Actually we can extract electricity from aluminium. A while ago someone proposed a "battery" that would consume aluminium as it provides electricity. Supposedly

Actually we can extract electricity from aluminium. A while ago someone proposed a "battery" that would consume aluminium as it provides electricity. Supposedly this battery was going to have 10x the energy density of today's li-ion batteries. Edit:as for crypto you're completely correct. If one set out to invent the most inefficient energy use possible in computing the result would be crypto proof of work that grows all the time.