Kim, Here is an outline from a friend of mine in India where biogas technology is quite standard. 1 Kg of starch or sugar produces about 400 liters of high quality biogas in about 8 hours which should be sufficient to cook your meals for the next day. It may require more manure by weight depending upon the volatile solids in the manure.
The system is pressurized by the weight of the top drum which serves as a gas holder. The biogas plant is a standard, moving dome type of a biogas plant. It can be fabricated, using two barrels, both of about 200 liter capacity. Such barrels are available in different sizes, being used as domestic water tanks. One of the barrels should have a slightly smaller diameter than the other, so that it can telescope into the broader barrel. One end of both the barrels is cut open. The broader barrel is kept on the ground with the open end pointing upwards. This barrels serves to hold the fermenting liquid.The narrower barrel is slid into the steel barrel with its open end pointing downwards. It serves as the gas holder. If two such barrels are not available, one can construct the broader container out of bricks and cement mortar. The fermenter barrel is provided with an L shaped inlet pipe, that is 5 cm wide. The horizontal arm of the L should be about 40 cm long and the vertical arm should be 100 cm long. It requires some plumbing skill to fit the inlet pipe. For fitting the inlet pipe, a hole of adequate diameter is cut into the vertical side of the barrel, as near the base as possible. The outer barrel is also provided with an outlet pipe near its top end, through which the effluent slurry can flow out. The inner barrel, that serves as the gas holder, is provided with a gas tap, fitted at the topmost part of the barrel. The gas is supplied to the burner through this tap. The gas holder barrel is weighed down by means of a sack filled with sand or any other material, weighing about 20 kg. In this way, the gas is provided to the burner under a certain constant pressure. In India, one can buy a special domestic biogas burner for this gas, but if that is not available, one can use an LPG burner, with the pin-hole nipple removed. To start the system, an aqueous slurry made of about 200 litres of water, about 10 kg cattle dung and about 200 grams of flour of any starchy material, is poured into the system through the inlet pipe. The gas cock of the gas holder barrel is kept open, while filling the slurry. After filling the slurry, the gas tap is closed. The fermentation process produces gas which will accumulate in the gas holder and lift it up. Test this gas for its combustibility. It may happen, that the gas produced during the first few days does not burn. Just let it exhaust by opening the gas tap so that the gas holder barrel sinks back into the outer barrel. But then do not forget to close the gas tap. Add daily about 200 g of flour, after mixing it with about a litre of water, to the fermenter, through the inlet pipe. Use a plunger to push the flour slurry into the barrel. Otherwise it would remain in the inlet pipe and ferment inside the pipe. Once the system starts to produce combustible gas, increase the amount of flour to daily 500 grams. Flour always contains a small quantity of protein, which gives rise to a small amount of H2S and NH3, which produce foul odour. Therefore the gas plant cannot be kept inside an unventilated kitchen. One should keep it outside the house, just beneath the kitchen window, and take the gas into the kitchen by means of a rubber pipe. There was a comment about the amount of methane produced by the system. It is right that one should get about 400 litres of methane from 1 kg starch or sugar, but the astonishing thing was that the gas that one obtained from this system consisted of almost pure methane. What happens to the carbon dioxide? I assume that it is dissolved in water and just diffuses out of the system. Have fun but just don't blow yourself up. :-) Art Krenzel ----- Original Message ----- From: Kim & Garth Travis To: biofuel@yahoogroups.com Sent: Thursday, April 15, 2004 1:06 PM Subject: Re: [biofuel] Re: Biogas was Rejoining list with a question I thank you for the offer, but at this time I think it is too large a capacity. While I do have 2 cows, they are pastured at all times, so collecting their dung is not convenient. We do have rabbits, [At present 30, but this changes constantly,]humans [2] and pigs [5] that the dung is easy to collect. I am hoping to create a small system that I can use to cook with in the summer and to learn on. When I find out how well the system works with our lives, then I will be looking at a larger system that can generate electricity. If I can eliminate my AC bill in the summer, the system could pay for itself fairly quickly. Bright Blessings, Kim At 01:12 PM 4/15/2004, you wrote: >Kim, > >Not much on this link unfortunatly http://www.biogasnepal.org/ > >I found the drawing and documents about BSP and their biogaz plant in my >pile of document. I have to say that I never build one. What I have is >drawing with size to build one and a "construction Manual" for a GGC 2047 >Model. They called it a fixed dome type design. I cote "This model was >designed and developed in Nepal. This model is considered as a reliable, >well functioning, simple, low maintenance cost and durable design." > >They give the quantity of dung and watter based on the volume of the >digestor. For example a 10 cubic meters capacity need Daily Fresh Dung >60Kg and Daily water 60 liters ( requires approx. 6-9 cattles). The Dome >type design is a "continuous" system where you add the dung+water in one >side via inlet pit with or without a mixer (to mix dung and water) and the >gaz pressure created push the "digested" slurry out the other side out of >an overflow outlet. > >If you want me to send you a copy of the document I have let me know, I >will need to scan them > >Olivier > > >[Non-text portions of this message have been removed] > > > > > >Biofuel at Journey to Forever: >http://journeytoforever.org/biofuel.html > >Biofuels list archives: >http://infoarchive.net/sgroup/biofuel/ > >Please do NOT send Unsubscribe messages to the list address. >To unsubscribe, send an email to: >[EMAIL PROTECTED] >Yahoo! Groups Links > > > > Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://infoarchive.net/sgroup/biofuel/ Please do NOT send Unsubscribe messages to the list address. 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