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Re:Tidal Energy Is Not Renewable by hn_throwaway_99 on Monday September 04, 2023 @03:26PM (#37384005)
But don't the tides naturally dissipate a lot of that energy anyway? E.g. whenever you go to the beach and see waves crash upon the shore, that's tidal energy being dissipated as heat. If you stick a turbine in the mix to extract useful work before it turns into heat, isn't it still turned into heat regardless?
Re:Tidal Energy Is Not Renewable by hollerith on Monday September 04, 2023 @04:27PM (#37384671)
Quoting from the OP:

>it will take about 10.468 billion years for Earth to lock to the Moon naturally.

Re:Tidal Energy Is Not Renewable by dre85 on Monday September 04, 2023 @11:23PM (#37387481)
That's exactly what I was wondering as well. I didn't really understand how tapping into the power source could possibly cause an additional loss that wouldn't otherwise happen.
Re:Tidal Energy Is Not Renewable by timmaxw on Tuesday September 05, 2023 @02:06AM (#37388381)
Yes, tides do naturally dissipate energy. The main source of tidal dissipation is friction between the moving seawater and the seabed. [1]

Current tidal generators work either by inserting a turbine into the moving water; or by a dam that captures the high tide, then releases it through a turbine at low tide. Depending on the exact details, it could slow down the rate at which the current later flows over the seabed, which would reduce the energy dissipated from friction with the seabed. But, there's no guarantee that this would compensate for the energy taken by the tidal power generator.

You could imagine a different type of tidal power generator: covering the seabed with a giant treadmill. As water flows past, it drags the surface of the treadmill, generating power. My guess is this would dissipate less total energy than the natural friction of the seabed does. But, it doesn't sound very practical.

(Anyway, all of this is a moot point. As other commenters have noted, if human energy consumption actually were to grow 2% annually for 1000 years, we'd have way bigger problems than the moon becoming tidally locked.)

[1] https://en.wikipedia.org/wiki/Tidal_acceleration#Angular_mom...