"Certainly the main driver has been government policy and clear signals it has sent to the market, and I'm sure the spirit of Chinese entrepreneurs has also contributed to the rate of growth," Sawyer told Xinhua via email.

Sawyer said the expansion partly resulted from "the close alignment between (wind power) industry and government".

"I think it goes deeper than that and is an artifact of the culture which contributes to the rapid execution of agreed policy in a way which I don't see in any of our other main markets," he said.

Shi said while government's policies had been the main driver for wind energy expansion, the market also played a major role in helping foster a strong manufacturing industry of wind turbines.

China's push for more wind power has helped create huge market demand for wind turbines. As a result, manufacturers propped up and investment flocked into the sector.

According to Shi, China boasts more than 80 wind turbine manufacturers currently, with a combined production capacity of more than 10,000 MWs. In 2004, China had only six manufacturers.

"In the last few years, the wind energy sector has never been short of money. As long as you have technologies or projects, investment will come to you very quickly," he told Xinhua.

U.S. Energy Secretary Steven Chu has his own assessment on expansion of China's clean energy. He said on Nov. 30 in South Carolina that China was spending 9 billion U.S. dollars a month on clean energy and it had passed the United States and Europe in high-tech manufacturing.

But many would say Chu's assessment sounded too rosy, at least on advanced clean energy technologies.

The UK think-tank Chatham House, in a report released this September, suggested that China lagged far behind developed countries regarding energy innovations and advanced technologies. The report, involving nine months of research across the technologies and over 30 sub-sectors, made analysis of 57,000 patents and the market adoption rates of energy technologies.

Emerging economies such as Brazil, China and India had no companies or organizations in the top 10 positions in any of the sectors and sub-sectors analyzed, it said.

It served to explain why China has repeatedly asked industrialized countries to transfer their clean-energy technologies.

Shi Pengfei said many Chinese wind turbine producers, which had never designed and produced a complete wind turbine, bought production licenses from overseas firms and jumped straight to making turbines.

Without the process on basic research and technological accumulation, Chinese manufacturers had been criticized for producing low-quality wind turbines, he said.

In addition, there was also increasing concern of over-capacity in the manufacturing sectors of both wind and solar power, which had recently even caused a dispute between central governmental departments.

Shi believed that overcapacity could probably be a reality in the wind energy sector since China was expected to install 7,000 MWs of wind turbines annually on average in the next 10 years, at least 3,000 MWs less than China's current manufacturing capacity.

Shi, however, said overcapacity, to some extent, could be a good thing because it would trigger fiercer competition among manufacturers. In the end, only those making good-quality turbines at lower prices would survive, he added.