TIANJIN, China — Towering over the Bohai Sea shoreline on this city’s outskirts, the Beijiang Power and Desalination Plant is a 26-billion-renminbi technical marvel: an ultrahigh-temperature, coal-fired generator with state-of-the-art pollution controls, mated to advanced Israeli equipment that uses its leftover heat to distill seawater into fresh water.

There is but one wrinkle in the $4 billion plant: The desalted water costs twice as much to produce as it sells for. Nevertheless, the owner of the complex, a government-run conglomerate called S.D.I.C., is moving to quadruple the plant’s desalinating capacity, making it China’s largest.

“Someone has to lose money,” Guo Qigang, the plant’s general manager, said in a recent interview. “We’re a state-owned corporation, and it’s our social responsibility.”

In some places, this would be economic lunacy. In China, it is economic strategy.

As it did with solar panels and wind turbines, the government has set its mind on becoming a force in yet another budding environment-related industry: supplying the world with fresh water.