Preliminary Feasibility Analysis For An Integrated Biomaterials And Ethanol Biorefinery Using Wheat Straw Feedstock

Biobased products and fuels appear to have a very bright future. A consortium led by NDSU is currently engaged in a project that would use cellulose nanofibers derived from wheat straw to make a product that could substitute for fiberglass and plastics in many applications, including automotive parts. The work described here analyzes the economic value of producing cellulose nanowhiskers (CNW) as a co-product in an ethanol biorefinery. An ASPEN Plus-based process model was developed to evaluate ethanol production from wheat straw. The base case model generated 54.418 million gallons per year (MGPY) of denatured ethanol, using approximately 900,000 tons per year of wheat straw feedstock. The capital cost was estimated at $185 million. Total operating costs, excluding by-product credits, were $92.4 million per year. Revenue from sales was estimated at $98.0 million per year from ethanol and $7.5 million per year from electricity. The earnings before interest and income tax (EBIT) are $13.1 million per year providing a return on investment (ROI) of 7.06 percent. The production cost of ethanol including by-product credit was determined at $1.56 per gallon. When production of CNW was added to the base case model, the manufacturing cost of producing CNW from wheat straw was estimated to be $.57 per pound. Economic analysis indicated that production of CNW would be an enhancement to the economic performance of a wheat straw to ethanol mill.