TECHNO-ECONOMIC PRE-FEASIBILITY ANALYSIS OF ALTERNATIVE SOLID-FUELS USE IN BAGASSE BOILERS DURING SUGARCANE OFF-SEASON

The production of electricity by sugarcane ethanol mills is generally interrupted for three months during the harvest off-season when sugarcane bagasse is unavailable. To extend the operational time of sugarcane bagasse boilers, this study evaluates boiler efficiency as well as the potential for electricity generation, and the economic feasibility of utilizing four alternative fuels: energy-cane biomass, coffee husk biochar, eucalyptus biochar, and refuse-derived fuel (RDF). A Python-based model of a cogeneration unit was developed to simulate mass and energy balances, incorporating experimentally measured fuel compositions and properties. The analysis focused on the gross profit margin calculated on a unit-energy basis. The simulations examined the potential of feeding the alternative fuels individually or mixed. Boiler efficiency ranges from 60% for energy-cane to 83% for eucalyptus biochar, electricity generation varies from 57 (energy-cane) to 87 MW (RDF). These findings reveal that lower moisture and higher carbon content increase boiler efficiency, whereas higher heating values positively correlate with electricity generation. The economic assessment indicates that RDF yields the highest profit margin at 21 $/MJ_Fuel, followed by energy-cane biomass (10 $/MJ_Fuel), eucalyptus biochar at -2 $/MJ_Fuel, and coffee husk biochar at -6 $/MJ_Fuel. This economic ranking is attributable to variations in electricity generation capabilities and to differences in fuel prices. When fuels are blended, maintaining a composition of at least 60 wt% RDF renders the blend competitive with energy-cane biomass in profit margin terms. Although both biochar types are still not competitive for electricity generation, the combination of energy-cane biomass and RDF presents a promising opportunity for generating significant revenue during the sugarcane off-season.