(396e) Developing Sustainable Biomass Supply Chains: AFEX Processing at Local Depots

The first biorefineries based on cellulosic biomass are now beginning to emerge.  However, it will be difficult if not impossible to develop large scale, sustainable cellulosic biofuels in the absence of a large scale supply chain to provide the necessary sustainable feedstocks.  Unfortunately, most raw cellulosic feedstocks are bulky, unstable and difficult to handle.  This presentation explores the potential of co-locating biomass processing facilities (called "depots") at existing grain elevators across a 10 state region in the U. S. Midwest.  The depots use the ammonia fiber expansion (AFEX) process with pelleting to pretreat and prepare cellulosic biomass (exemplified by corn stover and switchgrass) for subsequent hydrolysis and fermentation to fuel ethanol or for direct consumption by ruminant animals as enhanced feeds.  The AFEX pellets are dense, stable, storable and easily handled using existing grain handling equipment.  We model the interactions of these depots with the animal feed system and with very large scale biorefineries co-located at coal-burning power plants near cities where the ethanol can be easily transported to end users.  Metrics assessed include ethanol selling price, greenhouse gas emissions and return on investment at the depot level.  Different options for incentivized farmer participation in the biomass supply chains, including ownership of the depots, are explored. Depot level processing by AFEX appears to offer great potential for catalyzing the formation of sustainble biomass supply chains at a very large scale.