Energy performance of sugarcane potential ethanol production under different management systems

Crop rotation with leguminous species in sugarcane cultivation is increasing in the southeastern regions of Brazil. Studies on sugarcane ethanol production rely basically at the economic and sustainable points of view overlooking the energy analysis. This study aimed to evaluate the sugarcane ethanol yield under no-tillage and conventional systems with different green manure treatments using a published dataset at the energy point of view. Analysis of energy efficiency was carried out using the indicators: energy balance (EB), energy return over investment (EROI) and Energy Intensity (EI). Energy balance ranged from 129.78 GJ ha-1 to 216.92 GJ ha-1, with no-tillage system presenting the highest values of EB. EROI presented the highest values (334.19, 140.31 and 182.98 GJ GJ-1, for sunn hemp, jack beans and velvet beans, respectively) at the system with green manure and no chemical fertilization under no-tillage system. EI presented that no-tillage systems without chemical fertilization had the lowest values (average of 0.10 MJ L-1) compared to the conventional (1.03 MJ L-1) and no-tillage system with chemical fertilization (1.26 MJ L-1) which indicate that systems require less energy to produce the same yield than the conventional. Sugarcane cultivation with no-tillage and no chemical fertilization with green manure crop rotation are energetically feasible increasing sustainability of sugarcane ethanol production