CHINESE officials are fond of grandiose engineering projects. After more than a decade of toil, one of the biggest since the construction of the Great Wall is close to achieving what they like to call a “decisive victory”. In coming months, canals and pipelines hundreds of kilometres long will bring water from the Yangzi River basin to the parched north. But growing demand is forcing officials to look for other sources. A promising one, they believe, is the sea.

The Beijiang Power and Desalination Plant lies a few hundred metres from the coast; its chimney and two cooling towers dominate a desolate expanse of salt farms. The $4.1 billion facility is one of the pet projects of the government in the port city of Tianjin, a manufacturing and logistics hub that, like nearby Beijing, enjoys provincial-level status and is one of China’s fastest-growing regions.

The Beijiang plant began generating electricity in 2009, and the following year became China’s first large-scale supplier of desalinated water through a city main. For Tianjin at least, the plant offers a ray of hope. The city, like most of northern China, is desperately dry. Local water resources per person are less than 7% of the national average.

By the middle of this year the first of three planned water-diversion projects bringing water to the north from the Yangzi basin is due to open for trial use. This easterly route (see map), which is more than 1,100 kilometres (700 miles) long, was partly intended to help satisfy Tianjin’s thirst, but its construction has suffered years of delays. The project will initially provide water to the provinces of Shandong, Jiangsu and Anhui. No date has yet been set for Tianjin to tap in. The city will not get its first taste of Yangzi-basin water until the middle of the three routes is ready, which officials say will be late in 2014. This is also several years later than planned (moving 330,000 people to make way for the project has proved arduous). Even when the water flows into Tianjin, at an initial rate of about 1 billion cubic metres a year, it will still not satisfy demand. The government news agency, Xinhua, says Tianjin will need an additional 600m cubic metres a year. The delays, shortcomings and mounting costs of the water-diversion scheme (more than $34 billion spent so far) have encouraged officials to look at other solutions. China has been a slow starter in desalination, but in recent years the country has become one of the world’s fastest-growing markets for the technology. This does not come cheap, but the government can lean on state-owned enterprises such as SDIC, which operates the Beijiang plant, to shoulder the cost. A year ago the government said China would produce up to 2.6m cubic metres of desalinated water daily by 2015, a more than fourfold increase. That would be a tiny share of China’s unmet demand, but nearly the amount that Tianjin expects to receive from the diversion scheme’s middle route.

Dry days

China is still heavily dependent on imported technology. The Beijiang plant uses Israeli equipment to distil the seawater, but officials say China’s own technology will reach world standards in the next few years. Tan Peidong, a deputy general manager of the Beijiang facility, predicts that this will help reduce costs. He also expects help from rising water tariffs, which China has long kept below market levels in order to protect consumers. Within a couple of years, he says, Beijiang will begin turning a profit on its water, which by next year it will be able to produce at a rate of 200,000 cubic metres a day, twice today’s capacity (though current output is much less).

Mr Tan does not see any threat to his business from next year’s arrival of diverted water. Not only will there remain a shortage, but his water will be cheaper to supply to the grid than diverted water from the Yangzi basin. A cubic metre of water from the plant costs about 8 yuan ($1.30) to produce—slightly more than the price paid by industrial users, but 60% higher than the tariff for households. Mr Tan says a cubic metre of Yangzi-basin water will cost about 10 yuan. He says he is “very hopeful” that some of his output will be piped to Beijing. Supplying desalinated water to the capital will still cost about the same or only a little more than channelling in water from the south, he reckons.

In its first five-year plan for the industry, in December, the government insisted that desalination was “of benefit to sustainable development”. It was better, it argued, than sucking more water out of the north’s fast-diminishing aquifers. That is surely right. Yet desalinating water uses enormous amounts of energy, which comes mainly from highly polluting coal (though Beijiang’s advanced technology is more efficient than that found in standard power plants). And diverting water from the river basin could exacerbate the impact of droughts in the south. No wonder that environmentalists complain that the government is relying on costly remedies, and doing too little to encourage conservation.