Bright idea makes lights more efficient (hktdc.com)


	Prof Lee Wing-bun demonstrates the team's prize-winning LED lighting invention

	Accepting their award in Geneva are Hong Kong Polytechnic University representatives Dr Benny Cheung, Prof Lee Wing-bun, Dr Lui Sun-wing and Dr Sandy To

A Hong Kong team of researchers has come away with the top prize at an international invention exhibition in Geneva for designing a more environmentally friendly street lighting system. Researchers from the Department of Industrial and Systems Engineering of Hong Kong Polytechnic University came up with a high-power light-emitting diode, or LED street lighting system, which promises to be longer lasting, energy saving and cost-effective.

Team leader Professor Lee Wing-bun said the financial and environmental cost of lighting up major cities such as Hong Kong sparked the idea. "Imagine how much energy can be saved if you can come up with a way to make street lighting more efficient," said Professor Lee.

The design his team developed beat some 1,000 other inventions from more than 700 exhibitors at the International Exhibition of Inventions, New Techniques and Products in April.

LED lighting is not a new concept. There is growing demand for the system around the world because of its high energy efficiency. While the price of the LED street light is similar to conventional street lamps, LED lasts for up to 100,000 hours compared with traditional street lights, which need replacing after as little as 5,000 hours. The team's design builds on LED's energy efficiency, employing an advanced freeform optical component to allow light to be distributed more efficiently and effectively.

Home of innovation

The invention is a product of more than a decade of work at the Advanced Optics Manufacturing Centre, a mini laboratory tucked away at the Hong Kong Polytechnic University campus. Over the years, researchers there have come up with new and more sophisticated optical lenses used in cameras, DVDs and mobile phones. Because of growing demand for LED, Professor Lee's team branched out into designing LED automobile headlamps and street lighting. According to Professor Lee, the optical lenses in its LED street light design diffuses light more evenly and accurately without glare, which is considered a type of environmental pollution in a highly illuminated city like Hong Kong. Only half the number of LED lamps is needed because of the more efficient distribution of light, resulting in a saving of 50 per cent. The system requires only one-fourth the energy of traditional lighting systems.

The modular lamp holder is made up of five LED heat sink braces on which the high power LEDs are placed. The five LED braces are installed on a main brace, which can be customised according to use. The design allows for better heat dissipation and lets the burned-out lamp be replaced without having to dismantle the entire holder.

Saving cities money

Several manufacturers and city authorities have already expressed interest in exploring possible uses for the high-powered lighting system. The university is now collaborating with a Chinese mainland company to test a prototype lighting system for use on highways. It is estimated that for a city the size of Beijing, installing an LED street lighting system can save up to 190 million kilowatts daily on a 4,000-kilometre roadway that needs 300,000 street lights.

Factories, which operate around the clock, can also see enormous energy savings by converting to LED lighting. The system can also be used for decorative and indoor lighting as well as outdoor advertising systems.

"Our LED lighting system demonstrates how applying research can lead to practical applications that have huge energy and environmental implications, Professor Lee said. He noted that while Germany and Japan are leaders in the field, the Hong Kong operation proves that even a small set-up can produce state-of-the-art technology. "Being small doesn't mean you cannot be cutting edge," he said.