Ocean Thermal Energy Conversion (OTEC) is an energy technology that converts solar radiation to electric power. OTEC system uses the ocean's natural thermal gradient—the ocean's layers of water have different temperatures—to drive a power producing cycle. As long as the temperature between the warm surface water and the cold deep water differs by about 20°C (36°F), an OTEC system can produce a significant amount of power, with little impact on the surrounding environment. The oceans are thus a vast renewable resource, with the potential to help us produce billions of watts of electric power. This potential is estimated to be about 1013 watts of base load power generation, according to some experts. The distinctive feature of OTEC energy systems is that the end products include not only energy in the form of electricity, but also several other synergistic products.