Thermal gasification in dual fluidized bed systems is an efficient method to generate electricity and heat from biomass and to reduce greenhouse gas emissions. High operating costs due to the utilization of the catalytically active bed material olivine and high disposal costs for the ash due to the fact that olivine contains heavy metals have a negative impact on the economic operation of these plants.
This project aims to replace the bed material by an alternative, heavy metal free mineral which has catalytic activities at least in interaction with the biomass ash or additives.
Changing the bed material to a heavy metal free one enables the possibility to remove nutrient rich biomass ash early in the process as BioChar and to close the natural nutrient circle by using this BioChar as a fertilizer. Based on that process change low melting ash species are not in intensive contact with temperatures up to 900°C in the combustion reactor like nowadays which reduces the risk for fouling and agglomeration. As a consequence fuels with worse ash melting properties can be used. The ash after the combustion reactor can be aimed to be used as a fertilizer.
Within this project an alternative bed material should be found and tested in different pilot plant scales. A better understanding of ash related behaviour in dual fluid gasification systems should be gathered. The performance of low quality fuel should be tested by using chicken litter as an example.
Char-rich and nutrient rich biomass ash should be evaluated on the utilization as BioChar as a fertilizer. The economic efficiency for industrial scale plants considering the changes in operation, raw materials and products should be evaluated. An economic evaluation