This is something that I have wondered about for a while now which is related to how tidal power stations work and the law of conservation of energy. Scenario: As far as I am aware the tidal variations all around the world are primarily caused by the gravitational force of the moon on the vast oceans. To simplify the scenario, tidal variation in a certain area is 2m - that is at low tide height = 0, high tide height = 2m. If a Bucket suspended on a rope at a height of 1m at low tide, and then left for an entire cycle, that same bucket will now be filled with water. The gravitational potential energy has now been increased, as the mass inside the bucket has increased. The bucket is to represent a visual model of water being moved via the high and low tide variation. Using Dams instead of buckets, and using turbines electricity can be produced. My Query: My understanding is that the energy transformations go like this Gravitational potential energy from the moon oribitting the Earth transfers into kinetic energy in the waves around the world, this kinetic energy transfers into potential energy in the dam and then is transfered into electical energy via the turbines. What I don't understand is where the energy loss is. My understanding is that the energy ultimately is sourced by the moon orbitting the Earth, and if the orbitting radius stays constant and the Mass's of Earth and Moon stay constant. Where is the energy loss? The only solutions that I can think of is that either the moon is slowing collapsing into the earth, the masses of the Earth and Moon are increasing or that the conservation of energy laws need to be explained to me further. If anyone can explain to me this scenario I would be most thankful. (Also I apologise if this is not posted in the right thread).