Cement producers participating in the carbon market in China?s Hubei province have told the local government they cannot afford the millions of yuan required to buy permits to cover mitigation obligations for 2014 and may default. Refusal to pay would test China?s ability to force companies to comply with carbon targets and undermine efforts to curb greenhouse gas emissions, in which a planned national carbon market would have a central role. The 138 companies covered by the Hubei exchange have to hand over carbon permits to settle their obligations for last year. Around a quarter are cement firms, who complain they were not allocated enough credits. The firms are facing high environmental compliance costs at the worst possible time, as the economy slows and the construction sector struggles.