The diagram illustrates how electricity is made with geothermal energy.
Overall, the water flows down from the high-level resevoir into the power station then goes into the low-level resevoir, only for it to be pumped back into the high river at night to repeat the proccess when day comes.
During the day the water from the high-level resevoir goes into the power station to turn the turbines and generate energy. The energy then turns into electricity while the water flows down into the low-level resevoir. the water is then brought back up to repeat the process.
The water is stopped by a dam to prevent it from ruining the power station. The intake in the high river is open during the day and closed at night to prevent any water from flowing back down. Flow of the water during the day is directed downwards by gravity while at night its pumped up back into the high-level resevoir. The reversible turbines are ultimatley the ones doing all the work by pumping water up during the night and operating energy during the day.