Engineers Take Cues From Fish In New Energy Turbine Design

Traditional turbines are most effective in powerful currents, but researchers are trying to change that so that slower currents can produce power. Today, smaller-current turbines use principles of lift to become “underwater windmills” and maximize their production. But a team led by Michael Bernitsas at the University of Michigan is looking at underwater creatures for inspiration.

Most swimming organisms propel themselves by creating small vortices in the water.

“We live in air so we are used to lifting surfaces that support birds, sail boats and airplanes," explains Bernitsas. However, most swimming organisms propel themselves by creating small vortices in the water. To emulate the behavior, Bernitsas’s team built a device called VIVACE (Vortex Induced Vibrations for Aquatic Clean Energy) that features cylinders that oscillate in moving water as turbulence builds vortices. Because of water’s high density (relative to air), the vibrations carry quite a bit of energy: up to 10 times more than the same volume with tidal turbines. Yet the VIVACE system works in currents moving only 2 miles (3 km) an hour, so slow that tidal turbines are uneconomical.

Interestingly, the team was inspired by fish scales to create a rough surface in the VIVACE cylinders, which resulted in an increase in power output of between 40 and 70 percent over a smooth cylinder. According to Bernitsas, “The roughness helps to convert more of the kinetic energy of the water into vortex energy.”

The team is also attempting to learn from the efficiency of schools of swimming fish, which share vortices to move faster. While Bernitsas’s team does not know how to combine the vortices of individual cylinders, they have experimented with “tails” that prevent each cylinder’s vortex from interfering with the others’.

While the technology may be a long way off from competing with current power-harnessing systems on a large scale, it’s nonetheless an interesting nature-inspired design—and, hence, a nod to the Creator’s ingenuity!