3. Turbines

The choice of turbines is essential, and they are very different from those used in conventional hydroelectricity. Load can vary greatly, affecting efficiency, and two-way operation or pumping may be required. The cost of civil engineering per kW can also vary greatly with the choice of turbines, as well as construction and programming facilities. Finally, a different optimal turbine may be required for each type of pond use. The optimization of turbines and the corresponding civil engineering seems to be an essential element of optimization for the coming years, and could be applied worldwide.

The horizontal-axis bulb turbines at La Rance have been in operation for 50 years, and are designed to operate as turbines or pumps in both directions. They are therefore quite complex and costly, and their efficiency - very good for turbines in one direction under high load...