Keith, Keith Addison wrote: > Hello David > And back at you. Good to hear from you.
>> I've been contacted about a project in south Asia which would involve >> planting 600 ha to Jatropha, to produce 3,500 tonnes of biodiesel >> annually.... Since it bears on some of the points you raised, let me say that my connection to the project is indirect. An organization with which I've done some consulting re biogas has gotten interest from the folks who are developing the biodiesel plant, and so I've been asked to assist with the biogas add-on. As such, even if I had the answers to your [excellent] questions regarding the selection of Jatropha, monocultures, and whether mere jobs count as SED (social and economic development) since the information I have thus far makes only that connection, I neither know nor if I did would it make any difference. My position in the venture is rather humble, as befits my vast gifts (or perhaps they're half-vast). As such, I ask the questions I ask for two reasons. One is that I'm insatiably curious, just like Kipling's elephant child, and the other is that the biogas portion of the project, afterthought that it appears to be, should be designed with an eye towards the realities that are likely, as contrasted to simply what is stated as the plans. > I'm always suspicious of the "best crop" or the "best technology" approach > (see eg <http://journeytoforever.org/fyi_previous4.html#1511>Technology and > the poor), and 600-ha monocrop plantations don't have a very good record. > No question. We've talked about SED previously. My view, boiled down, is that what is needed is to attend to improving human capacity, in a manner which is very sensitive and wise regarding creating dependencies. Whereas, most "projects" that engage or purport to engage in SED aim themselves at problems identified by the external organization (not the people themselves; this is often the first mistake), and generally tend toward solutions that are impossible for the people themselves to implement. There are times, no question, where certain necessary solutions are and will remain beyond the capacity of people to implement, but generally those are not low on Maslow's hierarchy. That is, people everywhere are really pretty smart about their own circumstances, and usually with fairly modest help they can feed and shelter themselves. Where people provide these things themselves, there is an increase in dignity, confidence, and capacity. Where solutions are offered which require them to depend on external charity in a chronic manner (for example) usually things get worse. > Why jatropha? Whose choice was it? [... etc.] > As I said, excellent questions, but having an impact on the implied decisions is presently above my pay grade. My wisest option, I imagine, is to do the best possible job within the fairly obvious constraints of the situation, and try to make as valuable a contribution as I can. All else being equal, if there are follow-on projects, successful realization of those goals may give me earlier access, increase my responsibility, and make it more possible to be among the voices that determine the shape of critical aspects of those future projects. > Amid all the jatropha hype, this report is interesting, I don't know if you > saw it, from GRAIN: Jatropha - the agrofuel of the poor? GRAIN July 2007 > <http://www.grain.org/seedling/?id=480> > > That whole July 2007 issue of Seedling is worth a look: > <http://www.grain.org/seedling/?type=68> > Excellent resources. >> So, ... [w]hat size would/should [the mixer] be to produce that much >> biodiesel annually? >> > > You could probably set the upper limit of what would qualify as DIY or > homebrew or local coop or Appropriate Technology-level biodiesel production > at about 1,000 gallons a day, which is about a [third] of what they're > planning. They'll be wanting an industrial processor. [...] Yes, I think they are; or at least the plant will be at the small end of industrial. Where can I find a quick transform between gpd/lpd of biodiesel and mixer volume, for batch-process mixers? >> Second, am I near the mark with suggesting that the project consider >> producing ethanol (or butanol) rather than purchasing methanol? [...] > Nobody does it [...] I strongly suggest you stick with methanol. > Good to know. After modest research I had thought so, but I was not sure. >> Glycerol/glycerine would be one by-product at perhaps 10% of the amount of >> biodiesel (i.e. ~350 tonnes/yr?). >> > > Glycerol/glycerine plus soap, and it will take quite a lot of 85% phosphoric > acid (not cheap) to separate the two, which would probably be advisable, > unless you want a whole lot of powerful soap in the biogas digester, not sure > it would like that. If the feedstock is mostly oil cake (small particle size), it might be possible to deal with some of the soap-type contaminants, which would tend to increase problems with scum. "Although sodium soaps are soluble (they dissolve in water), the calcium and magnesium soaps are much less soluble, and so they precipitate (they come out of solution) and they form an important component of scum. Scum, the portion of the slurry which floats on the liquid portion, forms a dense hard mat if left alone, which will eventually completely stop gas production in a biogas generator.... These insoluble soaps, and various greases and oils, bind the other materials in the scum together and make it more difficult to break up the scum. In a similar way, wet hair, caught on a screen or in a trap in a bathtub drain, gathers oils, greases, and soaps, and begins to stick together in a way that clean wet hair would not." TCBH, p. 63 Even so, the presence of so-called soaps is essentially inevitable. ("Although fatty acids, in the presence of Ca++ ions, or Mg++ ions, form insoluble soaps, these acids are nevertheless extremely important in biogas production. Even if we did not want them to be present in the slurry, they would still be formed in the process of disassembling more complex molecules, for the volatile acids passed on from the AF [acid-forming] bacteria to the MF [methane-forming] bacteria are mostly fatty acids." ibid) >> I know that depending on how one handles this waste stream, it can be burned >> (at high temp), composted, used in soap-making, used to supplement the oil >> cake for biogas production, used in Clostridium fermentation to produce ABE, >> used to dry ethanol (and butanol?), et al. Are there other options? Among >> those possibilities, which might best serve the mix of goals? >> > > It depends whether you're talking of the raw by-product or the separated > components. Did you read the Glycerine page at the Journey > to Forever website? I did. That was part of the reason why I said "depending on how one handles... it...", although my sentence could have been clearer. The project information I have says that they intend to use "a suitable packed column, condenser, and receiver... to recover excess amount of Methanol in the system." As yet that means very little to me. I'm not sure, for example, whether they would take only the settled fraction of the trans-esterified result (what's the term of art for this?) and put it through such an extraction process, or whether they would put the whole lot through it, given that a minor portion of the excess methanol is mixed into the biodiesel fraction (if I understand correctly). Likewise, I don't know whether such a process would assist in separating-- or if one would need to separate-- further components of the glycerol-containing fraction, following such a process. The project information says they intend to make soap from the glycerol. One can make biogas from methanol, and it therefore seems possible to me based on what little I know about its contents that the whole unseparated glycerol fraction of the trans-esterified result could likely be put in the digester. However, given the value of methanol relative to biogas, that does not seem like an entirely sensible option. >> Lastly, the information I have says that "Furthermore, the process to >> manufacture biodiesel... has no waste at all [excepting the oil cake and >> glycerol]. The process employed has no emissions and absolutely no effluent >> treatment." I don't see how that can be correct. Can that be the case? >> > > Did you add "[excepting the oil cake and glycerol]"? I did, intending not necessarily to indicate they were waste products, but rather that there were such by-products. > The process itself has no emissions, but the power supply used might have > emissions. Would that be the biogas plant? There's also the water used for > washing, but it can all be accounted for with no addition to the waste > stream. I think that's all detailed at the Biodiesel section of the Journey > to Forever > website. > Again I know very little. It sounds as though the organization which is hiring me-- which itself is secondary to the project-- is planning on selling the biogas, or at least some of it. Still, it surprises me that given the use of so many chemicals (such as methanol, which evaporates, given half a chance), that there would be no emissions. In any case, as the bacteria of the world prove every day, one being's waste is another being's meal ticket. d. -- David William House "The Complete Biogas Handbook" |www.completebiogas.com| "Make no search for water. But find thirst, And water from the very ground will burst." (Rumi, a Persian mystic poet, quoted in /Delight of Hearts/, p. 77) -------------- next part -------------- An HTML attachment was scrubbed... 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