Aluminum - Fuel of the Future?

From the September edition of Southern Metal Finishing...

About a week ago I was scrolling through my select list of recorded television shows (TiVo is a God send). I settled on an episode about Future Fuels showcased during the Discovery Science channel’s “Eco-Tech” week. Among the technologies mentioned, including jet fuel derived from trap grease in New York City, and cellulosic ethanol produced by modifying E. coli bacteria to produce alcohol from wood chips, there was one fuel source that I thought had an especially interesting twist. We all know about hydrogen and the possibilities surrounding it as a future fuel source – if only it wasn’t so unstable. Perhaps a common metal is the answer to this problem.

Purdue University engineer Jerry Woodall, a distinguished professor of electrical and computer engineering, discovered that liquid alloys of aluminum and gallium spontaneously produce hydrogen if mixed with water. By adding water to a small tank containing pellets of the alloy, Woodall was able to generate hydrogen. Once the water is added to the pellets, the aluminum in the solid alloy reacts because of its strong attraction to the oxygen in the water. Gallium is a necessary ingredient because it melts at low temperatures and dissolves aluminum, thereby allowing the solid aluminum pellets to react with water – something aluminum cannot do on its own due to the natural formation of an aluminum oxide ‘skin’ that forms when the metal’s surface bonds with oxygen. 

Through this method, hydrogen could be fed directly to an engine – all you would have to do is replace the gasoline fuel injector with a hydrogen injector. Possible uses include running fuel cells or internal combustion engines, found in emergency generators, lawn mowers and chain saws. In theory, it could even replace gasoline in cars and trucks. Another positive factor is that since the hydrogen is generated on demand, you would only produce as much as you need at the time it is needed. The method also makes it unnecessary to store or transport hydrogen; so you wouldn’t have to fill up at a ‘hydrogen pump’, which would be extremely costly to the economy in terms of distribution and station construction.

Another upside is that the only waste product of combusted hydrogen is, well…water. There are no toxic fumes produced from the alloy and water mixture, only the waste product alumina remains, and even this can be recycled back into aluminum using a process called fused salt electrolysis. Since gallium does not react, it does not get used up, and therefore can be continuously recycled - and with the current price tag on gallium, this is a very good thing. Due to the high prices of these components, the technology is, at present, rather cost-prohibitive. If the process is widely accepted, however, the gallium industry will likely respond by producing large quantities of a lower-grade gallium.

I, for one, am very excited to see so many new varieties of alternative fuel sources, and the innovations being made by experimenting with theoretical fuels. Even if this aluminum alloy hydrogen source never inherits the fossil fuel empire, it is still fascinating to know that it exists, and that someone has taken the time to study it and harness its potential. For more information about this and other alternative fuels, check out the following websites:

- Science Daily(article on aluminum alloy hydrogen source)
- Cellulosic ethanol
- Alternative Energy News