Energy and the Environment-A Coastal Perspective

What is an Oscillating Water Column?

An Oscillating Water Column is where a large amount of moving water acts as a piston in a cylinder. The air is forced out of the column as a wave rises and new air is sucked in as the wave falls back down again. In the device, the movement of air will turn the turbine at the top of the column.

Here are models of Oscillating Water Column Devices:

  (this device is located in Scotland)

The moving parts of the Oscillating Water Column Device are not housed in the water itself and this helps to prevent damage done to the parts. These devices can be built near shore, allowing easy access to make repairs. Most of the device is submerged and is more difficult to see unless you get right up on the device. This helps cut down some of the visual impairment concerns that locals tend to have who live along coastlines.

How does an Oscillating Water Column Device Actually Work?

Essentially, the motion of the wave creates pressure changes under the column itself and these pressure changes cause the water level in the chamber to oscillate (hence where the device gets its name). Oscillate just means to swing back and forth, kind of like a pendulum. The oscillating water level makes the air flow into the chamber itself.

Here is an excellent explanimation video for the Oscillating Water Column:

http://www.youtube.com/watch?v=Mzyx0XDR-aw

The video below simulates an Oscillating Water Column:

Modern Uses of Oscillating Water Column Devices:

Arguably, the most successful use of Oscillating Water Column Devices is in Scotland. The company who has spearheaded this research is known as Voith Hydro Wavegen. They are leaders in wave power and wave energy research. Their most famous cite is the Limpet, which generates energy that can actually be used on the grid. Voith uses Well turbine power in order to power their devices. They developed the first near shore commercially oriented approach to capturing energy from waves.

Limpet also serves as a research center where the company can test new designs and try to increase the efficiency of their Oscillating Water Column Device.

Above is a picture of the turbine they use, taken from their website, which explains how they operate. They use turbo-generators so that breakwaters and coastal defenses can be incorporated. They state that these particular turbines are part of the fifth generation and that they have reduced the cost of these turbines at a tremendous rate since 2000 and are expected to become even more economically efficient. The Limpet plant has been able to generate power on the grid for a consistent 72,000 hours, making the Limpet the most efficient Oscillating Water Column Device currently available.

Future Endeavors:

Voith Hydro Wavegen states that their device can be used to make saltwater drinkable through desalination. Furthermore, the devices can also be used as artificial reefs (called mariculture). Their claim is that the device can provide a source of habitat for commercially popular species of fish. It is also widely agreed upon that the Oscillating Water Column Device has little to no negative environmental downsides and that they will not harm marine species that may somehow interact with the device.

Bibliography:

Johnson, Nicole and Eric Olson. What is an Oscillating Water Column? 2010. University of

Wisconsin Madison. CEE 514: Final Project.

http://owcwaveenergy.weebly.com/

Ram, Krishnil, Mohammed Faizal, M. Rafiuddin Ahmed,Young-Ho Lee. 2010. Experimental

Studies on the flow Characteristics in an Oscillating Water Column Device.

Journal of Mechanical Science and Technology. Volume 24, Issue 10 pp2043-2050.

Online Access: http://link.springer.com.libproxy.lib.unc.edu/article/10.1007%2Fs12206-

010-0621-z. (Date Accessed 18 May, 2013).

Voith. Wave power at Voith Hydro Wavegen. 2013. Vioth Hydro Wayegen, Inc.

http://voith.com/en/Voith_Wave_Power.pdf (Date Accessed 18 May, 2013).

 

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