Effects of coal and biomass types towards the quality of hybrid coal produced via co-torrefaction

Abstract

Coal is an abundant source of energy in Indonesia, but the reserves are dominated by low-rank coal, which is less favorable to be utilized. Indonesia also has various biomass that has potential to be used as an alternative energy source. Combining low-rank coal and biomass in a co-torrefaction process resulted in hybrid coal: an upgraded solid fuel that has higher calorific value than its original coal. The aims of this research are to analyze the effect of different biomass and coal blends on hybrid coal yield, calorific value, energy yield, and non-neutral CO2 emission reduction. This study utilized two types of coal that are X and Y, and three different types of biomass: (a) sugarcane bagasse, (b) rubberwood, and (c) empty palm fruit bunch that are being most widely found in Indonesia. The blends consist of 30%wt biomass were co-torrefied in a vertical tubular furnace reactor for 60 minutes with temperature 300°C in an inert environment and ambient pressure. Solid yields of hybrid coal founded in the range of 57.0 to 63.8% which different types of biomass gave significant effect. Calorific value was increased 37.6-44.1% to 5681-6288 kcal/kg from its original coal. The energy yield ranges from 77.0 to 89.0%. The product reduced non-neutral CO2 emission within the range of 18.1-22.2%.