cvitae.org - Corn ethanol: a review

In this paper, written for the EE293 class at Stanford University, I look at the use of corn ethanol as a fuel. I come to the conclusion that corn ethanol is not significantly efficient or clean given the current technology. The argument is mainly based on the low efficiency of photosynthesis, the energy inputs necessary for corn ethanol production, the fact that ethanol has a lower energy density than gasoline, and the fuel efficiency of vehicles using pure ethanol or ten and 85% ethanol blends. Although it is obvious that solar panels would result in higher conversion efficiency of sunlight to energy and higher energy output even in states with low insolation, ethanol can be stored fairly efficiently and so may be attractive from this standpoint. The greatest benefit of corn based ethanol seems to be the independence from foreign petroleum sources, because corn based ethanol production takes in few petroleum inputs. While bio-ethanol is considered to be clean in the sense that the greenhouse gases resulting from the production and combustion are the same CO2 that was in the atmosphere one year before, the energy inputs into corn ethanol production come from coal, natural gas, and some petroleum, and so the net effect of corn ethanol on the environment is just as bad as gasoline; especially when fuel efficiency reduction due to the lower energy content of ethanol is taken into account.