A decade ago, this ancient capital city in northern China was shrouded in coal dust. Now, in an ambitious bid to rebrand itself as a solar city, Datong has played host this week to Asia’s first-ever Solar Decathlon, an international intercollegiate competition organized by the U.S. Department of Energy to promote innovative solar-powered residential designs.

An Asian team, the South China University of Technology, came in second among 20 teams from around the world in designing a single-family home that operated exclusively on solar energy during the two-week-long contest.

Out of the 10 judging categories, the university and first-place winner the University of Wollongong from Australia ranked first in seven of them: architecture, engineering, solar application, energy balance, market appeal, home entertainment and appliances. Chalmers University of Technology from Sweden snatched third place.

For most teams, this was not an academic exercise. Each entry served as a living laboratory to test new innovations and products.

For instance, the Australian team fashioned a dual system that maximizes solar-power-generation efficiency by experimenting with second-generation, polycrystalline photovoltaic panels, compliments of its sponsor, BlueScope Steel Ltd. in Australia. This product has yet to be launched in the market.

The Chinese team, however, availed itself of cheap materials that grow all over in the southern Guangdong province, where the team came from: bamboo and sugar cane. The exterior, the interior and the furnishings of its house were all finished in bamboo. Cast-off sugar-cane fibers were pressed into service as wall insulation.

“These are all new ideas that are being tried out,” said DOE’s Richard King, founder of the Solar Decathlon, who for the sixth time shepherded it through, along with the National Energy Administration of China, DOE’s Chinese counterpart, and Peking University. “It’s also about education” – as much for the participants as it was for the public.

An export industry comes home

Nearly 200,000 people, mostly locals from this city of 1.4 million, streamed in during the 10-day viewing period. Quarter-mile-long lines of people, many armed with UV-proof umbrellas, snaked around the winning houses.

“The popularity totally exceeded what we imagined,” said Yu Pingrong, director of the Solar Energy Center at Peking University’s College of Engineering and head of China’s decathlon. “At first, we wondered if people would come.”

Sure they came to witness their city’s first act in its transformation from the nation’s coal capital, nestled in China’s version of the Appalachians, into what is intended to be a world solar powerhouse by 2015. Hong Kong-listed GCL-Poly Energy Holdings has begun work here on a 1-gigawatt solar farm. Boasting as much as 2,800 hours of sunshine a year, Datong has the natural endowment to compete with the more established solar farms out west.

“Although solar development here is only in its infancy,” said the city’s spokesman, Bai Yulong, “our city’s transportation infrastructure and proximity to Beijing (230 miles to the east) and the coast give it an edge.”

Until last year, China’s solar industry was primarily for export, but stiff tariffs imposed by the United States and the European Union have since forced the industry to set its sights on serving the domestic market (see related story).

Scaling up solar energy would be a boon to China and the world. China is the world’s largest greenhouse gas emitter and has severe health problems from urban smog. Despite policy moves toward solar, there’s still a question about how much solar energy actually feeds into the national electricity grid.

“The Renewable Energy Law mandates that all electricity generated by new energy sources be incorporated into the grid,” said noted economist and former legislator Cheng Siwei at the opening of the decathlon. “Needless to say, this mandate hasn’t been thoroughly carried out.”

‘Green homes’ remain pricey

At the decathlon, it was obvious some local entrepreneurs weren’t counting on the government to deliver soon. They touted solar-powered scooters and Segways to the public to promote carbon-free commuting, especially since the threat of global warming is intensely real this summer in many parts of China. Record-breaking heat has been scorching central and southern regions for nearly a month.

For many Chinese, green homes may still prove out of reach. Quite a few visitors exited the Chinese team’s house and dropped their jaws over its price tag: 2 million yuan ($327,000).

“This may be more suitable to the upper middle class,” said Wang Xinmin, a local. Even though Datong still supplies as much as one-third of the coal consumed by the country, Wang said her hometown’s bounty will one day be exhausted and popular acceptance of solar power is bound to be on the rise.

If anything, this first-ever decathlon in China no doubt sowed some seeds in the Chinese public consciousness of the country’s solar future.

“This competition certainly heightens the awareness about the possibility of zero-emission homes,” said architect Liu Xiaodu, one of the judges. “The general public has to want to spend money on them.”