Tianjin municipality in North China began carbon emissions trading on Thursday, with five deals for about 45,000 tons completed on the first day.

The transactions involved eight companies and were worth 1.25 million yuan ($210,000), with a price of 28 yuan per ton, according to the municipal carbon emission trading market.

An initial 114 companies from the power, iron and steel, chemical, petrochemical, and oil and gas extraction industries have been included in the quota allocation.

All the companies included have emitted more than 20,000 tons of carbon dioxide since 2009.

Under the trading program, companies that emit more than their fair share of emissions will be able to buy unused quotas on the market from firms that pollute less.

"For companies that are not included in the compulsory quota allocation, buying quotas is a way of investment to make profits," said Wu Hongjie, general manager of Cleanergy Investment Service (Beijing) Co Ltd under Hanergy Holding Group, Ltd.

Hanergy bought a quota of 10,000 tons on Thursday. The group also bought a quota of 10,000 tons in June this year at the carbon emissions trading market in Shenzhen city, the first of its kind in China, at prices of 30 yuan per ton.

In 2011, the National Development and Reform Commission, the top economic planning agency, approved pilot trading plans in Beijing, Tianjin, Shanghai, Chongqing, Hubei, Shenzhen and Guangdong.

Tianjin is the fifth trading market started this year, following Beijing, Shanghai, Shenzhen and Guangdong.

The pilot plans were a landmark for a China intent on building a nationwide carbon trading market. The country has pledged to reduce carbon dioxide emissions by 40 to 45 percent per unit of GDP by 2020, compared with 2005.