Valorization of landscape management grass

The aim of this review was to investigate and develop possible material and energetic utilization strategies for grass from nature conservation areas, which is harvested late in the year and currently largely unused. Compared to freshly harvested grass, it contains less proteins and higher contents of fibers. Landscape management grass has therefore poor forage quality and is not suitable as animal feed. Due to its high calorific value, grass biomass can be used as a material for combustion. However, combustion technology must be adapted to the high contents of inorganics. Fresh grass is a widely used feedstock in biogas plants; late-harvested grass however shows lower biogas yields. The integrated generation of solid fuel and biogas represents a promising combination of combustion and digestion. Grass biomass can also be used in a green biorefinery (GBR) or a lignocellulose biorefinery (LCB). A GBR uses fresh green biomass, producing a protein concentrate (recovery of 30–60%, w/w) and a fiber fraction (recovery of up to 95%, w/w). It is supposed that late-harvested grass is less suitable due to low contents of exploitable components. An LCB operates on dry lignocellulosic feedstock and produces a wide range of carbohydrate products. To date, no LCB or GBR operating on late-harvested grass from semi-natural grasslands was described, and further research on the practical implementation is needed.