Renewable energy source inspired by fish

[n2doc]

Artist's impression of an array of VIVACE converters in the ocean

An engineer in the US has built a machine that can harness energy from the slow-moving currents found in oceans and rivers around the world. By exploiting the vortices that fish use to propel themselves forward, the device could, he says, provide a new kind of reliable, affordable and environmentally-friendly energy source.

Turbines and water mills can generate electricity from flowing water, but can only do so in currents with speeds of around 8–10 km/h if they are to operate efficiently. Unfortunately, most of the currents found in nature move at less than 3 km/h. The new device is called VIVACE, which stands for vortex induced vibrations for aquatic clean energy, and its inventor claims it can operate in such slow-moving flows.

VIVACE has been developed by University of Michigan engineer Michael Bernitsas, and in its prototype form exists as an aluminium cylinder ( 91 cm long with a diameter of 12.5 cm) suspended by a pair of springs inside a tank. The tank, located in the university’s marine renewable energy laboratory, contains water that flows across the cylinder at around 2 km/h. The device does not convert the energy of the flow directly into electricity but instead exploits the vortices that form on opposite sides of any rounded object placed in a flow (J. Offshore Mech. Arct. Eng. 130 041101).

Vortex-driven fish
As such, it works like a moving fish. Fish cannot propel themselves forward using muscle power alone; instead they curve their bodies so that they form a vortex on one side of their body, straighten out, and then curve the other way to form a vortex on their other side, in order to glide between vortices. VIVACE remains in a fixed position in the water but is pushed and pulled by the vortices on either side, and these vibrations are then converted into electrical energy (the current cylinder is smooth, but future versions will have scale-like structures on the surface to enhance vortices).

more:
http://physicsworld.com/cws/article/news/36907;jsessionid=C1777CC2B966C7A955166149EA877D71

[midnight]

1. I wonder how many of those cylinders are needed to harness

the vibrations that are turned into electrical energy? I think the idea is incredible, but not sure if the votex will be independent of our natural water systems?

[tabatha]

2. Oh lord - more crap in the sea.

[Enthusiast]

3. It would become a valuable marine habitat.

Haven't you seen the abundant life around artificial reefs?

[Vogon_Glory]

4. Probably Hasn't.

I've noticed that a lot of the green-minded people who take issue with underwater construction HAVEN'T seen what sort of habitat such construction can provide--whether that construction is in the form of off-shore oil platforms, shipwrecks, or artificial reefs. A trip downside with scuba gear, mask, and flippers not only demolishes previously-held shibboleths, but can prove enlightening.

[tabatha]

6. See #5.

By the way, I have been to the Great Barrier Reef - lots of educational trips - and have seen marine life around oil rigs and other "artificial reefs".

[tabatha]

5. I think it was McCain who stated that on a trip to the Oil Rigs.

Here is what the Ocean Conservancy has to say:


ARTIFICIAL REEFS

The large industrial cylinders pictured here have formed an artificial reef. (Photo courtesy NOAA/Dept of Commerce)

Sometimes constructed from concrete blocks or acres of old cars, artificial reefs can be found from cold, rough waters to warm, tropical lagoons. While some artificial reefs might benefit some species of reef fish, they also raise many concerns.

Artificial reefs come in many forms: while some are created thoughtfully and purposefully, others represent an inexpensive way to throw out trash. Still others were put in place for other reasons, as is the case with oil rigs.

Although most artificial reefs offer potential habitat for certain kinds of marine life, these are not always happy homes. Artificial reefs can cause damage to natural habitats during their construction and can displace naturally occurring species and habitats. They also tend to concentrate fish unnaturally, making them more vulnerable to overfishing. In some cases, they introduce toxins and other pollutants into the ocean.

We typically oppose the creation of new artificial reefs that are used solely for fishing or tourism purposes. In some cases we support the removal of existing artificial reefs. However, we do not support their removal if an ecosystem is dependent upon their existence.

What We're Doing to Help

The Ocean Conservancy will continue to research and evaluate the long-term impacts of artificial reefs, while continuing to focus our energies on allowing degraded habitats to recover naturally and protecting natural reefs worldwide.

We strongly believe that artificial reefs should not be used as an excuse to dump trash into the ocean. Discarded vehicles cause even more pollution due to oil and other fluids that get released into the water.

http://www.oceanconservancy.org/site/PageServer?pagename=issues_artificialreefs

[NobleCynic]

7. I suspect that should large amounts of life begin to treat it as a habitat

It might disrupt the ability to generate energy.

That said, I'm interested in how much energy can be generated per square km in theory.

[tabatha]

8. Ocean currents can power the world, say scientists

I guess you read the article:

http://www.telegraph.co.uk/earth/energy/renewableenergy/3535012/Ocean-currents-can-power-the-world-say-scientists.html

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