How well does Miscanthus ensile for use in an anaerobic digestion plant?

This study examined the ability for early-harvested Miscanthus (Miscanthus x giganteus and Miscanthus sacchariflorus) to be stored in silage for later use in anaerobic digestion. Two silage additives favouring a homo and hetero-fermentation pathway were examined. The results show that silage additives are necessary to effectively ensile Miscanthus, otherwise untreated Miscanthus grasses incurred dry matter losses of 4% during three months’ storage. The silage additives improved the lactic and acetic acid production in the Miscanthus silages however did not have any effect on the biogas yield. On a ‘per tonne volatile solids’-basis, Miscanthus produces half the biogas yield of maize. The outlook for the use of Miscanthus AD therefore depends on the yield when harvested in autumn. A minimum yield of 19–26.5 t DM/ha is needed for Miscanthus to match the biogas production from a similar area of maize yielding 10–14 t DM/ha.