And that same site says this:
Most of the energy dissipates due to friction between the water and the shallow floor.
According to their report, appearing in the June 15 issue of Nature, about 1 trillion watts, or 25 to 30 percent of the total tidal energy dissipation, occurs in the deep ocean. The remainder occurs in shallow seas, such as the continental shelf off the southeast coast of South America.

The deep-water tidal dissipation occurs generally near rugged bottom topography (seamounts and mid-ocean ridges).

It also says that the rest of the tidal energy is probably used to mix the waters - There's lots of things going on in the ocean - Correct me if I am wrong but cold water sinks - as the polar caps melt their waters drop down and start the cycle of ocean currents - so not only is there tidal energy but there are hot/cold currents moving around too.