 The kinetic energy of marine currents can be converted in much the same way that a wind turbine extracts energy from the wind, using various types of open-flow rotors.The total worldwide power in ocean currents has been estimated to be about 5,000 GW, with power densities of up to 15 kW/m2.The relatively constant extractable energy density near the surface of the Florida Straits Current is about 1 kW/m2 of flow area.