New Publication – Case story: Deep bedding: a co-digestion substrate with significant potential (Denmark)
This case story, developed within the framework of IEA Bioenergy Task 37 (biogas), describes the Danish experience with handling and feeding deep bedding to biogas plants.
In Denmark, about one-third of all dry matter in livestock manure is contained in deep bedding. Over the last decade, most Danish biogas plants added deep litter to their codigestion substrates. This not only increased the biogas production, but also brought about environmental and agro-economic benefits. Mono-digestion of animal slurries can yield 15-25 Nm3 biogas / t biomass, depending on quality. However biogas plants need 35-45 Nm3 biogas / t to allow a financially sustainable facility. In a situation with shortage of biomass and high gate fees for industrial high yielding biomethane wastes, co-digestion of deep litter is an obvious solution. Economic, environmental, and agricultural benefits are also achieved through better fertiliser quality. Compared to untreated deep bedding, digested deep bedding is easier and cheaper to apply and incorporate in soil, and with a higher nitrogen utilisation efficiency.