Solid oxide fuel cell technology

4 September 2015

Dr Kawai Kwok, 2010 Croucher scholar, is a research scientist at the Department of Energy Conversion and Storage at the Technical University of Denmark, where he collaborates with a team of eletrochemists and material scientists to develop technology for solid oxide fuel cells, amongst other projects. As part of a small team of mechanical engineers, Kwok’s research has played a pivotal role in improving the structural integrity of solid oxide fuel cells.

Solid oxide fuel cells generate electricity from fuel oxidation. They typically comprise of three layers of ceramic: an anode, a cathode, and an electrolyte, stacked closely together at a few millimetres thick. At a high temperature of 500 to 1000 degrees Celsius, the ceramic layers become electrically and ionically active, thus allow oxygen ions to diffuse to the anode and oxidise the hydrogen fuel. The by-products of this reaction are electrons that can power an external circuit, and water in the form of steam that can be used to heat up a home or power a turbine to generate more electricity.

The solid oxide fuel cell design is scalable so each module can be stacked up in series to produce a large amount of electricity. As an emerging clean technology, solid oxide fuel cell offers many advantages, including high energy conversion efficiency, low emission, and a high operating temperature- removing the need for a precious metal catalyst, such as platinum. As such, solid oxide fuel cell technology is gaining popularity as an alternative energy source, and can be used to generate enough electricity to power a single home or even a whole data centre!

Despite these advantages, a high operating temperature makes manufacturing the fuel cell a challenge. Kwok notes, “The initial goal at the Technical University of Denmark was to develop a fuel cell that will last for 10 years. However, our industrial partner has found that half of fuel cells were broken even before they left the production line. It was increasingly clear to the research team that they needed both expertise from electrochemists and mechanical engineers to successfully develop and manufacture the solid oxide fuel cell.”. This is where an opportunity arose for Kwok, as a PhD in Aeronautics, and with a passion for exploring sustainable energy alternatives. In August 2013, Kwok was appointed to investigate the reliability issues with fuel cells.

Dr Kawai Kwok

Through discussions and investigations with field engineers, and analytical modelling, Kwok has pinpointed the issue in the ceramic material being used, which often broke after repeated usage at high temperature. Engineers chose to use ceramic in the fuel cell for its electrochemical property for electricity generation, extremely high melting point and high hardness. However, ceramic is also very brittle, and can break easily under thermal gradients and electrochemical reactions. Recognising this, Kwok has come up with new design concepts that reduce the risk of mechanical failure through detailed modelling and characterisation, enabling the research team to improve the production yield significantly.

Currently, Kwok is trying to understand another issue with solid oxide fuel cell production: that it tends to deform under high temperature, and leading to loss of electrical contact.

Despite the continuing challenges, Kwok is optimistic about the solid oxide fuel cell technology, and is determined to play his part in developing sustainable energy. Kwok attributes this determination to his studies at Caltech, commenting, “I am thankful for Croucher Foundation’s support during my graduate research at Caltech… because of the financial support from Croucher, I had the freedom to investigate an area of research that, back then, my advisor did not have funding to investigate. This experience has given me a valuable lesson in how to tackle a new research question, and gave me confidence that if I investigate the question systematically, I can make positive progress over time”

After receiving his undergraduate degree in Mechanical Engineering at the Lehigh University in 2007, Kwok attended the Caltech for graduate studies and earned M.S and Ph.D. in Aeronautics in 2009 and 2012, respectively. Kwok was awarded a Croucher scholarship in 2010.

To view Dr Kawai Kwok’s personal Croucher profile, please click here.