Use of Wild Plant Species: A Potential for Methane Production in Biogas Plants

Abstract

Sources of the input biomass for biogas plant (BGP) are very often communal biological wastes, farm materials such as slurry, dung or biomass of purposefully grown plants. Efforts aiming to support biogas yield from grass biomass with using additionally sown wild species can affect efficiency of the whole production process and improve its environmental impact. This was why 14 wild plant species were selected as a potential source of biomass for BGP: Trifolium alpestre L.; Trifolium rubens L.; Galega orientalis Lamb.; Medicago sativa L.; Onobrychis viciifolia Scop.; Vicia sylvatica L.; Astragalus cicer L.; Trifolium pannonicum Jacq.; Lathyrus pratensis L.; Melilotus alba Medic.; Trigonella foenum-graecum L.; Lathyrus sylverstris L.; Securigera varia L. and Dorycnium germanicum (Gremli) Rikli. The potential of individual crops for being used in BGP was evaluated based on calculating a theoretical methane yield (TMY). The calculated TMY values ranged from 0.130 m 3 /kg VS to 0.182 m 3 /kg VS . The demonstrably lowest (p<0.05) value of TMY was calculated for Medicago sativa L., which showed the lowest content of lipids and the highest content of ADF. By contrast, the highest TMY was recorded in Securigera varia L., which exhibited the highest content of carbohydrates and starch and the lowest content of ADF and NDF. An analysis of the biomass of grown species as well as the TMY calculation demonstrated significant differences between the respective plant species and a need to study in details the characteristics of wild plant species prior to their use for the production of biomass for BGP.