Solid biofuel and biogas production from grassland-willow alley cropping systems

Poster

Worldwide the demand for renewable energy is rising and biogenic energy carriers play an important role in bioenergy provision. However, increase and intensification of biomass production for energetic use has already shown adverse impacts on agro-ecosystems (e.g., biodiversity losses, nitrate leaching, and erosion). Energy cropping and related conversion systems should be improved in terms of their efficiency and environmental impact in future. Modern agroforestry systems offer an alternative agro-ecological approach to a sustainable intensification of energy crop production. The present study was part of the joint research project “BEST – Strengthening Bioenergy Regions“ (2010?2014) and analyzed the energetic potential of a young alley cropping system of grassland and fast-growing willows grown on a 3 to 6 year rotation. The study was conducted on an experimental area in Central Germany from 2011–2013. Two different grassland mixtures were established in a split-plot randomized block design with three replications, and intercropped with rows of willows. The woody biomass was converted to wood chips for thermal combustion. For the grassland biomass, three types of energetic conversion were evaluated: integrated generation of solid fuel and biogas from biomass (IFBB), anaerobic digestion and hay combustion. Overall, the three year old agroforestry system achieved a total gross energy yield of 96 MWh ha-1 by applying the IFBB procedure to the understory biomass. Grassland as pure stand achieved 133 MWh ha-1 and a single willow stand achieved 51 MWh ha-1 in 3 years after establishment. In addition, this study investigated the yield development in the alley cropping system and in the pure stands as control during the establishment phase.