Prof. ZHAO Tianshou, Director of the Energy Institute for Carbon Neutrality, Chair Professor of Mechanical and Energy Engineering, Southern University of Science and Technology (SUSTech), China, delivered the 41st PAIR Distinguished Lecture titled “Flow Cells for Long-Duration Energy Storage” on 4 July 2025 on the PolyU campus. In the lecture, Prof. Zhao stressed the critical role of energy storage in achieving carbon neutrality goals, particularly China’s pledge to be carbon neutral by 2060. He emphasised that future power systems will require energy storage solutions integrated across power generation, transmission and consumption, and the energy storage industry scale is projected to reach a trillion pounds. He mentioned that grid-scale energy storage must meet three core requirements: safety and reliability, cost-effectiveness, and not being limited by site and resource constraints. He also pointed out that changes in environmental conditions can cause fluctuations in renewables’ power generation, and this intermittency problem can last dozens of hours. As such, long-duration energy storage is the key to preventing energy curtailment and enhancing grid flexibility. Redox Flow Batteries are particularly suitable for large-scale energy storage due to their safety, durability, flexible storage duration, and detachable device design. Nevertheless, further efforts are needed to maximise battery performance. On this, his team has successfully developed of a flow battery with a charge/discharge cycle life of over 15,000 cycles, the longest cycle life for flow batteries. Furthermore, Prof. Zhao introduced the concept of “e-fuel”, a clean, renewable, electrically rechargeable liquid fuel. E-fuel represents an excellent alternative to conventional fuel cells. Its storage has no site or time limitations, and it exhibits high efficiency and power density, scalability, safety, and the potential for economic viability.
