Tidal turbines have blades that turn a rotor to power a generator just like other turbines. They are placed on the seafloor where there is strong tidal flow. Because water is denser than air, tidal turbines are much heavier than wind turbines. The turbines would be installed at depths of 300 feet (91 meters) or more, in areas of fast-moving water "where not many things live". However, blades of such turbines may injure or kill aquatic species. That is why new technologies to innovate underwater turbines are now a widely popular topic of research. Case Study.
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