Application of NIRS to the Direct Measurement of Carbonization in Torrefied Wheat Straw Chars

  • William CampbellEmail author
  • Amy Coller
  • Scott Noble
  • Richard Evitts
  • Kurt Woytiuk
Short Communication


Near infrared spectroscopy is demonstrated as a method for measuring of the increase in carbon content for torrefied wheat straw. Wheat straw was torrefied in both batch and continuous systems at the bench and pilot scale, followed by measurement of the elemental composition and diffuse reflectance/absorbance in the NIR spectrum. The changes in absorbance measured in the band from 960 to 1060 nm most closely correlated to the change in carbon content, which increased by more than 10% for the most severely torrefied samples. In general, the absorbance values in the NIR band for the char samples change very clearly and incrementally along with torrefaction severity. The average change in absorbance at each wavelength within the 960–1060 nm band was correlated to the increase in carbon concentration by a linear expression with an average R2 value of 0.949.


Torrefaction NIRS Quality measurement Wheat straw Char carbon content 





Dry, ash-free


Dry basis


Near infrared


Short-wave infrared




Reflectance of char


Reflectance of raw biomass


Root-mean squared error


Visible (spectrum)


Mass yield (% wt/wt)



This project was supported financially by the National Sciences and Engineering Research Council of Canada (Collaborative Research and Development Grant #442436-12), the Saskatchewan Ministry of Agriculture (Agriculture Development Fund grant # 20120072), SaskPower Corporation, and the Applied Bioenergy Centre at the Prairie Agricultural Machinery Institute. The authors also gratefully acknowledges the support and assistance of Dr. Aaron Phoenix, Dr. Kurt Woytiuk, and Regan Gerspacher in all of their efforts towards the design, assembly and operation of the torrefaction apparatus used in this work. This manuscript was derived substantially from chapter 6 of the Ph.D. dissertation by author William Campbell [33], that chapter titled "Application of NIRS to the direct measurement of carbonization in torrefied wheat straw chars", submitted to the University of Saskatchewan in partial fulfilment of the requirements for completion of a doctoral degree.  

Supplementary material

12649_2019_612_MOESM1_ESM.docx (17 kb)
Supplementary material 1 (DOCX 16 KB)


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© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.Department of Chemical and Biological EngineeringUniversity of SaskatchewanSaskatoonCanada
  2. 2.Department of Mechanical EngineeringUniversity of SaskatchewanSaskatoonCanada
  3. 3.FPInnovationsEdmontonCanada

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