Energetic study of ethanol production from the corn crops/Estudo energetico da producao de biocombustivel a partir do milho

This research analyzed the energetic consumption of etanol from the corn crops (Zea mays L.). The field surveys were carried out in the Midle Paranapanema River Region, Sao Paulo state, Brazil, in the period from January to December 2007. The energy consumption on stage of production and industrial processing of grain were evaluated. It was verified that the total energetic cost of the crop production corresponded to 15,633.7 MJ [ha.sup.-1], and the most onerous item was the "inputs" (77.5%). In the industrial step, the energetic consumption was equivalent to 3,882.2 MJ [t.sup.-1]. The operations of "hydrolysis, saccharification and treatment of the broth" represented 50.2% of the total energetic expenditure. It was also observed an energetic cost of 7.9 MJ [L.sup.-1] in relation to the etanol produced in the main crop production operations, and 11.8MJ [L.sup.-1] in the industrial processing. The energy balance of crop production and industrialization was of 1.2MJ.