malcolmf

A fine imagination, but charcoal sucks in water, including its dissolved nutrients, like a vacuum cleaner. What happens when your houseplants dry out? This may be a reason why today's Amerindians mulch on top of charred material.

The process heat is always useful, but you only get copious amounts from carbohydrate-rich feedstocks. But beware of by-products. They may define the best early niche applications but they can take your eye off the prize, which is 100% recovery of carbon followed by permanent sequestration. This reduces greenhouse gases by more than ANY bioenergy application. What the new information does is alter my view of the best niches and the prospects for farming biomass. It makes the food processing chain (with its mountain of waste) a potential major user, and algae and the grass family look rather attractive feedstocks. No different to pyrolysis. You can either burn feedstock (like traditional charcoal making) or an external fuel (like modern charcoal making and more efficient). Pyrolysis has to reach 400. This is no big deal. An electric oven does not need much to reach 200 and an autoclave (on which this technology might be based) is more efficient than an oven. Yes, that's always an option and it increases the speed at which you can process feedstock. Also, I don't see heat dissipation as a problem. Applications based on Turtle's heat exchanger and a well-insulated cooker would dissipate usefully, e.g. to a process such as drying, a house or a polytunnel. I see the kit as having a standard fitting to which you could plumb in any heating circuit. Where's our resident engineer? M

Excellent work Gerrit. "Boiling vegetable soup". I like that! Worries over dispersion and filtration disappear. Excess energy seems to come only from such feedstocks as fruit, roots, leaves, grasses etc, not from wood or animal remains. M

Laugh? I nearly died. Dame Edna has a saying. You'll find more culture in a pot of yoghurt than in Australia. And s/he's the best bit of it. ;)

Hardly killer questions, Gerrit. Dispersion and filtration are trivial processes compared to most in modern bioenergy. I've checked on the catalysts: Assuming that iron will suffice for the metal ions (as in the Max Planck experiments), iron plays a major role in the production of plant chlorophyll and in several enzyme systems. Its absence produces the plant disease called chlorosis. A first search finds no mention of iron overdose in soil. So in practice it might be better NOT to recover iron from HTC topsoil production; indeed, the process might be particularly applicable to reclaiming chlorotic soils. Citric acid occurs naturally as a fundamental part of the Krebs cycle, the fuel delivery mechanism of living cells. You are suffused with it! As such it is environmentally benign, although it may be beneficial as a nutrient to micro-organisms. One potential drawback is that it can reduce the availability of metals (like iron) to plants, depending on soil pH, by the process known as chelation. However I assume this effect is transient because citric acid is quickly mineralised in soil. The big unknown as far as I am concerned is simply whether HTC topsoil is any good. Is it terra preta nova? How does it compare with the productivity of ancient terra preta and modern char-amended soil as measured by nutrient productivity (via both cation exchange capacity and nutrient retention), water retention, N2O emission reduction, and micro-ecosystem production? If it fails there, it is nothing but another (albeit efficient) biofuel production technology. If it is near equal or better ;) M

I'm worried by the results that include dead or damaged plants after charcoal application. Enough of these reports in the hands of the less favourably inclined could kill terra preta nova stone dead. Posters have shrugged them off with a "must have been because ...". I think a more scientific approach to finding out why it happened or what prevents it is needed. Hypothesis: an addition of pure char to soil initially sucks up moisture and nutrients, making them unavailable to plants. (Don't forget: the Amazonians didn't use anything remotely like this method). Possible experiments: Drench half the char with water before application, half untreated. The water half should not then take up large amounts of dissolved nutrients from the soil. Drench half the char in liquid fertiliser (organic or not) before application, half untreated. Don't apply any of the leftover liquid, so that the effect is limited to what the char absorbed. Plots or pots of identical soil with char additions varying. Given the long tradition in Japan of char soil amendment, perhaps there are papers from it on precise soil management regimes? What did the Japanese speakers say at Terrigal? M

You'll find another link in the list of charcoal links that I posted to the original forum and then the charcoal-making subforum. FC's advantages are speed and carbon extraction efficiency. However it is hi-tech and patented, which seem to limit it to high added value applications, and thus make it less likely to spread as far as having an impact on climate. Like HTC, there is no data on how suitable its product is for the agri-char approach to carbon sequestration. No good if the porosity collapses due to the pressure, or the residues that encourage micro-organisms are destroyed, for example. The main difference between all pyrolysis methods and HTC is in the impact of moisture (in biomass and ambient) on their efficiency. Water is the basis of HTC, whereas it makes pyrolysis less productive, very much less when using fresh, undried material. You can use HTC at maximum efficiency direct from the harvest. Don't underestimate this parameter. M

It is addressed in Back in the black, if indirectly. The chemical reactions must in theory release one third of the energy in the biomass. This calorific value is often measured as energy per unit weight. Materials vary. Straw, for example, contains 15 GJ/t gross or 12.8 GJ/t net. I think we can use the gross (or Higher Heating Value) figure because the energy in any vapourised water will be recovered over time by natural or designed condensation, as long as the system remains closed. So the by-product energy from straw would be 5 GJ/t. Some of that would be used to run the process. Being pessimistic, lets say 3 GJ/t is left over. 3 GJ would replace a 2kW (output) greenhouse heater for slightly over 415 hours, or about 1/25th of the annual space and water heating of an average house in the UK. You can start to draw practical conclusions from this. For example, the waste from a garden could probably not do much except heat a small greenhouse, but the waste from a farm could do a lot by way of heating buildings, drying crops, and heating polytunnels. The most fitting form of heating would seem to be underground storage and circulation. In temperate climates like northern Europe HTC-heated polytunnels might create a serious carbon-negative low-miles alternative to the import of exotic fruit and vegetables. And that is before we figure out what the best output is: the so-called topsoil (I wonder how good it is) from 5 hours cooking or the bio-coal from 12 hours. From a global warming viewpoint the topsoil would reduce more carbon, and sequester it permanently. However the bio-coal might make up a shortfall in energy for a particular application. Thoughts? M

I hope you have not sent this off yet. Antonietti is a German academic. Some German academics are sticklers for proper titles. If he is "Professor Doctor", or whatever, he may not take kindly to being addressed on a particular field by a title less than his status in that field, dismissing the sender as either insulting or not worthy of a response. Find out first. It should be in Back in the black. Also that should be Terra Preta not Petra Terra, who is probably somebody's girlfriend :) M

I noticed the same thing and worried the same worry. However some of the source text suggests that the process works on intact biomass and a photo on the Max Planck website shows a catalyst being added to a vessel containing solid biomass. I suppose it might be a blender rather than a cooker. To be investigated. I doubt that it is problematic even if it is necessary. After all, wood is ground and pelleted, requiring relatively little energy and still producing an economical fuel; coal is pulverised for burning in a power plant, ditto. And there would be copious energy from preceding batches if this were an ongoing process. M

Hi Turtle Still following up references. A difficulty is that key papers, in which catalysts would be specified precisely, are in German. One catalyst that has definitely been used is citric acid, no doubt for the "weakly acidic conditions" mentioned in Back in the black. That source mentions no other. A different source says there are two components, but not what number two is. However we can infer from Back in the black that it provides the metal ions. So, the Earth will be saved by pressure cooking lemons with a bit of rust thrown in. Plus the occasional forest. :) The usual definition of a catalyst is that it is not changed by the reaction. I hope that it is recoverable from the solution and does not contaminate the carbon product. Otherwise there might be acidification and metal toxicity issues if the product becomes topsoil. M

Hi all This might rattle a few assumptions. Hydrothermal carbonization is another way to extract carbon from biomass, an alternative to pyrolysis / charcoal making. If pyrolysis is "baking biomass in the absence of air", then HTC is "pressure cooking biomass till it boils dry". For details see Magic Coal from the Steam Cooker, from the Max Planck Institute in Potsdam. This is a serious contender for saving the planet. Even lower tech than char-making. Exothermic, i.e. it gives off energy. As with pyrolysis, some of this energy can power the process while the remainder can be put to useful work and get carbon credits as bioenergy (space heating, etc.). Presumably there is also enough steam kinetic energy at scale for some electricity generation. No emissions. Just a risk of entertaining lab explosions until you understand how much energy is released.:umno: Carbon conversion efficiency near 100% in all cases as opposed to pyrolysis 60% in a high-tech retort and something around 20-30% or worse in a low-tech backyard, and 10% for composting. Operates in water so efficiency is not affected by the moisture content of input biomass: trumps pyrolysis here. Product controllable by length of cooking: 5 hours produces carbon-rich topsoil, 12 hours produces a kind of coal. Only "kind of" because the product is nano-porous. It is not known whether the porosity would offer a terra preta type of environment to soil organisms, but it would almost certainly offer the same water and nutrient retention properties. The Institute calculates that Germany's easily accessible waste biomass would balance out about 10% of the country's carbon emissions, allowing it to exceed its current Kyoto target with room to spare. Governments could be slavering at the chops for this once it becomes better known. The link is a must-read. Enjoy. M

This is a key point in relation to your beasties, Michael. Models of the soil carbon cycle (e.g. Colorado Uni's Century) usually allow for such pools as fast (1 year), slow (decades) and stable (centuries / millennia) turnover rates. However, even these are approximations: some papers on mycorrhizae suggest their turnover time can be as little as five days, as compared to the glomalin they produce which seems to join the slow pool. The headline is that, once creatures get hold of carbon, it is as good as gone, back to the air. This implies a trade-off between the two main goals of carbon burial, namely removal from the air and agricultural productivity. The former does not want creatures to access the carbon, the latter does. We have to examine our motivations for making terra preta, and the two camps might choose very different methods as a result. I suggest that atmospheric goals might require high-tech, high-volume, highly recalcitrant carbon while soil goals might require something much closer to Amazonian practices or RBlack's carbon-compost approach. Your history is in compost, isn't it? How do you feel about the potential conflict of goals between atmosphere and soil? M

Well done Michael. I can already see one problem with the new thread structure. My response to this news does not belong in the news thread. (Suggestions please Hypography). But here goes: The argument to try to convert agriculturalists seems straightforward: Why stop at credits for the carbon in plants? Good greenkeepers already know the benefits of horticultural charcoal. In your soil it will make your inputs more productive, improve water retention, and reduce soil erosion and nitrate leaching. You win every way. Charcoal should attract further carbon credits. At present you may have to lobby for this to be accepted, but the argument is strong because black carbon has a residence time in soil far in excess of what plants sequester. Representations are being made to the UN to add black carbon to the Kyoto protocol. Do not pay market prices for charcoal. Instead make your own black carbon by pyrolysing all waste from the perennials (mowings, prunings, windfall, etc.) and other crops. There is a range of technologies to do this, suitable for small-scale early DIY experiments right up to large-scale grower co-operatives. Some of the higher technologies use excess energy from pyrolysis as a heat source (e.g. for grain drying) or electricity generation, attracting further carbon credits for renewable energy and cutting your fuel bills. Black carbon also reduces natural emissions from soil of methane and nitrous oxide. These are both strong greenhouse gases. A combination of research into how to verify the reductions and persistent lobbying could attract yet more credits further down the line. Improvements and the best references to support the argument, anyone? M

Hello, Below is the thread to which I would like to request you copy some existing posts from the parent thread: http://hypography.com/forums/terra-preta/10546-making-charcoal.html Specifically, please copy posts #355, 423. Thanks. M

;) James, a blogger in Ireland has recently posted an instructive video on YouTube http://www.youtube.com/watch?v=3Wc8aqW4XBs of his gasifier. If "a picture says a thousand words", this says a million. The device will produce charcoal if you can find a safe method of stopping it when it switches from wood gas burning to charcoal burning, e.g. a cover to shut off all air supply. For another design see Philip Small's photos on Flickr. Come on Philip, get your mpegs out :lol: Does anyone know how far this would scale up, e.g. oil drum size? M

:rant: James, a blogger in Ireland has recently posted an instructive video on YouTube http://www.youtube.com/watch?v=3Wc8aqW4XBs of his gasifier. If "a picture says a thousand words", this says a million. The device will produce charcoal if you can find a safe method of stopping it when it switches from wood gas burning to charcoal burning, e.g. a cover to shut off all air supply. For another design see Philip Small's photos on Flickr. Come on Philip, get your mpegs out :) Does anyone know how far this would scale up, e.g. oil drum size? M

Suggest you read this post in another forum from a guy who unknowingly created something that behaves like TP by a combination of keeping chickens and periodic burning. I can imagine an early Amerindian discussing something similar with his mates. "All I did was burn our smelly stuff there for a few months, and now look at it ..." I'm beginning to wonder if terra preta implies a total rethink of household waste separation and collection as it is done today in so-called developed countries. Even recycling seems too stupid now, and household chemicals more of a problem than I thought. M

To RB Thanks for the kind words, but we are not likely to be admired much by the terra preta researchers. I've read their stuff. It is way out there. We aren't being scientific. But what we are doing, and what the world needs as much as their work, is throwing ideas around about how carbon burial and the modern world might meet in reality rather than in theory. What can Everyman and Everywoman do rather than wait for a technology that may never show up? Maybe one of these ideas will spread, who knows. All I know is that this feels better than sitting around waiting for the world to fry and feeling both guilty and powerless, like most everyone I know feels about global warming. (Which suggests society is heading for a communal neurosis that would let the extremists loose.) Hold on, Lehmann's paper is a modern experiment and says nothing about what the Amerindians did. Not sure about this. Activated charcoal, yes, but that is from high temperature pyrolysis and I don't think it occurs in TP. Another explanation, to me more likely, is that the reduction in emissions is directly related to the increase in compounds protected from decomposition within TP soil aggregates, a physical effect rather than a chemical one. Perhaps "all of the above" is the right answer. The issue underlines a need to analyse TP for glomalin and its effects on aggregation, pronto. Where is point 2 from? CH4 and N2O emissions are reduced, but who has measured CO2? To 3 I would add increased glomalin storage from increased fungal biomass. It can be huge over time (6% by weight of one Hawaiian forest soil).

To RB Thanks for the kind words, but we are not likely to be admired much by the terra preta researchers. I've read their stuff. It is way out there. We aren't being scientific. But what we are doing, and what the world needs as much as their work, is throwing ideas around about how carbon burial and the modern world might meet in reality rather than in theory. What can Everyman and Everywoman do rather than wait for a technology that may never show up? Maybe one of these ideas will spread, who knows. All I know is that this feels better than sitting around waiting for the world to fry and feeling both guilty and powerless, like most everyone I know feels about global warming. (Which suggests society is heading for a communal neurosis that would let the extremists loose.) Hold on, Lehmann's paper is a modern experiment and says nothing about what the Amerindians did. Not sure about this. Activated charcoal, yes, but that is from high temperature pyrolysis and I don't think it occurs in TP. Another explanation, to me more likely, is that the reduction in emissions is directly related to the increase in compounds protected from decomposition within TP soil aggregates, a physical effect rather than a chemical one. Perhaps "all of the above" is the right answer. The issue underlines a need to analyse TP for glomalin and its effects on aggregation, pronto. Where is point 2 from? CH4 and N2O emissions are reduced, but who has measured CO2? To 3 I would add increased glomalin storage from increased fungal biomass. It can be huge over time (6% by weight of one Hawaiian forest soil).

I like Susanna Hecht's translation from the Kayapo: "Cool Fire". Sounds like a great slogan for a movement. M

I like Susanna Hecht's translation from the Kayapo: "Cool Fire". Sounds like a great slogan for a movement. M

David I understand this. But you need to find out whether you are making terra preta or just burying charcoal to little effect on your soil fertility or the atmosphere. Digging could be destroying the soil structures and organisms that increase fertility and protect the carbon from decomposition. If so, what's the point in digging? Glaser writes in Amazonian Dark Earths (p153, without himself giving a reference) that "it is known that ADEs were not tilled by the native population", and this matches Hecht's present-day observations. Her observations and soil analyses suggest that the char they added was not lumpwood charcoal, just the residue from all manner of incomplete burning. Try using crushed char under mulch and let worms do the burying for you. They may be slow but my word are they thorough. M

David I understand this. But you need to find out whether you are making terra preta or just burying charcoal to little effect on your soil fertility or the atmosphere. Digging could be destroying the soil structures and organisms that increase fertility and protect the carbon from decomposition. If so, what's the point in digging? Glaser writes in Amazonian Dark Earths (p153, without himself giving a reference) that "it is known that ADEs were not tilled by the native population", and this matches Hecht's present-day observations. Her observations and soil analyses suggest that the char they added was not lumpwood charcoal, just the residue from all manner of incomplete burning. Try using crushed char under mulch and let worms do the burying for you. They may be slow but my word are they thorough. M

David I understand this. But you need to find out whether you are making terra preta or just burying charcoal to little effect on your soil fertility or the atmosphere. Digging could be destroying the soil structures and organisms that increase fertility and protect the carbon from decomposition. If so, what's the point in digging? Glaser writes in Amazonian Dark Earths (p153, without himself giving a reference) that "it is known that ADEs were not tilled by the native population", and this matches Hecht's present-day observations. Her observations and soil analyses suggest that the char they added was not lumpwood charcoal, just the residue from all manner of incomplete burning. Try using crushed char under mulch and let worms do the burying for you. They may be slow but my word are they thorough. M