Describe some of the possible ocean energy sources.

There are three approaches developed so far: Two involve motion and one involves temperature. Two types of kinetic energy show the most promise: the energy of wave motion and the energy of tidal motion. We can harness tidal energy by erecting dams across the outlets of tidal basins. The incoming tide is allowed through sluices past the dam and the outgoing tide is passed through the dam, turning turbines to generate electricity as is done in dams for conventional hydroelectric power. Tidal stations release few or no pollutant emissions, but they can have substantial impacts on the ecology of estuaries and tidal basins.

Wave energy could be developed at a greater variety of sites than could tidal energy. The principle is to harness the motion of wind-driven waves at the ocean's surface and convert this mechanical energy into electricity. Wave energy is greater at deep-ocean sites, but transmitting the electricity produced to shore would be expensive. Other designs are for coastal onshore facilities. Potential negative impacts include harm to coastal and marine ecosystems, hazards to boats, and aesthetic impacts on scenic beaches.

Other oceanic energy sources we have not yet tapped include the motion of ocean currents and the immense thermal energy contained in the oceans. The concept of ocean thermal energy conversion (OTEC) has been most developed. The ocean's sun-warmed surface is higher in temperature than its deep water, and OTEC approaches are based upon this gradient in temperature.