August 1, 2014

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Biochar

[IMAGE]Biochar Trading CardThe goal of this project is to characterize chars produced by CSET’s thermochemical processes, to test the char’s suitability as a biochar soil amendment, and ultimately, to engineer and produce biochars that exhibit desirable agronomic properties.

Biochar is the solid product of thermochemically processing biomass, used for agronomic or horticulture purposes.  As soil amendments, chars have been shown to increase soil fertility by improving nutrient and water retention, lowering soil acidity and density, and increasing microbial activity.  In addition, energy production from biomass that stores carbon as biochar can be considered carbon negative due to biochar’s high recalcitrance.

Multiple physical, chemical and soil analyses are used to characterize these chars to better understand how production conditions relate to end product biochar properties.  Particle size distribution, proximate analysis, BET surface area, pore size distribution, and particle density make up the physical characterizations.  Elemental CHNOS analysis and X-ray fluorescence spectroscopy (XRF) quantify the char’s chemical and trace mineral content. Fourier-transform infrared spectroscopy (FTIR) provides information about surface functional groups and cation exchange capacity (CEC).  Solid state nuclear magnetic resonance (NMR) is used to estimate the char’s degree of aromaticity, which is believed to relate to its long term stability in soil.

Chars from slow pyrolysis, fast pyrolysis and gasification of switchgrass and corn stover were studied first as a baseline for locally-producible biochars.  Compared to traditional wood char (charcoal), these chars have high ash content, which may provide a liming affect on soil.  Surface area and char aromaticity increase with process temperature, albeit with lower char yields.

After characterization, various lab, pot and field trials, conducted in collaboration with agronomists at ISU, will determine which kinds of biochars are the most successful as soil amendments.  New biochars will then be engineered from a wide range of biomass feedstocks using optimized thermochemical processing conditions for additional pot and field trials.

Principle Investigator:
Dr. Robert C. Brown, Iowa State University, rcbrown@iastate.edu

Publications:

  • Brewer, C. E. & Brown, R. C., (2010), Expending the Envelope: Biochar. In D. Ruddy (Ed.), Comprehensive Renewable Energy (Vol. 5): Elsevier. Submitted to Publisher.
  • Brewer, C. E., Schmidt-Rohr, K., Satrio, J. A., & Brown, R. C. (2009). Characterization of biochar from fast pyrolysis and gasification systems, Environmental Progress & Sustainable Energy, 28(3), 386-396.

Posters & Presentations:

  • Brewer, C. E., Schmidt-Rohr, K., Satrio, J. A., Brown, R. C. (2009). Characterization of biochar from fast pyrolysis and gasification systems, 2009 GTI TCBiomass Conference, Chicago, IL, September 16.
  • Brewer, C. E., Unger, R., Brown, R. C. (2009). Characterization of biochar from fast pyrolysis and gasification of switchgrass and corn stover, North American Biochar Conference, Boulder, CO,
    August 11.
  • Brewer, C., Treviño, H., Assmann, D., Satrio, J.; Brown, R. (2008)Engineering Biochar: Characterization of Chars Derived from Three Thermochemical Processes, 2008 International Biochar Initiative Conference, Newcastle, UK, September 8.
  • Brewer, C., Treviño, H., Satrio, J., Brown, R. (2008) Engineering Biochar: Characterization of Chars Derived from Three Thermochemical Processes, 2008 Growing the Bioeconomy Conference, Ames, IA, September 8.

Overall research plan for biochar engineering as collaboration between CSET thermochemical processing group and ISU Departments of Agronomy and Horticulture.

Scanning Electron Microscopy (SEM) images of various switchgrass chars compared to the original feedstock.  Note the similarity in structure but the difference in char size and porosity between production processes.

LINK: Related Presentations and Posters Featuring Biochar