You're off 3 orders of magnitude, 40,000,000,000 kg x 15,000 Wh/kg = 600TWh (you likely tripped on the kt, which is 1000x1000kg, at least I did the first time I ran your numbers). That's not 0.2% of Australia's energy use but 200%.
Ha! It figures. Further down that thread I wrote: "Also, I'm notorious for dropping three orders of magnitude when doing mental math using kilo/mega/giga/tera prefixes."
Turns out when you do the math right, Aluminium _is_ frozen electricity.
