Charcoal for terra preta Michael J. Antal, Jr, Goro Uehara, Jonathan - PowerPoint PPT Presentation

Charcoal for terra preta Michael J. Antal, Jr, Goro Uehara, Jonathan Deenik, and Tai McClellan Hawaii Natural Energy Institute and The College of Tropical Agriculture & Human Resources University of Hawaii at Manoa Nov 27, 2007 www.hnei.hawaii.edu 1 www.ctahr.hawaii.edu

Modern Biomass Refineries • Ethanol from corn grain and biocarbons from corn stover (USA) • Biodiesel from sunflower oil and biocar- bons from sunflower shells and stalks (EU) • Biodiesel from coconut oil and biocarbons from coconut shells, fronds, etc. (Malaysia) • Biodiesel from marine algae and biocarbons from residual (dry) algal material (Hawaii) Nov 27, 2007 www.hnei.hawaii.edu 2 www.ctahr.hawaii.edu

Fuel Costs FOSSIL RENEWABLE Coal Charcoal $8/GJ Oil $15/GJ Ethanol $14/GJ Gas $6-17/GJ Hydrogen $18-24/GJ Nov 27, 2007 www.hnei.hawaii.edu 3 www.ctahr.hawaii.edu

How can we use charcoal? • Potting soil (orchids and ornamentals) • Cooking (barbeque) fuel • Ultra clean coal (power production) • Activated carbon (water treatment) • Metal reductant • Terra preta (carbon sequestration!) • Biocarbon fuel cell Nov 27, 2007 www.hnei.hawaii.edu 4 www.ctahr.hawaii.edu

Some questions concerning the pro- duction of biocarbons: 1. In theory, what limits the yield of bioC (charcoal) from biomass? 2. In theory, what is the energy conversion efficiency of biomass into bioC? 3. In practice, what yield and energy conversion efficiency can be achieved? 4. In practice, how quickly can we convert biomass to bioC? Nov 27, 2007 www.hnei.hawaii.edu 5 www.ctahr.hawaii.edu

Useful definitions: 1. y char = m char / m bio 2. 100 = % VM + % fC + % ash; where VM = volatile matter; fC = fixed carbon 3. y fC = y char × {% fC / (100 - % feed ash)} 4. η char = y char × (HHV char / HHV bio ) Nov 27, 2007 www.hnei.hawaii.edu 6 www.ctahr.hawaii.edu

Thermochemical equilibrium predictions for the products of cellulose pyrolysis at 400 C ( Ind. Eng. Chem. Res. 2003, 42 , 3690-3699). • C, H 2 O, CO 2 , and CH 4 are the only 50 (a) CO 2 significant 40 Mass fraction (%) products. C(s) 30 • The theoretical 20 charcoal (i.e. C) H 2 O(g) yield is 28 wt%. CH 4 10 • The gas contains CO 0 0.001 0.01 0.1 1 10 significant energy Pressure (MPa) (i.e. CH 4 ). Nov 27, 2007 www.hnei.hawaii.edu 7 www.ctahr.hawaii.edu

Reaction stoichiometry for the products of cellulose pyrolysis at 400 C & 1 MPa ( Ind. Eng. Chem. Res. 2003, 42 , 3690-3699) C 6 H 10 O 5 → 3.74 C + 2.65 H 2 O + 1.17 CO 2 + 1.08 CH 4 Nov 27, 2007 www.hnei.hawaii.edu 8 www.ctahr.hawaii.edu

Energy balance for cellulose pyrolysis following thermochemical equilibrium ( Ind. Eng. Chem. Res. 2003, 42 , 3690-3699) cellulose cellulose carbon carbon work work exotherm exotherm specific heat specific heat gas gas sensible heat sensible heat input input output output 0 0 5000 5000 10000 10000 15000 15000 20000 20000 Energy [kJ/kg-cellulose] Energy [kJ/kg-cellulose] Nov 27, 2007 www.hnei.hawaii.edu 9 www.ctahr.hawaii.edu

Plot of charcoal yield from cellulose pyrolysis vs. pressure ( Thermochim. Acta , 1983, 68 , 165-186). • Pressure strongly favors formation of charcoal. • Low gas flow rates also favor the formation of charcoal. • Elevated pressure and low flow rates together double the yield of charcoal. Nov 27, 2007 www.hnei.hawaii.edu 10 www.ctahr.hawaii.edu

Flash Carbonization TM reactor schematic (U.S. patent # 6,790,317; September 14, 2004). flare SRD PG PT PRV ATW GSP UDV IV HIC IV TC TC WT TC TC DS TC TC PT R TC TC A MMV C TC H H DDV WT Nov 27, 2007 www.hnei.hawaii.edu 11 www.ctahr.hawaii.edu

Parity plot of Flash Carbonization TM fixed- carbon yields from various biomass feedstocks ( Ind. Eng. Chem. Res. 2003, 42 , 3690-3699) 45 • Fixed-carbon yields from corn cob, oak, 40 yfC - theoretical limit (%) and macshell LW-A1 MS 35 LW-A2 approach the OW-2 theoretical limit. LW-O 30 • Leucaena offers 80% CC OW-1 almost 90% of the 90% 25 100% theoretical limit. 20 20 25 30 35 40 45 yfC - experimental (%) Nov 27, 2007 www.hnei.hawaii.edu 12 www.ctahr.hawaii.edu

Flash Carbonization TM demo reactor on the UH campus Nov 27, 2007 www.hnei.hawaii.edu 13 www.ctahr.hawaii.edu

Terra Preta (Amazonian Dark Earths): Highly Fertile Anthropogenic Soils Picture source: http://www.gerhardbechtold.com/TP/gbtp.php Nov 27, 2007 www.hnei.hawaii.edu 14 www.ctahr.hawaii.edu

Photo source: University of Bayreuth Photo source: University of Bayreuth Typical Upland Terra Preta Soil Amazonian Soil Nov 27, 2007 www.hnei.hawaii.edu 15 www.ctahr.hawaii.edu

Effect of Terra Preta on Plant Growth Photo source: http://tinselwing.wordpress.com/tag/terra-preta/ Terra Preta Unamended Soil Nov 27, 2007 www.hnei.hawaii.edu 16 www.ctahr.hawaii.edu

Volcanic ash soil treated with flash carbonized macadamia nut shell charcoal 0% (w/w) 5% (w/w) 10% (w/w) 20% (w/w) Nov 27, 2007 www.hnei.hawaii.edu 17 www.ctahr.hawaii.edu

20% (w/w) charcoal 18 www.hnei.hawaii.edu www.ctahr.hawaii.edu Control Nov 27, 2007

Lettuce Shoot Biomass 160 a a 140 Plant weight (grams/pot) 120 b 100 80 60 c 40 20 0 0% 5% 10% 20% Charcoal Rate (w/w) Nov 27, 2007 www.hnei.hawaii.edu 19 www.ctahr.hawaii.edu

Charcoal Effect in an Acid, Infertile Soil 20 NPK + Lime www.hnei.hawaii.edu www.ctahr.hawaii.edu 5% 0% Nov 27, 2007

21 5% + NPK + Lime www.hnei.hawaii.edu www.ctahr.hawaii.edu NPK + Lime Nov 27, 2007

Preliminary Conclusion: Charcoal used in the experiment caused a negative effect on plant growth But why? • Crop? • Soil?? • Charcoal??? Nov 27, 2007 www.hnei.hawaii.edu 22 www.ctahr.hawaii.edu

• Volatile Matter (VM) content : a measure of the susceptibility of charcoal to further decompose and form carbon when heated Hydrophobic Hydrophilic 22.5% VM Content 6.3% VM Content Nov 27, 2007 www.hnei.hawaii.edu 23 www.ctahr.hawaii.edu

Effect of High Volatile Matter (22.5%) Charcoal on Plant Growth 10% 0% High VM Nov 27, 2007 www.hnei.hawaii.edu 24 www.ctahr.hawaii.edu

25 Effect of Low Volatile Matter (6.3%) Charcoal on Plant Growth Low VM 10% www.hnei.hawaii.edu www.ctahr.hawaii.edu 0% Nov 27, 2007

Low Volatile Matter Charcoal (6.3%) versus High Volatile Matter Charcoal (22.5%) High Low Volatile Volatile Matter Matter Nov 27, 2007 www.hnei.hawaii.edu 26 www.ctahr.hawaii.edu

Combined Effect of Low Volatile Matter Charcoal Plus Fertilizer NPK + NPK + Lime + Lime 10% Low VM Nov 27, 2007 www.hnei.hawaii.edu 27 www.ctahr.hawaii.edu

Volatile Matter or Feedstock? • VM content affected plant growth in macnut shell charcoal • Does feedstock make a difference? • Repeat trial with corn cob charcoal Nov 27, 2007 www.hnei.hawaii.edu 28 www.ctahr.hawaii.edu

Effect of corn cob charcoal on soybean 29 29 Low VM www.hnei.hawaii.edu www.ctahr.hawaii.edu High VM Control Nov 27, 2007

14 Waller-Duncan K Ratio t -test a 12 Soybean Fresh Weight (g/pot) 10 b b 8 6 4 2 0 Nov 27, 2007 www.hnei.hawaii.edu 30 Control HVM LVM www.ctahr.hawaii.edu

Low High Control Control VM VM Lime NPK NPK NPK Nov 27, 2007 www.hnei.hawaii.edu 31 www.ctahr.hawaii.edu

40 Waller-Duncan K Ratio t -test a b b 30 Soybean Fresh Weight (g/pot) 20 c 10 0 Nov 27, 2007 www.hnei.hawaii.edu 32 Control Lime+NPK HVM+NPK LVM+NPK www.ctahr.hawaii.edu

Conclusions • Volatile matter content influences a charcoal’s effectiveness as a soil amendment • Low volatile matter charcoals are more effective soil amendments than high volatile matter charcoals Nov 27, 2007 www.hnei.hawaii.edu 33 www.ctahr.hawaii.edu

Future Studies • Will the positive effects observed in greenhouse tests carry over into field trials? • Will the positive effects persist or diminish with time? • Will the negative effects of high volatile matter charcoal persist or diminish with time? Nov 27, 2007 www.hnei.hawaii.edu 34 www.ctahr.hawaii.edu