A Princeton-led team has built a tabletop device that generates voltage directly from Earth’s rotation through its magnetic field. While the power output is orders of magnitude too small for practical electronics, the breakthrough suggests Earth’s spin could someday provide constant, fuel-free energy if the effect scales up. The team is now calling for independent labs to reproduce the results.
Nikolai Tesla theorized this 100 years ago. The plans that explain how his Wardenclyffe Tower was expected to work for data transmission were found, BUT he has said there was a secondary purpose for generating power from the Earth’s magnetic field and core rotation that he never detailed. I dont think they ever got that far, but he was clearly aware that the Earth’s magnetosphere was not the only generated sphere that was useful.