Hugh McLaughlin - Biochar Workshop
- 1. Unique Biochar Phenomena Hugh McLaughlin, PhD, PE www.acfox.com November 23, 2014 @ Tufts
- 2. Despite their artistic pretensions, sophistication, and many accomplishments, humans owe their existence to a six-inch layer of topsoil and the fact that it rains. – anonymous
- 5. Theories for Ancient Practices • Prior to steel axes, fire was the main tool for modifying the landscape and clearing land • Staple crops tend toward starches, which require significant potassium and phosphates – which have to be added for sustained field productivity (and this field was a lot of work) • Field preparation by transporting water vegetation, like palm leaves, then “cool burning” to release fertilizers into soil
- 9. This is the tree as it grows. About one half of the carbon dioxide uptake results in additional carbon atoms in biomass This is when biomass dies and becomes detritus: such as leaves and tree death This is due to microbial breakdown of dead biomass – 95% in one to twenty years
- 10. 200 CO2 200 C <100CO2> 100C Fate of Reduced “Fixed” Carbon - After the plant takes care of energy requirements of procuring a balanced diet, the excess carbon is directed to seeds, biomass growth or stored as sugars for the next season. - Sugars are excreted into the soil biota in exchange for plant nutrients (NPK and micro-nutrients). - If NPK are available, the plant does not “waste” sugars on soil. microbes and puts that carbon into plant priorities = more plant growth -Without plant sugars, soil microbes attack each other and soil carbon decreases, leading to sterile soil.
- 11. Pyrolysis and Carbonization convert biomass into biochar: one half of the carbon atoms are released as volatiles and one half converted to biochar The volatiles contain carbon atoms that the tree removed from the atmosphere as it grew = carbon neutral A minority of biochar is slowly oxidized by soil microbes; the majority is stable for hundreds to thousands of years <10CO2> 40C remains in stable in the soil 200 CO2 50C <50CO2>
- 12. Climate Civil Disobedience Carbon Time-out
- 13. Biochar: “invented” 600 million years ago by Mother Nature
- 15. From: http://www.techtp.com/Torrefaction for High Quality Wood Pellets.pdf, page 7 of 36 Figure 2: Wood Physical Structure – from tree to molecules of lignin & sugars
- 16. From: http://www.techtp.com/Torrefaction for High Quality Wood Pellets.pdf, page 7 of 36 Figure 2: Wood Microscopic Structure – molecular mixtures at the atomic scale
- 17. Pyrolysis & Carbonization Reactions of Wood @300C: Below = Torrefied Wood Above = charcoal & biochar Hemicellulose Lignin Cellulose D Extensive Devolatilisation and carbonisation (E) Limited devolatilisation and carbonisation (D) depolymerisation and recondensation (C) drying (A) E D C A E D C A glass transition/ softening (B) 300 250 200 150 100 Temperature (°C) Hemicellulose Lignin Cellulose 300 250 200 150 100 Temperature (°C) TORREFACTION
- 18. Hardwood Pellets: Dried, Carbonized 200C to 300C
- 19. Amorphous Graphite = Domains of Graphene From page 8 Figure 3: Development of local Graphene domains during carbonization
- 20. Page 3 of J. Phys.: Condensed Matter 19 (2007) 9 Figure 4: Development of porous 3-dimension structure during carbonization
- 21. Figure 1: Yield and Adsorption Capacity of Lab Chars 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 10% 9% 8% 7% 6% 5% 4% 3% 2% 1% 200 300 400 500 600 700 800 900 Heat treatment temperature Celsius Char yield as wt % of dry biomass 0% Adsorption capacity as wt % R134a at 100C Yield Ads @ 100C
- 23. Pivotal Biochar properties: Short-term Effects are due primarily to • Ash Content – due to pH impact • Mobile Matter – due to stimulating parasitic soil microbes, which compete for nitrogen, but sometimes any microbes are better than none Long-term Effects are attributed to only the • Resident Matter – because it • Adds Volume with high porosity to the soil • Increases Cation Exchange Capacity • Introduces significant Adsorption Capacity
- 24. How does Biochar work in the Soil? • Biochar works in conjunction with the existing soil, crop and climate. • Biochar helps “soil” go back to being soil. • Improved Moisture Dynamics – high & low • Improved Nutrient Retention (N, P, K) • Improved Microbe survival during drought • Improved Plant-Microbe synergisms
- 25. This begs the question: How does Resident Matter accomplish the following in the Soil? • Improved Moisture Dynamics – high & low • Improved Nutrient Retention (N, P, K) • Improved Microbe survival during drought • Improved Plant-Microbe synergisms - and why does it depend on Biochar Porosity, CEC and Adsorption?
- 26. How does Resident Matter accomplish the following in the Soil? • Improved Moisture Dynamics – high & low Two different moisture regimes, with three different mechanisms: – High moisture in tight soils (flooding in clays) – High moisture in loose soils (flooding in sand) – Low moisture in all soils • desiccating or drought conditions
- 27. - applies to all micro-porous media including chars - Also Bulk Density or the box of corn flakes - this is the density of the individual corn flakes -this is the density of the corn flake “molecules” or the corn flake skeleton without vapor volume
- 28. Calculating the “density, porosity, voidage” of a typical biochar (a good one…) • Apparent Density = 250 kg/cubic meter • Skeletal Density = 1500 kg/ cubic meter – Skeleton = 250/1500 = 1/6 cubic meter – Total voidage = 1 – 1/6 = 5/6 cubic meter • Assuming 1/3 inter-particle voids – Space between particles = 1/3 cubic meter – Space inside particles = 5/6 – 1/3 = 1/2 m3
- 29. Summary: Biochar is 83% voidage and 17% graphitic skeleton • 33% of the volume is between particles – this improves soil drainage and aeration • 50% of the volume is inside particles – this volume is available to store bulk water This available volume improves overall soil properties during excess moisture – but what about desiccating soil conditions? That requires ADsorption of the moisture
- 31. Mechanis m
- 33. Linear isotherms
- 35. How does Resident Matter accomplish the following in the Soil? • Improved Nutrient Retention (N, P, K) This is the CEC = Cation Exchange Capacity property Biochar has both Cation and Anion Exchange capacity - Exchange Capacity is due to non-graphitic organic side chains, oxidized to organic acid functionalities and organic bases due to bound nitrogen molecules - Adsorption of Humic Acids also increases EC
- 36. How does Resident Matter accomplish the following in the Soil? • Improved Microbe survival during drought • Improved Plant-Microbe synergisms Microbes need two things to survive: food and water - Biochar adsorbs water and water soluble organics via isotherms – and desorbs them when background levels are below “equilibrium”
- 37. Freshly made Biochar is like raw Ground Beef; is it food? – not yet Steps to preparing biochar for optimal soil benefit: C-C-I - Conditioning: equilibrate with soil moisture properties - pH effects, total dissolved solids (salts), liming - desorb soluble sugars and other mobile matter - Charging: equilibrate with soil fertilizer levels - in balance with annual fertilizer fluxes - Inoculating: Biasing the Soil Microbial Populations - this may not be necessary or even work All of which happens during composting or given enough time
- 38. Make Biochar, and save your world
- 39. Options for obtaining Biochar • You can buy it – but from who? – Some charcoals are good biochars, some are BAD – and all need to be tested • You can make it – For “gardening”, TLUDs work best – The other approach is “Retort” processes – Equipment is coming to the market – slowly • Example: Adam Retort – about 350 kg/batch
- 40. How does wood burn? • Wood, consists of hemicellulose, cellulose and lignin – Hemicellulose gasifies at 250 – 300C – Cellulose splits into char and volatiles between 300C and 450C – Lignin splits into char and volatiles between 300C and 750C – Volatilization cools the remaining solid, but the gases burn and generate radiant heat (yellow to blue light) – Eventually, oxygen can react with the remaining char to make CO2, H2O and ash, plus more heat (red light) – Putting it all together, we have:
- 42. Figure 1: Yield and Adsorption Capacity of Lab Chars 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 10% 9% 8% 7% 6% 5% 4% 3% 2% 1% 200 300 400 500 600 700 800 900 Heat treatment temperature Celsius Char yield as wt % of dry biomass 0% Adsorption capacity as wt % R134a at 100C Yield Ads @ 100C
- 47. Any Volunteers for running a Earth mound Kiln? H-1.Charcoal burners were a strange breed, living a lonely life in the forest, like wild beasts… At its best, making charcoal was not for any normal human. The time required for charring a small mound varied from one to two weeks, but with mounds 30 feet or more round, a month was average. During all that time, through every kind of weather, the charcoal maker lived with his mound, sleeping only in dozes for fear a flame might start and explode into a full fire which would demolish the mound. There was no time for washing; there was seldom more shelter than a bark lean-to.
- 48. Earth Kiln – Ohio - 1942
- 49. Tropical Products Institute - Mark V
- 50. Tropical Products Institute - Mark V – IN ACTION
- 54. Google: 1G Toucan Figure 4: Completed TLUD
- 55. Figure 7: Half way through burn
- 56. Figure 10: 1G Toucan Biochar
- 57. Larger than TLUDs, appropriate for home gardeners and consuming small amounts of scrap wood or “forestry slash” are: • Two Barrel Retorts • Double Barrel Twin Keg Retorts • Jack Daniel’s Rickyard Technology
- 60. Google: Jolly Roger Ovens or JRO Biochar
- 61. Commercial operations require larger equipment and regulatory approval: • Adam-style Retorts • This is a developmental “Chicken or the Egg” – Nobody makes them because nobody wanted them
- 62. The Mobile Adam Retort c/o New England Biochar
- 65. Make Biochar, and save your world
- 66. Unique Biochar Phenomena Hugh McLaughlin, PhD, PE www.acfox.com November 23, 2014 @ Tufts