Carbon emissions allowances closed at 39.15 yuan ($5.55) per tonne on Wednesday, remained unchanged from the last transaction day at Guangzhou Emissions Exchange, the largest local carbon market in China.

A total of 100 tonnes of allowances were transacted on Wednesday with a turnover of 3,600 yuan.

The allowances, officially known as Guangdong Emissions Allowances (GDEA), are carbon dioxide emissions caps assigned to companies. Firms whose emissions surpass their share must buy extra quotas from authorities or purchase unused quotas on the market from those that cause less pollution.

Since its opening in December 2013, the market has traded about 232.85 million tonnes of GDEA, with a total turnover of 6.77 billion yuan.