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

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

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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

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 1

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

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 2

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)

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 3

Fuel Costs

$18-24/GJ Hydrogen $6-17/GJ Gas $14/GJ Ethanol $15/GJ Oil $8/GJ Charcoal Coal RENEWABLE FOSSIL

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 4

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
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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 5

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?

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 6

Useful definitions:

  • 1. ychar = mchar / mbio
  • 2. 100 = % VM + % fC + % ash; where

VM = volatile matter; fC = fixed carbon

  • 3. yfC = ychar × {% fC / (100 - % feed ash)}
  • 4. ηchar = ychar × (HHVchar / HHVbio)
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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 7

Thermochemical equilibrium predictions for the products of cellulose pyrolysis at 400 C (Ind. Eng.

  • Chem. Res. 2003, 42, 3690-3699).
  • C, H2O, CO2, and

CH4 are the only significant products.

  • The theoretical

charcoal (i.e. C) yield is 28 wt%.

  • The gas contains

significant energy (i.e. CH4).

Pressure (MPa) 0.001 0.01 0.1 1 10 Mass fraction (%) 10 20 30 40 50

C(s) CO2 H2O(g) CO CH4

(a)

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 8

Reaction stoichiometry for the products of cellulose pyrolysis at 400 C & 1 MPa (Ind.

  • Eng. Chem. Res. 2003, 42, 3690-3699)

C6H10O5 → 3.74 C + 2.65 H2O + 1.17 CO2 + 1.08 CH4

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Energy balance for cellulose pyrolysis following thermochemical equilibrium (Ind.

  • Eng. Chem. Res. 2003, 42, 3690-3699)

5000 10000 15000 20000 input

  • utput

Energy [kJ/kg-cellulose] cellulose specific heat carbon gas work sensible heat exotherm 5000 10000 15000 20000 input

  • utput

Energy [kJ/kg-cellulose] cellulose specific heat carbon gas work sensible heat exotherm

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 10

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.

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 11

Flash CarbonizationTM reactor schematic (U.S. patent # 6,790,317; September 14, 2004).

PG DDV SRD PRV flare IV UDV MMV R H ATW C A HIC DS TC TC TC TC TC TC TC TC IV TC PT PT GSP WT WT H

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 12

Parity plot of Flash CarbonizationTM fixed- carbon yields from various biomass feedstocks (Ind. Eng. Chem. Res. 2003, 42, 3690-3699)

  • Fixed-carbon yields

from corn cob, oak, and macshell approach the theoretical limit.

  • Leucaena offers

almost 90% of the theoretical limit.

yfC - experimental (%)

20 25 30 35 40 45

yfC - theoretical limit (%)

20 25 30 35 40 45

90% 80% 100%

MS LW-A1 LW-O OW-2 OW-1 CC LW-A2

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Flash CarbonizationTM demo reactor

  • n the UH campus
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Picture source: http://www.gerhardbechtold.com/TP/gbtp.php

Terra Preta (Amazonian Dark Earths): Highly Fertile Anthropogenic Soils

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Terra Preta Soil Typical Upland Amazonian Soil

Photo source: University of Bayreuth Photo source: University of Bayreuth

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Terra Preta Unamended Soil

Effect of Terra Preta on Plant Growth

Photo source: http://tinselwing.wordpress.com/tag/terra-preta/

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Volcanic ash soil treated with flash carbonized macadamia nut shell charcoal 0% (w/w) 5% (w/w) 10% (w/w) 20% (w/w)

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Control 20% (w/w) charcoal

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Lettuce Shoot Biomass

0% 5% 10% 20%

Plant weight (grams/pot)

20 40 60 80 100 120 140 160

a a b c

Charcoal Rate (w/w)

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Charcoal Effect in an Acid, Infertile Soil

0% 5% NPK + Lime

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NPK + Lime 5% + NPK + Lime

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Preliminary Conclusion:

Charcoal used in the experiment caused a negative effect on plant growth But why?

  • Crop?
  • Soil??
  • Charcoal???
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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 23

  • 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

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Effect of High Volatile Matter (22.5%) Charcoal on Plant Growth

0% 10% High VM

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Effect of Low Volatile Matter (6.3%) Charcoal on Plant Growth

0% 10% Low VM

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Low Volatile Matter Charcoal (6.3%) versus High Volatile Matter Charcoal (22.5%)

Low Volatile Matter High Volatile Matter

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Combined Effect of Low Volatile Matter Charcoal Plus Fertilizer

NPK + Lime NPK + Lime + 10% Low VM

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 28

Volatile Matter or Feedstock?

  • VM content affected plant growth in macnut

shell charcoal

  • Does feedstock make a difference?
  • Repeat trial with corn cob charcoal
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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 29

Control High VM Low VM

Effect of corn cob charcoal on soybean

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 30

Waller-Duncan K Ratio t-test

Control HVM LVM

Soybean Fresh Weight (g/pot)

2 4 6 8 10 12 14

a b b

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Control Control Lime NPK High VM NPK Low VM NPK

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Waller-Duncan K Ratio t-test

Control Lime+NPK HVM+NPK LVM+NPK

Soybean Fresh Weight (g/pot)

10 20 30 40

a b b c

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Nov 27, 2007 www.hnei.hawaii.edu www.ctahr.hawaii.edu 33

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

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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?