Exergy and economic assessment of renewable electricity generation from sugarcane straw for improved efficiency of sugarcane biorefineries

This work focuses on the revamp of existing sugarcane biorefineries and cogeneration units by using those byproducts, aiming to increase the selling of surplus electricity. The analysis allows identifying potential improvements in the sugarcane cogeneration plants. Simulation processes are employed to denote incremental modifications related to sugarcane straw recovery achieved in the harvesting systems. The results show that the straw recovery through harvesting systems may increase the surplus electricity by up to 30% when sugarcane biorefineries consider the maximum straw recovery fraction. Moreover, the increment in the exergy cost of the straw gathering influences the extended exergy efficiency of the cogeneration unit and, consequently, the entire sugarcane biorefinery. In brief, the capitalisation on sugarcane residues may increase the contribution of this industry to the decarbonisation of the Brazilian electricity mix and increment of profits resulting from the negotiation of decarbonisation credits in the Brazilian sugarcane market.