Academy's wave energy research faces major test in 2011

by Randy Roughton
Defense Media Activity - San Antonio

6/18/2010 - COLORADO SPRINGS, Colo. (AFNS) -- If a U.S. Air Force Academy scientist's idea is proven correct, his research could tap into energy from ocean waves that could supply a large chunk of the world's electricity needs.

A typical North Atlantic deep ocean wave is about 126 meters long and 3.5 meters tall, which could yield 100 kW per meter in the direction of the wave crest, according to Dr. Stefan G. Siegel's computer simulations.

The idea of harnessing power from ocean waves isn't new. The problem is creating a system that can survive in the open ocean. A cycloidal wave energy converter, based on the type of propellers on ferries and tugboats, is the focus of Doctor Siegel's wave energy converter research project.

Next summer, his work will be put to what he calls "a make or break test" in Oregon State University's giant wave tunnel.

"If the big test at Oregon State is a success, I think we can slowly transition this project from what is right now basic research and a very novel idea to more applied research and finally to industrial development," said Doctor Siegel, an Academy Department of Aeronautics research associate. "If we can get efficient energy out of the wave tank out there, I believe we can also do that in the ocean."

A magazine article in 2004 inspired Doctor Siegel's theory of a wave energy system based on the same principles that keep airplanes in the sky. The article was about state-of-the-art wave-powered devices, and caught his attention because his staff had already worked on the cycloidal turbine propeller. The advantage is that the thrust from the propeller can be directed for 360 degrees in any direction.

"While we have the means to tap into solar and wind energy, we don't have anything feasible right now to tap into ocean waves," Doctor Siegel said. "That's really, in a nutshell, what sparked my interest in wave energy, because I saw an unsolved engineering problem there, and it also played really well with the research I had been working on previously. I looked at it as a great application for feedback flow control, which is what we had developed in our department for more than 10 years."

The Academy's Aeronautics Department's wave energy project is funded through 2011. The department also received a $285,000 grant from the National Science Foundation to support the research.

As cadets work on calibrating gauges, Doctor Siegel and his staff are testing the cycloidal turbine in their scaled-down model of the wave tunnels that Oregon State University will use next year. They are setting up the system that controls the rotation and pitch of the propeller blades because it must be synchronized with the incoming wave to successfully harness the energy. This is probably the most important issue that must be resolved before testing in the Oregon State tunnel.

"Ultimately, if things keep turning out as we see them right now, we will develop this as a commercial product, and we believe it will make a significant impact on the overall renewable energy scheme worldwide," Doctor Siegel said. "What really makes me the most excited are the simulation results we have right now. The beauty of simulations is I can simulate full-sized ocean waves. We can analyze the data here and find out we can have 99 percent of the energy from one wave. It got us excited further when we realized this device can not only take energy from the waves, but also do it efficiently. Efficiency is the key to getting energy from ocean waves."