Petroleum meets 95 percent of the energy needs of this sector, and environmental reports show that this industry is responsible for about 20 to 25 percent of the world's energy consumption and carbon dioxide emissions.

Another study on greenhouse gases indicates that emissions from the transport sector in past years have been much higher than those from any other industry, with road transport being a major contributor to local air pollution and smog.

The rapid expansion of the transport sector is also another factor for the rising air pollution index. So to minimize pollution it is necessary to take a closer look at our transport systems.

I am glad that a new monorail system has been proposed for the Kai Tak redevelopment area to help solve traffic problems. This monorail is being billed as a clean transport system in East Kowloon.

However, this so-called green vehicle can be applicable only at the local level.

We will still have the issue of carbon emissions from power plants, if renewable energy is not used. Carbon emissions and global warming problems will still be there, though the overall energy utilization will be more efficient.

A research group in the department of mechanical engineering at the University of Hong Kong demonstrated an innovative design of solar powered light monorail system.

A prototype was designed, manufactured and tested using electricity generated through a solar photovoltaic panel. Preliminary findings indicate that the concept is technically feasible, and that the government should consider this new concept when designing the new monorail system.

Monorails are light and energy efficient and usually have lower energy requirements than light or heavy rail. They can also be potentially powered by renewable energy.

Compared with traditional systems, the new design is lighter, safer, more space-saving, has T-shaped tracks, and causes much less wheel noise.

Solar photovoltaic panels can generate electrical power by converting solar radiation into direct electrical current using semiconductors.

Feasibility studies indicate that an array of solar panels, with an area of around 1,500 to 2,000 square meters, will be required to provide self- sustaining energy for the monorail operation.

Although panels on the roof of the train compartments will not be sufficient to generate the desired amount of solar energy, adequate power can be obtained if we install such panels on station rooftops or along the elevated tracks. The system can also be connected to the power grid network so that excess electricity generated during off- peak hours can be fed back to public utilities.

Calculations are based on current photovoltaic panels having an efficiency of around 15 percent.

With advancements in technology and improvements in energy efficiency, a green monorail design looks to be a very promising prospect and should be further looked into when developing this new landmark in eastern Kowloon.

Fude Liu is an assistant professor at the department of mechanical engineering, University of Hong Kong.