Tidal energy is one of the most reliable and predictable source of renewable energy. There are two ways of creating tidal power: tidal dams and ocean currents. Dams are based on using a barrage at a bay or estuary with a large tidal range. Power is generated primarily at ebb tides as the barrage creates a significant head of water, much like a hydroelectric dam. Tidal turbines take advantage of fast-flowing ocean currents to create energy. The horizontal axis ocean turbines are the more common ones and are only half the size of the wind turbines, which are producing 1 MW of power.
The oceanís energy is created when the sunís heat warms up the ocean surface water. The Ocean Thermal Energy Conversion (OTEC) is a method that takes advantage of this temperature difference for generating electricity. There are three types of electricity conversion systems: closed-cycle, open-cycle, and hybrid. Closed-cycle systems use the ocean's warm surface water to vaporize a working fluid, which has a low-boiling point, such as ammonia. The vapor expands and turns a turbine. The turbine then activates a generator to produce electricity. Open-cycle systems actually boil the seawater by operating at low pressures. This produces steam that passes through a turbine. The hybrid combines both closed-cycle and open-cycle systems. OTEC is a successful system of power generation that has been in use since 1974. This system makes it wise thing to invest in tidal energy