Have you seen any videos of turbines with natural sound? Does this one have it? The last time I looked at a Pentrex video with turbines it had a music bed and another video from another producer had fake sound effects.
I hear plausible turbine noise behind the music and narration in several of the clips in the promotional video. You can check the Mighty Turbines video here to see if you can get anything out of the remarkably low sound quality (apparently not enhanced along with the picture!). The DVD version lets you shut off the narration to concentrate on the sounds, such as they are.
Much of the filming in those days was done with relatively low fidelity and bad microphone gain control, and easily overloaded media, so much of the low-frequency rumble and high-frequency shriek has likely not been recorded in the first place, or is drastically clipped to ringing feedback just as the sound starts to get interesting…