Steam explosion pretreatment for enhancing biogas production of Alpine hay

Growing grassland biomass in an extensive way and its subsequent transformation into hay for a further utilization in a biogas-based biorefinery concept could be a solution to increase incomes and maintain the grassland area. In this way, gassland can be promising biomass sources for decentralized energy generation. Efficient biogas production from this lignocellulosic biomass requires a pretreatment step. One of the most efficient pretreatment methods for lignocellulosic materials is steam explosion. The main objective of this work was to evaluate the effect of temperature and time that steam explosion pretreatment has on the biogas production and physico-chemical characteristics of Alpine hay. Results from scanning electron microscopy (SEM) images of the pretreated biomass indicated that steam explosion induced significant morphological changes. Steam explosion increased the methane yield up to 276 lN kg−1 VS, representing a rise of 14 % when compared to untreated hay. The outcomes indicate that hay can be effectively converted to methane after steam explosion pretreatment and its utilization could be a key strategy to obtain economical incomes that allow maintaining grasslands in Alpine regions. However, further attempts in optimizing the pretreatment process should be made since the efficiency of the total process can be improved significantly.