StrawSilage – Ensiling as combined pretreatment and storage of straw for biogas production

The aim of the project is to develop a biological pretreatment technology for straw for biogas production, based on ensiling of wet straw in bales that are stacked and wrapped. Ensiling of straw is expected to give a higher methane yield from straw and to reduce the tendency of straw to form a floating layer and be difficult to pump and stir in the biogas reactor. Also, the aim is to increase the value of moist second-class straw and to enable baling of straw also during periods with moist conditions.

The project will investigate the effect of water content, ensiling additives, ensiling duration etc. on biogas production. Technical solutions for baling and wrapping of wet straw will be developed and tested in pilot-scale and large-scale.

The concept will support slurry-based biogas production in Denmark by making the straw resource utilizable as supplementary biomass in biogas plants. This will have positive climate effect by reducing methane emission from slurry and increase overall energy production from slurry and straw. Finally, it will have positive economic impact for biogas plants, straw producers, contractors, transport companies etc. in the chain from field to biogas plant.