I've seen this idea before, and someone did the math showing that while it would be possible it would take an exceptionally large amount of energy to keep the m

I've seen this idea before, and someone did the math showing that while it would be possible it would take an exceptionally large amount of energy to keep the magnetic field running. Not impossible, but I recall it being equivalent to some significant fraction of the energy produced by all power plants on Earth or something like that. Have any advances been made to lower the energy needs for something like this?