Some questions about biofuels:

I've been reading up on this subject for quite a while now, and my favorite site is Journey to Forever. Frankly, if there's a better website out there on this topic, I haven't seen it. However, I do have some lingering questions, and if anyone who visits this blog regularly knows anyone with the answers, I'd be interested to find out. The questions are as follows: To create ethanol from any raw feedstock (cane sorghum, sugar beets, etc.), how many units of water are required to produce a unit of ethanol? After distillation, can that water be reclaimed and used for other purposes (drinking, etc.)? How many BTU's per unit of ethanol are required for the distillation process? Are there non-petrochemical denaturants or stabilizers for ethanol? Would a mild gelling agent reduce vapor loss of ethanol, and would this cause more problems for an internal combustion engine? Is there an environmentally-friendly bactericide to prevent losses of stored biodiesel? Finally, which engines can run on butanol, an alcohol that can be made with both cellulose and starch/sugars? I'm strongly in favor of biofuels, and I can envision the day when the United States becomes a net exporter of fuel and energy, much like the Middle East is today, only with much better human rights. I just don't know all the answers.