I recall estimating the power required to run an equatorial superconducting ring a few meters thick 1 km or so under the Mars surface with enough current to simulate Earth-like magnetic field. If I recall correctly, it would require about the current level of power generation on Earth to ramp it up over a century or so to the desired level. Then whatever is required to maintain it (mostly cooling the ring), which is very little. Of course, an accident interrupting the current flow would be an epic disaster.
Wouldn't it be more efficient to use that energy to destroy Mars and build start building a Dyson swarm from the debris?
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