ARS | Publication request: Bioethanol production from dedicated energy crops and residues in Arkansas, USA

Submitted to: Journal of Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 10, 2010
Publication Date: January 1, 2011
Citation: Ge, X., Xu, J., Phillips, G.C., Sivakumar, G., Burner, D.M. 2011. Bioethanol production from dedicated energy crops and residues in Arkansas, USA. Biotechnology Journal. 6(1):66-73.

Interpretive Summary: There is great urgency for developing biofuels, such as bioethanol, that are both renewable and environmentally friendly. Raw materials constitute about 60% of the production cost for bioethanol. The low cost and huge potential availability of lignocellulosic biomass such as agricultural residues, forestry wastes, waste paper, and energy crops make them particularly attractive biofuel commodities for the MidSouth/Mississippi Delta region, including Arkansas. However, a cost-effective method for converting lignocellulosic biomass to ethanol is a major technological impediment. Lignocellulose pre-treatment significantly influences the costs of upstream (e.g., lignocellulose particle size reduction) and downstream operations (e.g., enzymatic hydrolysis and fermentation). Our objectives were to test a cost-effective cellulose solvent-based lignocellulose fractionation (CSLF) pretreatment and enzymatic (cellulase) hydrolysis method to convert lignocellulose to reactive cellulosic intermediates and hydrolyze reactive intermediates to fermentable sugars, and develop ethanol fermentation methodologies with a self-flocculating yeast strain to reduce downstream process costs. Glucose yield of five dedicated energy crops and two crops residues ranged from 0.167 g/g (rice husk) to 0.295 g/g (giant miscanthus clone Q42641). A self-flocculating yeast strain (SPSC01) was used to ferment the lignocellulosic biomass hydrolysates. These methods may be useful for developing a cost effective downstream process for bioethanol production.

Technical Abstract: Globally, one of the major technological goals is cost-effective lignocellulosic ethanol production from biomass feedstocks. Lignocellulosic biomass of five dedicated energy crops and two crops residues were tested for bioethanol production using cellulose solvent-based lignocellulose fractionation (CSLF) pretreatment and enzymatic (Cellulase) hydrolysis: Miscanthus x giganteus from Illinois, Arkansas-grown giant reed, bical miscanthus and elephant grass, which yielded the most glucose based on biomass dry weight (0.291 - 0.295 g g–1), followed by Arkansas-grown sugar cane (0.264 g g–1), soybean (0.184 g g–1), and rice husk (0.167 g g–1). In order to reduce the capital investment for energy consumption in fermentation, the self-flocculating yeast strain was used to ferment the aforementioned lignocellulosic biomass hydrolysates. The bioethanol production was approximately 0.1g g-l in dedicated energy crops and lower in crops residues such as rice husk and soy beans. These methods and data may be useful for developing a cost effective downstream process for bioethanol production.