What are the potential negative externalities (effects) of producing/using this energy source?
Again, many potential negative externalities. Among them are loss of topsoil, increased pollution from pesticide and herbicide runoff, aquifer depletion, and an increase in food prices due to increased grain demand [a positive externality (effect) for those who farm]. What is the EROEI? The energy return on grain ethanol is very low. Published studies put this number at around 1.3, but the return for fossil fuels in (used in production) and ethanol out (amount gained during production) averages less than 1.1. Animal feed byproduct that is given a BTU value pushes the EROEI up to 1.3. Therefore, for 1 BTU of energy expended, less than 1.1 BTUs of ethanol can be produced, along with an additional 0.2 BTUs of animal feed. The net is then 0.3 BTUs with the byproduct credit, or about 1/17th of the fossil fuel net. Is it affordable? It is affordable, due to direct subsidies. But based on the current spot price (daily world price) of ethanol, it is slightly (a little bit more) over twice the
