Hybrid solar gasification of biomass in a dual fluidized bed reactor for the polygeneration of liquid fuels and electricity

Abstract

A biomass-to-liquids (BTL) polygeneration process with a solar hybridized, atmospheric pressure dual fluidized bed (DFB) gasifier is investigated. The energetic and environmental performance of this process is investigated as a function of the input solar ratio, the assumed carbon conversion in the gasification reactor, and, for various solar input strategies. It was found that solar input strategy has only a small effect on the performance of the solar hybridized BTL process. With the increase of solar ratio from 0 to 1, for an assumed carbon conversion of 73.3%, the overall efficiency and specific Fischer-Tropsch (FT) liquids output increase by 1.7% and 2.6%, respectively, while the specific CO2 emission decreases by 12%. If the assumed carbon conversion is increased from 70% to 85%, at maximum solar input, the overall efficiency, specific electricity output and specific FT liquids output increase by 4.3%, 2.9% and 5.1%, respectively, while the specific CO2 emission decreases by 23.3%. In this process, the maximum specific solar input to the process is limited by the extent of carbon conversion in the gasifier and so improved performance could be achieved through better gasifier design.