Robert N. Eaton wrote:

> How about electrolysis (is that the word I want?) of H2O powered by 
> solar cells?

Electrolysis of water with electricity from renewable sources is the 
preferred clean method for Hydrogen production.  The problem has been 
the total energy cycle cost.

In order to compare the price of gasoline to H2 from electrolysis, I 
will use BTUs (i.e. British Thermal Units) because every energy resource 
can be measured on a BTU basis.  A kilowatt hour of electricity has 
3,412 BTUs, and assuming an electrolyzer efficiency of 80%, roughly 45 
kilowatt hours of electricity will be needed to make the same energy 
contained in a gallon of gasoline.

Now if you assume that 1/2 of the price of transportation fuel is 
earmarked for distribution, taxes and markup, we are left with gasoline 
at ~1.00 per gallon.  Dividing this by 45KWh, we will need an 
electricity at ~2.22 cents per KWh to be competitive.  Currently the 
only electricity source that can hit this price point reliably is 
hydroelectric.

New H2 production techniques other than electrolysis are under 
development to split water, but I fear that none of them will see 
commercial deployment for 10-15 years.  The only way that we will see 
economical Solar-H2 at the pump is if it is subsidized.


> By the way, do you know the calories per kilogram of gasoline vs. the
> calories per kilogram of hydrogen?  Will the average hydrogen 
> powered vehicle have room enough for the spherical or cylindrical 
> with hemispherical ends tank (It must be one or the other, mustn't 
> it?) to give it a realistic cruising range?

Using a conventional combustion engine and mid-pressure tanks (~5,000 
PSI) your range would be about 200 miles.  If you replace the combustion 
engine with a fuel cell and electric drive train your range increases to 
~300 miles.  Other alternatives to storage, such as using Liquid H2, 
will give you a range comparable to gasoline cars, but they are either 
too expensive or not suitable for mass consumption.


> Damn, I ask a lot of questions :-).

Who questions much, shall learn much, and retain much.
      - Sir Francis Bacon


-- 
Chris Lewis
shadow@digitalnirvana.com

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