Substituting coal with renewable biomass for electricity production using co-gasification technique: a short-term sustainable pathway for developing countries

Coal is the cheapest and most reliable fuel source, meeting 36% of world power and over 40% of overall energy demand. However, coal is the single largest source of GHG emission, contributing about 40% of world CO2 emission. Advanced technologies are therefore, required to utilize this abundant cheap fuel environmentally friendly manner. One such technology is co-gasification of coal with renewable biomass, which is a promising technique to improve gasification performance besides reducing emission from individual gasification of coal. This chapter has described the fundamentals of (co)-gasification and its potential to substitute a certain percentage of coal with biomass, focusing on developing countries like Bangladesh. The current status of co-gasification, different challenges, and possible solutions have been discussed for its widespread sustainable implication. Co-gasification improves carbon conversion, syngas quality, and heating value of syngas while reduces pollutants emission markedly. The higher reactivity from co-gasification results from the synergistic effect is due to the dominant alkali and alkaline earth materials (AAEM) present in biomass ash and higher heating rate. The major challenges in co-gasification include nonuniform particle size of biomass, inhomogeneous mixing of particles, the temperature difference between coal and biomass particles, the higher moisture content in biomass and lower flowability. However, these challenges might be mitigated by the torrefaction of biomass using waste heat and maintaining an optimum blending ratio. Depending on the biomass type, up to 50% coal can be replaced with renewable biomass with minor modifications in the infrastructure and pretreatment of feedstock.