Tapping the Earthís Rotational Energy
Fig. 1 depicts an inertial frame side view of a flywheel and its gimbal, mounted on a merry go round. The flywheel and its gimbal are free to rotate (independent of the merry go round) around the gimbal axis. The merry go round can similarly be rotated around its vertical axis.
Side View of Flywheel and Merry Go Round
If the flywheel has a high rate of spin about its axle, then it (and its gimbal) will maintain its orientation in the inertial frame when the platform rotates beneath it. Indeed if the gimbal is rimmed by a large "equatorial" gear, and if this gear engages a smaller gear whose axle is fixed relative to the merry go round, then the smaller gear will spin relative to the merry go roundís (noninertial) rest frame (quite as the large gimbal gear will) when the platform rotates. (Viewed from inertial space, the small gear and the merry go round will rotate around the large, gimbal gear, which remains at rest.) Fig. 2 depicts a top view of the gears.
Top View, Showing Large and Small Gears
Now the small gear in Fig. 2 can be attached to a load (such as a generator), and can generate useful power. This power is of course obtained at the expense of the merry go roundís rotational kinetic energy. If the merry go roundís angular momentum is not kept constant by some other, external power source, then its angular velocity will decrease. The rate at which this angular deceleration occurs will depend on the merry go roundís mass and the rate at which energy is generated by the small gear/generator.
Let us substitute the rotating earth for the merry go round. Compared to mankindís energy requirements, the earthís rotational kinetic energy is enormous. The system depicted in Figs. 1 and 2 is most easily envisioned when the gimbal axis is mounted above either of the global poles. However, the system will in principle work anywhere on the earthís surface, provided only that the gimbal axis is oriented parallel to the planetís spin axis.
Of course one rotation of the large gear every 24 hours is tediously slow. The power obtained from such a device may not justify its expense (at least not while fossil fuels are available). However, the flywheels of such devices might do double duty, saving photovoltaic energy (generated during daylight hours) for use at night, etc.
If nothing else, it is entertaining to think that mankindís quest for (almost) perpetual motion with positive power output is physically realizable. The extremely gradual rate of decrease in the earthís spin rate caused by such devices would be nothing new. This rate has been decreasing for billions of years under the influence of tidal friction and other factors.