Answer:
When CO2 is breathed into the lungs, it dissolves in the water there, diffuses across the alveolar-capillary membrane, and enters the bloodstream. As it combines with water, it forms carbonic acid, making the blood acidic. So CO2 in the bloodstream lowers the blood pH.
I may be wrong but i think that they are
1. turbines are added under the water and when the movement of water effects that is uses power to gather electricity
2. there are big barries in the water that spin the water around and then that in turn creates energy