Ocean currents provide a clean, non-polluting, renewable energy capable of ending our dependence on fossil fuels and nuclear energy. Recently, the 650 kW H-axis tidal current turbine, developed by Zhejiang University, has been put into operation again.
“This 650 kW H-axis turbine is based on a chain of predecessors: the 30 kW, 60 kW and 120 kW turbines and it has the largest unit power in China,” said LI Wei, deputy director of the Zhejiang University Ocean Academy and chair professor of the interdisciplinary innovative team of mechanical equipment and marine engineering, “The larger the unit power is, the greater the capacity for the industrialization of the equipment will be, thereby facilitating the exploration of marine energy.”
“Tidal current turbines (TCTs) can be broadly divided into three types: vertical-axis TCTs, horizontal-axis TCTs and cross-flow TCTs,” said Prof. LIN Yonggang, “Compared with the other two, horizontal-axis TCTs possess higher efficiency and lower torque fluctuations. The development of TCTs in China has remained in its infancy, but most of the recently developed and planned TCTs in developed countries are horizontal-axis turbines.”
This interdisciplinary innovative team has made a host of groundbreaking achievements in horizontal-axis TCTs. “Like most energy equipment, the length-radius ratio design is a crucial consideration. Our studies indicate that the larger the length-radius ratio is, the better the turbine will perform,” LIU Hongwei, an associate professor on the team explained, “By optimizing the design of major components, including the blade, the low-speed gearbox and the medium-speed generator, we ultimately developed a large length-radius ratio and semi-direct-driven turbine with better performance.”
This series of novel studies helped resolve three key problems in TCTs: efficiency, reliability and stability. It will be of tremendous significance to harnessing ocean currents as a potential renewable energy source.