Page 397 - Handbook of Energy Engineering Calculations

2. Find the average power

The average power during the generation period of 4 h is

The average power during the total period of 6.2083 h is

In the simple single-pool system, the corresponding values are

Thus the simple single-pool system produces some 10 times the work and

average power of the modulated single-pool system. However, the former
does so almost in a “spike,” which is very hard on the power grid and
requires very large turbines that remain idle most of the time. The latter
produces its work over several hours and hence avoids these problems.
The actual work and power above must be multiplied by the efficiency of

the system, which is probably in the 25 to 30 percent range.

Related Calculations. In the simple single-pool system (above), two high-
peak, short-duration power outputs occur every tidal period. Such peaks
necessitate large turbine-generators that remain idle much of the time. The

power peaks also occur at different times every day (50 min later each
successive day), at times of high and low tides that almost surely will not
always correspond to times of peak power demand, and pose a burden on the
electric-power grid they are connected to.

The modulated single-pool tidal system partially corrects for these
deficiencies by generating power more uniformly at a lower average head,
though still with some periods of no generation. Because the average head h
2
is lower and work and power are proportional to h , the turbine-generators
are much smaller and operate over much longer periods. The resulting total