Theoretical and observed biogas production from plant biomass of different fibre contents.

The methane productivity of silage of four crop species -Zeamays L., Sorghumsaccharatum, Miscanthusxgiganteus and Miscanthussacchariflorus - was investigated. The experiments revealed that at a hydraulic retention time of 60days the volumetric methane yields from the Z.mays L. or S.saccharatum silages were higher than those from the Miscanthusxgiganteus or M.sacchariflorus silages because of the higher crude fibre content in Miscanthus spp. However, at comparable lignin concentrations in the feedstock, methane productivity for M.sacchariflorus (0.19+/-0.08L/g volatile solids) was twice that of Miscanthusxgiganteus (0.10+/-0.03L/g volatile solids). The efficiency of cellulose conversion varied from 83.6% (S. saccharatum) to 52.1% (Miscanthusxgiganteus), and hemicellulose from 88.9% (Z. mays L.) to 59.7% (Miscanthusxgiganteus). Conversion of cellulose and hemicellulose depended on the ratio of these polysaccharides to the lignin concentration of the feedstock. Copyright (c) 2010 Elsevier Ltd. All rights reserved.