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sensitivity analysis

ABSTRACT. Adding bioenergy to the U.S. energy portfolio requires long‐term profitability for bioenergy producers and long‐term protection of affected ecosystems. In this study, we present steps along the path toward evaluating both sides of the sustainability equation (production and environmental) for switchgrass (Panicum virgatum) using the Soil and Water Assessment Tool (SWAT). We modeled production of switchgrass and river flow using SWAT for current landscapes at a regional scale. To quantify feedstock production, we compared lowland switchgrass yields simulated by SWAT with estimates from a model based on empirical data for the eastern U.S. The two produced similar geographic patterns. Average yields reported in field trials tended to be higher than average SWAT‐predicted yields, which may nevertheless be more
representative of production‐scale yields. As a preliminary step toward quantifying bioenergy‐related changes in water quality, we evaluated flow predictions by the SWAT model for the Arkansas‐White‐Red river basin. We compared monthly SWAT flow predictions to USGS measurements from 86 subbasins across the region. Although agreement was good, we conducted an analysis of residuals (functional validation) seeking patterns to guide future model improvements. The analysis indicated that differences between SWAT flow predictions and field data increased in downstream subbasins and in subbasins with higher percentage of water. Together, these analyses have moved us closer to our ultimate goal of identifying areas with high economic and environmental potential for sustainable feedstock production.

Contact Phone
Publication Year
Contact Email
baskaranl@ornl.gov
Contact Person
Latha Baskaran
Contact Organization
Center for BioEnergy Sustainability, Oak Ridge National Laboratory
Bioenergy Category
Author(s)
Latha Baskaran

Abstract: Farmgate prices (i.e. price delivered roadside ready for loading and transport) for biomass feedstocks directly infl uence biofuel prices. Using the latest available data, marginal (i.e. price for the last ton) farmgate prices of $51, $63, and $67 dry ton–1 ($2011) are projected as necessary to provide 21 billion gallons of biofuels from about 250 million dry tons of terrestrial feedstocks in 2022 under price-run deterministic, demand-run deterministic, and stochastic simulations, respectively. Sources of uncertainty in these feedstock supply and price projections include conversion effi ciency, global market impacts on crop price projections, crop yields, no-till adoption, and climate. Under a set of low, high, and reference assumptions, these variables introduce an average of +/– $11 dry ton-1 (~15%) uncertainty of feedstock prices needed to meet EISA targets of 21 billion gallons of biofuels produced with 250 million dry tons of biomass in 2022. Market uncertainty justifi es the need for fairly frequent (i.e. annual or biennial) re-assessment of feedstock price projections to inform strategies toward commercialization of biofuels. Published in 2014 by John Wiley & Sons, Ltd

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Provided that you give appropriate acknowledgement to the Journal, Association/Society and the publisher, and give full bibliographic reference for the Article, and as long as you do not sell or reproduce the Article or any part of it for commercial purpo
Publication Year
Contact Person
Matthew Langholtz
Contact Organization
ORNL
Bioenergy Category
Author(s)
Matthew Langholtz , Laurence Eaton , Anthony Turhollow , Michael Hilliard
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