Integrated Feedstock Supply Systems for Corn Stover Biomass

Tasks

Task 1: Design and evaluate innovative harvest and fractionation technologies to collect high quality stover feedstock.  The focus of this effort will be developing new single-pass grain and stover harvest systems, with existing multi-pass systems evaluated for comparative purposes.  Design and evaluation criteria will include power requirements, stover harvest productivity, effect on grain harvest productivity, selectivity of stover constituents (stalk, leaves, cob), stover physical properties, improving and optimizing shipping density and efficiency, and ensilability as affected by changing physical and chemical properties as the harvest season progresses.  Changes in stover properties during senescence over the course of a harvest season are of particular interest – their impact on storage will be evaluated in Task 2.  Forage moisture sensors will be modified to measure stover moisture in real time during harvest.  Fractionation technologies will be evaluated in the laboratory to determine recoverability and develop next-generation harvest and post-storage processing strategies.  To facilitate next-generation design of corn stover harvesting equipment, stover physical properties and fractionation characteristics will be evaluated in various equipment configurations using virtual engineering computational tools.

Task 2: Develop and optimize technologies for high-volume, cost-effective stover storage.  Building on the harvest technologies evaluated in Task 1, this task will emphasize ensiled wet storage systems, but will also evaluate dry storage to permit comprehensive system analysis.  Bench- and full-scale tests will examine storage impacts on dry matter retention and subsequent densification.  Ensilage amendments will be investigated to provide concurrent pretreatment, enhancing cellulose and hemicellulose hydrolysis and resulting sugar and organic acid accumulation.  Trials in years 2 and 3 will examine improved corn genetic lines identified and developed in Tasks 3 and 4 and produced under a range of soil, climate, and harvest conditions.

Task 3: Identify and characterize corn varieties with beneficial traits for biobased industries.  This comprehensive evaluation will survey a broad spectrum of corn varieties during the initial 9 months of the project.  Varieties with promising characteristics will be grown out in quantities suitable for field-scale evaluation using the harvest and storage technologies developed in Tasks 1 and 2.  Subsequent characterization will be focused on the breeding program described in Task 4. Analytical methods including NIR and a new molecular assay will also be used to evaluate post-storage feedstock properties.

Task 4: Implement a breeding program to enhance stover properties.  Corn varieties identified in Task 3 will be used as foundation germplasm to initiate a breeding program to select for the desired physiological and biochemical properties of the plant. The breeding program can draw heavily on work done in corn silage breeding, where the stover requirements for animal feed are similar to stover requirements needed to use corn as a feedstock for bioconversion processes. There is also a need to study the physiological relationship between stover yield, stover quality, and grain yield to determine if there will be significant reductions in grain yield with increase in stover yield and quality.

Task 5: Evaluate the economic impacts of feedstock supply scenarios.  Analysis of production, harvest, storage and transportation costs will provide the basis for a comprehensive evaluation of the economic implications of alternative stover feedstock scenarios at regional and national scales.  Annual iterations will update and improve this analysis based on evolving scenarios from Task 7.

Task 6:  Life-cycle assessment of corn stover feedstock scenarios. Environmental impacts will be evaluated using a life-cycle assessment approach, adding energy, nutrients, organic matter, and erosion to the economic considerations analyzed in task 5.  Annual iterations will update and improve this analysis based on evolving scenarios from Task 7.

Task 7: Define and refine integrated, sustainable stover feedstock development systems. This task provides a mechanism for explicit feedback between improvements in harvest and storage technologies, variety performance, and overall system performance in terms of economic and environmental outcomes.  Initially, a range of alternative stover feedstock supply scenarios will be developed to define technology and plant science goals for Tasks 1-4, as well as context for the impact analysis in Tasks 5 and 6.  These scenarios will be reassessed and refined annually based on advances in the other tasks.

Task 8:  Develop an interactive web-based corn stover biomass planning tool.  This decision support freeware will allow on-farm assessment of the costs and benefits of biomass harvest.  Technology assessment models developed in Tasks 5-7 will allow producers to evaluate combinations of varieties, harvest, and storage technologies with respect to both input requirements and economic return. This software, built on the I-FARM platform (van Ouwerkerk 2003, http://i-farmtools.org), will also calculate field-specific sustainable biomass removal rates based on erosion and organic matter criteria for different crop rotation strategies. See also the technical approach/work plan.

Task 9:  Coordinate project team members, facilitate project advisory committee, and prepare reports.  Monthly project conference calls will include all principal investigators and participating staff and graduate students.  A technical advisory committee of technical specialists and industrial partners will meet annually with the project team to review progress and refine future directions. Administrative staff from ISU’s Center for Sustainable Environmental Technologies will assist with project financial accounting and technical reporting.