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    Following is a question by the Hon Lui Ming-wah and an oral reply by the Secretary for the Environment, Transport and Works, Dr Sarah Liao, in the Legislative Council meeting today (June 15):

Question:

    The visibility in Hong Kong during winter has often been low in recent years. An academic has pointed out that it is attributable to the emissions of pollutants from local power plants. Moreover, a local power company has also admitted that it has increased the usage of common coal in the generation of electricity in recent years. However, the Environmental Protection Department has pointed out that more than 80% of the pollutants come from the Pearl River Delta ("PRD") Region. In this connection, will the Government inform this Council:

(a) of the respective percentages of common coal, eco-coal and other fuels consumed by local power plants in the total fuel consumption in each of the past three years;

(b) regarding the pollutants causing the low visibility in Hong Kong during winter, of the respective quantities of various kinds of pollutants generated from the PRD Region and in Hong Kong, as well as their relative ratios; and

(c) whether daily satellite images of air pollutants in the PRD Region will be uploaded onto the government web-sites to inform the public of the sources and distribution of air pollutants; if not, of the reasons for that?

Reply:

Madam President,

    The sulphur content of coal supplied in the international market may be as high as 4% or above, depending on the sources. Coal with sulphur content below 1% is considered as low-sulphur coal, and has less environmental impact. Low-sulphur coal is used in local electricity generation since the licences issued to power plants by the Environmental Protection Department (EPD) under the Air Pollution Control Ordinance stipulate that the coal used for power generation may not exceed 1% in terms of sulphur content.

    Since the sulphur content of coal varies according to sources and batches, the annual average sulphur content of coal used for power generation in Hong Kong would also vary, normally within the range of 0.4% to 0.7%. Although the sulphur content of coal used by one power company last year was relatively higher than in the previous year, the annual average sulphur content did not exceed 0.5%, indicating that the coal used was still of reasonably high quality.

    Apart from the quality of coal, the emission levels of power plants are affected by many other factors, such as total coal consumption and the installation of emission reduction devices. To better control the pollution caused by power plants, the Government will specify the total emission cap in the licences of power plants upon their renewal. In order to meet the specified emission caps, the power plants may implement practicable measures in accordance with their own situations, such as increasing the share of natural gas in power generation, purchasing coal of even higher quality and retrofitting their coal-fired generation units with desulphurisation and nitrogen oxides (NOx) removal systems. The Government is now processing the application for the renewal of the Castle Peak Power Station licence. Upon renewal, the total emission cap will take effect. Similarly, when the licence of another coal-fired power plant (Lamma Power Station) expires in September next year, the Government will specify the total emission cap in the new licence.

    In the past three years, the percentages of electricity generated by local power plants using low-sulphur coal and natural gas were 69% and 31% respectively in 2005, 81% and 19% in 2003, and 74% and 26% in 2004.  Oil was also used, but it accounted for less than 1% of the power generated.

    Visibility is affected by fine particulates in the air, which absorb and scatter visible light. Besides respirable suspended particulates (RSP), other pollutants such as sulphur dioxide (SO2), NOx and volatile organic compounds (VOCs) may also affect visibility by forming particulates through photochemical reactions. According to the Hong Kong-Guangdong Joint Study on Air Quality in the Pearl River Delta Region completed in 2002, which analyses the quantities and percentages of different visibility-reducing pollutants emitted from the Pearl River Delta (PRD) and Hong Kong, the total emissions of RSP, SO2, NOx and VOCs from the PRD and Hong Kong amounted to 257 kilotonnes (kT), 596kT, 565kT and 465kT respectively in the base year of 1997. Of these four major pollutants, Hong Kong contributed to 5%, 13%, 20% and 12% respectively of the total emissions, with the PRD making up the rest, which is 95%, 87%, 80% and 88% respectively.

    At present, the EPD and Guangdong authorities are working in collaboration on the 2003 PRD Regional Emissions Inventory, which will identify changes in air pollutant emitted from the two places since 1997. The Inventory is expected to be completed by the end of 2005 and the latest data on PRD regional emissions will be available by then.

    Starting from January 6, 2005, the Hong Kong Observatory has been releasing daily Aerosol Optical Depth images on its website. These satellite images, which show the distribution of particulates with visibility impact over the PRD and Hong Kong, are useful in monitoring changes in the pattern of regional air pollution.

Ends/Wednesday, June 15, 2005

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