It is true that ethanol is not the best of fuels (“Ethanol, Schmethanol,” September 29, 2007). As you point out, in addition to its low efficiency, it is corrosive, too. The ongoing search for a better biofuel—such as butanol, octanol, etc.—thus makes perfect sense. But it is not true that America has recently embarked on ethanol mainly, let alone only, because it is green, as you imply. Its green credentials surely help at the time when climate change is on everyone’s mind, but the leading strategic reason for this choice is the need to reduce the country’s dependence on foreign sources of fuel. The growing mess in the Middle East is the main reason behind this shift, it goes without saying. All serious alternatives to ethanol will therefore have to satisfy this strategic objective. Of course, they will have to be about as green as ethanol, but they will have to be produced on American soil first and foremost.