What are the limitations of the energy that can be obtained from the oceans?

Explanation

Energy from the oceans can be obtained in the form oftidal energy, wave energy and ocean thermal energy. But these energy sources suffer from the following limitations:
• There are very few location where dams to utilise tidal energy can be built.
• Cost of installation of power houses is extremely high and efficiency of plant is comparitively small
• Power plant built in oceans or sea shores will need high continuous maintaince as chances of corrosion are exteremely high.