[Homestead] Biogas Digesters, mostly polyethylene bag
Tvoivozhd
tvoivozd at infionline.net
Wed Nov 10 17:27:22 EST 2004
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)
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