Energetics of Brazilian ethanol: Comparison between assessment approaches

As with any other bioenergy product, bioethanol production requires fossil fuel inputs; hence the alleged benefits of energy security and carbon mitigation depend on the extent to which these inputs are capable of drawing a substantive bioenergetic yield. Brazilian ethanol, made out of sugarcane, has been reported as the most efficient gasoline substitute that is commercially available nowadays. For that reason it has been the object of several analyses on the energetics, i.e. energy balances. These studies surprisingly vary widely according with the scholar approach and are not fully comparable among them due to divergences in the assessment method. This paper standardises results of the four most prominent authors in the field, establishing a point of comparison and drawing some light on the energetics studies on biofuels. The main result is shown in Table 5, which homogenises the outcomes for referred studies in terms of unit of assessment in the energy input analysis. Subsequently, this information is also charted (Fig. 2) explaining the source of divergence among authors. This work ends with a short reference and comparison to some energy balance studies carried out on feedstocks of diverse nature, highlighting the potential that sugarcane-based bioethanol represents nowadays.