adam rainye, mexico city. >> with soar and wind energy being popular alternatives, attention is beingurned to harnessing the nation's tides, daniel lak has this special report. can the planet's biggest tides be used? >> what we are exploring here 14 billion metric tons of water, more than the combined flow of all of the world's rivers moves through this passage each day. >> entering tidal energy is taking a wind turbine and putting it under water in a high-flow environment. >> in partnership with government and the local power company, a european firm is building a 15 meter wide turbine with plans to sub merge it this year. an attempt to install such a device failed in the smaller unit broke down hours. this time is different says the company. >> we have learned we have local, very local size of the characteristics. this is really where we have learned from this. this is why we are back again. >> low tide. from the bottom of the ocean. in here into a bay that can be 12 or more meters deep. north america's first tidal project is just across the bay. the annapolis generating station has