|Mitchell, Robert - Rob|
Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2013
Publication Date: 3/22/2013
Citation: Uden, D.R., Mitchell, R., Allen, C.R., Mccoy, T., Guan, Q. 2013. The feasibility of producing adequate feedstock for year–round cellulosic ethanol production in an intensive agricultural fuelshed. BioEnergy Research. doi 10.1007/s12155-013-9311-x. Interpretive Summary: US energy mandates require the development of second generation biofuels to meet renewable energy requirements. However, there are no commercial scale cellulosic ethanol production facilities in the United States. We evaluated the fuelshed around an existing starch-based ethanol plant in Nebraska to determine if adequate feedstock could be supplied to produce cellulosic ethanol at the commercial scale. In this fuelshed, we identified 34,900 acres of marginally productive cropland within a 25-mile service area suitable for conversion from annual crops to switchgrass and 325,000 acres cropland from which maize stover could be collected. This 25-mile service area could supply 470,000 to 830,000 US tons of combined annual maize stover and switchgrass biomass, producing 37 to 66 million gallons of cellulosic ethanol. We conclude that this area of intensive agricultural production can produce sufficient quantities of biomass near the existing ethanol plant to support year round cellulosic ethanol production. Adding a bolt-on cellulosic ethanol stream to an existing starch–based ethanol plant in this fuelshed could increase ethanol output, return marginally-productive cropland to perennial vegetation, and remove maize stover from productive cropland to meet feedstock demand.
Technical Abstract: To date, cellulosic ethanol production has not been commercialized in the United States. However, government mandates aimed at increasing second generation biofuel production could spur exploratory development in the cellulosic ethanol industry. We conducted an in–depth analysis of the fuelshed surrounding a starch-based ethanol plant near York, Nebraska that has the potential for cellulosic ethanol production. To assess the feasibility of supplying adequate biomass for year–round cellulosic ethanol production from residual maize (Zea mays) stover and bioenergy switchgrass (Panicum virgatum) within a 40-km road network service area of the existing ethanol plant, we identified 14,000 ha of marginally productive cropland within the service area suitable for conversion from annual rowcrops to switchgrass and 132,000 ha of maize enrolled cropland from which maize stover could be collected. Annual maize stover and switchgrass biomass supplies within the 40-km service area could range between 429,000 and 752,000 Mg. Approximately 140 – 250 million liters (l) of cellulosic ethanol could be produced, rivaling the current 208 million l annual starch–based ethanol production capacity of the plant. We conclude that sufficient quantities of biomass could be produced from maize stover and switchgrass near the plant to support year round cellulosic ethanol production at current feedstock yields, sustainable removal rates and bioconversion efficiencies. Modifying existing starch–based ethanol plants in intensive agricultural fuelsheds could increase ethanol output, return marginally-productive cropland to perennial vegetation, and remove maize stover from productive cropland to meet feedstock demand.