Harnessing the rotation of the Earth is certainly valid in theory, but a practical example is really hard to envision. At last one that generates the 30kW they quote. That page has elaborate scam written all over it.
An example of a machine that could harness the Earth’s rotation for near-unlimited power:
- Build a space elevator, with the far end past Geosync orbit and hooked to a counterweight.
- The Earth side is at the north or south pole, and it attached to a generator with a LOT of upgearing.
- As the Earth rotates it spins the generator. The counterweight is pulled towards Earth, but the centripetal forces on it should keep the line taut and straight.
This however would be by far the least practical energy system ever devised. Any other renewable energy source is going to blow it out of the water in a cost efficiency analysis.
