WUHAN - Central China's Hubei province Wednesday launched a carbon trading scheme, the country's sixth.

The scheme covers 138 companies in 12 high pollution industries, including power generation and steel, which have been given a combined carbon emission quota of 324 million tonnes this year, the Hubei carbon trade exchange said in a statement.

Under the trading program, those which emit below their quotas can sell their excess to other enterprises or even to investors for profits. Hebei is the first place where the government has sold reserve quotas. About 2 million tonnes of carbon have been sold at a price of 20 yuan ($3.20) per tonne.

The exchange also signed carbon trading agreements with other provinces including Shanxi, Anhui, Jiangxi and Guangdong.

The scheme is a big step for China in building a nationwide carbon trading market, with an expectation of 40 to 45 percent reductions of 2005's emissions slated for 2020.