How can we harness a lot more energy from the oceans?

Oceans represent a significant source of sustainable energy - in the form of wave, tidal, osmotic power, marine currents and ocean thermal energy. However, only a very small portion of the potential has been harnessed. What innovative technologies and solutions can dramatically enhance the amount of energy harnessed from the oceans?

How will it have a positive impact?

Who will it have a positive impact on?