It is pointed out in the passage that one advantage of harnessing the tidal flow to generate electricity is that —.

A curious form of renewable-energy generation may
be on the horizon - with underwater turbines. These
units harness the power of tidally driven currents,
which flow back and forth like clockwork, making it
possible to generate electricity on a predictable
schedule. In this respect, underwater turbines are
more attractive than their wind-driven counterparts,
which are now employed widely to help power
electric grids. Underwater structures are also less
likely to be damaged by violent storms which have
little effect on submerged objects. And using
underwater turbines sidesteps the common
objections to conventional hydropower - that
damming a river stops migrating fish and inundates
land upstream. Underwater turbines have long been
used on a small scale. But soon now they will be
used on a large scale to produce megawatts of
electric power.