Professor T S Zhao and his team at the Hong Kong University of Science and Technology (HKUST) have focused their research on finding alternatives to fossil fuels in the generation of electricity. Their work includes the development of Direct Alcohol Fuel Cells (DAFC) and research into hydrogen technology.

Research Grants Council funding has supported the successful development of a number of initiatives in this area.

DAFCs convert the chemical energy of liquid methanol or ethanol directly to electricity. This offers high efficiency and low emissions in a simple and compact design that is regarded as a competitive and viable technology. It has the potential to replace conventional batteries used in portable electronic devices. In the long run, these DAFCs may also evolve as competitive candidates to replace internal combustion engines in cars. Modelling, designing, fabricating and running diagnostic tests on DAFCs are continuing in Professor Zhao's lab at the HKUST. Many of his fundamental studies have provided important insights in the understanding of fuel cell mechanisms and help to improve fuel cell performance.

Professor Zhao says one of the hurdles faced in attempting to commercialise DAFC technology revolves around fuel crossover issues.

"For years researchers have been on a quest to drop fuel crossover without sacrificing proton conductivity. We can now show that by using Pd (palladium) and Pd alloys deposited membrane in a DMFC (Direct Methanol Fuel Cell) and by innovatively designing the membrane electrolyte assembly, we can considerably reduce fuel crossover rates and boost the power density of the cell."

Professor Zhao's group recently developed a passively operated DMFC that demonstrated a maximum power density that is the highest performance recorded in open literature. This type of fuel cell was applied to power a toy car that can run continuously for about 20 hours.

The group has also developed environmentally-friendly hydrogen generation techniques as part of their work on energy conversion technologies. They discovered that hydrogen evolves spontaneously from a DMFC. This has led to a new technique to produce hydrogen at room temperature and without the emission of CO species.

The discovery of hydrogen evolution in the DMFC development has also resulted in a number of other inventions at HKUST. These include a method to activate DMFCs, a measurement for the rate of methanol crossover from anode to cathode and an accurate way to measure the respective electrical potential of anodes and cathodes.

Professor Zhao is excited at the potential offered by this work in terms of renewable, sustainable and clean forms of energy.

"Hydrogen is an ideal energy carrier. It produces no emissions and has a high rate of efficiency. The problem however comes with the high costs of hydrogen production and storage and transportation problems. The future solutions to these problems are unclear yet.

"One solution is to find sources that are high in hydrogen content and yet relatively easy to transport and work with. Methanol and ethanol fit these criteria. As these alcohol fuels are in a liquid state at room temperature, their storage and transportation are less of an issue."

Professor Tianshou Zhao
Department of Mechanical Engineering
The Hong Kong University of Science and Technology
metzhao@ust.hk