Why haven't we tapped the energy in sea waves to rx our energy ?

Question

I have a prototype to do just that..

Answer 1

and what is the production cost for your prototype? Maintainability? Availability of resources to produce and install? Resiliance to attacks from undersea currents and animals? What about storms?
...
...
...
We use oil because its the cheapest way.

Answer 2

they already exist on a small private scale- wave turbines.