New pendulum-style cylinder system makes power from water currents

Spanish researchers at Universitat Rovira i Virgili (URV) have developed an innovative renewable energy system that harnesses water current vibrations using a pendulum-style submerged cylinder. Unlike traditional underwater turbines, which rely on rotating blades and suffer from complexity, corrosion, and maintenance issues, this system uses vortex shedding—a phenomenon where water flow creates alternating whirlpools around the cylinder—to induce oscillations. These oscillations cause the cylinder to swing like a pendulum, transferring mechanical energy to an external shaft and generator located above water, simplifying maintenance and protecting sensitive components from harsh marine environments. Tested in URV’s Fluid-Structure Interaction Laboratory, the system demonstrated a power coefficient of about 15 percent, roughly half the efficiency of conventional turbines but with significant advantages in compactness and durability. Its design allows deployment in various aquatic settings, including tidal currents and free-flowing rivers, and it may also be adapted for wind energy. The researchers plan to optimize power extraction, broaden operational speed ranges, and investigate the