yes I can answer this, very simple but before that just tell me how you undrstand the following terms , because if you dont know these, there is no point I am wasting my time.
Just come to the point without going around circles.
How could CEB generate cheaper power by pumping the water released from the turbine chamber back to the reservoir ?
Because of in-efficiencies it would cost more to pump the water back than it generates.
You go and consult whoever you want and come with the answer.