Central China's Hubei Province launched the country's sixth carbon trading scheme on April 2.

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 tons for 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 investors for profit. Hebei is the first place where the government has sold reserve quotas. About 2 million tons of carbon have been sold at a price of 20 yuan ($3.22) per ton.

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

The scheme is a big step forward 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.