[extropy-chat] [Bulk] Re: Forbes Magazine on Robotics

[Brent Neal]

On Aug 21, 2006, at 21:45, Keith Henson wrote:

> Ethanol is just barely a positive energy return.  If they didn't  
> cut the
> cane by hand in Brazil with extremely low cost labor, it probably  
> would not
> work at all.

Only if you use food-grade cane (or corn) to make it.  Fermentation  
processes in bioreactors can produce it quite efficiently and at  
reasonably high return rates. Or many other small molecules of that  
sort.  DuPont, for example, has designed a bioreactor that uses  
transgenic microorganisms to make propylene glycol.  (Which they then  
react with good old from-dead-dinosaurs terephthalic acid to make  
polytrimethylene terephthalate and claim its a "green plastic."  
Tradename is Sorona.)

The real issue with ethanol isn't the labor costs or the red herring  
of pesticide/fertilizer usage: the real issue is the water-ethanol  
azeotrope, which means distillation becomes a real bitch.  Some folks  
(I forget which group) are looking at using t-butanol instead, which  
has a lower vapor pressure, can be pipeline transported and has a  
better energy density (but is harder to make using conventional  
processes)

B


--
Brent Neal
Geek of all Trades
http://brentn.freeshell.org

"Specialization is for insects" -- Robert A. Heinlein