A new solar power collection and heating device could be used to turn salt water into fresh water at an unprecedented low cost, researchers said yesterday in Nanjing, capital of east China's Jiangsu Province.

The new invention, by scientists at the School of New Materials and New Energy in Hehai University (HHU) and Nanjing Fiberglass Research and Design Institute, has been reported in the local media.

According to Zhou Ningyu, a senior engineer with HHU, the new desalinating device consists primarily of a heliostat, which absorbs solar power and turns it into heat. The heat is then used to bring water to boiling point, and when vaporization occurs the salt becomes separated.

According to Zhou, the country currently has 20 desalination projects, which mainly use osmosis and electronic distilling technologies.

"These consume other resources, such as electricity and carbon, to produce fresh water. But our device makes use of solar power. The only costs are the heliostat system and the infrastructure construction. It is the most economical and eco-friendly desalination method invented so far," said Zhou.

Furthermore, a special heliostat, invented by a scientist in the team, costs only a quarter of the normal price but still generates the same amount of energy, Zhou told China Daily.

Zhou did not reveal the exact cost for fresh water production, but said it would definitely be much lower than the current technologies, which cost about 5-8 yuan (US$0.62-1) per cubic metre.

The water distilled by the new device meets the standard for drinking water and could be used in local houses, according to Zhou.

Zhou also revealed that salt companies are already interested in buying the salt produced, another form of economic return.

While they believe the system can be profitable, the scientists said they have not raised enough capital to put their design into large-scale production.

"The investment for a large-scale desalination project would be huge, and exceeds the capacity of ordinary individual enterprises," said Zhang Yaoming, a 63-year-old expert who led the research team.

Zhang said he is seeking financial support from relevant bureaus including the Ministry of Science and Technology.

He added that the abundant solar resources in China, if properly used, could equal "thousands of Three Gorges Power Plants."

Zhang said that he is confident of the future application of the new device in thirsty coastal areas in the country.

Listed among the driest countries in the world, two-thirds of China's cities are suffering from water supply shortages for domestic and industrial use.

According to the National Development and Reform Commission and other State-level agencies, desalinated sea water is expected to contribute 16 to 24 per cent of the water supply in coastal areas by 2010, with a daily capacity of up to 3 million cubic metres in 2020.

(China Daily June 8, 2006)