Assessment of options for the integration of food and fuel production in cellulosic ethanol refining.

摘要

Reducing petroleum consumption is one of the primary challenges of the United States and the world in the 21st century. Biofuels are seen as a primary alternative, yet concerns of decreasing food production due to increased demand for land remain. This research proposes two technologies to integrate biofuel production with animal feeds and lessen this demand: using AFEX treated biomass as a fiber source for ruminants and extracting leaf protein as a protein source. The purpose of this study is to investigate the viability of these two technologies for both economic value and increasing the productivity of land.;Experimental results indicate that an early harvest of switchgrass, which would be required for protein production, requires milder pretreatment condition and has higher yields than late harvest biomass. Ammonia-based extraction was successful in removing approximately 40% of the protein from switchgrass. However, AFEX did not increase extraction yields, and resulting sugar yields decreased after extraction. After hydrolysis, nearly all of the protein was soluble, but ultrafiltration could only concentrate 30--45% of the protein. AFEX increased the digestibility of fiber in multiple feedstocks and increased the crude protein content to levels comparable to common forages. The digestibility of pretreated late harvest switchgrass is comparable to high quality forages, while the energy in corn stover is approximately 85% of the value of corn grain.;From these experimental results, two models were created to determine the potential of these technologies. The first, an economic and material model, suggests that animal feed integration with ethanol production can displace the equivalent of 2900--4800 L gasoline per ha of land removed from feed use compared to 1600 L/ha if no feed integration is performed. Likewise, the profitability of the land increases to ;Thus, this study suggests further research into integrating animal feed production with biofuel production should be pursued. Emphasis should be applied to readying AFEX-treated feeds for commercialization, primarily through animal feeding trials. For protein extraction, future research should be focused primarily on using the remaining fiber for ethanol production.