On Jan 29, 2009, at 5:27 PM, [email protected] wrote:
In reply to Horace Heffner's message of Thu, 29 Jan 2009 13:38:49
-0900:
Hi,
[snip]
The reason Si is such a great element for energy transportation and
storage is, if you look at energy production on a global basis, there
is so much of it cheaply available in desert areas, where the solar
energy to refine it is located. And it has a double whammy - money
is to be made on both the energy and the byproduct. This is a fairly
quickly implementable scheme for power utilities, and the economics
certainly *were* there if they aren't now, and should be there again
soon.
Availability would be an important bonus, however according to the
Wiki page on
silanes (http://en.wikipedia.org/wiki/Silane), silane is toxic, and
also
pyrophoric. The latter would probably prevent its use as an
automotive fuel,
since any accident leading to a tank rupture would instantly result
in a fire
(not sure about the heavier silanes).
[snip]
Similar dangers exist for compressed natural gas (CNG). In fact,
quick ignition of natural gas in the case of an accident might
prevent large explosions. CNG is compressed to 3000 PSI, thus the
energy released by a broken tank can turn the tank into a high energy
projectile, so that too is of concern.
I certainly must agree that I wouldn't want to be filling up a car
tank with silane gas, due to the fact any leaks would tend to explode
(pop) or catch fire! 8^)
My point in mentioning silane and tetrasilane was mainly to point out
there is a variety of silicon based fuels or feed stocks that are
analogs to carbon based fuels. By "enviromentally friendly" I meant
in terms of carbon use and CO2 generation. The actual proposal I
referenced was to ship pure solid silicon, possibly coated or
encapsulated to avoid reaction with air or water. See (again):
http://tinyurl.com/cuaryk
However, silane is manufactured and shipped for use in a variety of
industrial processes. It is a gas at STP so has the advantage it can
be shipped by pipeline. I wouldn't see silane gas as a good
prospect for powering motor vehicles, but it might have application
for large scale power. Silane has application in making thin silicon
coatings, which has application in solar cell manufacturing. [Btw,
also check out Fig. 6 on page 7 of the above reference for an
interesting perspective on energy density vs safety of various
fuels.] Silane is not very toxic. It is mainly an irritant. See
the MSDS:
http://www.vngas.com/pdf/g97.pdf
The handling toxicity risk seems comparable to gasoline or MTBE:
http://msds.chem.ox.ac.uk/OC/octane.html
http://msds.chem.ox.ac.uk/BU/tert-butyl_methyl_ether.html
In global trades, solid silicon provides an alternative to shipping
anhydrous ammonia, which can be extremely hazardous. Silicon does
have a problem in that in the event of a shipwreck it can form
ammonia when exposed to water and air. For long term damage to the
environment this is not as bad as oil, but it would be pretty
hazardous to the crew I would think, but not as hazardous as liquid
anhydrous ammonia. Adequate encapsulation should prevent the major
risks of exposure to water and air for the silicon. It seems to me a
feasible scheme to run power plants with solid Si. An alternative
means of solar energy storage and transport is to directly create
anhydrous ammonia. This takes less energy than making hydrogen,
creates a liquid product for transport, and the ammonia is valuable
for fertilizer production, and other chemical feed stock uses, as
well as for energy production. Anhydrous ammonia is currently
shipped by barge, truck and ship, despite the obvious safety
concerns. I would think encapsulated solid silicon would be a big
step up in safety, as would some silicon compounds.
Unless some very good means of storing hydrogen is found, silicon and
silicon compounds appear to provide a means to convert world energy
production to renewable means, i.e. solar and wind, using existing
technology now. No great scientific discoveries required. Makes me
wish it were my idea. 8^) OTOH, it is just another idea out there
waiting for the right opportunity, and may never have its day.
Best regards,
Horace Heffner
http://www.mtaonline.net/~hheffner/
