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Energies 2014, 7(2), 548-567; doi:10.3390/en7020548

Characterization of Biochar from Switchgrass Carbonization

1,* , 1
1 Department of Biological and Agricultural Engineering, University of Arkansas Division of Agriculture, Little Rock, AR 72204, USA 2 Center for Native Grasslands Management, University of Tennessee, Knoxville, TN 37996, USA 3 Department of Plant Sciences, University of Tennessee, Knoxville, TN 37996, USA
* Author to whom correspondence should be addressed.
Received: 17 November 2013 / Revised: 24 December 2013 / Accepted: 14 January 2014 / Published: 24 January 2014
(This article belongs to the Special Issue Renewable Energy for Agriculture)
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Switchgrass is a high yielding, low-input intensive, native perennial grass that has been promoted as a major second-generation bioenergy crop. Raw switchgrass is not a readily acceptable feedstock in existing power plants that were built to accommodate coal and peat. The objective of this research was to elucidate some of the characteristics of switchgrass biochar produced via carbonization and to explore its potential use as a solid fuel. Samples were carbonized in a batch reactor under reactor temperatures of 300, 350 and 400 °C for 1, 2 and 3 h residence times. Biochar mass yield and volatile solids decreased from 82.6% to 35.2% and from 72.1% to 43.9%, respectively, by increasing carbonization temperatures from 300 °C to 400 °C and residence times from 1 h to 3 h. Conversely, biochar heating value (HV) and fixed carbon content increased from 17.6 MJ kg−1 to 21.9 MJ kg−1 and from 22.5% to 44.9%, respectively, under the same conditions. A biomass discoloration index (BDI) was created to quantify changes in biochar colors as affected by the two tested parameters. The maximum BDI of 77% was achieved at a carbonization temperature of 400 °C and a residence time of 3 h. The use of this index could be expanded to quantify biochar characteristics as affected by thermochemical treatments. Carbonized biochar could be considered a high quality solid fuel based on its energy content.
Keywords: switchgrass; carbonization; biochar; BDI; co-firing switchgrass; carbonization; biochar; BDI; co-firing
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

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Sadaka, S.; Sharara, M.A.; Ashworth, A.; Keyser, P.; Allen, F.; Wright, A. Characterization of Biochar from Switchgrass Carbonization. Energies 2014, 7, 548-567.

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