Mankind has been adopting the working principles of natural phenomenons and animals since ages. Now, when it’s time to learn from fish to develop wave-powered generators, it’s also time to learn what others have learned from birds – and use them in the seas, to gather energy which they would later turn into electricity.
If you were confused by the previous statement, let me clear this out for you: a team of aerospace engineers created a new wave energy system by using the same principles that keep the airplanes aloft. The big advantage is that, unlike other systems, this one is more durable and can be placed virtually anywhere in the ocean, not only on the seafloor.
The principles that the researchers from the U.S. Air Force Academy have used are already in action in modern wind turbines, and use the lift force instead of drag to create electricity. They are still in early design stages, but computer simulations prove that their design works with a higher efficiency than it does on wind turbines. In fact, the idea came to them from reading an article on wave energy in a magazine, and then they (Stefan Siegel and colleagues) realized how the wind turbine lift technique can be adapted for use on waves.
“Our group was working on very basic research on feedback flow control for years,” says Stefan Siegel, referring to efforts to use sensors and adjustable parts to control how fluids flow around airfoils like wings. “For an airplane, when you control that flow, you better control flight–for example, enabling you to land a plane on a shorter runway. […] Every airplane flies with lift, not with drag,” says Siegel. “Compare an old style windmill with a modern one. The new style uses lift and is what made wind energy viable–and it doesn’t get shredded in a storm like an old windmill. Fluid dynamics fixed the issue for windmills, and can do the same for wave energy.”
Windmills have active controls that turn the blades to compensate for storm winds, eliminating lift when it is a risk, and preventing damage. USAF Academy scientists used the same technique with a hydrofoil (just like an airfoil, but designed for water), built it into a cycloidal propeller (a design that emerged in the 1930s), and currently use it to propel tugboats, ferries and other highly maneuverable ships.
For this wave energy generating system, the researchers used a vertical propeller orientation, instead of a horizontal one, thus allowing direct contact with the cyclic up and down motion of the wave. Individual control systems have been developed for each propeller blade, allowing the system to shut itself down in case of a wave that it’s more powerful than the blades could bear.
The final device could reach 40 meters in diameter, but the lab models the researchers are currently playing with have less than a meter. Hopefully, with financial support from the National Science Foundation, the researchers will test a larger version of the wave power system at NSF’s Network for Earthquake Engineering Simulation (NEES) tsunami wave basin at Oregon State University. The experiment will be important, because it will prove the design’s efficiency in real life conditions.