(587m) A Granulation Based Biomass Supply Logistics System for a Modern Biorefinery
Economic and efficient conversion of biomass into fuels and chemicals depends not only on the cost of feedstock but also the quality of feedstock delivered to a biorefinery. Feedstock cost has become one of the major challenges that limit the growth of biofuel industries in US. The existing baling based feedstock supply logistics system has several challenges including high cost, low bulk density, other storage issues. Densification of biomass is a critical preprocessing step in the supply logistics system as densified biomass improves the bulk density, flowability and bulk storage capability of large volume of biomass. However, the current pelleting and briquetting technologies required high energy input and high cost to supply to a biorefinery. In this project, we have developed a novel lignocellulosic biomass granulation technology to replace existing pelleting and briquetting processes. Granulation is a process of agglomerating fine particles by shear/vibrating forces with or without liquid binders. Granulation of lignocellulosic biomass will not only densify the biomass, but also improve the bulk flow properties of a final product at low cost. A proof of concept granulation process was developed using a lab-scale granulation unit. Wood chip and switchgrass powders were prepared to a required particle size and were granulated with two different types of binders at three different binder concentrations. A techno-economic evaluation of granulation technology was conducted for large scale production. The granules generated from wood powders were superior in granule quality compared to switchgrass granules. The bulk flow properties and granule strengths were comparable with existing pelleting technology. Economic analysis of granulation technology demonstrated that the cost of densification can be reduced up to three fold compared to pelleting technology. It was concluded that granulation based biomass densification technology can be very attractive to transport and store large volume of biomass at low cost for a modern biorefinery.