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Friday, January 18, 2019

Nano-Aluminum-New Energy Source

Sorry, but it is complete BS - at least the way it's being presented.  I'm not saying that there is no place for nano-Aluminum in the pantheon of energy systems but not as implied.

I get this investment advice site on the web and they are promoting nano-aluminum as the energy source that will soon be found powering virtually everything in our modern society.  They don't say it in so many words but leave the impression that nano-Aluminum - very small particles of Aluminum, is a catalyst which causes water to disintegrate into it's component parts, Hydrogen and oxygen, and that it does this at room temperature.  Either they are ignorant of the most basic chemistry and physics or they are trying to play the market so that they can make a buck on it's ups and downs.  Let's start by looking at what it would mean if Nano-Aluminum was such a catalyst.

As anyone who has taken first year chemistry in High School or even basic science in year 9 knows, a catalyst does not take part in a reaction.  Rather, it enables a reaction to proceed and quite often at lower temperatures than would be necessary without the catalyst.  In some cases the reaction would not occur at all without the catalyst.  So let's pretend, for a moment, that nano-Aluminum is such a catalyst.  What would bubble off.

You are probably way ahead of me.  We would have bubbles of the perfect stoichiometry* mix of Hydrogen and Oxygen  in the exact proportions to convert back to water with one mother of a bang with the slightest spark. And you certainly wouldn't want to try to compress this mixture into a high pressure tank!!!  Let's look at the claim that this is a source of energy.  Clearly the reaction would be endothermic.  It takes energy to split water and if this reaction took place at room temperature, the reaction vessel would cool down, creating a 'delta T' (temperature difference).  Heat from the environment would move toward the cool reaction vessel and continue the reaction.

*Reagents in proportion so that when they react, none of the reagent is left over. All of it reacts.

Of course you could add heat from, say, solar panels, to speed up the reaction but my investment-advice-web-site is presenting this as a source of energy.  Mind you it would be pretty neat and you would have found a way of absorbing surrounding low level heat energy and converting it into a high energy mix of H and O. 

What the reaction between nano Aluminium and water actually produces , is pure hydrogen which can be used in a fuel cell which  by the by, also work at room temperature. What is actually happening here chemically.

The Aluminum is pulling the oxygen off the water, forming Aluminum oxide and in the aqueous environment of the reaction, probably Aluminum Hydroxide and releasing the Hydrogen.  Nano Aluminum is not a catalyst but a reagent which is taking part in the reaction and is used up.  So let's look at how we got our Nano Aluminium in the first place and particularly how much energy went into the process..

First you ship the Aluminum ore, Bauxite, from where it is mined to somewhere that has abundant electricity.  First energy cost.  Aluminum is a tri-valent element.  That means for every atom of Aluminum released from the Bauxite, three electrons are needed. Second energy cost. It is an electrically hungry process but this is not all.  The process takes place in molten reagents.  You have to heat up the Bauxite and other reagents to 1000 degrees centigrade.  No matter how well insulated your reaction vessel, it looses heat and energy must be constantly added to keep the temperature up. Third energy cost.  Then you have to ship the ingots of Aluminum to where they are turned into nano-Aluminum. Fourth energy cost.  And finally it takes energy to convert a block of Aluminum into nano Aluminum. Fifth Energy cost.  We could add one more.  The energy cost of shipping the nano-aluminium to where it is to be used.

But this is all moot.  In fact, as noted above, the Aluminium is not a catalyst.  If it was a catalyst, all the above energy costs would be worthwhile since the Aluminum would remain for a very long time or perhaps forever without being used up and you would have a continual source of hydrogen (mixed with Oxygen)

The Aluminum pulls the oxygen off the water making Aluminum Oxide (Bauxite basically) which probably converts to Aluminum Hydroxide in the watery environment of the reaction.  The Hydrogen is released.  The hydrogen can then be used in a fuel cell.  You can never get more energy that the amount that actually split the bauxite in the first place and actually there are inefficiencies in this process.  AND....You certainly do not recover the other 5 energy inputs listed above.  So you have used a lot of energy to get a relatively small amount at the location where you want to use the energy.

At the very most, the use of nano-Aluminium is a sort of battery or if you like an energy storage device and not a very efficient one and one at that.  It is not chargeable.  In that sense it is comparable with the old Zinc batteries.  Of course you also need a fuel cell as part of the package in order to produce electricity.  At the most, nano-Aluminium could serve as an emergency source of electricity in a pretty safe and compact form for specialist applications where it is worthwhile to go to the expense of the whole process.    It is not a source of energy but at best an energy storage mechanism which could use wind, hydro or solar to product it in the first place and not very efficiently when you consider the total energy input and the final energy output.

It might, for instance, be used for the military in remote areas.  Getting their fossil fuel to their tanks, trucks and generators is not only expensive but highly dangerous.