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Northeast Woody/Warm-season Biomass Consortium

Harvest, Preprocessing, and Logistics of Integrated Biomass Supply Chains

For perennial crop systems like willow, miscanthus and switchgrass, harvesting and transportation can account for 40–60% of the delivered cost of biomass.20,55,80 Preprocessing of biomass through drying, size reduction, storage and compaction can increase transportation efficiency, reduce delivered costs, and improve conversion efficiency.81 Reducing these costs associated with biomass logistics, including harvest and collection, processing, transportation, and storage unit operations, is key to establishing a commercially-viable, sustainable biorefinery. Partly because logistics costs associated with low density, and unstable, biomass is so high, much of the physically available supply is not available at delivered prices of $60-100/dry ton.

Task 3.1. Significantly reduce the harvesting cost per ton of biomass feedstocks from willow and perennial grasses in the NE (Wang, Volk, Liu, Searcy)

Case New Holland and SUNY ESF, with support from USDOE and NYSERDA, have developed a single pass cut and chip harvester based on a New Holland forage harvester. Preliminary ground speeds were around 2.5 km hr-1 with harvesting costs of around $40 per dry ton. Improvements in the specially designed harvesting head have increased ground speeds to about 6 km hr-1, reducing harvesting costs by almost 50%. The challenge now is to optimize the operation of the forage harvester with a collection and delivery system that allows it to operate at peak capacity while minimizing handling and costs. Detailed time motion and fuel use data will be collected from large scale harvesting operations undertaken by commercial partners and used to develop logistics supply chain models. A biomass feedstock logistics model55 (Tasks 1.1 and 3.4) will be used to optimize the harvesting and biomass collection and shared with commercial partners so that improvements can be incorporated into future harvesting operations and the effect of these changes will be measured and documented.  Improvements in efficiency of the feedstock harvest and supply chain are expected to reduce the delivered cost of the materials by 20% to 30%;19 which will result in greater supplies of reasonably priced cellulosic biomass for advanced biorefineries.

Task 3.2. Quantify the role of preprocessing for densification and storage on transportation efficiency and downstream fuel conversion (Boateng, Richard, Liu, Ciolkosz, Volk)

Torrefaction, pyrolysis, and hot-water extraction are preprocessing technologies that increase energy density with minimal loss of content, and are attractive for providing consistent feedstocks for further thermal conversion, but are relatively untested as a pretreatment for biochemical conversion.82 While recent evidence suggests that comparable sugar yields can be obtained from torrified biomass and that cellulose is less recalcitrant following hot water extraction, it is unclear what the impacts will be to downstream biochemical conversion processes. Quantitative metrics will be collected using well characterized and documented feedstocks and preprocessing parameters to relate conversion potential to preprocessing attributes and provide a basis for robust supply chain development.  We will select willow, switchgrass and miscanthus samples based on harvesting system and time of year to rapidly quantify the effects of constituents and particle size on product yield, quality, and efficiency using bench-scale processing equipment. A subset will be down-selected for a larger scale production of pellets, wood extracts, torrefied biomass, and pyrolysis oil samples for further characterization of resulting precursors of advanced biofuels expected to be produced in the large central biorefineries. Selected samples will be provided for test runs at pilot scale systems with commercial partners (Praxair, Primus Green Energy, Mascoma, Applied Biorefinery Science, TerraGreen). Effects of baling and bulk densification will also be tested at commercial-scale (Aloterra Energy, Ernst Conservation Seeds and Double A Willow), and data will be used to evaluate impacts on transportation and logistics.

Task 3.3. Assess the storage requirements and effects of long term storage on the quality of willow and perennial grasses (Volk, Richard)

Given the temporal nature of biomass feedstocks, the ability to store large quantities will be necessary to maintain constant supply to production facilities throughout the year.  Effective, cost efficient storage systems for lignocellulosic materials have not yet been developed, as storage for an extended period results in reduction of quality and loss of dry matter.83 Perennial grasses stored as “dry” bales wrapped in plastic can lose 4-15% dry matter outdoors in humid climates.84 Wet herbaceous biomass can be stored in silage systems with losses below 1%,84 but higher moisture affects transport and thermochemical conversion energy requirements and costs.55 Preliminary tests suggest that moist willow biomass chips harvested in the early spring can be stored in open piles for about 3-4 months without significant loss in energy content.85 While data are available for small scale systems, this study will collect quantitative data of feedstock quality as a result of storage during other times of the year, along with relative differences among types of preprocessing and season of harvest.  This information will be used to develop storage systems that will allow for the accumulation of the feedstock supply needed to maintain constant levels of biofuel production year round.

Task 3.4. Techno-economic Analysis, Cost Engineering, and Life Cycle Analysis of densification, storage, preprocessing, and biorefinery integration (Searcy, Wang, Boateng, McAloon, Spatari)

An integrated supply chain simulation model55 will be populated with data from Tasks 1.1, 3.1, 3.2 and 3.3 and used to simulate harvest and collection, transportation, preprocessing, and storage in integrated supply chains. Of particular interest in the NE is preprocessing at multiple satellite facilities in a hub-and-spokes model.86  Prior analysis by team members at DOE-INL and USDA-ARS, and independent scientists indicates satellite facilities that produce high energy-density biofuel precursors and intermediates, can provide the cost advantages of small-scale modular preprocessing combined with more dense, low volume transportation.82, 87-94 Cost engineering models for satellite preprocessing and storage will be developed and integrated with our comprehensive supply chain model to project impacts on both feedstock cost and biofuel yield.  Using these integrated models we will project the yield of both biofuel and co-products along with the economic cost and potential returns. 

Expected outputs and outcomes

Expected outputs and outcomes include:

NEWBio (consortium members below) is supported by Agriculture and Food Research Initiative Competitive Grant no. 2012-68005-19703 
from the USDA National Institute of Food and Agriculture.
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