Researchers have devised many creative methods to generate energy from the sea, without producing pollution. Most are in the prototype stage, but several hold a good deal of promise. The ocean is an enormous, untapped source of energy.
The methods for capturing ocean energy are generally based on waves, tides or temperature differentials. Waves are very concentrated forms of energy, but are difficult to harness; the equipment is easily damaged. Tides are reliable and easier to tap, but often, tidal generators interfere with shipping or they are widely dispersed, creating transmission difficulties. Ocean thermal energy conversion (OTEC) has been well-tested, but is not likely to be a major power supply because it is expensive, highly distributed, and may have adverse effects on marine creatures because the devices alter the temperature of the water at different depths.