You can add power to your golf swing from increasing your hip rotation. A fast and full hip rotation adds club-head speed which translates to increased distances to your shots. A good example of someone who has excellent hip rotation is Rory McIlroy. He is a man of average stature – 5′ 9″ and 161 lbs. But hits the ball far and at speeds of around 175 mph.
Rory has a hip speed which is 25% faster than most other professional golfers. His hips rotate 720 degrees per second on the downswing. Other professional golfers average about 550 degrees per second and most amateurs 300-350 degrees per second.
Faster hip rotation = longer driving distance!
Faster hip speed(s) result in very small increases in club head speed. Rory's distance is not due to his hip speed, it's due to the lag between his right hand and the club shaft. His faster hip speed is most likely due to his over rotation of his hips during the takeaway and backswing, so he has to rotate them really fast to get them back to neutral at impact.