초록
<P>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 (<I>Panicum virgatum</I> L.), a crop chosen to benchmark biomass and lignocellulosic biofuel production. The EO crops of interest were peppermint (<I>Mentha</I> × <I>piperita</I> L.), “Scotch” spearmint (<I>Mentha</I> × <I>gracilis</I> Sole), Japanese cornmint (<I>Mentha canadensis</I> L.), and sweet sagewort (<I>Artemisia annua</I> 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<SUP>-1</SUP>) 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<SUP>-1</SUP> from peppermint, $1309 and $5580 ha<SUP>-1</SUP> from spearmint, $510 and $2460 ha<SUP>-1</SUP> from Japanese cornmint, and $3613 ha<SUP>-1</SUP> 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.</P><BR>[FIG OMISSION]</BR>