In practical applications, efficient and cheap energy storage is the key to utilizing the natural energy of temperature differences. Currently, humans have discovered a variety of efficient energy storage organisms. It can be mainly divided into two categories: one is organic materials such as propionic alcohol; the other is inorganic materials, such as compound salt water, calcium sulfate and other substances. These substances can store the natural energy absorbed by the temperature difference and release it when needed. The United States and Germany have used these energy storage materials to construct energy-efficient buildings and put them into operation.
The temperature of the seawater surface and that of the deep layers can differ by more than 20 ℃, and this difference also contains enormous energy. It is estimated that the cTotal capacity can reach 2 billion kilowatts. At present, scientists are actively working on the development and utilization of thermoelectric power, and ocean thermoelectric power generation has entered the experimental stage. The United States and France successively built small experimental power plants. In 1990, the thermoelectric power station built by Japan in Kagoshima now provides normal electricity supply. In addition, using the temperature difference of sea water to generate electricity also has the function of desalinating sea water. A 100,000 kilowatt thermoelectric power plant can produce 378 cubic meters of water sweet every day. Generating electricity from ocean temperature differences can also extract rich nutrients from deep waters and increase offshore fishing. The idea of using temperature differences as a sourceof energy in the ocean is fascinating. This is the ocean temperature difference energy, also called ocean thermal energy. Since seawater is a substance with a large heat capacity and the volume of the ocean is so large, the amount of heat retained by seawater is enormous. This thermal energy comes mainly from solar radiation, in addition to the heat emitted from the interior of the earth to sea water; heat released by radioactive materials present in seawater; and the radiant energy of other celestial bodies; but 99.99% comes from solar radiation. Therefore, the thermal energy of seawater varies considerably depending on the location of the sea area. Ocean thermal energy is one of the sources of electrical energy, and 2 billion kilowatts can be converted into electrical energy. However, the idea of producing electricity from eau de mer, first proposed by the French scientist Delson in 1881, was buried for almost half a century. It was not until 1926 that his student Claude realized his teacher's wish.