In the last decade, the tidal energy industry has witnessed significant growth, with numerous commercial-scale schemes now in development or deployed globally. However, several early projects have suffered setbacks, in part due to harsh operating environments. Tidal flows are considerably complex and turbulent that can result in fluctuations in force, which is detrimental to the fatigue life of the turbine or requires stronger, more expensive structures. In recent years, several studies have reported the characteristics of the tidal flow (consisting of cyclical mean flow and elevated levels of turbulence intensity). In most cases, natural tidal flows had mean velocities between 1.3-3.5 m/s with elevated levels of Turbulence Intensity (Ti) in the 8-30% range, categorizing the tidal conditions into different sub-classes (A-C) as per the proposed marine energy classification system. Inflow turbulence and anisotropy in the freestream is rarely accounted for during the design and testing phase of a device. Turbulence at a tidal site is highly anisotropic, a feature that is not replicated (or controlled) in experiments and computations. To date, there have been several efforts in Europe, especially at the wave and current flume tank, where higher Ti inflow was attained by removing the flow conditioning screens upstream of the test section. These studies are limited since inflow turbulence is not tunable as they use passive turbulence generators and cannot mimic features (anisotropy, length scale, spectrum) of high energy tidal sites.
At Lehigh, Prof. Banerjee has developed one of its kind and the first water tunnel facility in the world that uses active-turbulence generation techniques. The Tidal Turbulence Test Facility (T3F), contains an active-grid turbulence generator that can mimic elevated freestream turbulence in the tidal energy sites with Ti>10%. Current research work focuses on twinning the inflow flood and ebb tide conditions from different tidal energy sites. See YouTube Video of facility in operation here.
This research is funded by the National Science Foundation and also by the U.S. Department of Energy. Prof. Arindam Banerjee and his team is also part of a multi-institution research consortium, the Atlantic Marine Energy Center (AMEC) that is led by the University of New Hampshire, with key partners at Lehigh University, Stony Brook University, the Coastal Studies Institute, NREL, Sandia National Lab, and Pacific Northwestern National Lab. Together, we are strengthening our individual and collaborative marine renewable energy (MRE) research, testing, educational, and public engagement interests focused on advancing the commercialization of wave, tidal current, and ocean current technologies. Our team is also developing solutions to power aspects of the blue economy with MRE, including aquaculture, ocean observing, coastal resiliency, and marine microgrids. AMEC collectively leverages our open-water, laboratory, numerical and analytical test capabilities. Our goal is to utilize and upgrade wave and tidal current energy device testing infrastructure at our institutions.
Read more about marine energy research from Lehigh in the journals Applied Energy, Renewable Energy, and Ocean Engineering.
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