Switchgrass and Giant Miscanthus Biomass and Theoretical Ethanol Production from Reclaimed Mine Lands

Abstract

Switchgrass (Panicum virgatum L.) and giant miscanthus (Miscanthus x giganteus Greef & Deuter ex Hodkinson & Renvoize) are productive on marginal lands in the eastern USA, but their productivity and composition have not been compared on mine lands. Our objectives were to compare biomass production, composition, and theoretical ethanol yield (TEY) and production (TEP) of these grasses on a reclaimed mined site. Following 25 years of herbaceous cover, vegetation was killed and plots of switchgrass cultivars Kanlow and BoMaster and miscanthus lines Illinois and MBX-002 were planted in five replications. Annual switchgrass and miscanthus yields averaged 5.8 and 8.9 Mg dry matter ha, respectively, during 2011 to 2015. Cell wall carbohydrate composition was analyzed via near-infrared reflectance spectroscopy with models based on switchgrass or mixed herbaceous samples including switchgrass and miscanthus. Concentrations were higher for glucan and lower for xylan in miscanthus than in switchgrass but TEY did not differ (453 and 450 L Mg , respectively). In response to biomass production, total ethanol production was greater for miscanthus than for switchgrass (5594 vs 3699 L ha ). Relative to the mixed feedstocks model, the switchgrass model slightly underpredicted glucan and slightly overpredicted xylan concentrations. Estimated TEY was slightly lower from the switchgrass model but both models distinguished genotype, year, and interaction effects similarly. Biomass productivity and TEP were similar to those from agricultural sites with marginal soils.Keywords Cellulosic bioenergy feedstock . Mine reclamation . Near-infrared reflectance spectroscopy . Theoretical ethanol production . Theoretical ethanol yield Abbreviations ADLAcid detergent lignin ARA Arabinan GAL Galactan GLC1

Miscanthus x giganteus Stem Versus Leaf-Derived Lignins Differing in Monolignol Ratio and Linkage

“…In literature, carbohydrate contents vary in the range of 40 to 50 wt % for Miscanthus x giganteus genotypes, mainly consisting of glucan and xylan [70]. Other sugars, i.e., arabinan, mannan, and galactan are usually below 2%, which was very recently reported by Scaglione-Mellor for different Miscanthus genotypes [71]. No significant differences were found for the total lignin content for leaf and stem-derived biomasses.…”

Miscanthus x giganteus Stem versus Leaf-derived Lignins Differing in Monolignol Ratio and Linkage

“…In literature, carbohydrate contents vary in the range of 40 to 50 wt.% for Miscanthus x giganteus genotypes, mainly consisting of glucan and xylan [70]. Other sugars, i.e., arabinan, mannan and galactan are usually below 2 %, very recently reported by Scaglione-Mellor for different Miscanthus genotypes [71]. No significant differences were found for the total lignin content for leaf and stemderived biomasses.…”

Comparing chemical composition and lignin structure of Miscanthus x giganteus and Miscanthus nagara harvested in autumn and spring and separated into stems and leaves

“…Hemicellulose has been determined to mostly consist of xylan with minor contents of arabinan, which was also observed in previous studies for M. x giganteus genotypes. 13,14,61 The content of both hemicellulose monomers were higher in leaves than in stems.…”

“…11 Potential applications of Miscanthus plants include renewable energy as well as the production of fuel and chemicals. [12][13][14] Recent studies include the investigation of cascade utilization of Miscanthus crops analogous to procedures reported for fruits. 15 In difference to wood, grass-derived lignins show a signicant amount of H units which is interesting for future applications.…”