The project led by Professor Ron S.Y. Hui, Chair of Power Electronics at the Faculty of Engineering of the University of Hong Kong on sustainable lighting systems has led to both theoretical and practical breakthroughs. Novel LED systems with not only high energy efficiency and luminous efficacy, but also lifetime exceeding 10 years and over 80% product materials recyclable have been studied and developed.

The project was funded by the Research Grants Council’s Theme-based Research Scheme (TRS) (Second round).

(Image: the University of Hong Kong)

Passive LED drivers developed under the project were tested in Heshan City, Guangdong in over 100 street lamps. Zero failure rate was recorded for a three-year trial period. This has been the world’s first and only “sustainable LED street lighting system” that meets the three sustainability criteria of high energy efficiency, long product lifetime and recyclability. The team is planning to extend the system to cover over 8,000 street lamps in the Mainland.

(Image: the University of Hong Kong)

The research team stresses that sustainable lighting technology should incorporate a new principle that includes (i) energy saving, (ii) long product lifetime and (iii) recyclability of product materials. It highlights the important point that “energy-saving technology is not necessarily environmentally-friendly if it generates lots of harmful electronic waste within a short product lifetime”. The idea deviates from the traditional Energy-Star concept which focuses on energy saving only.

(Image: the University of Hong Kong)

The project has been visible internationally, with 27 journal papers with collaborators either published or already accepted. Among them 20 appeared in the field’s top academic journal IEEE Transactions on Power Electronics. A total of 11 patent applications have been filed.

The team’s latest innovation is a smart system for precise dimming and colour control of bicolour adjustable LED lamps comprising warm-white and cool-white colour, which is a major breakthrough both in technology and theory. In addition, the research team has classified all LED driver topologies and their suitability for various applications. This classification provides a guideline for lighting industry to select the appropriate topologies for their products. New LED structures with new features have also been studied. New approaches to highly efficient LED panel display and current-balancing technologies have been successfully developed. A group of high-quality research students in LED technology have been trained. In addition, several patent-pending technologies have been transferred to industry for production. The outcomes of this TRS project are expected to be beneficial to thousands of LED companies in South China, Hong Kong and the nearby region.