Groothuis, Mitch D. | Search NASA

DOE OSTI2020

Techno-Economic Impact of Diesel Fuel, Labor, and Interest Rates on Bulk-Format and Round Bale Logistics Expenses for Switchgrass

Highlights System-wide sensitivity of bulk-format and round bale logistics responded to different degrees of expense inputs. Biomass size-reduction expenses for bulk-format were consistently less than round-bale chopping. Stack/reclaim operations with high-density-capacity equipment for bulk-format were the highest expenses. Clean-sheet design of stacker/reclaimer and self-compacting bulk trailer may significantly reduce expenses. Abstract . Deterministic cost analyses were conducted for a harvest, storage, preprocessing, and supply system providing 371,870 dry Mg (dMg) year-1 of milled switchgrass (SG) to a biorefinery from 21,929 ha of production fields within 72 km of the biorefinery. Varied input costs of diesel fuel, labor, and interest rate were input into a highly detailed cost analysis for bulk-format and baseline round bale logistics. These operational input factors, potentially reflecting an evolving economic climate or paradigm shift, were examined to provide insight into the cost to deliver preprocessed biomass feedstock for centralized commercial-scale conversions. Total annual costs per dry unit of SG were determined for all combinations of diesel fuel prices of $0.53 L-1, $0.92 L-1, and $1.32 L-1; total labor costs of $20.00 h-1, $28.85 h-1, and $40.00 h-1 singly and uniformly applied across all labor inputs; and three representative interest rates of 6%, 8%, and 12%. Increases in total cost most depended on increases in diesel fuel cost, followed by labor rate, and finally interest rate. Increases in fuel costs from $0.53 L-1 to $1.32 L-1 yielded a total cost increase of about $11.56 dMg-1 and $13.36 dMg-1 for bulk-format and round bale logistics, respectively, for all combinations of labor and interest rates. The overall increase in labor rate ($20.00 h-1 to $40.85 h-1) resulted in increased total costs of about $10.32 dMg-1 for bulk-format logistics and $9.94 dMg-1 for round bale logistics for all fuel and interest rates. The overall increase in interest rate (6% to 12%) resulted in increased total costs of about $6.72 dMg-1 for bulk-format logistics and $4.21 dMg-1 for round bale logistics for all fuel and labor rates. Increases in total costs for combined increases in fuel cost, labor rate, and interest rate were $28.60 dMg-1 and $27.48 dMg-1, yielding maximum total costs of $87.87 dMg-1 and $86.53 dMg-1 for bulk-format and round bale logistics, respectively. Costs were determined for existing equipment systems, including novel use of waste compaction and ejector semi-trailers. The highest potential for cost reductions may require clean-sheet equipment designs specifically tailored for SG, such as forage harvesters that direct-cut standing SG, mobilized stacker-reclaimer technology to not inhibit stack-area footprint, self-compacting ejector trailer technology, and bale grinding technology incorporating controlled mass feeding and shear failure elements. Keywords: Bales, Bioenergy, Bulk-format, Densification, Field chop, Logistics, Transportation

Agriculture↗

DOE OSTI2018

Low-Moisture Switchgrass Bulk-Format Logistics Costs Based on Engineering Data

Abstract. Logistics costs that spanned harvest, transport, storage, preprocessing, and year-round delivery of 371,870 dMg year -1 of milled, low-moisture switchgrass (SG) to a local biorefinery were determined for bulk-format versus round-bale systems. Separate spreadsheet analyses were conducted for three diesel fuel prices ($0.53 L -1 , $0.92 L -1 , and $1.32 L -1 ) because of the wide range of fuel prices during the project. A detailed analysis scenario identified a common harvest period, equipment annual use, other equipment uses, and protected SG storage on gravel pad, along with equipment performances based on previously published tests primarily for commercially available equipment. The bulk-format system used a depot equipped with stacker/reclaimer technology for storage, whereas the round-bale system used field-side bale stacks for storage, with both systems assuming 6% losses, primarily attributed to storage. Results indicated total costs for bulk-format versus round-bale systems of $54.63 per dry Mg (dMg -1 ), $60.41 dMg -1 , and $66.21 dMg -1 versus $54.59 dMg -1 , $62.10 dMg -1 , and $67.93 dMg -1 corresponding with diesel fuel costs of $0.53 L -1 , $0.92 L -1 , and $1.32 L -1 , respectively. The most significant bulk-format system total cost of $22.79 dMg -1 was associated with a stacker/reclaimer, conveyance, and dust collection at the depot, which was 42% of total costs at a diesel fuel cost of $0.53 L -1 . For the round-bale system, bale chopping total costs was highest and represented an average of 27% of total costs, with costs ranging from $14.63 dMg -1 to $19.08 dMg -1 for diesel fuel input costs ranging from $0.53 L -1 to $1.32 L -1 , respectively. For comparison, the forage harvester provided harvesting and chopping in the bulk-format system at total costs ranging from $6.47 dMg -1 to $8.80 dMg -1 across the same range of diesel fuel input cost. The forage harvester provided an economic advantage in size reduction compared to tub grinding. Truck hauling for both the bulk-format and round-bale systems represented significant expenses at all selected fuel costs. In addition, the multiple times that round bales were handled represented accumulating costs that were sensitive to diesel fuel costs. Keywords: Bales, Bioenergy, Bulk format, Densification, Field chop, Logistics, Transportation.

Agriculture↗