Houdini - there are loads of tidal energy companies out there, but none that are public. As with other energy segments, there are many different and interesting approaches being researched and developed, including wave energy, tidal energy, ocean thermal energy and even leveraging the desalinization process through extracting the delta of energy between converting salt water to fresh water.
No real significant commercialization of the technologies at this point and the contribution to the grid is inconsequential as yet. But there is alot of attention looking in this direction, as the ocean represents and endless source of potential energy.
This June, there is actual the 5th annual Energy Ocean conference being held in Galveston which will garner more attention to the sector.
Here is a companies that could be an early benefactor from the space:
* Oyo Geospace (Nasdaq:OYOG) - equipment manufacturer, also a good company to know that will benefit from deepwater drilling.