Re: Engineering Economics 101, example II...

"Fred B. McGalliard" wrote:
> 
> "Don Lancaster" <[EMAIL PROTECTED]> wrote in message
> news:[EMAIL PROTECTED]
> >...
> > Only when you get down around a dime per peak watt (starting with $10
> > per day and ending up with $100) does pv solar become a truly renewable
> > and sustainable source.
> 
> This assumes rather boldly that the price of the hardware is intimately
> connected to the value of the electricity produced. There are several strong
> disconnects that make this assumption quite questionable. All that is
> necessary to make solar PV a sustainable source is that a typical unit of PV
> (including all the support hardware, transportation, assembly, etc.) at some
> ideal location produce as much energy over it's life as was consumed to
> build it. This gets sticky because much of the energy consumed is not
> normally electric and this makes a lot of difference for chemical processes
> like the production of steel (which usually uses a lot of carbon), and
> transportation fuels. But one could design, at least in concept, an energy
> system based on any system with a return of just a bit more than 1.00. By
> comparison, we might want to consider the use of plant oils, where as little
> as 2-3% of the solar energy is captured,

Failure to do arithmetic. The figures at 
http://www.journeytoforever.org/biodiesel_yield.html 
translate into oil yields ranging up to about 0.1 percent.

Especially annoying was the use of the phrase, "as little as", 
as if the number following were conservative rather than 
Sunday-supplement wallyjabber fantasy.


--- Graham Cowan
http://www.eagle.ca/~gcowan/Paper_for_11th_CHC.doc --
fireproof fuel, real-car range, no emissions