Chemical composition and bioethanol potential of different plant species found in Pacific Northwest conservation buffers

Abstract

Lands producing mixed lignocellulosic ethanol feedstocks may be able to produce more biomass with fewer resources than conventional monoculture crops, but lignocellulosic ethanol production processes and efficiencies can be highly dependent on feedstock composition. In this study, plants were collected from areas planted to simulate conservation buffers alongside stream channels within three common resource areas the interior Pacific Northwest. Two grasses (tall wheatgrass and alfalfa) and seven forb species (fiddleneck tarweed, dog fennel, kochia, downey brome, tall annual willowherb, prickly lettuce, and tumble mustard) commonly found in these buffers were examined to determine their chemical composition, potential bioethanol yields, and difficulties that may arise if they were to be harvested and processed in a single facility. Potential ethanol yields calculated on the basis of sugar monomer composition in the biomass ranged from 181.5 to 316.5 l/dry ton of biomass. Significant differences were noted in terms of structural sugars (cellulose 19%–33% w/w; hemicellulose 14%–26% w/w), lignin (10%–18% w/w), extractives (20%–40% w/w), and ash content (4.0%–13.8% w/w). These composition variations could vary the processing efficiency in terms of sugar recovery and eventual ethanol production yield.