Making Coffee With Hydrogen – Hackaday

Something of a Holy Grail among engineers with an interest in a low-carbon future is the idea of replacing fossil fuel gasses with hydrogen. There are various schemes, but they all suffer from the problem that hydrogen is difficult stuff to store or transport. It’s not easily liquefied, and the tiny size of its molecule means that many containment materials that are fine for methane simply won’t hold on to it.
[Isographer] has an idea: to transport the energy not as hydrogen but as metallic aluminium, and generate hydrogen by reaction with aqueous sodium hydroxide. He’s demonstrated it by generating enough hydrogen to make a cup of coffee, as you can see in the video below the break.
It’s obviously very successful, but how does it stack up from a green perspective? The feedstocks are aluminium and sodium hydroxide, and aside from the hydrogen it produces sodium aluminate. Aluminium is produced by electrolysis of molten bauxite and uses vast amounts of energy to produce, but since it is often most economic to do so using hydroelectric power then it can be a zero-carbon store of energy. Sodium hydroxide is also produced by an electrolytic process, this time using brine as the feedstock, so it also has the potential to be produced with low-carbon electricity. Meanwhile the sodium aluminate solution is a cisutic base, but one that readily degrades to inert aluminium oxide and hydroxide in the environment. So while it can’t be guaranteed that the feedstock he’s using is low-carbon, it’s certainly a possibility.
So given scrap aluminium and an assortment of jars it’s possible to make a cup of hot coffee. It’s pretty obvious that this technology won’t be used in the home in this way, but does that make it useless? It’s not difficult to imagine energy being transported over distances as heavy-but-harmless aluminium metal, and we’re already seeing a different chemistry with the same goal being used to power vehicles.


This sounds like a very expensive and complicated form of the carbide lamp. The question is not whether it would work, of course it would, but whether it could ever be economical in comparison to other available methods of energy storage. For example, lithium batteries. I’m really dubious about that.
It would address the “rare element” problem. Kind of like the iron battery.
Yeah, aluminium is notoriously energy intensive to make and reasonably expensive too.
And while the aluminium part might be reasonably safe, the sodium hydroxide is not very nice to biological things (or as I recently found out, flexible rubber buckets – plastic buckets seem OK)
>> aluminium is notoriously energy intensive
There’s also what amounts to the opportunity cost. yes, it *is* totally possible to refine aluminum from bauxite with clean hydropower, in fact, that’s why many aluminum mills are located in places that provide this kind of cheap electricity.
But the thing about hydropower is that, by and large, much of that power was going to be generated anyway because you can’t really stop a river just because nobody is running their air conditioning today.
Given that, there’s probably a better way to use it or at least, a cheaper way to store it, even if you simply decide to skip the aluminum and go right to electrolytic hydrogen.
Also, it should be noted that even though *refining* aluminum from bauxite is all about electricity, and some of that can be pretty clean, actually *mining* the ore and transporting it to the mill is a story about fossil fuels.
>you can’t really stop a river just because nobody is running their air conditioning today.
Yes you can. That’s kinda the point of hydroelectric dams and their reservoirs.
The ‘green’ claim got pretty thoroughly debunked the last time a similar scheme came around these pages: https://hackaday.com/2020/05/26/aluminium-pucks-fuel-hydrogen-trucks/ (yes, the last link in TFA)
How much energy comes out in the form of hydrogen, vs. just heating up the reactants?
Hydroelectric power has its own downsides. Many dams built in the western United States with hydroelectric power in mind are hated vigorously by environmentalists for a myriad of reasons. So low carbon footprint is not the only relevant metric.
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