Techno-economic evaluation of energy efficient briquetting system for rice straw and quality of briquettes

Energy-efficient briquetting system comprises biomass shredder and briquetting machine which was used for the formation of binderless briquettes from shredded rice straw without grinding of biomass. Open sun-drying was carried out for the removal of excess moisture from rice straw. Grinding of biomass is the main energy-intensive operation involved in conventional briquette formation method which includes chopping, grinding, and briquetting of rice straw. In this system, briquettes were formed after open sun-drying and shredding of biomass. Round-the-year evaluation of the developed method was conducted, and the specific energy consumption was found to be 282.42 MJ/t in comparison to 423.9 MJ/t for conventional method of briquette production. The method was found to be 33.4% energy-efficient than the conventional method of briquette production. Proximate composition of the rice straw briquettes was ascertained, and the average values of MC, VM, AC, and FC were found to be 10.65%, 64.03%, 23.46%, and 12.51%, respectively. The average value for GCV of rice straw briquettes was observed to be 15.27 MJ/kg. Briquette durability index was found to be more than 97% with a good water resistance (89.05%). Amongst the operational costs, the cost of raw material is the significant cost followed by electricity cost, labor cost, packaging cost, and repair and maintenance cost.