Dual production of biofuels and chemicals can increase the economic value of lignocellulosic bioenergy feedstocks. We compared the bioenergy potential of several essential oil (EO) crops with switchgrass ( Panicum virgatum L.), a crop chosen to benchmark biomass and lignocellulosic biofuel production. The EO crops of interest were peppermint ( Mentha × piperita L.), "Scotch" spearmint ( Mentha × gracilis Sole), Japanese cornmint ( Mentha canadensis L.), and sweet sagewort ( Artemisia annua L.). We also assessed each crop for EO production in a marginal production environment in Wyoming, USA, with irrigation and nitrogen (N) rates using a split-plot experimental design. Oil content ranged from 0.31 to 0.4% for Japanese cornmint, 0.23 to 0.26% for peppermint, 0.38 to 0.5% for spearmint, and the overall mean of sweet sagewort was 0.34%. Oil yields ranged from (in kg ha-1) 34 to 165 in Japanese cornmint, 25 to 108 in peppermint, 29.3 to 126 in spearmint, and 39.7 in sweet sagewort. EO production, but not composition, was sensitive to N fertilization. The alternative bioenergy crops and switchgrass produced similar amounts of ethanol from bench-scale simultaneous saccharification and fermentation assays. Value-added incomes from the EO proceeds were estimated to be between $1055 and $5132 ha-1 from peppermint, $1309 and $5580 ha-1 from spearmint, $510 and $2460 ha-1 from Japanese cornmint, and $3613 ha-1 from sweet sagewort under Wyoming growth conditions. The advantage of the proposed crops over traditional lignocellulosic species is the production of high-value natural products in addition to lignocellulosic biofuel production.
Keywords: Artemisia annua; Mentha canadensis; Mentha × gracilis; Mentha × piperita; Panicum virgatum; bioproducts; essential oils; ethanol.