I believe aluminum is nicknamed "solid electricity" due to the ore purification process or somesuch; which dovetails well with the strategy you outline here!
Unfortunately it doesn't. Aluminum needs a lot of electricity, but it needs to be consistent for several hours. It takes a lot of energy true, but the furnaces need to be at operating temperature. You can't just turn them on and off, there are startup and cool down times that need to be accounted for.
If I understand right, that figure is measuring the accuracy of a prediction of electricity production, not the constancy of the production. We can't smelt aluminium with no power even if we have predicted that there'll be no power.
To be honest I don't know, but I do know taking advantage unpredictable power of this sort is why Aluminium plants are built in the first place. Where I live they are paired with coal fired plants. The reason they are paired with coal fired plants is coal can't change it's output fast enough to match the somewhat unpredictable changes in electricity usage.
So the coal plant needs someone who will buy power when it's cheap, and not use (much) when its expensive. Apparently an Aluminium smelter fits the bill nicely. I presume it uses enormous of amounts of power to disassociate the Al(OH)3 but needs only a small amount of power to keep the pots at operating temperature which is not particularly surprising as the pots can be thermally insulated.
Maybe the above claim that Aluminium can't tolerate rapid changes in available electricity is true, but it sounds odd. Coal fired plants often "trip out" - meaning the generator drops off line without warning. This is an unpredictable change that happens much faster than the sort of unreliability we see from renewables - it's a huge change that happens in milliseconds. And it's not uncommon: https://leadingedgeenergy.com.au/coal-fired-generators-trip/ Again, the Aluminium plants seem to cope with this extreme unreliability just fine.
Current furnaces do. But what if you changed the manufacturing process as well so that maybe the yield isn't as high but it's essentially "for free" in terms of electricity?
About ten years ago I read a paper describing a pilot plant in 1950's Norway that was electrowinning iron from sulfide ore. I think the energy usage was 4-5kwh/kg.
Roughly the reason it's not economic is electricity nominally costs about 5 times what coal/nat gas does. And with the current carbon footprint of the grid it probably doesn't reduce CO2 emissions.
But that could change with as clean grid that has wild daily price swings. Electrowinning iron and other metals could easily soak up excess power.
There are some aluminum plants in Germany that do this[1]
More ambitiously ARPA-E has a program where one of the goals is light metal production(aluminum, magnesium,etc) using variable energy sources[1]. One of the interesting possibilities they present in the program is being able to use molten metal produced in refining as an energy storage medium. Although I couldn't find any program participants doing this one is using thermal energy storage for metal production[2]. A fair amount of metal refining processes need high amounts of heat and heat can be stored easier than electricity at scale.
Haha, I like that description a lot. You can even make small batteries out of little more than aluminum, an electrolyte like salt, and (I think) a way to bring oxygen to the cathode like activated charcol:
