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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.

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From harvesting to consumption of the faba bean (Vicia faba), different plant residues such as stems, leaves, pods, and seed husks remain as by-products. The harvest residues constitute about 50% (w/w) of the whole aboveground biomass, while the empty pods and the seed husks account for 11% and 6% (w/w) on average, respectively. Due to the environmental and dietary benefits, the global production of faba beans is most likely to increase in the future. Concomitantly, the amounts of by-products will rise as well. So far, mainly the harvest residues have been widely studied, whereas the pods and husks have received less consideration. Therefore, the aim of this review was to provide an overview of the composition of the faba bean plant residues and to illustrate their potential of being used as feedstock in food, feed, or even non-food applications. This literature survey clearly reveals that all the residual materials of faba beans contain valuable compounds and might be suitable for a multitude of different applications. The residual material should thus not be disposed of but further valorized in order to exploit the full potential of the biomass.

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