Emergy accounting of coffee husks for the generation of energy

Abstract

Coffee husks are an abundant and underutilized waste product from the Brazilian agro-industry. The present study employs the emergy methodology to investigate the potential of utilizing coffee husks as a co-product for efficient energy generation. Emergy Accounting key findings indicate high transformity and specific emergy values, endorsing their substantial energy potential. Emergy accounting evaluate indices such as emergy economic efficiency (EYR), environmental loading ratio (ELR), and environmental sustainability index (ESI). Results indicate that the system operates with an EYR of 1.19, demonstrating that the energy output exceeds the invested energy, while the ELR of 6.42 suggests a moderate environmental impact and low ESI of 0.19 underscores the need for more sustainable practices in the coffee production system. Despite environmental impacts, the system yields net energy with 103% higher ecosystem efficiency. Coffee husks, compared to sugarcane straw and bagasse, boast advantageous traits—favorable ash content, optimal particle size, and low moisture, thereby reducing the need for energy-intensive processing. These results support investment in the husks' combustion process, akin to sugarcane bagasse, reducing reliance on non-renewable sources in the thermoelectric system. This study underscores coffee husks as a promising alternative energy source, repurposing an abundant agro-industrial waste.