Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 4/12/2011
Publication Date: 10/16/2011
Citation: Schmer, M.R., Vogel, K.P., Mitchell, R., Dien, B.S., Jung, H.G., Casler, M.D. 2011. Temporal and spatial variation in switchgrass biomass composition and theoretical ethanol recovery [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts. Abstract No. 64434. Available: http://a-c-s.confex.com/crops/2011am/webprogram/Paper64434.html. Interpretive Summary:
Technical Abstract: Information on temporal and spatial variation in switchgrass (Panicum virgatum L.) biomass composition as it affects ethanol recovery (L Mg-1) at a biorefinery and ethanol production (L ha-1) at the field scale has previously not been available. Switchgrass biomass samples were collected from a regional, on-farm trial and biomass composition and ethanol recovery was quantified using newly developed near-infrared reflectance spectroscopy (NIRS) prediction equations. Total hexose (cell wall carbohydrates and soluble sugars) concentration means ranged from 342 g kg-1 to 398 g kg-1 while pentose (arabinose and xylose) concentration means ranged from 216 g kg-1 to 245 g kg-1 across fields. Theoretical ethanol recovery rates varied significantly by year and field, with 5 yr means ranging from 381 L Mg-1 to 430 L Mg-1. Total theoretical ethanol production ranged from 1749 L ha-1 to 3691 L ha-1 across fields. Variability (coefficient of variation) within established switchgrass fields ranged from 1% to 4% for theoretical ethanol yield recovery (L Mg-1) and 14% to 38% for theoretical ethanol production (L ha-1). Most fields showed a lack of spatial persistence across harvest years for theoretical ethanol recovery rates or total theoretical ethanol production values. Switchgrass biomass composition from farmer fields can be expected to have significant yearly and field-to-field variation in a production region and this variation will significantly affect ethanol or other liquid fuel yields per ton or hectare. Biorefineries will need to assay biomass for quality to optimize conversion efficiency. Research to develop improved biomass cultivars and management practices that stabilize and increase biofuel recovery and production will be essential for an emerging cellulosic biofuel industry.