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  • From: Tvoivozhd <tvoivozd AT infionline.net>
  • To: homestead AT lists.ibiblio.org
  • Subject: [Homestead] Biogas Digesters, mostly polyethylene bag
  • Date: Wed, 10 Nov 2004 14:27:22 -0800

It is not likely anyone is going to rush right out to build a biogas digester unless gasoline goes to ten dollars a gallon, or they own a big hog or chicken operation---but ever since Fry ran his his vehicles on PigPower, it has been a fascinating technology, fine integrated farming technique, and something to file away (where it won't disappear) for possible future use, along with other biofuel manufacture such as woodgas.com, Journey to Forever ethanol and McDonald's throwaway deep fat fryer discards, Peter Singfield (Belize denizen) use of sugar cane squeezings turned to vinegar, to which he adds cow manure pudding to generate methane etc.



http://www.ias.unu.edu/proceedings/icibs/ibs/info/ecuador/install-polydig.htm
(very simple, cheap polyethylene bag in hole in ground)

http://www.ias.unu.edu/proceedings/icibs/ibs/info/country.htm
(integrated biosystems, mostly rice and fish---many links, some dead)

http://www.mekarn.org/sarpro/preston.htm
(integrated farm biosystems in tropics for food and energy. Sugar palm at top, next oil palm as source of farm fuel)

http://listserv.repp.org/pipermail/gasification/2004-October/007338.html
(also in tropics, use two-roll mill to squeeze sugar cane, ferment cane juice to vinegar with aid of photovoltaic air pump emitting air through a porous stone. Resultant vinegar is one component of methane production---the other component is cow patty soup.)

http://www.fao.org/docrep/T4470E/t4470e09.htm
(farther north and based on pig manure---methane produced by plastic-covered pond of pig manure. Just a side note---while methane is not as compressible as LPG, in South Africa a good handling system is a compressor-truck that comes around, extracts CO2 from methane, compresses methane in high pressure metal tanks, removes hydrogen sulfide, in which form the methane is easy to use for vehicle engines or household cooking)

http://payson.tulane.edu:8085/cgi-bin/gw?e=t1c11home-envl-1-T.1.B.27.1-500-50-00e&q=&d=T.1.B.27.14.1&a=t
(scrub carbon dioxide from methane with limewater, ash etc. , and hydrogen sulfide

The Indian Agricultural Research Institute has reported the following method for removing carbon dioxide from biogas (as reported in Nepal's Biogas Newsletter). Biogas is bubbled through a solution of ten percent monoethanolamine (MEA) in water. The carbon dioxide content of the biogas is reduced to 0.5 to 1.0 percent by volume from an initial content of about 40 percent by single bubbling through a plain column 6.0 cm (2½ inches) in height. The scrubbing column is made of an inexpensive plastic bubbler (5.0 cm in diameter and 15 cm in height), having only one opening. Maximum removal of carbon dioxide is observed when the bubbling coming from the opening comes out slowly enough so that each bubble is separate from the others and the stream of bubbles is never in danger of merging into a continuous "tube."

The ideal rate of flow is 100 milliliters per minute at the regulator. This rate yields 60 milliliters of pure methane per minute. A decrease in this rate of flow does not result in any increase in scrubbing effect. Initial pressure of the biogas introduced into the bubbler is 10.0 cm (4.0 inches) of water column, and the drop in pressure head is about 5.0 cm (2.0 inches) of water.

Both caustic potash and MEA are equally effective. But MEA solution can be completely stripped of the carbon dioxide by boiling it for five minutes, after which it can be used again. MEA is also less caustic (able to cause chemical burns) than other solutions that can be used. It will not cause any damage to the skin in case of accidental contact.

http://cgpl.iisc.ernet.in/iset.html
(hydrogen sulfide scrubber using two-sizes impregnated Raschig Rings. Not here, but note that the Columbia Boulevard system uses a potassium hydroxide impregnated activated carbon filter to remove hydrogen sulfide from methane.

Hydrogen sulfide in a 2.8 percent concentration is hell on internal compustion engine valves, rings, pistons and cylinders---so corrosive the engine will wear out in a couple hundred hours.)

http://www.oceta.on.ca/profiles/apollo/scrubber.html
(diagram of commercial Apollo H2S scrubber)

http://www.dmtcalaska.org/course_dev/processtech/03/notes03.html
(scubbing H2S from methane, converting the H2S to elemental sulfur---AND taking out water content with regenerative glycol solution)

http://www.cleantechindia.com/eicimage/220504_10/MGFLW.htm
(methane content, CO2,H2S, water)

http://www.solarengineering.co.za/plasticbiogas_htm1.htm
(two-bag polyethlene-tube biogas system, on as biogas generator, one at kitchen to improve methane gas-flow and pressure.)

Farmer to Farmer notes on using HDPE instead of ordinary polyethylene bag, zipper for cleanoug, or joining sections, insulating trench, and solar heat to maintain polytube at 35 degrees Centigrade for optimum biological activity)
Farmer to Farmer Volunteer Trip Report May 12-24, 2002, Michael Tierney


What was the purpose and primary objective of your trip?
To survey several large and small dairy farms and propose the feasibility of developing manure biogas systems (or troubleshoot under performing existing biogas systems) that would supplement the energy needs of that farm. These energy needs could range from cooking gas, lighting and refrigeration for the small farm, to full-scale commercial electrical generation.

What future volunteer assignments do you think are needed, and what are the next steps in moving the project forward?
Julio Solorzano of MAGFOR did mention at the end of our meeting that the World Bank “Agricultural Technology” project might have an interest in funding a few demonstration biogas digesters at small sustainable farms. If he was serious, I think a low cost approach would involve a collaboration of a volunteer, Professor Raul Botero Botero of Earth University with Ronald Blandon and Ing. Maria Mercedes Oblong to build an upgraded Columbia “tube type” digester out of a tough, black, lightweight, woven hi density polyethylene (HDPE) material that is widely used for pond liners in the United States. At the agricultural collage in Managua I saw a Swiss funded biotube type demonstration project, fed by pig manure, which will soon be rebuilt. Upgrading from the lightweight plastic forage storage tubing that is now used to the tough, ultraviolet resistant, HDPE would be an economical demonstration. The membrane material needs no ultraviolet (UV) protective covers and I understand it could be fitted with a zip lock type seam that can be opened and closed to form a gas tight tube that can be built to any length desired. This “plug-flow” membrane type digester will also provide gas storage at a pressure that makes it useable for appliances. It can also be zipped open and repaired when necessary. I can assist in getting membrane prices and the knowledge and materials for manufacturing the zipper type seam. Off the shelf appliances such as, a biogas cooking stove, gaslights and a biogas refrigerator should be installed at this demonstration project so the gas flows and livestock manure needed to operate them can be measured an compared with published figures. A small, duel fuel, biogas and LP gas fueled electrical generator would be an economical and useful addition to the demonstration.

I would improve the performance of the biotube digester by installing closed-cell insulation (like blue board) at the base of the trench that the biotube would be installed in. The black membrane plus a separate solar panel heated, thermal circulating pipe grid at the base of the trench would allow heating or, if necessary, cooling of the biotube digester to the more optimal 35 degree C.

I had a recent discussion with an Engineering Professor at my Alma Mater, the University of Wisconsin Civil and Environmental Engineering School, Professor Daniel Norguera, about my concept of a domestically manufactured, insulated, 3 chambered, fiberglass, solar heated, anaerobic digester that operates at a steady state of a thermophilic 45-50 degrees C followed by a mesophilic phase at 35 C with a hydraulic detention design of about 20 days. The unit’s modular design provides flexibility plus I envision a simple low pressure, high volume in line hand operated mechanical pump system could be installed to store low-pressure gas in bladders such as truck tires inner tubes for peak gas demand. The gas storage will even out the 24-hour gas demand cycle and should allow a 4-5 pigs or 2-cow farm to generate enough gas in 24 hrs for cooking, lighting and refrigeration for a family of 4-6 people. Manure storage could be provided by off the shelf polypropylene water tanks. The retail cost of Rotoplas brand water tanks in Nicaragua is $180.00 for a 291 gallon or $335.00 for a 661 gallon

Professor Noguera has lived in Columbia, and has some familiarity with the biogas technologies of South and Central America. He noted his willingness to provide some oversight opinions on such a project but has other persons he considers more involved in anaerobic digesters that he would discuss any funded projects with.

If funding requests for biogas demonstration projects were successful, I would complete my design of the portable anaerobic digester unit and peer review it to finalize the design. It seems logical to build and operate a prototype in Wisconsin, correct any problems, and ship two prototypes Nicaragua. If agreed to, one prototype could be installed at the Managua Agricultural College and one demonstration on a small Nicaraguan farm site with cooking, lighting and refrigeration appliances. The project could perhaps involve a cooperative research effort between the UW Madison Civil and Agricultural Engineering Departments and The Agricultural College in Managua. Perhaps Ronald Blandon would see this as a project where he would be a central figure in this collaboration.

Would Farmer to Farmer consider serving as a sponsoring agency for this educational project over a two-year period to provide expert volunteers? Funding and technical support might be provided by other sources like USAID, Peace Corps, World Bank / Japan Social Development Fund (JSDF), PRODEA or private organizational funds?

The lightweight, non-corrodible, portable, solar heated, modular designed, anaerobic digester should be a low cost and low risk project to fund. There is a large technical knowledge base on anaerobic digesters and the use of sour gas appliances. The proposed digester's advantage is that with its higher, optimal, temperature operation it should be much, smaller, faster and rapid at converting volatile organic substances to methane. Conceivably, since pathogen reduction is so significant, the higher initial thermophilic operating temperatures would make it suitable for combining human waste with animal waste. It could provide a low cost energy source that can be easily manufactured in Central America, Africa, Asia and any country with the desire to do so.

Any recommendations/suggestions for future volunteers, or comments?
This project for biogas energy integrates closely to the need to reduce the massive deforestation that is occurring in Nicaragua due to the demand for firewood. Providing cooking gas, lighting, refrigeration at small and midsize farms from biogas has large public health implications. However, the use of other biofuels, such as ethanol, could be explored to see if it could provide energy in a manner similar to what Brazil and other countries have done. You might consider sending volunteers with commercial ethanol production experience that could discuss and demonstrate how to use crop and other organic residues to provide a relatively clean, safe, storable and easily transported fuel. This might allow farmers to produce a product from residuals that would be salable to people in cities for homes or vehicles. Bio diesel is another subject to explore for running diesel generators and vehicles.

Large dairy facilities that want to consider biogas production have an obvious problem. The common or preferred method of maintaining dairy cattle is on pasture. I understand farmers pasture their cows because in a feedlot they do not get sufficient nutrition. Unless the nutritional issues are addressed, promoting the free stall type dairy cattle operations to obtain manure for biogas production may be counter productive. The primary issue at most of the large farms (except the Blandon farm) that I saw was the cows spent most of theirpasture versus feedlot.

It would be useful to have a visit and seminar by Professor Raul Botero Botero of Earth University in Costa Rica to discuss the performance of their biogas digester on their environmentally friendly farm model they developed at Earth University. The operator of the 1990 German designed biogas system at “EIAG” The Rivas Agricultural Collage was very knowledgeable regarding the day to day operation of the anaerobic digester that provides cooking gas and gas for classroom Bunsen burners.

It would be useful to expand our thinking from biogas production from animal manure to utilizing a mix of many residual organic substances for biogas production. For example, Los Angeles Airport has a demonstration biogas digester it feeds with ground cafeteria wastes. Agricultural markets might consider using market wastes to generate gas for adsorption refrigeration for meats and seafood preservation. Modular biogas generators would produce a clean fertilizer byproduct for city gardens.

Rural human waste handling would be an excellent subject since outhouses are everywhere in rural areas and in some smaller cities. Composting toilet technology can be very effective in disease reduction and reducing water pollution. During this trip I saw composting toilets being built at a national park in Nicaragua. While they will work, there are better aeration designs that would make it less costly easier to build.

Please provide some comments on how the trip affected you personally, or how you feel generally about the Farmer to Farmer program.

Thanks to the extensive logistic support and advice from Arlen Albright I had an enjoyable, busy, and fulfilling experience. It was enhanced by being able to work with Aleen, my Peace Corps Volunteer daughter, as our pre-travel coordinator and interpreter during the second week of my assignment . My wife and I had been in Nicaragua last year to visit our daughter, so we had a sense of the country and some acquaintances who were helpful in introducing us to people in their communities. Ronald Blandon, Ing. Maria Mercedes Oblong and Estaban, our guardian and driver and Juillo, our interpreter for the first week, provided very professional yet personal host services. I think we introduced both basic concepts, such as the Columbia biotube type digester, to small, midsize and large farmer owners and more advanced operational discussions for those entrepreneurial people in Nicaragua who have independently built and effectively operate biodigesters on their farms.

I brought Spanish language brochures for the World Dairy Exposition in Madison and provided information to Ronald Blandon and Maria Mercedes regarding a UW Madison 3 day, pre-expo short course on International dairy operations. If I am in town I would be pleased to help them coordinate a visit to the Expo and arrange field trips to farms with bio-digesters and appropriate small cheese factory operations.

I find Farmer to Farmer emphasizes practical applications and promotes direct action. I would be interested in future assignments where I could work on integration of energy, agriculture and public health in rural areas.

http://www.ias.unu.edu/proceedings/icibs/rodriguez/picture7.gif
(photo of two polytubes on ground under pule structure to provide protection)

http://www.ias.unu.edu/proceedings/icibs/rodriguez/picture6.gif (polybag under pole and thatch cover)








  • [Homestead] Biogas Digesters, mostly polyethylene bag, Tvoivozhd, 11/10/2004

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