(76f) Native and Pretreated Switchgrass Surface and Ultrastructure Imaging Analysis and Process Modeling Update of Various Leading Pretreatment Technologies

The Biomass Refining Consortium for Applied Fundamentals and Innovation (CAFI) was formed in 1999 as a multi-institutional effort to develop comparative information on lignocellulosic biomass pretreatment options. In the current CAFI 3 project utilizing different varieties of switchgrass (Panicum virgatum L.), the National Renewable Energy Laboratory (NREL) is employing various analytical microscopy tools within the Biomass Surface Characterization Laboratory to identify surface and ultrastructural characteristics across a range of switchgrass varieties that represent different cultivation and harvesting practices. Additionally, these imaging tools are being used to characterize structural differences in switchgrass pretreated via the various CAFI pretreatment processes. Surface and ultrastructural differences in switchgrass pretreated via the various CAFI pretreatment processes is being related to the chemical compositional differences resulting from these pretreatments, where a wide range of hemicellulose and/or lignin solubilization has been observed. The imaging and chemical composition differences in pretreated switchgrass are also being related to the subsequent enzymatic hydrolysis performance of these substrates, as reported by the various CAFI research teams.

Additionally, ongoing work to update and utilize process economic models for the various CAFI pretreatment processes across a range of feedstocks will be reported. Recent pretreatment and enzymatic saccharification data on hybrid poplar for each pretreatment process has been incorporated into the overall economic models. The resulting process economics are heavily dependent on overall sugar and ethanol yields, which vary significantly across the different pretreatments for hybrid poplar. The application of these models to the current CAFI project using switchgrass will also be described.