Search

Torrefaction of energy sorghum and sweet sorghum bagasse was investigated at three different temperatures (250, 275 & 300°C) for 30min to determine product yields and its compositions. The torrefied solid yield ranged from 43% to 65% for sweet sorghum bagasse and 51-70% for energy sorghum. The energy density of both torrefied sorghums increased between 1.6 and 1.4 folds. Besides water, the acetic acid, with a maximum yield of 101.90gL -1 was the dominant compound in the aqueous fraction of liquid products. The aqueous fraction from sweet sorghum bagasse contained furfural and furan carboxyl aldehydes, while ketones and alcohols were dominant from energy sorghum as other key compounds. Phenolic type chemicals and furan derivatives were the major compounds in the oil fraction of the liquid product, accounted up to 58wt%. The condensable liquid products can be further upgraded into high-value platform chemicals., (Copyright © 2017. Published by Elsevier Ltd.)

Strip-mined land (SML) disturbed by coal mining is a non-crop land resource that can be utilized to cultivate high-yielding energy crops such as miscanthus for bioenergy applications. However, the biomass yield potential, annual availability, and environmental impacts of growing energy crops in SML are less understood. In this study, we estimated the yield potential of miscanthus (Miscanthus sinensis) in SML and its environmental impacts on local streams using the Soil and Water Assessment Tool (SWAT). After calibration and validation of the SWAT model, the results demonstrated that miscanthus yield potentials were 2.6 (0.8−5.53), 10.0 (1.3−16.0), and 16.0 (1.34−26.0) Mg ha−1 with fertilizer application rates of 0, 100, and 200 kg-N ha−1, respectively. Furthermore, cultivation of miscanthus in SML has the potential to reduce sediment (~20%) and nitrate (2.5−10.0%) loads reaching water streams, with a marginal increase in phosphorus load. The available SML in the United States could produce about 10 to 16 dry Tg of biomass per year without negatively impacting the water quality. In conclusion, SML can provide a unique opportunity to produce biomass for bioenergy applications, while improving stream water quality in a highly dense mining area (the Appalachian region) in the United States. [ABSTRACT FROM AUTHOR]

Abstract Torrefaction of biomass improves the grindability of raw biomass by the transformation from a fibrous structure to a more brittle and friable, coal-like material. Torrefied biomass is a more desirable feedstock for co-firing applications, especially in existing coal-fired power plants. Therefore, measuring the grindability and the specific energy consumption are critical for understanding the comminution behavior of torrefied biomass, and thus selecting appropriate milling equipment. In this study, the effect of torrefaction temperature on the specific grinding energy consumption and the grindability of torrefied wood pellets and wood chips was investigated and compared with that of coal. The applicability of three well-known grinding equations (Kick, Rittinger and Bond) was studied for the torrefied biomass using a knife mill. The specific grinding energy of both torrefied wood chips and pellets linearly decreased with increased torrefaction temperature over a range of 250–290 °C. Rittinger's model was the best-fit for both wood chips (R2 = 0.72–0.90) and wood pellets (R2 = 0.67–0.76). When the intercepts were considered, the Rittinger's and Bond's equations fitted well with the experimental data (R2 = 0.79–0.99) for all torrefied biomass. The grindability of torrefied biomass was measured using the Hardgrove Grindability Index (HGI) and the International Organization for Standardization (ISO) grindability index. A relationship between the Bond Work Index (BWI), based on the Bond's theory and HGI was developed for wood chips and wood pellets. Contrary to HGI index, BWI decreased with an increase in torrefaction temperature. The grindability parameters developed for torrefied biomass can be used for modeling and selecting suitable milling equipment. Highlights • Specific grinding energy required for torrefied wood chips and pellets were determined • Grinding energy decreased linearly with increased torrefaction temperature (250–290 °C) • Rittinger's equation was fitted the best with grinding data for all torrefied biomass. • HGI and BWI for torrefied biomass produced at 290 °C were comparable to that of coal. [ABSTRACT FROM AUTHOR]