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United States Department of Agriculture

Agricultural Research Service

Research Project: Novel Technologies for Field Fractionation, Harvesting and Storage of Perennial Bioenergy Crops Project Number: 3655-41000-006-02
Project Type: Specific Cooperative Agreement

Start Date: Sep 02, 2008
End Date: Sep 01, 2013

Objective:
Our overall goal is to develop a productive, efficient, and sustainable biomass feedstock supply system using perennial grasses and legumes as a primary feedstock. This project addresses critical needs for feedstock development using perennial grasses and legumes by developing innovative ways to fractionally harvest and store these feedstocks. Specific objectives are: 1) design and fabricate new harvesting mechanisms to separate the high-protein and high-fiber fractions from these crops at harvest; 2) quantify the machine's field performance using a controlled set of operating variables; 3) use this information to improve the mechanisms through re-design during the off-season; and 4) collaborate to develop on-farm storage and pretreatment systems to preserve and add value to both the high-protein and high-fiber fractions. Additional objectives in the extended project include: 5) determine storage characteristics of switchgrass & reed canarygrass stored under anaerobic conditions in bunker & bag silos at different moisture contents; 6) quantify packing density, porosity & temperature profile of biomass materials during storage; 7) determine aerobic stability of stored feedstocks; 8) assess composition & bioconversion potential of feedstocks before & after storage under various conditions; & 9) estimate storage costs under different conditions, taking into account storage losses & changes in quality, as well as bioconversion potential of the stored material.

Approach:
Design and fabricate equipment for field-fractionation of bioenergy crops during harvest. Test equipment on established fields of alfalfa, switchgrass, and reed canarygrass. Determine yield and quality of fractions obtained, along with power requirements and operating costs. Improve design of equipment to improve performance, reliability, and operating costs. Store harvested materials under different conditions, and determine dry matter losses and quality changes resulting from storage under these methods. We will also compare the yield and quality of switchgrass and reed canarygrass when stored at different moisture levels in either bag silos (a widely adopted storage technology) or in bunker silos (a potentially lower-cost method that does not generate plastic waste). Conventional measures of silage preparation (packing density, porosity, temperature profiles) will be combined with measures of microbial conversion in the silo (fermentation acid production), and of subsequent bioconversion potential of feedstock after storage to fuels and fuel precursors. Because exposure of anaerobically stored feedstocks to air can cause undesirable spoilage by microorganisms, we will conduct aerobic stability tests to determine if storage method affects the rate and extent of feedstock spoilage, and if different microbial agents are responsible for spoilage of different feedstocks stored under different conditions. We will estimate costs of storage of each feedstock that will take into account the dry matter losses and quality change of each feedstock during storage, and the bioconversion potential after storage.

Last Modified: 9/23/2014
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