At historical rates of power-efficiency scaling (which haven't changed much in the past 10 years either) ... by 2040 we'll have the currently estimated computational power of a human brain (~1 exaflop) running on a 20Watt processor, which is about as much as an iPhone CPU uses.

It's not guaranteed that some AI supercomputer will be using megawatts of electricity and couldn't siphon what it needs from small parasitic loads.