Cost analysis of switchgrass harvesting, hauling and storage for ethanol biorefineries
Agriculture inputs and production costs are important factors for farming decisions. A major hurdle facing commercial biofuel production is the cost of producing the feedstock. Since biofuel feedstock is bulky in nature, transportation costs could be high. Thus, a large proportion of cost needed to be allocated for harvesting and transportation of feedstock. Economic viability of ethanol production from cellulosic feedstock such as perennial grasses depends in part on the cost to produce, harvest and deliver feedstock to the ethanol production facilities. So far, a well-developed harvesting and transportation system does not exist for perennial grasses and crop residues. Here I conducted a study on the cost analysis of switchgrass harvesting and hauling for ethanol biorefineries. The specific objectives of this study are 1) to determine the optimal harvesting unit for small-scale ethanol biorefinery, and 2) to estimate harvesting, storage and transportation costs of switchgrass under various harvesting schedules. A small-scale biorefinery with an annual capacity of processing 5 million gallons of ethanol was considered. Based on average dry matter yield, total production area of switchgrass needed for annual harvesting was estimated. The harvesting units needed for the continuous harvest and supply of biomass were estimated based on the capacity of machineries etc. Accordingly, various costs associated with operating and maintaining harvesting unit were estimated. Transportation units needed were estimated for continuous supply of feedstock to the refinery and the associated costs were calculated. Results showed that the harvesting units needed on a 3 month harvesting schedule were the most while year round harvesting schedule the least. Harvesting switchgrass in 3 months was the most expensive scenario with all harvesting, hauling and storage costs added together. Six month harvesting schedule occurred as the least costly scenario. Estimated costs were sensitive to the variables such as price of diesel, biomass yield, ethanol conversion ratios and operating speed of the truck. As diesel price, yield and conversion rate increased, the costs increased as well. When truck speed increased, the costs decreased in a very small amount. The results could be useful for supply chain development and setting up harvesting, transport and storage infrastructure for ethanol biorefinery. Biorefineries may evaluate options for maintaining own harvesting unit for the field operations or consider custom harvesting. The estimated marginal profits for custom harvesting companies indicated that performing a year round harvesting schedule will generate the most marginal profit compared to other two harvesting schedules.
"Cost analysis of switchgrass harvesting, hauling and storage for ethanol biorefineries"
ETD Collection for Tennessee State University.