This has the potential to radically transform life as we know it (Jim).
Capability is another matter and is to be seen.
It's a way of "storing" energy (probably electrical) and recovering it as 
Hydrogen at reasonable if not totally stunning energy densities.

The mystery metal "Aluminium" referred to throughout the following has 
identical properties to the US substance Aluminum. [ :-) ].

A "new process" is being commercialised to produce Hydrogen from the 
reaction between Aluminium and water. The actual reaction is well know but 
difficult to utilise because of the oxide layer which forms on the Al 
surface.


        http://pesn.com/2007/05/17/9500471_Hydrogen_via_Aluminum_Gallium/

        http://www.physorg.com/news98556080.html

        + Gargoyle knows ...

The new process uses a mixture of Gallium and Aluminium to produce an alloy 
that reacts with water to produce hydrogen without forming an oxide skin. 
The by products are alumina (aluminium oxide / Al2O3) and Gallium metal. The 
gallium can thus be reused. It is effectively equivalent to a catalyst in 
this role - albeit in an essentially mechanical role.

The energy available as in the generated Hydrogen is less than from an 
equivalent mass of hydrocarbon fuel (eg about 4.4 kWh/kg compared to about 
10 kWh/kg for petrol) and the energy cost of aluminium is higher than this 
again due to the need to originally convert it from alumina in mined ore.

However, the process also produces about the same amount of energy as heat 
when the Al and water react. If used as a micro portable cogeneration unit 
the process has the ability to provide energy densities in excess of what 
are available from current primary or secondary batteries. Use of the 
hydrogen in fuel cells promises a future for Aluminium powered laptops and 
similar.

I got excited at this and did some energy density calculations to compare 
hydrogen production from Al compared with say Ca, Na and K which will 
produce hydrogen by reaction with water without forming oxide skins. Results 
are extremely good.

Grams of hydrogen produced per gram of metal are

Al        0.11
Ca       0.043
Na        0.043
K         0.026

The above ignores the mass of water required for reaction. The relative 
simplicity of the process suggests that not especially pure water should be 
able to be used and it may be possible for future fuel cell users to employ 
local water sources for hydrogen generation. [[ "A Coke for me and an Evian 
for my palm top please".]].

Calcium and sodium have the same result as sodium is monatomic with half the 
atomic weight of diatomic calcium.

Of these calcium is probably the preferred contender if Hydrogen alone is 
wanted and heat is an unwanted byproduct.
Aluminium is 2.6 times better than Calcium if the weight of the gallium is 
ignored. (I don't know what % gallium is required)

Gallium has a density of 5.1 so if a significant amount is required it could 
reduce mass energy density considerably.
Aluminium density = 2.7.  [[ Calcium density is 1.6 and Sodium is 0.97 so if 
mass density was of interest then these may still be contenders as a 
portable hydrogen source]].


        Russell

_________________

Original reference - Matthew McMahon


Subject: New process generates hydrogen from aluminum alloy to run engines, 
fuel cells


http://www.physorg.com/news98556080.html
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