Woody Feedstocks 2021 State of Technology Report

Abstract

The U.S. Department of Energy promotes production of advanced liquid transportation fuels from lignocellulosic biomass by funding fundamental and applied research that advances the state of technology (SOT). As part of its involvement with this overall mission, Idaho National Laboratory completes annual SOT reports for nth-plant biomass feedstock logistics. The purpose of the SOTs is to provide the status of feedstock supply system technology development for biomass to biofuels, based on actual data and experimental results relative to technical targets and cost goals from specific design cases. Conventional feedstock supply systems need to be modified to meet the demands of conversion pathways, specifically to have the ability to adjust the quality of the materials. Advanced systems incorporate innovative methods of material handling, processing and supply chain configuration. In advanced designs, variability of the feedstock can be reduced to produce feedstocks of a uniform format, moving toward biomass commoditization. Against this backdrop, the 2021 Woody SOT for low-ash woody feedstocks utilizes feedstock fractionation by incorporating technologies that can separate the biomass by its fractions (wood, bark, needle, and extrinsic ash) to reduce impurities and attempt to maximize the retention of usable biomaterials that satisfy downstream quality considerations. By using a series of air classification steps the process is able to reduce the extrinsic ash in forest residues. The forest residues are then blended with clean-pine chips in a 50-50 mix to prepare the feedstock for the desired conversion pathway. The Nth plant analysis estimated the delivered cost for feedstock at $75.87 (2016$) which represents an increase of $8.84 compared to cost estimate for the 2020 Woody SOT supply system for the CFP pathway. However, the quality requirements in the 2021 Woody SOT for low-ash feedstocks was more stringent at =1.00 wt% ash compared to =1.75 wt% in the previous year. Similarly, the GHG emissions for the Nth plant analysis were estimated at 171.71 kgCO2e/dry ton, compared to 163.50 kgCO2e/dry ton in the 2020 Woody SOT, an increase of 8.21 kgCO2e/dry ton attributed to preprocessing. In the first plant analysis of the 2021 SOT system, the average throughput was approximately 2101 dry tons/day or 95.27% of the name plate capacity. During the simulation the daily throughput ranged from 1146 dry tons/day to 2163 dry tons/day, 51.97% to 98.10% of the daily nameplate capacity. After the year of operation 735,541 tons (101.45% of yearly nameplate) of processed feedstock were produced in total. The variability in throughput is primarily caused by equipment failures in the system. Extrinsic ash emerges as a pinch point for system performance as it contributes to a majority of equipment failures. Furthermore, steps undertaken to reduce the quantity of extrinsic ash in the feedstock face challenges, especially in the form of reduced efficiency of soil removal in air classification – which are exacerbated at higher levels of moisture in the incoming material. Failures due to wear was the largest cause of disruption within the system accounting for 52.78% of the failures and 36.21% of the total downtime. Ultimately the system was on stream for 90.98% during the simulation period. The production cost of the system averages $82.29/dry ton. The costs ranged from a minimum of $72.83/dry ton to a maximum of $727.38/dry ton. When losses are considered the costs increase to an average of $86.93/dry ton with a minimum of $77.18/dry ton and a maximum of $741.91. When compared to the ideal nth-plant cost, the average cost from the first plant analysis $11.06/dry ton greater than the n-th plant estimate. While the nth-plant analysis assumes a constant quality feedstock, the first plant analysis utilizes variability in the material to assess the impact. In the first plant analysis, it is assumed that any material that does not meet the base quality specifications of = 50.51 wt% carbon and = 1.0 wt% ash is discarded. From this simulation, only 76.72% of the material met the defined quality specification, requiring the disposal of 23.28% of the biomass. The material that is discarded due to quality, represents an additional cost that must be accounted for in the total cost of the material. When the cost is fully burdened considering system disruptions, material lost during operation, as well as material removed for quality considerations the average cost per ton of biomass was $113.28/dry ton, with a range from $103.59/dry ton to $767.83/dry ton. The resulting Overall Operating Effectiveness (OOE) for the system, from the simulation, was found to be 77.87%. A feedstock performance factor of 76.72% and a fully burdened cost that is $37.41/dry ton higher than the estimated n-th plant cost suggest that additional technology development is needed to further address the variability of quality within the feedstock and improvem