Text 2105, 114 rader
Skriven 2006-06-07 23:31:00 av Robert E Starr JR (2551.babylon5)
Ärende: Re: Atheists: America's m
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On Tue, 6 Jun 2006 20:55:34 +0000 (UTC), Charlie Edmondson
<edmondson@ieee.org> wrote:

>Hi Josh,
>Try hanging out at sci.energy.hydrogen for a while.  A real eye opener. 

>  All these 'achievements' you have seen are just marketing speak and 
>research grant fodder.  That cost per gallon equivalent of hydrogen 
>makes some interesting 'assumptions' that basically says - the equipment 
>is free, the windmill is free, and we don't actually violate any laws of 
>physics, just bend them a little.  A more reasonable estimate (which is 
>hard to really do, because some of the equipment just doesn't exist..) 
>has it pegged between $6.50 (wildly optimistic) to $30 (pretty 
>pessimistic) and again, assumes that some of the 'bugs' have been solved 
>by then.  Again, this is just the PRODUCTION side of the coin.  The 
>additional costs of the transport, storage, and use of the hydrogen 
>isn't addressed here.  And that equipment that hasn't been built yet? 
>That is the inexpensive industrial electrolysis unit.  They do make 
>these, as they are used in petroleum refineries where they produce a LOT 
>of hydrogen to use as a feedstock in the production of gasoline.  But 
>inexpensive is not a term applied to them...

Well, here's the source for my figure, an excerpt from an article
published in Science by some researchers at Stanford:

"The unsubsidized near-term (<10 years) cost of producing hydrogen
from wind is estimated as follows (table S2) [direct electricity from
modern wind turbines in the presence of annual winds at speeds of >6.9
m/s, present over >20% of the United States]: cost, $0.03 to $0.05 per
kilowatt-hour (kWh); transmission cost, $3.45*10^-6 to $1.38*10^-5 per
kWh/km; transmission distances, 20 to 1500 km; internal combustion
engine efficiency, 0.16; HFCV efficiency, 0.43 to 0.46; electrolyzer
cost, $400 to $1000/kW; interest rate, 6 to 8%; electrolyzer energy
requirement, 53.4 kWh/kg of H2; fraction of time wind is available to
electrolyzer, 0.5 to 0.95; compressor cost, $0.7 to $1.34/kg of H2;
and storage cost, $0.31/kg of H2. The total is $3.0 to $7.4/kg of H2,
or $1.12 to $3.20/gallon of displaced gasoline/diesel, which compares
with the actual costs of U.S. gasoline and diesel in mid-March 2005 of
$2.06 and $2.19 respectively. Adding the reduction in health and
mortality costs from wind HFCV's of $0.29 to $1.80/gallon, which is
the externality cost of gasoline, gives a direct cost plus externality
cost of U.S. gasoline/diesel of $2.35 to $3.99/gallon, which exceeds
the mean cost of hydrogen from wind ($2.16/gallon) even if retail
hydrogen is marked up."

http://www.stanford.edu/~wcolella/pubs/SciencePubHyd.pdf

I haven't checked all the figures, but the ones with which I'm
familiar, e.g., the current cost of wind, seem accurate, and their
results seem consistent with the back-of-the-envelope calculations I
did a few years back.

And another source I've referred to (the table is much clearer in the
original and it has some interesting info in general, so you may want
to go to the URL rather than try to figure out my kludgey
transcription):

A. Current Technology with Grid Backup
A. Current Technology No Grid Backup
C. Future Technology with Grid Backup
D. Future Technology No Grid Backup
 
Average cost of electricity (cents/kWh)

A        6
B        6
C        4
D        4
 
Wind turbine capacity factor (%)

A        30
B        30
C        40
D        40
 
Hydrogen ($/kg)

A        6.64
B        10.69
C        3.38
D        2.86
 
Carbon emissions (kg C/kg H2)

A        3.35
B        0
C        2.48
D        0
 
http://darwin.nap.edu/books/0309091632/html/228.html

This last source appears to significantly overstate the cost of wind
using current technology, BTW: 3-5 cents/kW-hr is the figure I usually
see for current turbines, not the 4-5 cents they're assuming. And they
seem to be presupposing a lower capacity factor.

Care to poke holes in these figures?

-- 
Josh

"I'm not going to play like I've been a person who's spent hours involved with
foreign policy.
I am who I am." - George W. Bush
  
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