Hi Murdoch, >Ad hoc comment: > >One of the issues that tugs at me when I have seen recent "debate" (or >quasi-science or shouting) over whether some of the biofuels are >"sustainable" is that the fuel itself, if it is a relatively simple >standardizeable not-horrifically-toxic chemical, is a somewhat >*separate issue* from how it is derived. > >So, a debate over the sustainability of ethyl alcohol as a "fuel of >the future", whether it took place in the 30s or today, should include >the concept that while it may well be presently sourced from much >agriculture or semi-agriculture, I'd think we could somehow >*manufacture* such a fuel, going forward, by new innovative methods as >well. What is to prevent us, with all the scientists we have sitting >around, from taking some solar-derived electricity and trying to make >such relatively simple chemical compounds as ethyl alcohol from widely >available chemicals such as water and CO2 and O2 and what-have-you.
Another ad hoc comment: I guess the problem is just basic thermodynamics really! And you can't beat it. Just about every carbohydrate and hydrocarbon that occurs in nature can be constructed from water, CO2 and O2 . The Big Search is to find a series of selective catalysts or enzymes so you get just the one product that you want and not the complete organic catalogue. Even common yeast hasn't managed to make ethyl alcohol free of by-products and it has been "sitting around" in incredibly large numbers for a lot longer than "all the scientists". And of course we humans would rather like alcohol which is free of water to run our vehicles. As it happens, this universe was cobbled together with some strange little quirks. One is called "hydrogen bonding". It is responsible for keeping water as a liquid at most temperature encountered on planet-Earth. And even when it turns solid, the ice has a strange property of floating. (I'm sure you'll agree that both of these properties are highly desirable.) Well the strangely strong bond between ethanol and water is also (in part) due to hydrogen bonding. So any fermentation or water-based ethanol process has this big energy hole where we try to separate the two. And for those of you who think that moleculart sieve is a kind of angel dust which magically separates water and ethanol, look carefully at the extra energy you have to put into your expensive dehydrating agent just to recycle it. There is no such thing as a free lunch! Incidentally, the quirky hydrogen bond is also responsible for that azeotrope between ethanol and water. This means that even the earliest humans could make a relatively safe potable spirit from just about anything which will ferment. In effect, they let botany do most of the synthesis from CO2, water and O2 for them using widely available sun-power. Perhaps we should simply give up motoring and take up mellow drinking. It's much easier technologically. : - ) Entropy Rules OK? [_]? [_]? [_]? Michael Allen Biofuels at Journey to Forever http://journeytoforever.org/biofuel.html Biofuel at WebConX http://webconx.green-trust.org/2000/biofuel/biofuel.htm List messages are archived at the Info-Archive at NNYTech: http://archive.nnytech.net/ To unsubscribe from this group, send an email to: [EMAIL PROTECTED] Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
