CLP Power emitted more air pollutants and greenhouse gases last year as a result of more coal burning, but was confident of meeting the more stringent emission targets this year.
The city's largest electricity supplier still complies with the 2009 emission caps set by the Environmental Protection Department, though the emission of three main air pollutants - nitrogen oxides, sulphur dioxide, and particulate matter - grew by 6 per cent, 20 per cent and 30 per cent respectively last year.
The carbon dioxide released by local power generation also rose by 6 per cent, to 19 million tonnes.
The power firm said the increases were only 'temporary fluctuations' and blamed dwindling reserves at the gas field in Yacheng, Hainan province, for the shift.
The field has been supplying natural gas to CLP Power since 1996 but is expected to run out by 2012. Replacement supplies are expected to be ready by no later than 2013.
'We have to carefully allocate the natural gas and that's why we deliberately cut the intake to save the gas until 2013 when the new supplies are ready,' Lo Pak-cheong, commercial director of the CLP Power, said.