Upcycling waste for a carbon-neutral tomorrow

Zero waste for zero emissions in a world of modern consumerism

The current consumer economy has been enormously wasteful. We acquire resources, make products, use them, and then throw them away. “The Centre aims to be a global research centre in the area of solid waste recycling. We support the Hong Kong government’s policy of achieving carbon neutrality by 2050. We are also committed to minimising the waste that goes to landfills,” said Ir Prof. POON Chi Sun, Director of RCRE.

In fact, carbon neutrality is only one of the many environmental issues that RCRE has pledged to tackle. A sustainable society necessitates a shift in consumer behaviour. The Centre hopes to develop Hong Kong and the Greater Bay Area into models of resource engineering towards a circular economy. A circular economy moves away from wasteful consumerism. It stresses the use of “waste” as a resource to manufacture new products and deliver services; as a result, the whole economy becomes less resource intensive.

Novel ways of managing resources and waste

The realisation of a zero-carbon society and a green economy is one of the biggest problems on our planet, requiring combined efforts and wisdom from policymakers, scientists and community. The Centre’s four main research directions provide multifaceted solutions to this complex problem. “Waste recycling and management has great relevance to policy-making and social implications. Our studies under Policy and Society focus on social impact assessment and policy evaluation, social entrepreneurship for waste recycling, and individual waste management behaviours. Environmental and Economic Impact includes life cycle analysis of organic and inorganic waste, so that it helps inform decisions about proper recycling technologies for the reutilisation and sustainable applications of various waste materials,” Prof. Poon explained.

“Under Waste Valorisation Technology, we explore the reuse of waste materials like algae, food, yard waste, etc., and convert them into useful products like biochar and biofuel. Under Recycling and Sustainable Construction, we recycle the waste from construction and other materials and turn them into useful construction materials,” Prof. Poon said. The Centre developed an Eco-Block technology which utilises these construction and demolition wastes together with recycled glass and incinerator ashes to make construction materials. The Centre also developed a carbonation technique that sequesters carbon dioxide and transfers concrete waste powder into high-value nano-construction materials.

Cutting-edge research platforms and facilities for innovative and advanced waste technologies

The scientific study of waste and wide-ranging resources on our planet is highly complex and technical, requiring high-tech infrastructure. The six research facilities on the PolyU campus are where RCRE research outputs are incubated. These include the Bioenergy Research Laboratory dedicated to biofuel and non-catalytic research, the Concrete Materials Laboratory for the characterisation of cement-based and constructional materials, the Road Research Laboratory that supports the performance testing of road and pavement materials, the Transport and Highway Engineering Laboratory for conducting experiments on bituminous materials and transport-related measurement, the Water and Waste Laboratory for extensive characterisation of physical, chemical and biological samples, as well as the Joint Laboratory on Solid Waste Science in which research on safe waste treatment and resource utilisation technologies is conducted.

Waste management is an acute problem in Hong Kong. The three major landfills in the region are expected to be filled by 2030, and their capacity is decreasing fast. “In the 2021/22 year, our Centre obtained a total grant of over HK$16 million from external bodies, to conduct fundamental and impactful research on woody waste, waste glass and incineration ashes,” Prof. Poon said.

Among the four externally funded projects are two large projects funded by the HKSAR Government’s Green Tech Fund. In Biochar-enhanced Construction Materials for Sustainable Waste Management and Decarbonisation, Prof. Daniel TSANG, Professor in the Department of Civil and Environmental Engineering, leads his team in developing innovative designs and science-informed manufacturing technologies for biochar-enhanced construction materials. This work has given rise to pioneering products, including a biochar partition block and biochar porous paver.

“I am leading a team on the project Low-carbon Transformation of Construction Materials Using Waste Glass, which just started in January 2023. We will use glass powder and cullet derived from waste glass bottles to produce high-performance construction materials,” Prof. Poon explained. “Glass waste is a major component of solid waste in Hong Kong, and its recovery rate has consistently been under 20%. On the other hand, in the construction industry, concrete production accounts for about 8% of global anthropogenic carbon dioxide emissions.” The project is expected to reduce the production of glass-based and embodied-carbon concrete materials, thus reducing carbon emission that results from glass waste and concrete production.

Ambitious efforts by high-calibre researchers and engaging the wider community for a greener tomorrow

The funding success marks RCRE’s remarkable research development since its inception. The Centre also has published 19 articles in high-ranking scientific journals and filed one patent for the development of low-carbon fibrereinforced cement using cement clinker and flue gas in a cement plant.

The success would not be possible without the efforts of RCRE scholars. “Currently, the Centre has 27 highcalibre researchers from different departments at PolyU. Seven RCRE scholars were named among the top 2% of the most-cited scientists worldwide in 2022, according to a list by Stanford University,” said Prof. Poon, who ranks third globally in the field of Building and Construction. Another RCRE member, Prof. Daniel Tsang, is the only RCRE scholar and one of the twelve PolyU academics recognised on the 2022 Clarivate Analytics list of highly cited researchers.

Encouraging new solutions and amplifying research impact

RCRE scholars are encouraged and well supported to engage in interdisciplinary projects in line with the Centre’s research direction. The Centre’s internal seed fund programme 2021/22 has received a very positive response and a high number of excellent proposals. Sixteen proposals among the twenty submissions have been funded. “The seed projects are led by PolyU academics from various schools and departments. For example, our members from the School of Fashion and Textiles (SFT), Associate Professors Dr FEI Bin and Dr FAN Di, are studying the upcycling of home textile wastes into organic carbon electrodes for rechargeable batteries, and the factors motivating carbon neutrality goal settings in local manufacturers, respectively. Dr WONG Ka Hing, Director of the Research Institute for Future Food (RiFood) and Associate Professor in the Department of Applied Biology and Chemical Technology (ABCT), is researching carbon-neutral materials using major types of commercial and industrial food waste in Hong Kong. Dr REN Jingzheng, Associate Professor in the Department of Industrial and Systems Engineering (ISE), is investigating urban waste biorefinery for a circular economy and industrial symbiosis,” Prof Poon explained.

“The first internally funded project started in February 2022, and we look forward to seeing further progress in the future,” said Prof. Poon. The RCRE seed fund helps PolyU researchers try out new solutions, technologies and research, paving the way for seeking large external funding from the government and industry for knowledge and technology transfer. The Centre has also been building links and partnerships with major stakeholders in government and commerce to help amplify research impact. “We are now in discussions with various government departments involved in Hong Kong’s infrastructural development on collaborative trial projects on the use of low-carbon construction materials and methods,” Prof. Poon added.

Thirty-year journey at PolyU

The year 2023 is Prof. Poon’s thirtieth year at PolyU, since he joined as a lecturer in 1992. He earned his doctorate degree in public health (environmental) engineering from Imperial College London in 1985 and began his academic journey the same year as a Research Fellow at Oxford University. Prof. Poon joined The Hong Kong Polytechnic (the predecessor of PolyU) and has been developing his professional and academic career until the present time.

“I am greatly interested in the work that I am doing—turning waste into resources. This not only helps develop my research career but also helps protect the environment by minimising carbon emissions and sequestering carbon dioxide,” Prof. Poon said. The ambitious scientist has published more than 500 papers including over 400 peerreviewed research papers in international journals, filed 10 patents, authored six books, and contributed to a wide variety of international conference proceedings, journals, as well as professional and governmental bodies.

A brighter future for environmental research

The scientist is optimistic and confident about the future of research in sustainable construction and waste management. “The growing awareness of climate change in recent years has greatly promoted interest in carbon neutrality. We are seeing more research funding opportunities from the public and private sectors. I really hope young researchers can dwell in, on one hand, something that is interesting to them, and on the other hand apply their research results to contribute to the well-being of society.”