Can controlled nuclear fusion really provide nearly unlimited energy for mankind?

The fuel consumed by fusion is deuterium (an isotope of hydrogen), and the content of deuterium in seawater is very high, with an average of one deuterium atom in every 6420 hydrogen atoms. There is about 100 tons of seawater on the earth, which means 100 tons (4 trillion tons) of deuterium. Regardless of the energy conversion efficiency, so much deuterium can theoretically generate kWh (900 billion kWh) of energy. According to the data of IEA, the global energy consumption in 20 13 years is about kwh. At this consumption rate, deuterium on the earth will last for 90 billion years. From the perspective of fuel reserves, controlled nuclear fusion can indeed be regarded as an almost infinite energy source. The ultimate source of the earth, whether stored in the form of wind, water or animals and plants, is the sun: fossil fuels evolved from animals and plants millions of years ago, and the energy of animals and plants (whether today or before) finally comes from the solar energy stored by photosynthesis of plants at the bottom of the food chain; The cause of wind is the uneven heat and cold caused by the sun heating the atmosphere; Hydraulic water depends on the heating of the sun to make the water in the lower layer evaporate and rise, and then it is "transported" to a higher layer in the form of precipitation, thus forming potential energy. So no matter what kind of energy people use, in the final analysis, they are all using solar energy, and the energy of the sun comes from nuclear fusion. Therefore, if human beings master the method of orderly releasing nuclear fusion energy, it is equivalent to mastering the energy of the sun, which is equivalent to mastering inexhaustible fossil fuels, wind power and hydropower energy. Some people advocate that modern industry will go extinct and go bankrupt because there is no energy. Therefore, it is well-deserved that the controlled nuclear fusion reactor is called "artificial sun". China is in a leading position in controlled nuclear fusion's technology, and the EAST reactor, which is about to start operation, is the first reactor in the world to meet the practical engineering standards. If it can be successfully operated, the time for commercial power generation in controlled nuclear fusion is not far away.