How do you measure windmill efficiency without using a generator?

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Question by Emilita: How do you measure windmill efficiency without using a generator?
Is there a formula I can use to convert the number of the windmill’s rotations into watts or some other measurement? I’m doing a science fair project about windmills and I don’t have a generator I can use to measure the amount of electricity produced. The only formula I found is watts = (Kh x number of disk rotations x 3600) / number of seconds, but I don’t have the Kh.

I’m really confused, please help!

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