Re: [biofuel] Biogas Digester
Hello Marc snip Aerobic composting produces a (very) useful product, the compost, with the heat essentially a by-product, often a waste-product (very under-utilized); anaerobic digestion primarily produces energy, the biogas, and a resultant sludge that isn't useful and is difficult to handle. Biogas proponents commonly call it a useful fertilizer, rich in nutrients, but this is a chemist's view. It may contain quite useful amounts of N, P and K but it's full of VFAs (volatile fatty acids) which are phytotoxins (plant poisons) and it kills the soil micro-life upon which fertility depends (including worms). ..and this comment from me: Aha! Now I understand why the biogas materials I've downloaded recently are cooler about the potential of the sludge. One even recommended that the sludge be composted... Really? Progress?? In this day and age? I am surprised - I've been viciously attacked more than once for suggesting that. Many of the biogas proponents seem quite married to the idea. Funny sort of thing to be married to. But they're just more of the best technology people - adapt the community to the tech, rather than the other way round. I know there are a lot of more sensible folks working with these issues. About the hazards of digesting. The el cheapo Fijian bag digesters are actually quite safe. 1. No missiles - if they do explode, the bag ruptures and that is that. Yes. Pity about the neighbour's tea party on the lawn perhaps. :-) The bags are safer, and I think better. You find them elsewhere too, not just in the Philippines. 2. Continuous rather than batch mode - less gas resident at any one time 3. Variable volume - collapses when gas is withdrawn, making air entry less likely As for variable input quality - yes, that's a problem with mixed waste, but for a piggery or a chicken yard a digester is a boon, turning a serious pollution and health problem into an asset. But piggeries and chicken yards are best part of a mixed farm, not standalones. In Hong Kong's rural areas the guvmint, being a guvmint, and very much subject to Chris's Leviathan's First Rule, decided specializing was best. Previously the peasant system was mixed, like all peasant systems, but soon there were piggeries on one side of the river, with no crop wastes to feed nor soil to fertilize, and veggie farms on the other side, with no fertilizers and no use for the crop wastes, so they burnt them and used massive amounts of chemicals (more is better). Poor river. Black with pig shit and dead with chemical run-off. Whatever one might think of Chairperson Mao, his Seven Characters, rules for agriculture, were pretty good. One pig per mou was one of them - that's about 15 per hectare, and I've never been able to fault it. regards Keith Marc de Piolenc Yahoo! Groups Sponsor -~-- Sell a Home with Ease! http://us.click.yahoo.com/SrPZMC/kTmEAA/MVfIAA/FGYolB/TM -~- Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [biofuel] Biogas Digester
- Original Message - From: Marc de Piolenc [EMAIL PROTECTED] To: Biofuel List biofuel@yahoogroups.com Sent: Wednesday, September 18, 2002 02:46 Subject: [biofuel] Biogas Digester Recently, there have been addenda to the anaerobic digestion schemes involving an aerobic post-processing step - no doubt in response to the volatile fatty acids problem that you mentioned, though that is not stated in anything I've seen. I seem to remember a process that digester effluent/sludge is mixed with aspen chips and then allowed to compost, the result being marketed as an artificial peat from renewable recourses. Of course I could just be remembering 2 or 3 things and putting them together. Greg H. Yahoo! Groups Sponsor -~-- Sell a Home for Top $ http://us.click.yahoo.com/RrPZMC/jTmEAA/MVfIAA/FGYolB/TM -~- Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [biofuel] Biogas Digester
I found a web site that discusses an aerobic/anaerobic biodigester. They claim that what is left after the methane is removed is so clean that the effluent can be used as a complete hydroponics solution or as a conventional organic fertilizer. http://www.hydor.eng.br/Pag21-1.html --- Keith Addison [EMAIL PROTECTED] wrote: Read interesting article in Permaculture Magazine no.30 about Jean Pain and his work with shredded woodland thinnings. A search on the net turned up this http://lists.ibiblio.org/pipermail/permaculture/2002-March/000294.html which summerizes(follow the threads for more) . Sorry if this has been discussed before but I either wasn't paying attention or wasn't about. Interesting he produced methane from the woodland wastes and used the compressed gas for vehicles, machinery and generator. Used the heat of the compost process for his house and greenhouses. The system brings woodlands into economic use while maintaining them in a good condition. Provided employment and useful compost. __ Do you Yahoo!? Yahoo! News - Today's headlines http://news.yahoo.com Yahoo! Groups Sponsor -~-- Sell a Home for Top $ http://us.click.yahoo.com/RrPZMC/jTmEAA/MVfIAA/FGYolB/TM -~- Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [biofuel] Biogas Digester
Sirs, It may not be feasible to simultaneously utilise the heat of composting and the methane. Composting is an AEROBIC process while methane production is ANAEROBIC. Different groups of bacteria which are entirely different are resposible for the processes. No utilisable heat is evolved in anaerobic process leading to combustible gas (methane) production. This is my observation. Shaji James Missed your favourite TV serial last night? Try Yahoo TV [Non-text portions of this message have been removed] Yahoo! Groups Sponsor -~-- Sell a Home with Ease! http://us.click.yahoo.com/SrPZMC/kTmEAA/MVfIAA/FGYolB/TM -~- Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [biofuel] Biogas Digester
hello Marc Keith wrote: But piggeries and chicken yards are best part of a mixed farm, not standalones. In Hong Kong's rural areas the guvmint, being a guvmint, and very much subject to Chris's Leviathan's First Rule, decided specializing was best. Previously the peasant system was mixed, like all peasant systems, but soon there were piggeries on one side of the river, with no crop wastes to feed nor soil to fertilize, and veggie farms on the other side, with no fertilizers and no use for the crop wastes, so they burnt them and used massive amounts of chemicals (more is better). Poor river. Black with pig shit and dead with chemical run-off. I agree in principle that a piggery or chicken yard should be integrated with other agricultural activities, which would preferably absorb its wastes and make good use of them. Unfortunately, the disastrous land tenure system in the Philippines (compounded of customary inheritance rules and agrarian reform) guarantees that all family holdings are small - only corporate farms achieve any decent size and maintain it. How small is small? Integrated traditional Chinese-type farms, which you do get in the Philippines, are usually less than 5 acres, often much less. You can do a lot with half an acre. This means that by the time Jose de la Cruz has set up a piggery worthy of the name, he has run out of land. What's more, his neighbor is not going to cooperate in any sort of integrated farming scheme, because he sees Jose making good money sending his pigs to market and decides to set up his own piggery on HIS postage-stamp lot! The Fijian bag digester is a response by NGO workers to this problem, which apparently exists in Fiji as well. It mitigates the impact of concentrated pig and poultry raising by killing off the pathogens in the waste and preventing groundwater contamination. It doesn't kill off the pathogens. Digesters are aptly named - not that much different to an intestine. From the NGO standpoint, the gas is a bye-product, but it serves as an incentive to the landowner to maintain the gas plant. As government subsidies of consumer petroleum prices are withdrawn, the free domestic gas will become more attractive. Here at least, the copycat tendency could be harnessed to put one of these things on every pig-raising microlot - a practical proposition because of the cheapness of the bag digester (a complete impossibility with the concrete Gobar digesters). Recently, there have been addenda to the anaerobic digestion schemes involving an aerobic post-processing step - no doubt in response to the volatile fatty acids problem that you mentioned, though that is not stated in anything I've seen. It's not just the VFAs that make it bad stuff for soil, it takes the soil life about two years to recover, a poor soil probably longer. The aerobic composting might have more to do with the pathogen problem, which I know has put a lot of NGO people right off the idea of biogas digesters. How are they doing it Marc - each landowner's supposed to make his own aerobic compost, or is the sludge collected for central composting? If it were properly done, ie the sludge mixed with sufficient dry, carbonaceous material and the correct moisture ratio maintained, about a week's aerobic pre-composting, in a climate like the Philippines, should be enough to produce a good feed for red worms (Eisenia foetida or Lumbricus rubellas). The worms eat their weight a day and breed fast, doubling at least (by total weight) in six weeks. The worm casts are much higher value than ordinary compost, and excess worms are a high-grade protein livestock feed (better protein than beef), ideal as a supplement for pigs, or chickens or fish. And red worms definitely do cut off pathogens, any that might be left after the first week of hot pre-composting. Red worms are available in the Philippines. That would close the loop well. In an ideal world, these gizmos would be superfluous. But I figure three generations to rationalize land tenure here, and that's longer than anybody should have to put up with smell, flies and disease. Sure, a lot better than nothing. Fairly typical American land reform scheme, IIRC, during the Marcos era - I think he cited land reform as a major reason for martial law. I had some experience of that, awful. regards Keith Best, Marc Yahoo! Groups Sponsor -~-- Plan to Sell a Home? http://us.click.yahoo.com/J2SnNA/y.lEAA/MVfIAA/FGYolB/TM -~- Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [biofuel] Biogas Digester
Kris Book wrote: I found a web site that discusses an aerobic/anaerobic biodigester. They claim that what is left after the methane is removed is so clean that the effluent can be used as a complete hydroponics solution or as a conventional organic fertilizer. http://www.hydor.eng.br/Pag21-1.html I wouldn't place too much weight on what hydroponics people say about fertilizers and organics. It's NPK thinking - they think in terms of plant nutrients. Organics doesn't feed the plant, it feeds the soil - true organic fertilizers build the soil, building and maintaining high humus levels and helping to optimize the soil micro-life. I don't think any kind of effluent will achieve that. Better, simpler, cheaper to use a simple digester to provide methane and compost the sludge separately in a well-managed aerobic treatment with a lot of other material. No need for a nine-part system, and a trained operator and ongoing maintenance, and for that, we need people who have been trained by qualified professionals. Keep your money, learn about soil, do it yourself. Keith Yahoo! Groups Sponsor -~-- Sell a Home with Ease! http://us.click.yahoo.com/SrPZMC/kTmEAA/MVfIAA/FGYolB/TM -~- Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [biofuel] Biogas Digester
- Original Message - From: Keith Addison [EMAIL PROTECTED] To: biofuel@yahoogroups.com Sent: Wednesday, September 18, 2002 00:21 Subject: Re: [biofuel] Biogas Digester Whatever one might think of Chairperson Mao, his Seven Characters, rules for agriculture, were pretty good. One pig per mou was one of them - that's about 15 per hectare, and I've never been able to fault it. So how does this translate for us non-metric people? http://www.onlineconversion.com/ Online Conversion - Convert just about anything to anything else Greg H Yahoo! Groups Sponsor -~-- Home Selling? Try Us! http://us.click.yahoo.com/QrPZMC/iTmEAA/MVfIAA/FGYolB/TM -~- Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [biofuel] Biogas Digester
Sirs, It may not be feasible to simultaneously utilise the heat of composting and the methane. Composting is an AEROBIC process while methane production is ANAEROBIC. Different groups of bacteria which are entirely different are resposible for the processes. No utilisable heat is evolved in anaerobic process leading to combustible gas (methane) production. This is my observation. Shaji James If you look at the link Darren posted, they're using two different processes, and using the heat from the aerobic composting process to warm the anaerobic digestion. See also: http://archive.nnytech.net/index.php?view=16736list=biofuel Keith Yahoo! Groups Sponsor -~-- Home Selling? Try Us! http://us.click.yahoo.com/QrPZMC/iTmEAA/MVfIAA/FGYolB/TM -~- Biofuel at Journey to Forever: http://journeytoforever.org/biofuel.html Biofuels list archives: http://archive.nnytech.net/ Please do NOT send Unsubscribe messages to the list address. To unsubscribe, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [biofuel] Biogas Digester
Read interesting article in Permaculture Magazine no.30 about Jean Pain and his work with shredded woodland thinnings. A search on the net turned up this http://lists.ibiblio.org/pipermail/permaculture/2002-March/000294.html which summerizes(follow the threads for more) . Sorry if this has been discussed before but I either wasn't paying attention or wasn't about. Interesting he produced methane from the woodland wastes and used the compressed gas for vehicles, machinery and generator. Used the heat of the compost process for his house and greenhouses. The system brings woodlands into economic use while maintaining them in a good condition. Provided employment and useful compost. An operation on 2,500 acres was calculated to require 26% of energy yield (including all inputs for machinery construction etc), pay for itself (and finance) within ten years and employ 16 people on good wages. 2.5 acres providing equivalent energy to 4,000 litres of petrol. Darren Hello Darren That's not quite right. It doesn't say what he produced the methane from. It says he composted the woodland wastes. Composting and digestion are different. Composting that produces heat is aerobic composting (with oxygen), utilizing mesophilic and thermophilic (hot) bacteria and fungi; biogas digesters that produce methane utilize anaerobic bacteria that produce no heat - this is not composting. You can use the same materials up to a point but in somewhat different proportions and with totally different moisture content (methane digestion is wet). Aerobic composting produces a (very) useful product, the compost, with the heat essentially a by-product, often a waste-product (very under-utilized); anaerobic digestion primarily produces energy, the biogas, and a resultant sludge that isn't useful and is difficult to handle. Biogas proponents commonly call it a useful fertilizer, rich in nutrients, but this is a chemist's view. It may contain quite useful amounts of N, P and K but it's full of VFAs (volatile fatty acids) which are phytotoxins (plant poisons) and it kills the soil micro-life upon which fertility depends (including worms). NPK content can be quite misleading - it's not necessarily the rule, but it's been shown that compost (aerobic) with low NPK content can produce better crop growth and yield than a compost with much higher NPK content. Other factors are more important (biological factors, not chemistry). The best way to treat biogas sludge is to compost it - small amounts evenly distributed in the pile, maintaining the correct moisture content. Aerobic composting cuts off pathogens and destroys weed seeds; with anaerobic sludge, pathogens are not cut off and are a considerable problem. And as the guy said, biogas digesters can explode. They're difficult things - best perhaps for where they're now mostly used, in municipal waste treatment, a controlled setting where the waste stream is consistent. In a village or homestead setting the waste stream tends to vary, and digesters don't like that, and they often don't get the management they need. Also they usually have to be purpose-built for each application. They do have a niche in that setting, and in the Third World rural development setting, but I wouldn't see it as a first choice. The other niche for methane is in containment livestock operations. Every winter we're assailed with loud wailings from chicken and pig factories in the US about crippling heating costs for LPG while the manure lagoon outside pollutes air, ground and water, very dumb. On the other hand there's really isn't a niche for containment livestock operations anyway, let 'em die. I'm not sure whether forest wastes are suitable for methane digestion, I wouldn't have thought so. Thinnings could be hot-composted, but not just the wood (no nitrogen), and it'd have to be shredded, not just chipped - green leaves don't decompose readily because the wax coating excludes the bacteria. It's quite feasible to use methane gas from a digester to power vehicles. See for instance: Put a chicken in your tank http://journeytoforever.org/biofuel_library/methane_bate.html This could be a sustainable forestry operation, though running vehicles (and the chipper? - off a PTO) on methane means a lot of troublesome sludge to deal with. Nonetheless it's feasible. I'd say it's preferable to burning chips in a gasifier and producing a fuel from the gas, with merely the ash returned to the forest. What's lacking is power generation. I shouldn't think methane to an ICE's the best way of doing that, and would probably mean too much methane, not a balanced system anymore, unless maybe you added a livestock module, could probably fit it in somewhere. Should do actually - pigs and chickens. Regards Keith Yahoo! Groups Sponsor -~-- 4 DVDs Free +sp Join Now
