Longstanding driving force for electric vehicles
Even before the holding of the Climate Summit in November 2021, sustainable energy had long been a buzz word, attracting huge attention worldwide. At HKU, sustainable energy engineering is among the two major streams of the environmental research cluster, with the other stream being water environmental engineering.
Overseeing the energy part of the environmental research cluster for HKU Engineering, Professor K.T. Chau from the Department of Electrical and Electronic Engineering says HKU Engineering is well-positioned to accelerate the development of energy-saving, especially electric vehicle (EV), technologies. It coordinates the theme-based research project armed with a total budget of HK$30 million funded by the Research Grants Council - “Wireless Power Transfer: The Next Stage” - aiming at advancing wireless power charging. The project also involves CityU and CUHK.
Decades-long efforts
Professor Chau himself has spent decades researching EV technologies, and is hopeful EV will become a popular choice among drivers, replacing fossil fuel vehicles notorious for generating high levels of roadside air pollution.
As the former Director of HKU’s International Research Centre for Electric Vehicles and now Co-Editor of the Journal of Asian Electric Vehicles, Professor Chau says the popularity of EVs hingers on two factors: improving driving range and lowering the costs.
His research project on wireless power transfer holds the key to addressing the issue of range anxiety, ie. drivers’ anxiety about not being able to drive to their destination without sufficient energy storage in EVs. The anxiety is due to the fact that EVs’ energy storage is much smaller than that in gasoline vehicles. Tesla tackles the problem by putting a number of batteries in their vehicles but that results in a heavy price tag.
“We have tried to reduce the price by offering fast, wireless charging station,” says Professor Chau, who is also the Editor of the Studies in Science and Technology. “Our research goal is to develop and promote wireless EV charging systems, which can provide safe and convenient charging for EVs, especially in multi-storey carparks and outdoor parking lots common in Hong Kong.”
Based on the principle of electromagnetic wireless power transfer, electrical energy can be wirelessly transferred without involving metallic contacts or cables, hence allowing EVs to park-and-charge, and avoiding the problem of cable entanglement, Professor Chau adds.
He expects stationary wireless charging systems to be widely available in local carparks in 10 years, and EVs to become popular in 5-10 years.
Alongside that will be continuous development in dynamic wireless charging on electrified roads. But that will take time and needs huge investment, according to Professor Chau.
EV’s projected popularity
Undoubtedly he is approaching realizing his dream of popularising EVs, a dream he had held since he was an engineering student at HKU in the 1980s. He was inspired by his then teacher, Emeritus Engineering Professor Chan Ching Chuen, the founder of the International Research Centre for Electric Vehicles at HKU who now jointly supervises PhD students with Professor Chau. “I wanted to be another CC Chan,” laughed Professor Chau.
Fourteen countries including Canada, China, France and Germany have set a collective aspirational goal of having EVs capture 30% car sales by 2030, according to the international publication Global EV Outlook 2021.
Under the Hong Kong Roadmap on Popularisation of Electric Vehicles, the Hong Kong Government plans to cease the sale of conventional fuel-propelled private cars including hybrid vehicles in 2035 or earlier.
Professor Chau adds: “In the next few years the boundary between gasoline vehicles and EVs will become blurred; most will be hybrid vehicles.”
Nano-scale membrane behind breakthrough in water re-use
The concept of filtering is known to many, but it takes a highly inquisitive, scientific mind to invent an advanced filtering method that both costs less and saves energy.
Professor C.Y. Tang from HKU’s Department of Civil Engineering was among the seven HKU researchers awarded in the Research Grants Council’s inaugural Research Fellow Scheme, for his outstanding achievement in creating novel membranes with enhanced mass transfer and integrity for highly efficient water re-use.
“It’s very important to enhance the efficiency of filters; we tried to find out about how to make improvements and eventually managed to patent a novel approach to make the membrane much better,” said Professor Tang, who was awarded under the inaugural Senior Research Fellow Scheme of the Research Grant Council in 2020.
His research team has already obtained up to 15 patents for different membranes, some of which have also been licensed.
Discovery of new nanoscale structures
Professor Tang is a world leader in membrane technology, desalination, and water re-use, having made critical contributions to the better understanding of the nanoscale structures of desalination membranes and their transport behaviors. He led the invention of aquaporin-based biomimetic membrane technology that has been widely recognized in the desalination field.
For long he had been intrigued by the huge energy consumption required for water re-use in the industrial setting. “In the conventional way, people would use separation, that is you heat up water to turn it into vapour to do the separation or use organic solvent to extract certain elements. But that is costly and energy intensive.”
His idea of a membrane resembling a piece of filter paper turns out to be a good solution. “It works on a very simple principle,” said Professor Tang. “You design the pore size of the membrane so that contaminants, either water or air, can be removed, or organic solvents can be extracted from a mixture. It is a neat and simple process, and requires only one-tenth of the conventional energy consumption.”
But his project borne out of mere curiosity involves much high technology. Professor Tang explains: “The membrane technology has been around for almost 40 years, what we were trying to do was to invent new materials, to make materials with defined pores, very uniform pores so water can be channeled through those porous structures.”
In contrast to conventional filtering, his membrane invention is of tremendously small, molecular size. Some pores are less than 1 nanometer in size.
Finding a new direction
A structural engineer by training, he switched from concrete structures to membranes while he was a graduate student at Nanyang Technological University in Singapore. It happened because of an inspiring encounter with a professor from Stanford University. “I became his PhD student eventually,” he recalled. “I was among the very few working on the technology in his group but the more I looked at it the more I got fascinated. Though I have been in this field for 20years, there are still many critical questions unanswered and so many puzzles that I like to solve.”
The recipient of a string of international awards including the International Desalination Association Fellowship Award, he has certainly far more to work on. In Hong Kong, he is a technical consultant to the Tseung Kwan O desalination plant due to be completed in 2023. The plant could provide about 10 per cent of the water supply in Hong Kong.
“We are trying to make the membranes more permeable, 10 times more compared to existing ones and reduce 80 per cent of energy consumption in enabling water re-use,” he said.
Towards the goal of sustainable urbanization
Rapid urbanization in the world over the past decades has been an area of focus for Professor Chen Ji of the Department of Civil Engineering.
His efforts paid off last year, when his research with his PhD student in Shenzhen drew widespread attention from the media and scientific organisations. Together they had produced mappings contrasting built-up areas (BUAs) with pleasant green environments with those without in various parts of the world.
“One of our findings is that cities in the lowest income countries face a serious problem with population growth and have an urban expansion path that is below that growth. The population is growing too fast,” said Professor Chen.
“Another big issue is that their urban environment is getting even worse. We hope the study will provide some warning signals to those cities to have more governance over their urbanization.”
Unearthing valuable data
Based on a rich dataset from 841 cities during 2001–2018, the study was published in Nature Communications last October. The team collected the data using a newly developed method that can rapidly analyse several terabytes of data from publicly available US satellite data. A vegetation index was deployed to measure the extent of greening in different areas.
It is the first time such a global picture of urbanization and greening was discovered. Professor Chen calls for speedy action from governments in regions that failed to provide a suitable living environment for their growing populations. “If no strategy is taken, then those regions will face very serious problems like slum, traffic chaos, education, etc. Millions of people are living in cities in low-income, or least-developed countries,” he said.
As shown by his research, greening is generally satisfactory in developed cities such as New York, whereas in cities like Lagos in Nigeria, which is also the largest city in Africa, a decent living environment is lacking, despite the vast number of residents there. The situation in some cities in India covered by the research is equally problematic.
On the contrary, some 325 cities saw significant greening, including new parks, green spaces and roofs, in more than 10 per cent of BUAs and nearly one-third of those were in China. Overall, greening in Chinese cities increased by 32 per cent.
Professor Chen adds: “The greening in large Chinese cities actually ranks top in the world. It’s a positive trend.”
Rapid rise in global population
The world’s population is projected to rise to 10 billion by 2050, up from the present 8 billion. A green environment is pertinent for mitigating the growing effects of climate change caused by urbanization. “There is a need to safeguard people’s living environment both for public health and sustainable growth of the world’s population,” said Professor Chen, whose other research interests include management of water resources, and climate change.
Using artificial intelligence, he is collaborating with the Hong Kong Observatory and Shenzhen Meteorological Bureau to improve the forecast, or what is known as nowcast, of heavy rainfall in just the next few hours. The prediction could work for the entire Greater Bay Area. Several of his students are involved in the AI project.
Building structures in the seabed for energy conservation
Tall, smart, structurally safe buildings above ground are not the only projects engineers are fascinated with. Albeit making up only a minority, some researchers are eyeing structures underground or undersea.
Professor Yang Jun from the Department of Civil Engineering is a leading figure in the field of geomechanics and geotechnical engineering, being listed among the top 1% Scholars by citations by Clarivate Analytics and elected to Fellowship in the American Society of Civil Engineers and the UK’s Institution of Civil Engineers.
One of his research areas involves promoting renewable offshore wind energy to reduce greenhouse gas emission. That might require the design of offshore turbines built in the seabed. “They could have a height of 200 meters, and diameters of more than 100 meters. It is very challenging to put such a structure in the seabed. The design requires multi-disciplinary research,” he said.
Hong Kong in a key position
Lying along the southern coast of China and with a high population density, Hong Kong is well-positioned and could benefit much from the use of wind energy, says Professor Yang. “Wind is a more efficient power source compared with solar energy. Wind turbines release less Co2, consume less energy and produce more energy overall so it has great potential.”
Under a government drive to generate more wind energy, several large wind farms are already under construction in the eastern coast of China, in provinces such as Jiangsu, Guangdong and Fujian, says Professor Yang. Researchers in Hong Kong and the entire Greater Bay Area could contribute more in enhancing the feasibility and efficiency of generating wind energy, he adds.
Recently the Research Grants Council has for the first time provided a HK$3.2 million funding for a joint project on design for offshore wind turbine – a collaboration between Professor Yang’s team and researchers from local and German universities. Among his research team members are specialists in aerodynamics, hydrodynamics, structural dynamics, and earthquake engineering.
“Collaboration is very important because we need different areas of expertise,” he said. He hopes the project will also increase public awareness of the importance of geotechnical engineering to the environment and energy conservation. “The discipline is not just about construction of MTR stations which everyone can see. It can provide solutions for other important problems too, such as wind energy, underground Co2 storage or offshore exploitations. Everybody is talking about low carbon emission now, so I hope our students can make contributions in that area.”
Important engineering disciplines
Professor Yang’s other research specialties lie in soil liquefaction and earthquake engineering. “Soil liquefaction occurs when the stiffness of soil is reduced by pore water pressure. When this happens, the ground will not be able to support the structure above. In New Zealand, Japan and China, earthquakes have induced extensive soil liquefaction, or in the case of heavy rainfall, some slopes could become fluidized and collapse.”
HKU’s civil engineering programme imparts knowledge in both structural engineering and geotechnical engineering. Professor Yang and colleagues also carried out research on safe and cost-effective design for iconic infrastructure such as the Hong Kong-Zhuhai-Macau Bridge.
Given its importance, the study of a stable foundation – onshore and offshore – has always remained his focus. “Once the foundation fails, the whole structure fails,” he said.