A marine engineer and naval architect has designed a new way of drawing energy out of slow-moving rivers and gentle tides. The researcher says the unobtrusive device, which was inspired by the way fish move through the water, could be set down on riverbeds or suspended in the ocean just about anywhere. Existing technologies which use water power, relying on the action of waves, tides or faster currents created by dams, are far more limited in where they can be used, and also cause greater obstructions when they are built in rivers or the sea. Turbines and water mills need an average current of five or six knots to operate efficiently, while most of the earth’s currents are slower than three knots [Telegraph].
Engineer Michael Bernitsas’s device is called VIVACE, which stands for Vortex Induced Vibrations for Aquatic Clean Energy. How does the technology work? A cylinder-shaped object in the water current causes alternating vortices to form above and below the cylinder. The vortices push and pull the passive cylinder up and down on its springs, creating mechanical energy. Then, the machine converts the mechanical energy into electricity [Greenbang]. Bernitsas explains that fish also create vortices as they swim, and in a large school each fish curves around the vortices left by the fish in front, using the tiny whirlpools to propel themselves forward.
Bernitsas says that if a field of cylinders about the size of a running track and the height of a two-story house was positioned in a place with a flow of just three knots, could generate enough power for around 100,000 homes. Just a few of the cylinders, stacked in a short ladder, could power an anchored ship or a lighthouse [Telegraph]. Bernitsas estimates that a large system could produce energy at a cost of 5.5 cents per kilowatt hour–cheaper than solar and wind power, but not quite as cheap as nuclear energy. He has founded a company called Vortex Hydro Energy to work on commercial applications of the technology, and is currently working on a pilot project in the Detroit River which should be deployed within the next 18 months.
A recent study showed that marine energy from sources such as wave energy and tidal projects could provide 10 percent of the world’s energy needs…. Last year California’s Electric Power Research Institute predicted that ocean-based energy could someday meet as much as 10 percent of the total U.S. demand [Cleantech]. However, such projects have been slow to get off the ground, as few sites have the powerful tides needed to produce cost-efficient energy, and wave power technology is in its infancy. Some environmental groups have also worried about the impact of large turbines on marine animals. This new technology would be easy on aquatic wildlife, Bernitsas says, because its parts move slowly.
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Image: Omar Jamil
December 3rd, 2008 at 1:15 pm
When you say, “not quite as cheap as nuclear” are you leaving out the enormous cost of handling nuclear waste and decommissioning the plants after twenty or thirty years?
Probably. Everyone does.
Mark McKenna
December 3rd, 2008 at 5:39 pm
I am unsure about Bernitsas claims that “new technology would be easy on aquatic wildlife”. Looking at the image (that shows a fairly large field of the VIVACE device laid on some substrate), I am concerned about the response of benthic organisms to such a change in habitat availability and complexity.
December 4th, 2008 at 8:38 am
Yeah I also do not see how it could be “easy on aquatic wildlife”. It would seem that barnicals, algae, or fish could ubstruct the VIVACE. Just because something is slow moving doesnt mean it isn’t harmful take for instance a machine to compact pavement, they are slow but they are harmful.
December 4th, 2008 at 2:18 pm
I’m also skeptical. About the only place I could see this being used without it affecting the environment too much would be in the open ocean. Maybe that floating island by google could use it?
December 4th, 2008 at 5:48 pm
I foresee in any warmer currents this not working after a month due to algae growth, and other plant life, regardless of what its made of. Perhaps the technology would work in the northern climates that rarely reach a temperature that is conducive to plant growth, but that’s it. Although, once in place, after the initial cost of materials and installation, to pay a snorkeling maintenance crew to do routine cleanings would be still make this a viable energy source. I admire this type of thinking and look forward to future stories on the subject.
December 4th, 2008 at 10:38 pm
We could have endless strings of remarks on why this idea will not, could not, should not work.
I am interested in response on why it should, how it should, how to make it, work.
December 4th, 2008 at 11:42 pm
How to make it work means looking at and overcoming the reasons it might not work. And thinking about those ahead of time can save the investment of time and resources lost to false starts. The low flow will allow colonisation by both plants, particularly algae, and sessile mollusks, barnacles, etc. and will probably be the largest issue to overcome. That said, I hope they come up with workable and environmentally benign solutions.
January 26th, 2010 at 1:52 pm
I thing they are thinking the system would not be laid out flat… so that would make it easier to place. and if it is cheap and small enough to remove and clean every few weeks.
March 7th, 2010 at 4:32 am
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August 14th, 2010 at 6:23 am
waiting for more info about this topic