Seawater desalination

On the surface of the earth, seawater occupies 97%; fresh water occupies 3% in a non-uniform distribution. In some regions, fresh water resources are extremely absent. As a consequence, the worldwide first set of solar vaporizer appeared in Chile in 1872, making seawater desalted by use of solar energy with the fresh water production capacity of 17.7 tons per day, which had been operating until 1910. There were 25 sets of large scale solar vaporizer constructed in the world until 1974, among which more than 10 sets had the daily production of more than 1 ton, and the biggest set had the daily production of 28.08 tons with the area of 8640 m². After the 1980s, reports on the construction of solar seawater desalination device have rarely few.

In the 1970s, one set of solar vaporizer with the area of 385 m², daily fresh water production of 1 tons, and one set with the area of 50 m², daily fresh water production of 0.2 tons were constructed respectively in Wuzhizhou island and Xisha Zhongjiang island of Hainan province.