LPG taxis are cleaner, insists government

PUBLISHED : Tuesday, 06 November, 2007, 12:00am
UPDATED : Tuesday, 06 November, 2007, 12:00am

LPG-powered taxis are more environmentally friendly than diesel ones provided they are maintained regularly, the government said yesterday.

The comments came after a study found taxis running on the gas could be four times as polluting as those running on diesel. The government admitted not all taxis were well maintained.

The study, conducted by Polytechnic University, compared the emissions of LPG- and diesel-powered vehicles using a remote sensing system. As part of the research, a fleet of 20 local taxis running on LPG and manufactured from 2000 to 2005 was studied.

The study found older LPG-powered taxis emitted two to four times the volume of carbon monoxide and hydrocarbons as diesel taxis.

The researchers concluded that replacing diesel taxis by LPG-powered vehicles had reduced roadside pollution in urban areas, but pointed to the need to ensure older LPG taxis were properly maintained.

The government criticised reports yesterday about the research, saying they had generalised from the study to say that the LPG taxi fleet as a whole was more polluting than a diesel fleet.

Assistant departmental director Tse Chin-wan admitted some LPG vehicles were not properly maintained. But he said that if such vehicles were correctly maintained, they produced far lower emissions than diesel-powered ones.

He said emission tests conducted by car makers showed diesel vehicles emitted 50 per cent to 200 per cent more carbon monoxide than a standard LPG-powered vehicle.

Mr Tse said that, compared with diesel engines, LPG-powered engines produced negligible amounts of respirable suspended particulates.

He said the department planned to introduce remote sensing of vehicle emissions and would seek the views of the public about the proposal from January.

Remote sensors record emissions using an ultraviolet beam and camera. They would be placed beside busy roads and in road tunnels, and would photograph vehicles emitting excessive pollutants and transmit the data automatically to the government.

The government proposes vehicle owners would be penalised if the emissions are not reduced.

Conversion job

The government offered taxi owners subsidies of HK$40,000 to switch to LPG

By last year, only five of the city's 18,000 taxis were diesel-powered. The LPG-powered fleet numbered: 17,995

Source: Atmospheric Environment