The oceans cover more than 70% of Earth's surface and capture a large part of the sun’s heat in the upper layers, making them the world's largest solar collectors and energy storage system. Utilizing just a small portion of this energy, can cover the global energy need.
The energy source of OTEC is free, available abundantly and is continually being replenished as long as the sun shines and the natural currents drive the process at the earth’s poles where the water is chilled and sink to the lowest points of the ocean floor.
Various parties estimate the amount of energy that can be practically harvested to be in the order of 3 to 5 terawatts, without affecting the temperature of the ocean or the world's environment. That’s about twice the global electricity demand. The oceans are thus a vast renewable resource.
The technology is viable primarily in equatorial areas where the year-round temperature differential is at least 20 degrees Celsius or 36 degrees Fahrenheit.