[Terrapreta] Re Charcoal and------Bokashi
Sean K. Barry
sean.barry at juno.com
Tue Apr 17 01:52:53 CDT 2007
Hi Bakary,
The "producer gas" from a biomass pyrolysis reaction in a retort is composed of many gases and vaporous components. Molecular hydrogen gas (H2), carbon monoxide (CO), and methane (CH4) are energy containing fuel gases. Combined they make up about half of the gas volume (methane at < 3%). The other half of the gas volume, is carbon dioxide (CO2), molecular nitrogen gas (N2), and water vapor (H2O), molecular oxygen gas (O2), and very small amounts of some others (like argon). These are all inert gases (chemically inert and useless as fuels), but they do carry heat energy away from the retort. Additionally, mixed into these gases will be vaporous, less partially combusted, longer hydrocarbon chains; pyroligneous oil, acetic acid, poly-aromatic hydrocarbons, etc. These are more generally called "bio-oils", "volatile matter", "wood tars", or simply tars. Lastly, depending on the design of the retort and the amount and direction of air or oxygen flow through the charcoal bed, there can also be a fair amount of soot or smoke in the effluent. Soot is smoke; it is simply exploded off, very small particles of unburned charcoal (nearly pure carbon). These particles rise with draft of the heated gases venting away from the combustion, because they are so small and porous. They have a fairly low density and float up, until they are free from the hot gas stream. Then they fall, because these very small and fluffy carbon particles really are denser than air.
As for storing the gases, the issue is cleaning the effluent of undesired components. When the tar components cool they turn to liquids and even solidify. The liquids mix with the soot/smoke and then you just get a lot of tarry, black, gunk (some people call it creosote). It will clog any small piping very fast and will line the innards of any compressed gas storage tank. But, there are ways to go tar cleanup on the gases. Simplest is to blow the exhaust through an enclosed chamber filled with biomass (wood chips for instance) and capture the cleaned gas on the other side. The soot and tars will condense onto the wood chips. Eventually the chips need to be replaced (throw them into the retort!).
There are other ways to clean the tars but they require more complicated equipment and techniques. If you burn the gases immediately, with enough air added, then the tars can be burned completely in the flare.
So you can cleaner gas. But its half fuel (maybe) and half inert. I say maybe half fuel, because it the retort has too much air, then more completely combustion occurs, resulting in less charcoal, less fuel gases, and more inert gases. The inert gases are the products of complete combustion. The inert gases are hard to separate, so, if you attempt to store the gases in a compressed storage tank for instance, then you will end up compressing and storing them too. This will lower the BTU density of the stored fuel gas. Unless the storage tanks are very large and the residence time is very low before the gases are used, then compression level will have to be high. High rates of compression require energy to achieve. It is possible that you may need to use more energy compressing the gas than is contained in the volume you would compress.
Realistically, its better to convert the energy from the hot gases sooner, immediately out of the retort into some other form of stored energy. Consider that clean producer gas can run an internal combustion engine, which could turn a generator, and the generated electricity could charge batteries. Consider that both the direct heat from the pyrolysis reactor and heat from combustion of the producer gases could be used to make steam and turn a steam turbine/electric generator to charge batteries. Or the heat could be used directly (to heat a greenhouse for instance) or the heat could be stored into a well insulted heat sink, underground, and used sometime a little while later (like stored in the day and used at night in winter).
A retort can be designed, which produces little or no fuel off gases, low amounts of exhaust, and more charcoal (which contains higher volatile matter content). The charcoal yield can be impressive (40% by weight, 60% of the energy content). Such retorts operate at higher pressures and have very well controlled airflows. When its sealed, there are only energy containing bio-oils (no charcoal, no gases). These are not low-tech retorts.
Now I want to make a very important point. Whenever you have a pyrolysis reactor (retort) which produces off gases containing fuels (H2, CO, CH4), those gases should definitely be flared off (burned) rather than simply released into the atmosphere, even if you cannot find a use for the energy. Methane (CH4) is a much more potent greenhouse gas than CO2 OR H2O and its much worse for the environment to release it raw rather than to burn it (CO2 and H2O are the combustion products of CH4). In the United States, it is illegal to release landfill gas directly to the atmosphere. It must be burned, because it contains methane. It's also illegal to vent gases directly from a digester to the atmosphere, for the same reason.
Regards,
Sean K. Barry
Principal Engineer/Owner
Troposphere Energy, LLC
11170 142nd St. N.
Stillwater, MN 55082
(651) 351-0711 (Home/Fax)
(651) 285-0904 (Cell)
sean.barry at juno.com<mailto:sean.barry at juno.com>
----- Original Message -----
From: bakaryjatta<mailto:bakaryj at gamtel.gm>
To: terrapreta at bioenergylists.org<mailto:terrapreta at bioenergylists.org>
Sent: Monday, April 16, 2007 7:36 PM
Subject: Re: [Terrapreta] Re Charcoal and------Bokashi
Dear Tom Miles and list members,
Reading these posts made me reflect more on how to try and restore soil
fertility to the totally degraded land I have been working with for more
than twenty years. Agro-Forestry was given a try and there were a number of
trees surviving each year. Some species were better survivors than others.
Some improved crop yield was noticeable around the survivors. Cowpeas did
not fix nitrogen where groundnuts and Gliricidea did. Organic material broke
down very fast during the rainy season. Termites consumed a lot during the
dry season. A rapid change came after I constructed the Biogas digester and
applied the effluent in combination with mulch from AF tree leaves and
elephant grass cuttings. The termites did like a number of the resulting
giant Sorghum stalks they consumed while still alive but left enough to have
a greatly improved harvest.
I had previously received the Bokashi manual but found a scarcity of
materials in my vicinity for starters and fermentation consumes time. So I
abandoned it when I read Dr AD Karve's information about feeding soil
organisms with sugar or the better effluent of the digester.
Now finding out about Terrapreta, I think there may be an excellent
combination for a long term improvement. Ground up, but not to fine a char
does not break down fast like mulches or other organic matter incorporated
in the soil and provides a home for soil organisms provided by the digester
effluent. Moisture will likely be retained better and there will be less
leaching of solluble minerals. Mulching will be continued but assisted with
perennial cover crops.
To beat the problem of the usual dry spell after the first rains that often
kills early planted crops, we are putting in the extra effort and plant
grain crops in nurseries for transplanting when the heavier rains come later
in the season. It worked fine the previous two years.
As there is no equipment besides hand hoes, we practice minimum tillage as a
matter of necessity. Hopefully this addaptive strategy will show real
noticeable results so it will inspire others to emulate. Many people have
abandoned farming as an exercise in futility. Many are now destroying more
of the environment by (illegal) wood cutting instead.
Making char with my retort is producing more energy than necesary for
keeping the process going. I am trying to find a low cost method to store
the gas for later use. Can anyone tell whether the extra gas can be stored
together with the methane of the digester?
Thanks for everyone's contributions to the list.
Bakary Jatta
----- Original Messages -----
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Mon, 16 Apr 2007 13:21:08 -0700
> From: "Tom Miles" <tmiles at trmiles.com<mailto:tmiles at trmiles.com>>
> Subject: Re: [Terrapreta] Re Charcoal and-----Bokashi
> To: <terrapreta at bioenergylists.org<mailto:terrapreta at bioenergylists.org>>
> Cc: Christoph.Steiner at uni-bayreuth.de<mailto:Christoph.Steiner at uni-bayreuth.de>
> Message-ID: <006701c78064$c612e340$5238a9c0$@com<mailto:006701c78064$c612e340$5238a9c0$@com>>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Christoph,
>
>
>
> Which is the best of your many collaborative publications to answer Dr.
> Karve?s questions about the mechanism of terra preta in making inorganic
> nutrients available to plants?
>
>
>
> I have linked many publications on the Terra Preta website. The most
> recent
> is:
>
> Long
> <http://www.css.cornell.edu/faculty/lehmann/publ/PlantSoil,%20online,%202007<http://www.css.cornell.edu/faculty/lehmann/publ/PlantSoil,%20online,%202007>
> ,%20Steiner.pdf> term Effects of manure, charcoal and mineral
> fertilization
> on crop production and fertility on a highly weathered Central Amazonian
> upland soil Plant Soil January 2007
> Christoph Steiner ? Wenceslau G. Teixeira ? Johannes Lehmann ?Thomas Nehls
> ?
> Jeferson Luis Vasconcelos de Mac?do ? Winfried E. H. Blum ? Wolfgang Zech
>
> http://www.css.cornell.edu/faculty/lehmann/publ/PlantSoil,%20online,%202007<http://www.css.cornell.edu/faculty/lehmann/publ/PlantSoil,%20online,%202007>,
> %20Steiner.pdf
>
>
>
>
>
> Tom Miles
>
> http://terrapreta.bioenergylists.org<http://terrapreta.bioenergylists.org/>
>
>
>
>
>
> From: terrapreta-bounces at bioenergylists.org<mailto:terrapreta-bounces at bioenergylists.org>
> [mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of adkarve
> Sent: Sunday, April 15, 2007 2:24 AM
> To: terrapreta at bioenergylists.org<mailto:terrapreta at bioenergylists.org>
> Subject: Re: [Terrapreta] Re Charcoal and-----Bokashi
>
>
>
> Dear readers of terrapreta list,
>
> I had already written about my hunch, that the micro-organisms in the soil
> disintegrated soil minerals into their component ions, because these
> mineral
> ions were needed by the soil micro-organisms themselves for their own
> metabolism. Unfortunately, I have not been able to find any author
> verifying
> the phenomenon that the soil micro-organisms actually disintegrated soil
> minerals. The fact that grasses accumulate silica is only indirect
> evidence.
> Silica or SiO2 is highly insoluble in water. Therefore the plants must be
> taking up silicate ions. Most soil minerals are in the form of silicate.
> This indicates that somebody must be converting the generally non-soluble
> minerals into water soluble ions, and that somebody can only be the soil
> micro-organisms.
>
> There are large areas in India, where farmers grow crops without
> irrigation.
> They apply neither chemical fertilizers nor organic manures. Not applying
> fertilizers or manures is their way of reducing the risk of total loss, if
> monsoon rains were to fail. The most common rainfed crops in our area are
> sorghum and safflower (Carthamus tinctorius). The water of guttation of
> both
> the crops contains sugar. That means, even when the farmers do not apply
> organic matter to the soil, the plants themselves feed the micro-organisms
> below their canopy with sugar. The yield from such fields is fairly high,
> if
> the rainfall is adequate. Analysis of these soils generally shows
> deficiencies of N and P, but that does not seem to affect the yield.
>
> It is generally accepted by the science establishment that soil
> micro-organisms have a symbiotic relationship with green plants, in which
> the micro-organisms get organic matter from green plants and the green
> plants in turn get the mineral nutrients required by them through the
> activity of the soil micro-organisms. However the source of mineral ions
> is
> always considered to be humus and other organic matter and not the soil
> minerals. Literally thousands of farmers in this state practice a form of
> organic farming in which they apply 25 kg sugar, 25 kg cow dung and 25 kg
> cow urine to a hectare, once every three months. They get higher yield
> from
> their crops than their neighbours who apply chemical fertilizers to their
> fields. Analysis of the soil in the organic fields invariably shows
> deficiency of N and P, in spite of which the crop yield is high. Two of my
> students interviewed these farmers and they verified these facts.
>
> My explanation of this phenomenon is that the soil analysis only catches
> the
> water soluble components of the soil and not the minerals. In the organic
> fields, the farmers do not apply the recommended dose of manure (20 to 50
> tonnes per hectare, which is calculated on the basis of the N,P and K
> content of the manure), but small quantities of high calorie organic
> matter
> to feed the microbes, which convert the insoluble minerals in the soil
> into
> soluble ions. This is what must be happening in nature, where plants grow
> luxuriously without any chemical fertilizers.
>
> We are facing an energy crunch. If we can use agricultural waste biomass
> as
> a source of energy instead of using it as manure, we can make a lot of
> energy available to satisfy the energy needs of the people. Making compost
> is a wrong practice, because composted organic matter has no nutritional
> value for the microbes in the soil. In fact, the dose of compost
> recommended
> by traditional agronomists for application to a hectare, requires biomass
> produced in ten hectares. Such practices make organic farming
> impracticable.
>
>
> I would like to know if somebody has established the fact that the soil
> microbes actually disintegrate soil minerals in order to feed themselves
> and
> also to feed the green plants. The only reference that I have so far
> unearthed is that in the case of lichens growing on rocks, the rock
> underneath the lichen shows signs of dissolution. The degree of
> dissolution
> is much greater in the case of limestone but even silicious rocks show
> this
> phenomenon.
>
> Yours
>
> A.D.Karve
>
> ----- Original Message -----
>
> From: bakaryjatta <mailto:bakaryj at gamtel.gm<mailto:bakaryj at gamtel.gm>>
>
> To: terrapreta at bioenergylists.org<mailto:terrapreta at bioenergylists.org>
>
> Sent: Sunday, April 15, 2007 4:06 AM
>
> Subject: [Terrapreta] Re Charcoal and-----Bokashi
>
>
>
> To Kurt and list members,
>
>
>
> There was an extensive post to the gasification list on Mon,10 April 2006
> by
> Roger Samson of REAP-Canada with a great deal of details about Bokashi and
> its preparation. A manual is available from REAP- canada is available on
> request. One of the ingredients of Bokashi is bio-char.
>
>
>
> I am applying char dust to soil at planting stations, covering it with
> leaf
> and/or grass mulch and giving it a dose of of effluent from Dr AD Karve's
> model biogas digester. There is not enough material to cover an entire
> area,
> therefore improve soil peace meal. The char is made from the trimmings of
> Gliricidia and Cashew trees in an old water heater used as a retort.
>
>
>
> Hopefully this makes it to the list as I am unfamiliar with posting
> procedures.
>
>
>
> Bakary Jatta, experimenting in The Gambia
>
>
>
>
>
>
>
> Kurt wrote:
>
>
> Hi folkes,
>
> Somewhere in the bioenergy archives, not sure which particular list, I
> remember seeing a description of Bokashi preparation, using local
> wormcastings, plantjuice (for enzymes) etc etc. This was being done in
> SE Asia, probably the Philippines. The resultant material was then used
> to inoculate compost which was applied to the soil; as per usual.
>
> The method used the ubiquitous Asian rice husk, but I think it could be
> adapted to any other area, using whatever waste biomass was available
> there and also using local wormcasts, plant juice and so on. Sugar,
> possibly molasses also figured in the method, to feed the culture.
>
> Such a "local" Bokashi solution could be applied to charcoal just prior
> to application to the soil, giving it an initial charge of wee beasties
> to speed up the results.
>
> / /I doubt that Bokashi powder being sold for use in garbage digesters
> would be quite up to the job, being a centrally produced, industrial
> product and not at all adapted to any one soil situation.
>
> It would be interesting if someone, more versed in searching the
> archives could dig the message out of them. I'm not at all knowledgeable
> in that activity.
>
> Kurt
>
> _____
>
> _______________________________________________
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>
Snipped......
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