Bioenergy potential of fast-growing trees, perennial grasses, and agricultural residues for renewable natural gas production in Canada

This study presents a comprehensive evaluation of fourteen lignocellulosic biomass feedstocks—including fast-growing trees (FGT: poplar, willow), perennial grasses (PG: switchgrass, miscanthus, phragmites), and agricultural residues (AR: hemp and canola straw)—to assess their potential for biogas production. Proximate and elemental analysis (C, H, N, S), fiber composition (cellulose, hemicellulose, lignin), and energy values were determined to characterize biodegradability and energy potential. FGT species exhibited high fixed carbon and energy density (up to 19.9 MJ/kg), favoring thermochemical conversion but having low biogas yield due to elevated lignin content. In contrast, PG and AR showed higher volatile solids and cellulose content, enhancing anaerobic digestion. Hemp straw exhibited the highest renewable natural gas yield (163.8 ± 25.8 m 3 tonne/TS), while several PG species, including switchgrass (148.0 ± 17.5 m 3 tonne/TS), and miscanthus (143.4 ± 16.4 m 3 tonne/TS) also demonstrated high yields. In contrast, canola straw showed comparatively moderate performance (78.9 ± 5.9 m 3 tonne/TS). A 10% NaOH pre-treatment at room temperature significantly improved digestibility, with post-treatment biomass yields of canola straw (64.3 wt%), hemp straw (62.4 wt%), and willow (60.9 wt%) showing the highest treatment efficiencies. Supporting metrics such as total solids reduction, volatile solids degradation, and pH stability confirmed digestion performance. Statistical analysis identified cellulose as a key predictor of biogas and renewable natural gas yields, exhibiting a moderate positive correlation (r = 0.60), strong explanatory power (R 2 > 0.65), and acceptable prediction accuracy (RMSE = 7.2; p < 0.05). In contrast, lignin exhibited a negative influence on digestibility. These findings highlight the importance of biomass composition and pre-treatment strategy in optimizing methane yield and support targeted feedstock selection for sustainable bioenergy development in Canada and beyond.