Page 398 - Handbook of Energy Engineering Calculations

work is reduced, however.
In the system, shown by the ocean and pool level and power diagrams of
Fig. 5, the reversible turbines are allowed to operate during periods of pool
filling and emptying instead of at high and low levels only. They cease to
operate when the head is too low for efficient operation. Period C begins
1
with both pool and ocean at low-tide level 1, the ocean at the beginning of
tide rise, and all gates closed. When the head is sufficient 2, gates to the

turbines are opened and water from the ocean is allowed through. Power is
generated during period G as both ocean and pool levels rise. The ocean
1
level reaches its peak and begins to decrease but the pool level is still

increasing until, at 3, the head is too low for efficient generation. The gates to
the turbines are closed and bypass gates are opened so that the pool is
allowed to fill up during period F to 4. At 4 all gates are once again closed

and the pool level remains constant while the ocean level decreases during
period C . At 5 the head is once again sufficient to allow for turbine water
2
flow in the opposite direction and a second generation period G begins. At 6
2
generation ceases but the pool is allowed to empty during period E and the
system goes back to point l, repeating the cycle. The power generation shown

is certainly not uniform but much more so than in the case of the simple
system.