Switchgrass Biofuel Production on Reclaimed Surface Mines: II. Feedstock Quality and Theoretical Ethanol Production

Abstract

Switchgrass (Panicum virgatum L.), a warmseason perennial grass, is an important bioenergy crop candidate because it produces high biomass yields on marginal lands and on reclaimed surface mined sites. In companion studies, dry matter (DM) yields for Cave-inRock, Shawnee, and Carthage cultivars varied from 4.2 to 13.0 Mg ha −1 averaged over 6 years at the reclaimed Hampshire site, and fertilization increased yields of Cave-in-Rock at Black Castle and Coal Mac sites from 0.3 to 2 Mg ha −1 during the first 3 years. The objective of these experiments was to compare the impacts of cultivar and soil amendments on biomass quality and theoretical ethanol production of switchgrass grown on surface mines with differing soil characteristics. Biomass quality was determined for fiber, ash, lignin, digestibility, and carbohydrate contents via near-infrared reflectance spectroscopy, and carbohydrates were used to calculate theoretical ethanol yield (TEY; L Mg −1 ) and multiplied by biomass yield to calculate theoretical ethanol production (TEP; L ha −1 ). Cultivars at the Hampshire site did not differ in TEY and ranged from 426 to 457 L Mg −1 . Theoretical ethanol production from Cave-in-Rock at Hampshire was 7350 L ha −1 , which was higher than other cultivars because of its greater biomass production. This TEP was higher than in other studies which predicted 4000 to 5000 L ha −1 . At the Black Castle and Coal Mac sites, fertilizer applications slightly affected biomass quality of switchgrass and TEY, but provided greater TEP as a function of increased yield. Similar to other findings, total switchgrass biomass production has more impact than compositional differences on TEP, so maximizing biomass production is critical for maximizing potential biofuel production. With appropriate soil substrates, fertilization, planning, and management, large areas of reclaimed surface mines can be converted to switchgrass stands to produce high biomass quality and yields to support a bioethanol industry.

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

“…Switchgrass glucan and xylan values were higher than those in Schmer et al [11] and Vogel et al [29], and similar to those in Dien et al [43,60] and Adler et al [56], with approximately the same proportions as in the present study in all cases. Switchgrass cultivars did not differ in cell wall polysaccharide levels except for GAL and MAN, consistent with findings by Brown et al [64] of only a few differences in cell wall carbohydrate levels among Cave-InRock, Carthage, and Shawnee switchgrass. Illinois and MBX-002 miscanthus also showed differences in GAL and MAN.…”

“…Brown et al [64] compared NIRS-predicted composition of Cave-In-Rock, Carthage, and Shawnee switchgrass biomass grown on mine [29] reported NIRS-predicted values of 5.8% for ASH1 and 73.7% for aNDF for Kanlow switchgrass. No published information is available for ash, lignin, and aNDF concentrations of miscanthus grown on mined lands.…”

Pyrolysis of dedicated bioenergy crops grown on reclaimed mine land in West Virginia

“…While theoretical estimation of ethanol production from switchgrass grown on reclaimed mine lands has been carried out [24], there is no report on the pyrolysis of biomass resources grown on reclaimed mine lands in West Virginia. Therefore, the objective of this study was to compare pyrolysis product distribution and characteristics of selected dedicated energy crops cultivated on reclaimed mine lands of West Virginia.…”

Enhanced Growth Performance and Salinity Tolerance in Transgenic Switchgrass via Overexpressing Vacuolar Na+ (K+)/H+ Antiporter Gene (PvNHX1)

“…Switchgrass ( Panicum virgatum L.), a perennial C4 warm-season grass belonging to the Poaceae , has been increasingly recognized as a dedicated bioenergy crop for its agricultural, industrial, and ecological advantages (Brown et al, 2015). Nowadays the cultivations within the marginal land are concerned, screening varieties of high resistance especially the salt resistance will be of great significance.…”