Erhalt ökologisch wertvoller Grünlandstandorte durch eine Integrierte Festbrennstoff- und Biogasproduktion aus Biomasse (IFBB-Verfahren)

Summary

As a new utilisation concept for the conservation of ecologically valuable habitats the
integrated generation of solid fuel and biogas from biomass (IFBB) was tested on five
semi-natural grasslands from typical German mountain areas. Through hydrothermal
conditioning and mechanical dehydration grassland silage was separated into a press
cake and a press fluid. In anaerobic digestion experiments with press fluids methane
yields of 304 to 522 normal litre per kg organic dry matter were obtained within 13
days. The specific methane production was higher and went faster compared to the
fermentation of the untreated grassland silage. Elemental analyses of the press cakes
showed a significant reduction in compounds detrimental for combustion. The ash
softening temperature and the lower heating value of the press cakes increased
compared to the parent material. The conditioning at high temperatures (60°C and
80°C) showed the best effects for a qualitative improvement of the press fluid as
fermentation substrate and the press cake as solid fuel compared to the untreated
grassland silage. The energy conversion efficiency of the IFBB procedure (52-62%)
was higher compared to a conventional digestion of the whole crop silage (26%). In
view of the results, the IFBB procedure is a promising utilisation alternative for areas
managed under nature conservation standards, whose biomass is difficult to exploit.