|
Letter to the Editor of SCMP - Response to commentary entitled "Bring out the blue skies by encouraging more biodiesel use" by Prof Marcel Lie (March 28)
Prof. Marcel Lie's letter (March 28) entitled "Bring out the blue skies by encouraging more biodiesel use" suggested biodiesel as a solution to roadside air pollution.
The use of biodiesel will not help improve roadside air quality. Many existing vehicles are designed to run on mineral motor vehicle diesel but not biodiesel. Overseas studies have confirmed that fuelling them with biodiesel would increase their nitrogen oxides emissions and might cause problems to their fuel-related engine components.
On the other hand, there is a case to promote biodiesel which is a form of renewable energy. The wider use of the fuel can reduce our greenhouse gas emissions and is helpful to the global efforts being made to avert climate change. Although in-use diesel vehicles are not designed to run on biodiesel, vehicle manufacturers consider it acceptable for them to use up to 5% biodiesel in ultra-low sulphur diesel provided the biodiesel can meet certain quality specifications. This is confirmed by a recent Japanese Government study, which has recommended additional biodiesel quality requirements to prevent problems. If higher biodiesel contents are used, some fuel-related engine components such as fuel injectors can be corroded. A fine balance is required as though the use of biodiesel may reduce green house gas emission, the emission of nitrogen oxides would increase.
Taking into account the Japanese Government's findings, we have drawn up a draft specification for biodiesel for use as a motor vehicle fuel. In January 2007, we kicked off consultation with relevant stakeholders on the draft specification and sought their views on how to promote its use with due consideration to the emission and vehicle compatibility implications. Upon our invitation, Professor Lie joined hands with us in December 2006 to promote biodiesel among stakeholders.
To improve roadside air quality, the Government has been taking other measures more effective than biodiesel - Euro IV standards have been introduced for vehicle fuel and new vehicles in tandem with the European Union, almost all diesel taxis and over half of the diesel public light buses have been replaced by LPG vehicles, particulate emission reduction devices have become mandatory for pre-Euro diesel vehicles and strengthened actions has been taken against smoky diesel vehicles.
Since this month, the Government has been offering a time-limited one-off grant to encourage the early replacement of pre-Euro and Euro I diesel commercial vehicles by Euro IV or better models. If all pre-Euro and Euro I diesel commercial vehicles are replaced by Euro IV models, the vehicular emissions of particulates and nitrogen oxides will be reduced by 74% and 38% respectively and there will also be marked improvement to roadside air quality.
(W. C. Mok)
Principal Environmental Protection Officer
for Director of Environmental Protection
|
