There is energy expended during the process though. I imagine if this continues 'banks' of the future will be data centers. Also might be a way to make money on idle servers at data centers.

If anything this is an extremely interesting time in currency experimentation. Side effect of this is massive energy cost, another awesome side effect is hardware/supercomputer miniaturization and evolution. Great for really hard problems like verification (as in mining here) and maybe brain research/processing or other really hard data crunching problems.