<html><head></head><body bgcolor='#FFFFFF' style='font-size:10pt;background-color:#FFFFFF;font-family:Verdana, Arial, sans-serif;'>Dear Anand,<br/>
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I realize that one would not normally carry a biogas plant around. There is some confusion here, I think because Crispin and I were bantering some and using some inuendo that maybe people who know English dialects than those in N.America wouldn't understand. The bag in the link _might_ be suitable for adaptation to a small biogas plant (by adding parts), but its designed use is to transport gas from a larger plant to a private home where it would supply circa one day's cooking gas. I don't know, however, how practicable this would be since I haven't seen anything of the bag except the picture on the linked page. I have, however, read the complete page and the primary design feature after gas-tightness appears to be the transportability.<br/>
<br/>
Sorry for any part I played in the confusion. If their is interest in the list, I can try to get in touch with the people who are producing the bag or the manufacturer, but I'd need someone to give me some further design parameters: like preferred closure method for the opening, preparatory internal fasteners for additions to a plain bag to be pre-installed, etc. before I do that.<br/>
<br/>
regards,<br/>
Ronald von Nohotwaterthismorning.<br/>
<br/>
<br/>
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<b>Von:</b> "Anand Karve" <adkarve@gmail.com><br/>
<b>Gesendet:</b> Jan 10, 2012 4:11:38 AM<br/>
<b>An:</b> "Discussion of biomass cooking stoves" <stoves@lists.bioenergylists.org><br/>
<b>Betreff:</b> Re: [Stoves] Biogas backpack<br/>
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Dear Ron,</div>
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the 500 litre or 1000 litre flexible biogas plant would not necessarily be carried around. Food waste is readily available in a city ( stale food or leftover food from a restaurant, unsold, stale or spoilt fruits and vegetables from a fruit & vegetable vender, etc. But space in an urban house is the limiting factor. It takes just 1 kg (dry weight) of food waste to produce about 700 or 800 litre biogas. A biogas plant made from a plastic film or rubber would allow it to be made into any suitable shape for keeping it in a narrow balcony or a niche next to the kitchen. We currently make our biogas plants from plastic water tanks, which are generally available everywhere in India. But these tanks are generally round and squat, requiring a relatively large area.</div>
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Yours</div>
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A.D.Karve<br/>
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On Tue, Jan 10, 2012 at 4:06 AM, Ronald Hongsermeier <span><<a href="mailto:rwhongser@web.de">rwhongser@web.de</a>></span> wrote:<br/>
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Dear Crispin,<br/>
<br/>
On 09.01.2012 19:02, Crispin Pemberton-Pigott wrote:
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Dear Ron</span></p>
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"> </span></p>
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Good to hear from you in the new year.</span></p>
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"> </span></p>
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<b><span style="FONT-FAMILY:'Tahoma','sans-serif';COLOR:#1f497d;FONT-SIZE:10pt">></span></b><span style="FONT-FAMILY:'Verdana','sans-serif';FONT-SIZE:10pt">I think you misunderstood the article. The bag is only for transport and temporary storage. They take the empty (and some dung) to a biogas producer, get it filled and go home to cook with it. It is supposed to be about a day's cookin' worth.</span></p>
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">I am with David House </span><code><span style="FONT-SIZE:10pt"><a href="http://www.completebiogas.com/">www.completebiogas.com</a> </span></code><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">on this one: it is a portable digester with nothing but gas in it! </span><span style="FONT-FAMILY:Wingdings;COLOR:#1f497d;FONT-SIZE:11pt">J</span><span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"> </span></p>
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">He writes, “</span>It's actually a gas bag, not a digester. Even so, it's an excellent innovation, and a worthy addition to the armamentarium, wherever it can serve as a means of transport in connection with a large digester near any large population.<br/>
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And as well, from my point of view, it's also a bit ironic, since the very sturdy bag, selling for ~$US38, could actually <i>be</i> a digester if it had two additional pipes (an inlet and an outlet), and further that since it's about a cubic meter in volume, it would produce about a cubic meter of gas every day, if fed and kept warm.<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:rgb(31,73,125);FONT-SIZE:11pt">”</span></p>
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That may well be, but, not having seen the bag, it may well need some additional features apart from two pipes. You'd have to get solid materials in and out, etc. Also, I think that his proviso: "...wherever it can serve as a means of transport ... large digester ... any large population." is overwrought. When compared with walking 10 km with 20 or more kg on your head, a 3kg bag is gonna add up to 30 € pretty quick. I'm not dissing the idea of making a digester of that size, just have the impression from the relative clause that he is degrading the usefulness of the idea unnecessarily.<br/>
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<br/>
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:rgb(31,73,125);FONT-SIZE:11pt">I think David is working on a bag digester himself. The transport of gas is interesting. If it turned out to be attractive as a cooking fuel (and delivery system) the users would perhaps be convinced to install their own systems. I am not convinced that a minibus would accept the gas ‘package’ without fear or charge.</span></p>
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I think they limited the size to keep it a relatively manageable size.<br/>
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:rgb(31,73,125);FONT-SIZE:11pt">It is a lot lighter than a load of wood and the walking distance might be less. I wonder if a tire on a rim might be as good, and could be pumped by hand. Will a tire hold a useful volume of gas if hand pumped?</span></p>
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Even if the walking distance was more, one would not have the same fatigue. i think you'd have to work pretty hard to compress a whole m^3 into anything like a regular tire-- and a tractor tire with rim would be more taxing to manage than a load of firewood on one's head. ;-) If this was done in cooperation with schools, they could even get the transport with larger school children on the way home from school, delivery before school, pick up the bag and go home after school. hoping you're doing well.<br/>
<br/>
regards,<br/>
ron<br/>
w<br/>
h<br/>
<br/>
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Regards</span></p>
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt">Crispin</span></p>
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<span style="FONT-FAMILY:'Calibri','sans-serif';COLOR:#1f497d;FONT-SIZE:11pt"> </span></p>
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--<br/>
***<br/>
Dr. A.D. Karve<br/>
Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)<br/>
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