I'm not sure aluminium is a good example - while your foil is high purity aluminium, large part of Earth is aluminium bound with other elements. Traditionally t

I'm not sure aluminium is a good example - while your foil is high purity aluminium, large part of Earth is aluminium bound with other elements. Traditionally the main issue was separating it from those. It's questionable storing all this for later would be more efficient, even with higher purity, than just raffine it from rocks at industrial scale.