I wasn’t able to find anything about it on Google nor peswiki.com so I can only comment on the information contained in the question.
It’s true that the Earth has a big old planet-sized magnetic field. The problem is that the field doesn’t fluctuate a whole lot from the perspective of someone on the planet’s surface. In order to generate energy from a magnetic field, the field has to be moving. That makes the concept unsuitable (at best) for terrestrial power generation. If you happen to be in space, it might work- except that you’d need to be in orbit around the Earth, far enough away to move perceptibly relative to the field but close enough that the field is still strong. The inverse-square law tells us that the field strength falls off really rapidly with distance. Another problem is that, well, the energy has to come from somewhere. If your hypothetical satellite was extracting energy from its motion relative to the Earth’s magnetic field, then it would slow down. This would change its orbit and probably make it stop working (and if it slowed down enough, it would deorbit.)
Also, if you happen to be in space, it’s a lot easier to just put up a solar panel :^)