Life cycle assessment of calcium oxide pretreatment of corn stover with carbon dioxide neutralization for ethanol production

This work used life-cycle assessment (LCA) to determine the environmental and human health impacts of four ethanol production scenarios (S1: CaO pretreatment + H2SO4 neutralization + C6 yeast fermentation; S2: CaO pretreatment + CO2 neutralization + C6 yeast fermentation; S3: CaO pretreatment + H2SO4 neutralization + C6/ C5 yeast fermentation; and S4: CaO pretreatment + CO2 neutralization + C6/C5 yeast fermentation), with the functional unit being 1 kg of 95 % ethanol. The LCA results showed that the total ozone depletion, global warming potential, smog, acidification, eutrophication, and ecotoxicity values were comparable when CO2 or H2SO4 were used to adjust the pH of CaO-pretreated slurry. However, using CO2 for neutralization and C6/C5 yeast for fermentation demonstrated significant benefits in terms of carcinogenicity, non-carcinogenicity, res-piratory effect, ecotoxicity, and fossil fuel depletion. The findings indicate that the choice of chemicals and strains plays a key role in determining environmental and human health impacts.