(737c) Assessing the Effect of Biomass Properties on Biomass to Biofuel System Performance Using Overall Operating Effectiveness

The development of a sustainable bioeconomy is threatened by the operational inefficiencies that are a result of the wide variability in the compositional and physical attributes of the feedstocks. Examining performance of supply systems at mean feedstock properties provides an often optimistic picture of system performance. We are proposing the use of a new metric, “overall operating effectiveness” (OOE), which uses dynamic performance information of the system to assess the composite impacts of feedstock quality on the operational efficiency and productivity of the system. For this analysis, discrete event simulation was used to conduct stochastic feedstock property-dependent throughput analysis of a conventional corn stover supply logistics-preprocessing-conversion system. Pilot scale preprocessing equipment data and experiential information were used to inform failure frequency and down time. With a 55% total carbohydrate specification for conversion, the modeled OOE values for the supply logistics, preprocessing and conversion subsystems were 56.9%, 24.4%, and 101%, respectively. The severity of throughput impacts depended primarily on moisture, while performance impacts depended on the range of corn stover compositional variability. Costs varied significantly as a function of assumed minimum acceptable carbohydrate contents from 45-59 wt% (proxy for conversion robustness), with a mean feedstock cost of $249.93/dry Mg (median of $146.39/dry Mg) for a 55% minimum carbohydrate content. As the floor was relaxed from an nth-plant specification of 59%, a higher proportion of the preprocessed feedstock was fed to conversion leading to feedstock contributions to biofuel costs ranging from $4.15-$8.73/gge (2016$). It is concluded that while conversion robustness can serve to minimize discarded feedstock, properties other than yield potential are more significant contributors to the feedstock contribution to biofuel cost.