BEIJING -- Despite being a global leader in wind energy installations, China now faces a conundrum as under-use of wind turbines is prevalent across the country.

China's idle wind power capacity totaled 20 billion kWh in 2012, as wind turbines' average time in use shrank sharply from the previous year, according to a document issued by the National Energy Administration (NEA).

The new issue of fortnightly Caijing Magazine quotes Qin Haiyan, secretary-general of the China Wind Energy Association, as saying of the data, "It means we could have burned 6.78 million fewer tons of coal equivalent. The smoggy weather may have much to do with this."

In northeast China, north China and western parts of Inner Mongolia, wind turbines have been running below capacity, according to Zhang Zhengling, spokesman for the State Grid.

In recent years, China has stepped up installations of wind-energy facilities, while the market falls short of absorbing the output. On the other hand, the construction of the grid still lags behind in many regions, making it harder for wind electricity to be integrated into the grid, according to Zhang.

China's installed wind energy capacity hit 60 million kilowatts last year, making this the country's third power source after coal-fired power and hydropower, official data has showed.

The NEA issued a document last month to promote the integration and absorption of wind power, underlining the task of boosting grid construction.