    Member

    Residual solids from digesters is the potential fly in the ointment. Recent tests by reputable university investigators found that any toxins and chemical contaminants present in the feed stock remains in the solids after the methane is extracted. Depending on what was fed to the animals or sprayed on the plants the resultant fertilizer may also contains toxins or contaminants.

    GRIST magazine had an article about a month back by tom Phillpot if I remember ccorrectly. He has been writing about big ag and their hidden sins for quite a while.

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