The interesting thing here isn't a clock, it's the novel power harvesting device. There simply happens to be a clock tied to the output end of the shaft.
You could get some random highly-accurate clock and put that on instead, or you could put a wheel with an arrow on it, and it would be no more or less interesting.
You could get some random highly-accurate clock and put that on instead, or you could put a wheel with an arrow on it, and it would be no more or less interesting.