From: stead@skadi.CSS.GOV (Richard Stead)
Newsgroups: sci.energy,talk.environment
Subject: Re: NEWS: Pioneer Project: Solar Hydrogn Power
Date: 25 Jul 92 22:11:59 GMT
Followup-To: poster

In article <EcoNet.19Jul1992.5pm1@naughty-peahen.org>, jym@mica.berkeley.edu (EcoNet via Jym Dyer) writes:
> =o= The attached is interesting, but not the first time this
> kind of approach has been tried.
>     <_Jym_>
> ================================================================
> [From EcoNet ecotopia.news Conference]

Definitely not the first.

> Pioneer Project: Solar Hydrogen Power
> 
> by Elaine Weinreb
> 
...
> Through the support of a private single benefactor, the Schatz
> Solar Hydrogen Project uses photovoltaic modules to capture
> energy from the sun and convert it to electricity, which then
> hydrolyzes water molecules into hydrogen and oxygen in a fuel
> cell to produce power.
> 
...
> The conventional way of doing this is through batteries, which
> are toxic, heavy, relatively inefficient and use non-renewable
> materials.  In the Schatz system, the electrical energy is used
> to separated hydrogen from oxygen.

Would you believe I did similar work as a high school science-fair project
back in the 70's?  My system did not have an electrical stage - I used
a lens to concetrate the solar energy and directly heated a reaction
vessel (chemical dissociation rather than electrical).  The reactions
were designed to regenerate all reagents except the water.  One was
based on Lithium Nitrite, another on Ferric Chloride Hexahydrate.
The Lithium Nitrite one was a little cleaner, but harder to make it
work.  The Ferric Chloride one involved handling chlorine gas - a bit
messier, could be nasty in a big system if there's an accident.  There
were a series of reactions in each case.  One of the reaction would generate
hydrogen gas.  A separate one at a different stage in the series would
generate oxygen.  Theoretically, only water would be used up, but I never
got through more than one cycle of the reactions.  Being only a high school
student at the time, I really had no idea of the procedures that might be
required to maintain pure reagents and control the reactions better.
Now I'm a seismologist and so I stilll don't know the details of what
would really be required to get these to work.

But the final point here is that avoiding the photoelectrics avoids the
problem of inefficient photovoltaic conversion.  I had considered
photovoltaics at the time and rejected them for this and other reasons.
the process problems could be worked out, the efficiency of the
chemical system should be much better.  Also, the initial cost of
photovoltaics is much higher than simple solar heat collection.  (Not
to mention the environmental problems associated with the production fo
photovoltaics).

> Unlike natural gas, which is a non-renewable resource, hydrogen
> can be continually remanufactured from water.  It does not
> require refineries or mines or logging, and contains no sulfur
> or other polluting chemicals.  It can be burned in an internal

Not quite - if you were to use hydrogen on a large scale, it would require
a scent marker like natural gas - methyl mercaptan (which has sulfur).
In addition, fuel cells could not be the sole use of the gas, it would
be hard to power a car directly of a fuel cell (or a stovetop in a home
or something).  It will be burned and will thus produce nitrous oxides.
If fuel cells were currently practical, I think people would be running
methane through them, especially since methane is so readily available.

> Unlike traditional photovoltaic systems, which best serve small
> isolated areas, solar hydrogen would be most economical if
> produced on a large scale, with the hot desert areas becoming
> major energy producers and exporters.

I think a chemical system could be produced on a small enough scale to be
more generally useful, particularly in rural areas.  The idea I had when
doing the project is that the ultimate system would be a bit like a small
still - some sort of small scale automated chemical processor powered by
solar heat (most probably some sort of pipe with a lens on top to raise
a higher temperature than available without concentration).  Something
that could be installed in a small shed, with the collectors on the roof
or beside it, and a bank of gas bottles containing titanium or some other
metal that stores hydrogen.  The hydrogen would be tapped as needed.

> (From ECONEWS, Newsletter of the Northcoast Environmental Center,
> June 1992. Write 879 9th St., Arcata, CA 95521, or e-mail
> nec@igc.org, for a free copy.)


--
Richard Stead
Center for Seismic Studies
Arlington, VA
stead@seismo.css.gov
Xref: sparky sci.energy:3641 talk.environment:2959