Laying waste to energy waste
After learning about superconductivity during her Master’s study at Beijing Jiaotong University (BJTU), Yueming Sun wasn’t prepared to stop exploring, and decided to continue with PhD study.
A collaboration between her BJTU supervisor and researchers at Paihau—Robinson Research Institute (RRI) gave her the opportunity to be the first student to take up a new dual PhD programme, which means Yueming will submit PhD theses at both Beijing Jiaotong University (BJTU) and Te Herenga Waka—Victoria University of Wellington.
Her research is on high-temperature superconductors (HTS), which have been employed in numerous applications around the reduction of energy waste and have the potential to make energy systems more compact, economical, efficient, and reduce carbon emissions.
“Superconductivity is usually defined as a series of physical characteristics of a certain material, and generally, these characteristics are having zero electrical resistance and an ability to expel magnetic fields. When the material is operated at a very, very low temperature—for example, at liquid nitrogen (–196°C) or liquid helium (–268.93°C) temperature, the material enters a superconducting state.”
Yueming says the superconductive material can transport current as high as one thousand times the current of copper and has much lower power dissipation compared with the copper used in existing power grid system.
“This means there’s the potential to save a lot of money and save a lot of power for large-scale power applications—it’s quite amazing.”
“Although superconductors show zero electrical resistance in direct current operations, power dissipation still occurs under specific conditions—such as when they are carrying alternating currents, or are exposed to time-varying magnetic fields,” Yueming says.
Yueming’s research looks specifically at these power dissipations, known as alternating current (AC) loss. AC loss is one of the challenges of superconductors—the AC loss produces heat, requiring the system to be cooled, and this refrigeration process has implications for efficiency and cost-effectiveness.
“If the parametric heat from AC loss isn’t removed quickly enough, it can lead to the destruction of superconducting devices. So AC loss directly determines the cost and reliability of superconductor-based applications and can limit its commercialisation.
“I predict the loss using simulations and develop measurement systems to quantify the loss. Getting accurate measurements of AC loss is quite demanding, which is why there’s a lot of work to do in this area.”
Yueming says she values the support and world-leading instruments and resources provided by the University for her to complete her research.
“I have enough resources to complete my project—the world-leading experimental platforms, and the positive research environment. But I think the thing that makes me happiest here is that my voice and ideas are valued. In RRI, we communicate openly with each other and everyone in the team is professional and friendly. Honestly, I'm so honoured and lucky to have been selected to complete my PhD here.”
Yueming has two supervisors at RRI, Institute Director Professor Nick Long, and Principal Scientist Dr Zhenan Jiang, who was the Royal Society Te Apārangi’s Scott Medal in 2021 for his work on measuring and modelling the response of superconductors.
“I'm really honoured—not only is Dr Jiang completing world-leading AC loss research, but he's a great supervisor. He always gives me very prompt, constructive, and patient feedback, and I can call him anytime. Professor Long is approachable and has a good knowledge of superconductivity. Together they’ve given the perfect amount of direction and structure to my project and career plan.”
While her research may be intense in nature, Yueming is quick to point out that the international environment at the Robinson Research Institute has been very welcoming and open, with students from all over the globe, including China, Germany, India, Iran, Japan, Korea, the Philippines, and the UK.
“We have a good community of postgraduate students at Robinson, we organise morning teas, and there’s a journal club to share academic topics.”
The occasional chance to make liquid nitrogen ice cream doesn’t hurt either.
“Before I knew anything about superconductivity, I ate liquid nitrogen ice cream and thought ‘if I work in this lab, maybe I can make ice cream every day!’ [laughs]. But seriously, I think my favourite part of my research is that you can always find something new.”
“During the research process you’ll come across many practical problems, and you’ll solve them by yourself, which gives you a real feeling of achievement and confidence. I think that’s the reason I still do the research—you can always extend your knowledge. Every day you will have new things to learn, and every day is a different experience.”
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