Ethanol contributes more to global warming than gasoline

Global warming due to emission of GHGs from transportation vehicles is an issue of great concern globally. To cut down on the emission of greenhouse gases, finding alternative to the traditional transportation fuels like diesel and petrol is a continuing process worldwide. Countries are going for ethanol- gasoline mix for use in vehicles to reduce environmental pollution. Ethanol is supposed to be cheaper and much environmentally cleaner fuel than the petroleum products. Several countries, including US, Sweden, Brazil and Australia are already produce cars which run on petrol-ethanol blends. For example, 30% of vehicular fuel produced in Brazil is ethanol.

However, if one considers the entire fuel cycle, there is, in fact, increase in the weighted GHG emissions (emissions in moles of carbon dioxide per vehicle mile traveled x global warming potential per mole relative to carbon dioxide) if one switches from gasoline (10.71) to ethanol (13.88). It is also reported that ethanol from corn produces the largest nitrous oxide emissions (another GHG) across the total fuel cycle.

Thus, it can be concluded that except that it is cheaper, from the consideration of global warming, contribution from ethanol for global warming seems to be higher than gasoline. In fact, use of LPG (8.61) and CNG (9.03) contribute less as compared to ethanol (13.88) to the global warming. Then, why ethanol mix?