Greenhouse gases emissions and energy use of wheat grain-based bioethanol fuel blends

This study focuses on the potential energetic and environmental impacts associated with the production of wheat grain-based bioethanol in Lombardia (Italy), with a “seed-to-wheel” approach (i.e. taking into account the production and use phase). Greenhouse gas emissions (GHGs) were estimated through the CML 2 baseline 2000 methodology counting the CO2 equivalent emissions, while the energy flow indicator was estimated using the Ecoindicator 95 methodology. The impact of the different phases involved in the production and use of bioethanol have been analysed: the agricultural production of wheat grain, its transformation into bioethanol, the production of gasoline and the use of 5 different blends (from pure gasoline to pure ethanol). The results show that ethanol fuel, used in the form of blends in gasoline, can help reduce energy use and GHGs. In particular, the use of pure ethanol was found to be the best alternative presenting the lowest GHGs (saving about 32% of CO2eq emissions in comparison to gasoline) and the minor energy use (63% saving). Differences between low-ethanol blends and gasoline are minimal and dependent on the specific fuel consumption of the vehicle. The sensitivity analysis performed to test the robustness of results through the change of some basic assumptions (specific fuel consumption, N2O emissions from agricultural phase, allocation method) shows the sensitivity of GHGs saving to the adopted allocation method.