Within the biorefinery, CO2 is emitted during ethanologen fermentation, combustion of lignin and unreacted carbohydrates to produce steam, and decomposition of organic matter in the waste water treatment.
Combustion of ethanol in an automobile produces CO2 and other GHGs.
Both biorefinery and fuel use CO2 emissions originate from the poplar trees (biogenic source).
CO2 stored as carbon in the harvested wood and non-harvested biomass (carbon in biomass inFig. 2) offset the CO2 emissions produced during the ethanol life cycle.