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I suppose it's similar to why you cannot have a 100% efficient wind farm?

Wind is not thermal energy, so energy extraction from it can achieve 100% efficiency in theory.

Turbines do have some theoretical limitation, but it's a technology limitation, not an ultimate theoretical one.

I thought it was more fundamental than that; to capture energy, there needs to be energy, if your wind turbine transforms all of it, there's no current anymore and the system will change phase.

Yes, Betz's law [0]:

"Consider that if all of the energy coming from wind movement through a turbine was extracted as useful energy the wind speed afterwards would drop to zero. If the wind stopped moving at the exit of the turbine, then no more fresh wind could get in - it would be blocked."

[0] https://en.m.wikipedia.org/wiki/Betz's_law

Thanks, I didn't know the name.

This is a fundamental limitation of turbines. Thus, a technological limitation for wind-power. Other technologies could have other limits.

Besides, that's a limit on collecting efficiency (how much you can collect / how much is there), not usage efficiency (how much you can use / how much you collect). You don't "destroy" the wind when your turbines don't collect it, it's still there.

I see, I considered the turbines as the only mean. Are there other transformer types for fluids ?

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