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Gasification of Level 4 Organic Wastes

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  • Gasification of Level 4 Organic Wastes

    Under the Waste Transformation model, Level 4 organic wastes...low value non-putrescent materials...are gasified to produce high-grade heat and biochar.

    Dr Paul Olivier has designed a range of small top it updraft (TLUD) gasifiers that burn level 4 wastes like rice hulls, nutshells and other dry wastes of consistent particle size. These little units are ideal replacements for the smoky solid fuel stoves often used in developing countries. Read more about them...HERE.

    Paul has even developed a roaster attachment capable of roasting a kilogram of coffee beans. You can see a video...HERE.

  • #2
    Last night, I was treated to a home-cooked meal of Tennessee-style pork ribs, chips (fries) and grilled vegetables...cooked on a gasifier fuelled by rice hulls. Burning rice hulls in the gasifier not only provided the heat to grill the food but it also yielded several litres of high quality granular biochar. This is waste transformation at its best.


    • #3
      Hi Gary
      I miss a picture of the biochar prouced from one cooking
      Also wondering if these gasifiers are available for sale for me in Europe ?
      I think it would/could, make a nice camping/outdoors cooking tool alternative, you can run them on uniform zized woodpellets I take it ?



      • #4
        Hi Ande...I don't think they are sold in Europe but you may be able to import one from Vietnam. I'll ask the person responsible for getting them built over here. The very small the one that I have at home...would be perfect for camping. Wood pellets are a perfect fuel for them...providing a useful burn time and excellent biochar.

        The amount of biochar that you get from each burn is approximately that the volume of the combustion chamber. The fuel largely maintains its form with only a small reduction in overall volume.


        • #5
          Yesterday, I observed another firing of a small top lit updraft gasifier. Once again, the fuel was rice hulls...but, this time, it was the 100 model....the smallest one (just like the one I bought on my previous trip to Vietnam in 2015.

          I've also attached a photo of a coffee roaster (capacity about 1.7kg) that fits on the Model 150 that I saw trialled several days ago.


          • #6
            I forgot to mention that the burn time for the small Model 100 gasifier...using rice about 20 minutes...enough to cook breakfast. If you use wood pellets, the burn time is extended to about 90 minutes.


            • #7
              Biochar is, along with high grade heat, a byproduct of gasification of Level 4 organic wastes. I found this useful document on Biochar...HERE.


              • #8
                I couldn't resist bringing one of Paul Olivier's Model 150 gasifiers back home with me. I intended to get the coffee roaster attachment, too...but then I remembered that I don't even drink coffee - much less process it.


                • #9
                  I've been hoping that, sooner or later, I'd overcome my inhibition around gasification...and actually do it.

                  Well, this morning wasn't that time.

                  I attempted to use one of my gasifiers to convert wood pellets into high-grade heat and biochar. While things got hot, and I did end up with some black stuff that looks like biochar (although much less than I'd have expected), I don't think I achieved gasification.

                  I started by assembling all of the stuff....the gasifier, wood pellets, steel wool, and a lighter.

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                  I filled the gasifier with wood pellets and inserted some coiled steel wool. When lit, the steel wool acts as a source of radiant heat - to light the wood pellets evenly.

                  I lit the steel wool. It seemed to be working but, when it had burned out, it had not ignited the pellets. So, I tore up some strips of cardboard and used them to get the pellets burning. That was successful.

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                  Although there was vigorous burning, the colour of the flame suggests that the pellets were burning rather than giving off the syngas that should have been evident.

                  I tried different air flow rates...

                  ...and the burn continued until the flame extinguished itself.

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                  Anyway, long story short, this is what I ended up with....about a quarter of the volume of the wood pellets that I started with.

                  With gasification (like everything else), seeing ain't doing.

                  Suffice to say, I have to consult with the experts. More later.


                  • #10
                    Today, I made the second attempt to make biochar...having consulted with Paul Olivier. Arising out of that conversation - and today's effort - it seems that I actually made biochar on my previous attempt. Regrettably, some of it was burned because I failed to discontinue the process when the syngas was exhausted.

                    I also learned that different feedstocks behave in different ways. For example, the pine wood pellets that I'm using currently do not gasify with a blue flame (but rather a yellow one)...and the volume of biochar produced is less...about 50% of the orginal volume of the wood pellets. I also managed to terminate the burn at the correct time so I ended up with a satisfying haul of biochar this time.

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                    While I'd have judged the flame in the photo to be combustion rather than gasification, it turned out to be the syngas that was burning rather than the wood pellets. The flame also behaves very differently when a pot is placed on the gasifier.


                    • #11
                      Gary, I am interested in low-tech solutions for sustainability going forward. The posts here are "high tech" solutions for creating Biochar. I have read articles about how the Amazon (I believe) is littered with ancient sites where massive amounts of biochar were used to increase soil fertility and water retention. So there are low tech ways to produce it. Since Biochar production is one of the ways touted to deal with atmospheric C02, its an important subject. In the past I tried building a rocket stove consisting of a metal bin with an internal metal flue (the rocket stove flue). I packed the bin with bamboo leaves and twigs. At the base of the flue I punched holes so that gas from the bamboo would be pulled into the rocket stove. So when the stove was lit using bamboo twigs, the heat along the flue was transferred to the packed bamboo which gassified, the gas feeding back into the flue and sustaining the burn. So there was a feedback loop. The end product was a fine (due to the size of the bamboo pieces) charcoal-like substance that I then put into a garden bed. Obviously this would never be as efficient as a system described above, but true sustainability would be to move away from technology that requires a massive amount of embedded energy to create. A low tech solution (for any problem) that is generally available at low cost, that is 50% efficient, is preferable to a high-cost, low availability solution that is 100% efficient, in my view.


                      • #12
                        Originally posted by fknader View Post
                        A low tech solution (for any problem) that is generally available at low cost, that is 50% efficient, is preferable to a high-cost, low availability solution that is 100% efficient, in my view.
                        I would agree, in principle, with this observation if making biochar was the only purpose of the gasifier stoves. They were, however, designed by Dr Paul Olivier for use by poor people to provide a cleaner cooking device - the existing cooking arrangements cause eye and respiratory problems. They are also intended to be a much cleaner alternative to the simple biodigesters that were being encouraged in Vietnam.

                        So, they provide clean, high-grade heat for cooking and water heating...using low value wastes (like rice hulls or nut shells)...with biochar as a bonus. Animal manure is too valuable, in a waste transformation context, to use as a biodigester feedstock. By using low value organic wastes as gasifier fuel, the manure is available to feed to BSF larvae...and all that happens from there.

                        When viewed as a whole, they stack up pretty well.


                        • #13
                          For those who may be interested in learning more about the range of gasifiers...or purchasing them...please contact [email protected]. He manufactures the gasifiers and he lives in Vietnam.