By the time the city is complete, probably in 2020, it should accommodate 350,000 people over 30 square kilometres. Five years into the project, however, only about three square kilometres have been finished, housing 6,000 permanent residents. There are no hospitals or shopping malls. Its empty highways traverse a landscape of vacant mid-rises and dusty construction yards.

"This place is like a child; it's in a development phase," Wang said. "But it's chasing an ideal. It's the kind of place where people can … pursue their dreams."

Last month, Beijing announced its new urbanisation plan, a massive feat of technical and social engineering which will move more than 100 million country-dwellers into cities in the next six years. The question is how. The current development model has proved environmentally disastrous; ghost cities and towns spur fears of an impending real-estate meltdown.

The authorities began encouraging the construction of "eco-cities" in the middle of the last decade. Since then, hundreds have sprouted across the country. While the concept is vaguely defined, most eco-cities are built on once-polluted or non-arable land, comply with stringent green architectural standards, and experiment with progressive urban planning and transport infrastructure. The catch is that they simply may not work, if they get finished at all.

Many other ambitious eco-city projects - including Caofeidian in Hebei province, once considered the crown jewel of the movement - have ground to a halt. The problem, said Neville Mars, a Shanghai architect writing a book about the concept, is the "new city model", which involves building a whole city from the ground up rather than letting it develop organically.

"You can want to design your urban landscape, but in reality, on a fundamental level, that's impossible," he said. "We have to acknowledge that it's extremely hard to build a regular city from scratch."

Some experts say that certified green buildings and pedestrian-friendly roads are a patch, not a solution, for the nation's environmental woes. "Chinese people use a lot of coal because it's very cheap," said Tao Ran, acting director of the Brookings-Tsinghua Centre for Public Policy. "If coal doesn't become much more expensive, then enterprises won't use more green energy."

At present, the Tianjin eco-city feels more like a simulacrum of a viable community than the real thing. Its buildings are designed to the world's most stringent environmental standards, but they stand mostly unused.

Tianjin has an advantage because of its proximity to a major metropolis and shipping hub. "It's already proving to be successful, because it's still building," Mars said. Planners are proceeding carefully. "The idea is to ensure that what we build here is commercially viable," said Ho Tong Yen, chief executive of the city's developer. "It should not be an expensive project funded mainly through government subsidies." He said the project had made strides over the past year, selling about 400 homes a month - a rate which Ho describes as "healthy". President Xi Jinping visited last May. In January, the city's developers presented their project before the United Nations in New York.

"If you ask me what is most unique about Tianjin Eco-city," Ho added, "it is the comprehensiveness with which we are tackling the question of sustainability in the development of a city."

On an official city tour, assistant public relations manager Gang Wei walked through a sparkling, yet unoccupied, glass-and-steel office building, enumerating its environmental advantages. It's designed so that nearly a third of its energy would come from turbines and solar panels, he said.

While the developer claimed that more than 1,000 companies had registered in the city, many storefronts on the main shopping plaza stood empty. Two frozen escalators lead to a mostly vacant upper floor. In the middle of the afternoon its few occupants - a noodle joint, a coffee shop, a Japanese restaurant advertising "suisi" - were padlocked. The city's first food market opened in November, but its supplies were limited to a few well-stocked produce stalls. The massive space echoed like a gymnasium.

At one of the city's three schools, the red-brick Ivy Mi Kindergarten and Primary School, office manager Xu Wenjiao stood in a sun-drenched front lobby more befitting a wealthy technology start-up than an educational institution. Xu said tuition of about 400 yuan (HK$500) a month was less than half that in central Tianjin. "It's to encourage people to move here," she said. "Investors want homes occupied."

Xu strode through pristine hallways, opening doors to a music room, a spacious kitchen and a library furnished with beanbag chairs and potted plants.

"This is our garden," she said, pointing out of a window at the school's backyard, a small brick terrace dotted with dry plots of brown earth. Behind the garden a low wall was plastered with English phrases like "the seeds of fresh life, new bungalow" and "fresh air, bright sunshine, broad view, free breath". Beyond that, a construction yard stretched into the distance. The air reverberated with reports from a pile driver.

It is a familiar sound in Tianjin. With support from the central Chinese authorities, the municipality has shaped its outlying areas into an endless sprawl of showcase projects. Beyond the eco-city lies an ersatz ancient town, a free market zone with its own soccer team, and a half-built financial centre that, according to its developers, will someday rival Manhattan. Construction is everywhere; people are scarce.