Limits on the amount of pollution CLP Power's gas-fired power station may emit have been renewed, but with the proviso that the company may breach them if it reduces pollution from its coal-fired turbines. The Environmental Protection Department said the proviso was intended to encourage the company to use more gas. 'This offsetting arrangement will ensure a greater net reduction of the overall emissions from power generation, which is the biggest local source of air pollutants,' a spokeswoman for the department said. However, CLP Power says it faces a shortage of gas supplies - the reason for its application to build a liquefied natural gas terminal on South Soko Island, in a marine reserve off Lantau, to receive overseas gas supplies shipped by tanker. There are no figures for its output of pollutants last year, but it announced in December 2006 that the proportion of electricity it would generate in 2007 from gas would drop by a third to conserve supplies from its Yacheng gas field off Hainan , and that it would burn more coal, pushing up emissions. The power station at Black Point, Tuen Mun, will be allowed to emit 520 tonnes of sulfur dioxide, 5,200 tonnes of nitrogen oxides and 65 tonnes of particulates per year this year and 2009. In 2006, the latest year for which figures are available, emissions of sulfur dioxide and nitrogen oxides came in far below the caps, at 180 tonnes and 1,962 tonnes respectively, but particulate emissions, at 70 tonnes, breached the cap. The cap extension was announced as the deadline for agreement between the government and Hong Kong's two electricity suppliers on new scheme-of-control agreements regulating profits on their investments passed without a deal. 'The talks have been very difficult. So far there is no comprehensive and concrete agreement,' a source close to the negotiations said. The source would not say whether the talks would be extended. The government had said earlier that if the deadline passed without agreement, it intended to draft a law to regulate the companies. Tso Kai-sum, managing director of the other power generator, Hongkong Electric, said three weeks ago that a deal was close. Both companies were tight-lipped yesterday over the talks.