In the face of dwindling fossil fuel reserves such as those of coal and oil, scientists are at pains to generate electricity by harnessing the temperature difference between the oceans' surface and the deep waters. The sun bestows heat energy to the oceans, land and the atmosphere. It is estimated that the solar radiant energy of 80,000 million MW is 10,000 times that of what is used by the human race. It is also estimated that the difference between surface and deep-ocean water is around 27 degrees Centigrade. In the tropical countries, the temperature of the ocean surface is a good deal higher than that of the deep-waters.