Impact of Temperature, Moisture, and Storage Duration on the Chemical Composition of Switchgrass, Corn Stover, and Sweet
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Impact of Temperature, Moisture, and Storage Duration on the Chemical Composition of Switchgrass, Corn Stover, and Sweet Sorghum Bagasse Arun Athmanathan & Isaac R. Emery & Thomas Kuczek & Nathan S. Mosier
# Springer Science+Business Media New York 2014
Abstract Packaged samples of three bioenergy feedstocks— sweet sorghum, corn stover, and switchgrass—were stored indoors under aerobic conditions to determine the change in chemical composition, track loss of specific chemical constituents, and determine the impact of dry matter loss on saccharification yields with and without pretreatment. Biomass samples were stored under controlled temperature conditions at varying stable biomass moisture contents (10–34 % w/w), temperatures (8–35 °C), and durations up to 16 weeks. Total dry matter losses were measured and sample compositions determined to develop a material balance of storage losses for free sugars, glucan, xylan, and lignin. Maximal losses (24– 30 %) were observed for sweet sorghum bagasse at high moisture, while minimal losses (0 %) were observed with switchgrass below the highest tested moisture. Sorghum losses predominantly consisted of free sugars, while switchgrass and stover losses consisted of structural carbohydrates— cellulose and hemicellulose. The mass fraction (% dry weight) of lignin was observed to increase in samples showing dry matter loss, as a result of carbohydrate consumption.
A. Athmanathan : I. R. Emery : N. S. Mosier (*) Laboratory of Renewable Resources Engineering, Room 216, Potter Engineering Building, 500 Central Drive, Purdue University, West Lafayette, IN 47907-2022, USA e-mail: [email protected] A. Athmanathan : I. R. Emery : N. S. Mosier Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN 47907, USA T. Kuczek Department of Statistics, Purdue University, West Lafayette, IN 47907, USA
Keywords Biomass storage . Corn stover . Switchgrass . Sweet sorghum . Bagasse . Storage losses
Introduction Biorefineries capable of transforming lignocellulosic biomass into fuels and products will need a stable, yearround supply of feedstock [1, 2]. Agriculturally produced feedstocks are harvested seasonally and require storage for several weeks to several months in order to establish a year-round supply of feed biomass. Harvested biomass must thus be densified and stored for mid- to long-term periods either at the farm or an appropriate storage site. The principal problem during storage is that biomass is susceptible to microbial activity under specific conditions of temperature, moisture, and exposure [3, 4]. These processes can cause extensive loss of useful biomass carbon [5, 6], reducing the economic efficiency of the manufacturing process. Moreover, the degradation generates such greenhouse gases as methane and nitrous oxide, which may affect the environmental sustainability of biofuel manufacture and usage [7]. As a critical step in the sequence of operations for the manufacture of biofuels and chemicals, storage must be examined for its impact o
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