China science

China’s desalination system may ‘tip the balance’ in South China Sea land disputes, scientists say

Research team says compact new device only needs low levels of heat and energy, making it suitable for use on remote islands and reclaimed land masses

PUBLISHED : Friday, 15 January, 2016, 8:30am
UPDATED : Monday, 12 June, 2017, 12:53pm

China has made a breakthrough in desalination technology that could help it produce fresh water on remote islands and also quickly expand habitable areas on reclaimed land or natural islets in the South China Sea, where it is engaged in territorial disputes with several of its Asian neighbours.

Moreover, the country often faces droughts in its arid north and has been looking at ways of getting more fresh or potable water to dry provinces and municipalities. According to a report by Bloomberg in April of last year, the Chinese government has been planning to quadruple desalination by 2020.

As such, the recent test run of a new desalination system that can remove salt and other harmful elements from seawater using heat produced by a diesel generator may come as music to the ears of Chinese authorities.

The system is currently in operation on Guishan Island off the coast of Zhuhai city in the southern Chinese province of Guangdong.

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The tests were carried out by a researcher at the Guangzhou Institute of Advanced Technology in Guangdong, and the heat drawn from the generator would otherwise have been considered a waste product, according to an announcement on the institute’s website.

Although the system is intended for peaceful purposes, it has been hailed in some quarters as being of strategic interest to the nation and its military “comparable to an air carrier fleet”.

The last remark was made by a Chinese scientist who was involved with the project but did not want his name used due to the politically sensitive nature of the work.

“It will further tip the balance of power [in the South China Sea],” he added.

Diesel generators are commonly found on islands in the Paracels and other disputed areas in the South China Sea. They generate electricity for military facilities such as radar and communication devices, among other tasks.

On most of the islands controlled by China in the South China Sea, drinking water comes in barrels together with other supplies from small boats, making it as scarce as fuel.

According to reports in the country’s state media, some soldiers could not take a shower for months on end and had to rely on rain water when their water supplies became ruined by the weather.

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The water shortages experienced on remote islands like these also frustrate China’s ambition to build civilian facilities such as hotels and tourism resorts there, as part of its bid to strengthen its claim and control of the region. But the new desalination technology could change all that, the researchers said.

First, the device requires no extra energy input, making it relatively cheap to use. Using the waste heat produced by a 1000kw diesel generator, it can produce up to 60 tonnes of fresh water a day. This is enough to cater to the consumption needs of 300 residents or a battalion of soldiers, the scientists said.

Using heat for desalination usually requires a tremendous amount of energy that no small island could easily produce. Conventional methods simply bring seawater to the boil and condense the vapour to make drinkable water.

But the Guangzhou team used a different approach. They reduced the seawater to tiny droplets at the top of a chamber filled with heat-exchanging rods. The rods were warmed by water from the diesel generator’s cooling system. Upon touching the rods, the droplets evaporated, and the resulting vapour was blown into a condenser, where it became fresh water.

One of the boons of the system is that it only requires relatively low heat, which can be produced easily by the generator, the team said. It is also compact, making it suitable for transport to local islands.

Moreover, lab tests have shown that the fresh water which is produced fully meets national safety standards and is immediately drinkable, the team added.

Other desalination methods, such as those relying on solar-powered plants, require large areas of land for construction.