How does using Tidal energy affect the moon? Reading another question Where do we have it from that the Moon is migrating away from Earth?
I makes me ask what effect does harvesting tidal energy for electricity production have on the rate the moon gains angular momentum?
Presuming the most common harvesting methods involve underwater turbines in tidal zones with water flowing regularly in both directions (twice per day).
It is minute and inconsequential.  Without tidal energy harvesting, the motion of the water is ultimately converted into heat, it has a very small heating effect (that is swamped by the heating caused by the sun). With tidal energy harvesting, instead of heating the water, a little of the energy is converted to electricity (which is then converted into light or heat,  ultimately the energy becomes heat)
The tidal dams can change local tidal patterns, which could have a minute effect on the moon's motion, but this effect is minuscule.