Desalinated water is expected to account for up to one-third of the nation’s water supply in coastal regions by 2020, as demand for purified saltwater rises in the wake of a worsening water shortage, according to a chief engineer in Tianjin.
Areas desperate for more reliable water sources include 11 provinces and cities in the east, as well as the dry north, experts say.
While thirsty cities await a massive 140.5 billion yuan ($20 billion) project to pump 40 billion tons of water to parched northern regions - an initiative dubbed the South-North Water Diversion Project - Tianjin, located 140 kilometers southeast of Beijing, has already turned to the sea for fresh water, making it a pilot city in the desalination efforts.
Despite huge investments in building reservoirs and water-diversion projects, China will face a water shortage of 201 billion cubic meters by 2030, with about 300 million people lacking safe drinking water, according to a report issued in April by consulting firm McKinsey & Company.
Tianjin now has a daily production capacity of 100,000 tons of desalinated water, about 10 percent of the city’s total water demand, according to Ruan Guoling, the chief engineer of the Tianjin Institute of Seawater Desalination and Multipurpose Utilization, which operates under the State Oceanic Administration.
Guo Qigang, general manager of the Tianjin Beijiang Power Plant, said the company now produces and supplies 30,000 tons of desalinated water daily to Tianjin’s Hanggu District and the Binhai New Area, as of this month.
Yang Suoying, an engineer with Beijiang, a major producer of desalinated seawater in Tianjin, told the Global Times that the company’s production capacity could be doubled to 200,000 tons within a year.
“As a subsidiary business, we use wasted steam gas emitted from electricity production to produce desalinated water, which in turn increases 10 percent of our thermal efficiency,” Yang said. “Though the desalination business doesn’t make much money at the moment, we are quite optimistic of its economic returns in the long run.”
One unit of desalinated seawater is mixed with three units of fresh water before it is pumped into the water supply to local households, Ruan said, adding that the safety and quality of the mixed water is under strict supervision.
Liu Baoliang, who lives in Hangu District, offered his support to the project, as long as it stays safe and relatively inexpensive.
“I don’t think there is a difference in the taste between ordinary fresh water and seawater turned into (drinking) water. Local bottled water Haiderunzi, which is made of desalinated seawater, tastes the same as other bottled water,” Liu said.
Ruan predicted that, in the next decade, the proportion of treated seawater in Tianjin will increase to 30 percent of the total used water.
The environmental impact and hefty price tag of the technology, however, seems to be worrisome for some experts who question whether the practice should be promoted in a larger context.
“It could be a supplement to the current water supply in some coastal areas, but its development comes at the expense of energy depletion,” Ruan conceded, noting that the desalination process basically trades energy for water.
Despite the planet’s vast oceanic water resources, experts warn that desalinated water is not inexhaustible, as its production is restricted by energy and environmental capacities.
“In an effort to tackle the dwindling water resources, we always seek to explore more water supplies while ignoring resource reserves. It’s pathetic that we now have to turn to the sea, which faces severe pollution and may run out of clean water for us to use,” Ma Jun, director of the Institute of Public Environmental Affairs in Beijing, told the Global Times.
The production of desalinated water is coupled with energy consumption and emissions, and the discharge of high-density saltwater could harm the already-polluted oceans, Ma said.
“We have been exploring water sources over the past 50 years, but what is missing here is how to protect the resources in the meantime. So when we start to explore water resources from the sea, we should also learn lessons from the past,” Ma said.
During the past three decades, Tianjin has largely relied on large-scale hydro projects to divert water from the the Luanhe River, which consequently alleviated the water shortage until the river recently has been running out of water.
“Due to the shrinking water level of the Luanhe River, the project can no longer meet the city’s increasing demand,” Guo Youzhi, general secretary of the China Desalination Association, told the Global Times, adding that seawater desalination may be a solution.
According to Beijiang’s Yang, the cost to produce desalinated water is about 8 yuan ($1.17) a ton, which is twice as much as the current price of water in Tianjin.
“It’s hard for desalinated water to compete with other water resources whose prices are greatly depreciated,” Ruan said, adding that, without government subsidies, treated seawater can be hardly put into the market while the national water price is not market oriented.
With mature technology, Ruan noted, water conservancy and quality supervision authorities should collaborate to set up a trial zone to study the side effects before such projects are massively implemented.
