If you want efficient rotation get a politician.

Seriously ... I would be thinking cryogenics ... superfluidity.

It is true that any moving magnetic field will create an electric field. That is middle school physics.

The question is really one of what is creating the magnetic field (there must be a cost) and what is creating the movement (there must also be a cost).

My preference would be all the prisoners in all the prisons on a very large wheel. Now that would be paying their debt to society.

DA Morgan