(556f) Mesoscale Modeling of Thermochemical Conversion of Biomass

Authors: 
Ciesielski, P. N., National Renewable Energy Laboratory
Pecha, B., NREL
The outcomes of thermochemical conversion processes are governed by an intricate coupling of chemical reaction kinetics and complex transport phenomena. Computational tools provide an excellent complement to experiment for the purposes of process optimization and interpretation of experimental results. While much attention has been devoted to modeling conversion processes at extreme length scales (i.e., the molecular scale and the bulk process scale), relatively little effort has been focused on understanding the role of lignocellulose mesostructure via computational modeling. In the context of this presentation, the mesoscale architectural features of biomass are defined as the higher-order assembly of biopolymers in the plant cell wall and the species specific microstructure present in biomass particles. In this presentation, I will present general methodology by which the impact of structural features of lignocellulose may be assessed in silico. A general method based on constructive solid geometry will be presented that can be used to explicitly model lignocellulosic biopolymer assemblies on the length scale of ~ 100 nm. Several examples of how quantitative microscopy and chemical analysis can be used to parameterize the model for various scenarios will be included. Next, I will describe how morphologically accurate 3D biomass particles may be constructed and employed in finite element simulations of heat and mass transport coupled to conversion kinetics. Finally, I will present an example of how this methodology may be employed to estimate optimal conversion conditions for specific biomass feedstocks.