Preparing Biomass for Storage and Transportation

If very large scale biofuel/bioenergy systems are to emerge, significant logistical challenges must be overcome.  Some of these challenges include low biomass energy density, its tendency to decompose and difficulty of handling and the lack, in many cases, of established markets to help catalyze the formation of the required biomass supply chains. One way of addressing such challenges is to preprocess and densify biomass close to where it is grown, thereby enabling shipment of the densified biomass to much more distant locations.  It would also help if at least some of the products from such preprocessing operations could fit into current markets, where there is existing demand.  Such preprocessing/densification centers, which we call local biomass processing depots or LBPDs, would require relatively low capital cost processing technologies. LBPDs would need to deal effectively with the wide variety of biomass materials available within various landscapes and must have attractive economic and environmental performance.  Ideally, they would also be owned wholly or in part by local interests, thereby increasing the likelihood that some of the added value or wealth generated by processing will stay in the local community.

We have evaluated several low capital cost preprocessing technologies for their potential to be used in the LBPD setting.  Among these, the ammonia fiber expansion or AFEX™ process stands out for its potential to pretreat, densify and add value to biomass at the LBPD scale. AFEX™ produces valuable animal feeds as well as uniform, stable, densified feedstocks for biofuel production, thereby providing a market pull to help establish the needed supply chains. Coproducing food/feed helps avoid the “food versus fuel” issue that is frequently associated with biofuel production.  Indeed, the production of valuable animal feeds helps reduce the cost of feedstocks for biofuel production while also reducing the risks of feedstock supply interruptions, a “win-win-win” situation. 

We have used system wide, life cycle, models to evaluate AFEX™ and other technologies used in an RBPD context to a specific area in southwest Michigan. The modeling exercise evaluated the potential for coproducing biofuels/bioenergy/animal feeds in ways that are more much sustainable than current agricultural and fuel production practices.  By integrating biofuel production with enhanced animal feeds, we find that much larger volumes of biomass can be sustainably and profitably harvested from existing lands in order to meet national energy and environmental goals.