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[OM] Re: lithium iron phosphate batteries, was: TSA: Safe Travel

Subject: [OM] Re: lithium iron phosphate batteries, was: TSA: Safe Travel
From: Tim Hughes <timhughes@xxxxxxxx>
Date: Wed, 2 Jan 2008 01:00:13 -0800 (PST)
It used to be that demonstration technology solar cells ran a bit over 20% 
efficient. But I think
many new solar cell companies are talking about production level cells being 
around 20%, so the
10% is definitely on the pessimistic side. On the other hand the 10hrs/day etc 
Chuck used, are
optimistic as pointed out.  So maybe in the south of the US you could get 
something like 50% more
than originally calculated? 

There was study done in Britain many years ago showing that silicon cells (even 
then) were cheaper
than polished stone etc which is often used on commercial buildings as a facing 
material. So if
you replaced vertical sufaces on buildings with solar cells it costs about as 
much as many
existing finishes and you then got some free energy thrown in! This is a very 
long way from ideal
as the cells orientation to sun, adjacent buildings etc, greatly reduce 
collection efficiency, but
I like the lateral thinking though.

For people interested in integrated design for energy efficiency, watch the 
Amory Lovins lectures
made at stanford university at the begining of 2007 (streamed free from the 
web):
http://sic.conversationsnetwork.org/series/si-energy.html
some of the building case studies are particularly interesting. 

Tim Hughes

 
--- Jan Steinman <Jan@xxxxxxxxxxxxxx> wrote:

> 
> > From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
> >
> > From somewhere I have a note that it takes about 33 kwh to produce
> > enough hydrogen by electrolysis to equal the energy equivalent of a
> > gallon of gasoline.
> 
> I think that's off a bit, but probably not by much.
> 
> There's 37.6 kWh in a gallon of gasoline. If you can produce that with  
> only 33 kWh input, you've got the foundation for a good perpetual  
> motion machine. :-)
> 
> I don't know the typical conversion efficiency of electrolysis, but  
> assuming 90%, you'd need about 42 kWh.
> 
> All minor quibbles in what looks like a sound analysis: you probably  
> ain't gonna get your transportation fuel off your roof...
> 
> Other analyses I've seen show batteries trumping fuel cells for  
> transportation needs. Fewer conversions typically mean better  
> efficiency.
> 
> :::: "We need a revolution."
> :::: "Keep saying that, and we'll need a lawyer, assuming they let us  
> have one."
> :::: Jan Steinman http://www.VeggieVanGogh.com
> 
> 
> 
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