Biorefinery developments for advanced biofuels from a widening array of biomass feedstocks

Authors: Orts, William; McMahan, Colleen

Submitted to: BioEnergy Research
Publication Type: Review Article
Publication Acceptance Date: 4/7/2016
Publication Date: 5/15/2016
Citation: Orts, W.J., McMahan, C.M. 2016. Biorefinery developments for advanced biofuels from a widening array of biomass feedstocks. BioEnergy Research. 9(2):430-446. doi: 10.1007/s12155-016-9732-4.

Interpretive Summary: Implementation of the Renewable Fuel Standard of 2007 has been hampered by multiple factors, including the high costs of most biomass resources, the recalcitrant nature of lignocellulosic feedstocks, the high cost of enzymes or chemicals to de-construct biomass, and the need for optimized bioprocesses for a wider array of varying feedstocks. The USDA Regional Biomass Research Centers, include field researchers, crop developers, and biorefinery designers, are implementing strategies to address these challenges. Step-wise improvements in biorefinery concepts include building in enough flexibility in the process to use the “cheapest source of renewable carbons” within a given region. Such flexibility implies, for example, using grain sorghum, switchgrass, or miscanthus in the Midwest, sweet sorghum or cane sugar in the South, guayule bagasse in the Southwest, almond hull sugars in California and even citrus peel waste in California and Florida. Another key element is the ability to integrate existing ethanol plants with other operations; specifically utilizing thermochemical conversion of all biomass sources or utilizing integrated digesters to produce biogas and biogas-derived products. As briefly outlined here, biorefinery operations are best optimized when field research data on yield, crop quality, and biomass cost are well-integrated into biorefinery strategies.

Technical Abstract: When the United States passed the Renewable Fuel Standards (RFS) of 2007 into law it mandated that, by the year 2022, 36 billion gallons of biofuels be produced annually in the U.S. to displace petroleum. This targeted quota, which required that at least half of domestic transportation fuel be “advanced biofuels” either produced from lignocellulosic feedstocks or be a sustainable liquid fuel other than corn ethanol, will not likely be met due to the difficulty in commercializing advanced biofuels. The number one cost to a biorefinery is the biomass feedstock cost. Thus it is important that research into biorefinery strategies be closely coupled to advances in crop science that account for crop yield and crop quality. To reach the RFS targets, step-wise progress in biorefinery technology is needed, as the industry moves from corn ethanol toward utilizing a wider array of biomass feedstocks. In 2010, the U.S. Department of Agriculture created five Regional Biomass Research Centers to optimize production, collection and conversion of crops to bioenergy, thus building a network that fosters collaboration among researchers to improve the biorefinery industry. An important component of the five Regional Biomass Research Centers is the four USDA Agricultural Research Service (ARS) regional utilization laboratories located across the country. This review outlines some of the recent advances from the ARS Labs in developing new bioprocessing strategies required to develop bioenergy from new crop sources.