Process Modeling and Economics

Modeling

Flow sheets and process models will be developed for all bioconversion technologies evaluated. For the gasification-fermentation process, design premises have been established for the gasifier, bioreactor, final product purification and ancillary equipment. These premises will be modified, optimized and refined over the length of this project and ultimately provide the basis for a commercial scale plant. Based on these premises process models and process flow sheets have been developed and refined for the gasifier and the bioreactor.

Economic Analysis

Conventional methods of economic analysis will be used to determine the cost of system components. In the case of selected perennial grasses, initial budgets for stand establishment have been produced based on the physical experiments. These budgets will be revised continually based on new and revised data. Technical information will be combined with historical price relationships to generate estimates of returns and costs. Work on perennial grasses harvest, storage, and transportation are currently underway dependent on the determined optimal physical strategies for harvest and storage. Enterprise budgets will be used to determine production costs of dedicated agricultural biomass production activities. A multi-region, multi-period, mixed integer mathematical programming model encompassing alternative feedstocks, feedstock production, delivery, and processing has been development and will be enhanced as data becomes available. It is designed to address a number of very specific questions essential to determine the economics of a lignocellulosic bioconversion facility.

Energy

For most bioconversion technologies evaluated, net energy requirements of the system will be determined by summing all the energy required to produce, transport, store, and process the feedstock. Optimization is required to minimize the primary energy sinks.

Environmental Impact

The focus will continue to be on developing a computational tool that can predict changes in runoff, sediment yield, and nutrient yield for land use changes from traditional agriculture to switchgrass production. Direct and indirect benefits and costs will also be determined, including costs/benefits of environmental impacts. The study uses the SWAT (Soil and Water Assessment Tool) model as the base tool to predict biomass production and environmental impact. Procedures are being developed to predict the economic impact of these changes. Full Cost Accounting will be used to convert physical environmental outputs into dollar-equivalents such that these estimates may be added to the overall economic analysis to arrive at the “full” cost of each process.