Harnessing Slow Water Currents For Renewable Energy

Julie188 writes "Slow-moving ocean and river currents could be a new, reliable and affordable alternative energy source. A University of Michigan engineer, Michael Bernitsas, has made a machine that works like a fish to turn potentially destructive vibrations in fluid flows into clean, renewable power. This is is the first known device that could harness energy from most of the water currents around the globe because it works in flows moving slower than 2 knots (about 2.3 miles per hour). Most of the Earth's currents are slower than 3 knots. Turbines and water mills need an average of 5 or 6 knots to operate efficiently. Further details and a few brief movies of the technology are available, as well as a video explanation by Professor Bernitsas himself."

Comments

Secondary effects?

[Vellmont]

I'm not a fluid mechanic, but I wonder what the effects would be of slowing down already slow moving river water. Increased silt deposits? More flooding upstream? Anyone with more knowledge about river flows care to comment?

Re:Secondary effects?

[canthusus]

IANAFM also, but yes, I'd expect to see slower water, as we have extracted energy from it. With care, this need not be a bad thing - for example, groins have been constructed on parts of the Thames to slow the water near the banks, encouraging scour of the main shipping channel. Erect a vortex generator instead of groins and you can control flow and generate electricity. Downside is it may become too successful, and the silting could interfere with operation.

Re:Secondary effects?

[sdpuppy]

Sounds like the energy is taken from eddy and vortex currents which, for the most part, is lost energy anyway (destructive interference) and don't add to river currents anyway.

If it works (both technologically and financially) , it's brilliant - harnessing energy that would be lost anyway.

Re:Secondary effects?

[pushing-robot]

Erect a vortex generator instead of groins and you can control flow and generate electricity.

Yes, but you completely ignore the benefits of erecting groins.

Re:Secondary effects?

[maxume]

"A damming effect" would never be a problem, the slower the water is moving the less energy available for extraction, so you would stop installing them long before the water stopped moving. I would guess that capital return rates would convince investors to stop installing them long before environmental impact became a significant problem.

Re:Secondary effects?

[Ex-MislTech]

Water runs down hill due to gravity, once it is passed the device
it will return to its prior speed.

The water does not get and keep its speed from its headwaters.

It varies based on the grade as it moves downstream.

In an ocean, it is not due to grades is more about thermal
differential due to the ocean heating the water.

It might have an impact there, but some of the current
contain flows that are many times the flow of all the rivers
in the world.

Like the Antarctic Circumpolar current:

http://en.wikipedia.org/wiki/Antarctic_Circumpolar_Current

Doubling the Global Warming Reduction

[Doc Ruby]

Replacing petrofuels (and even their waste heat) with this alternative generator would help slow climate change from the eliminated petrofuel waste.

But there's a vast amount of energy already retained in the Earth's oceano-atmospheric system. Vast rivers of undersea currents now store truly huge amounts of energy newly accumulated since industry's byproducts started the Earth retaining more energy. Undersea currents have grown much twistier in their paths around the globe. When that energy cycles through the interconnected systems on its own rhythms, the energy is sometimes transmitted into other media than seawater, that is much more disturbed by it. This is what the El Nino / La Nina cycle is an instance of: energy from heavy sea currents periodically enters the much lighter air, pushing it around much more. That kind of cycle, in a myriad of other such interactions, contributes to larger and more frequent storms.

If we harvested some of that energy from these currents with these new devices, we would be reducing the energy in those currents. The currents would return to their previous less twisty tracks. They would have less energy to transmit to the atmosphere and other climate engines. It would take a very large scale deployment, over a substantial period of time. But the double benefit would be well worth it.

The Æolian Harp

[Doc Ruby]

This technology works the same way as Davinci's "aeolian harp", as immortalized in The Æolian Harp by Samuel Taylor Coleridge:

The Æolian Harp

My pensive SARA ! thy soft cheek reclined
Thus on mine arm, most soothing sweet it is
To sit beside our Cot, our Cot o'ergrown
With white-flower'd Jasmin, and the broad-leav'd Myrtle,
(Meet emblems they of Innocence and Love !)
And watch the clouds, that late were rich with light,
Slow saddenning round, and mark the star of eve
Serenely brilliant (such should Wisdom be)
Shine opposite ! How exquisite the scents
Snatch'd from yon bean-field ! and the world so hush'd !
The stilly murmur of the distant Sea
Tells us of silence.
        And that simplest Lute,
Plac'd length-ways in the clasping casement, hark !
How by the desultory breeze caress'd,
Like some coy maid half-yielding to her lover,
It pours such sweet upbraiding, as must needs
Tempt to repeat the wrong ! And now, its strings
Boldlier swept, the long sequacious notes
Over delicious surges sink and rise,
Such a soft floating witchery of sound
As twilight Elfins make, when they at eve
Voyage on gentle gales from Faery-Land,
Where Melodies round honey-dropping flowers,
Footless and wild, like birds of Paradise,
Nor pause, nor perch, hovering on untam'd wing !
O ! the one Life within us and abroad,
Which meets all motion and becomes its soul,
A light in sound, a sound-like power in light,
Rhythm in all thought, and joyance every where--
Methinks, it should have been impossible
Not to love all things in a world so fill'd ;
Where the breeze warbles, and the mute still air
Is Music slumbering on her instrument.
        And thus, my Love ! as on the midway slope
Of yonder hill I stretch my limbs at noon,
Whilst thro' my half-clos'd eye-lids I behold
The sunbeams dance, like diamonds, on the main,
And tranquil muse upon tranquility ;
Full many a thought uncall'd and undetain'd,
And many idle flitting phantasies,
Traverse my indolent and passive brain,
As wild and various, as the random gales
That swell and flutter on this subject Lute !
        And what if all of animated nature
Be but organic Harps diversly fram'd,
That tremble into thought, as o'er them sweeps
Plastic and vast, one intellectual breeze,
At once the Soul of each, and God of all ?
        But thy more serious eye a mild reproof
Darts, O belovéd Woman ! nor such thoughts
Dim and unhallow'd dost thou not reject,
And biddest me walk humbly with my God.
Meek Daughter in the Family of Christ !
Well hast thou said and holily disprais'd
These shapings of the unregenerate mind ;
Bubbles that glitter as they rise and break
On vain Philosophy's aye-babbling spring.
For never guiltless may I speak of him,
The Incomprehensible ! save when with awe
I praise him, and with Faith that inly feels ;
Who with his saving mercies healéd me,
A sinful and most miserable man,
Wilder'd and dark, and gave me to possess
Peace, and this Cot, and thee, heart-honour'd Maid !

That acronym is so 1980's...

[mangu]

FTFA: "VIVACE stands for Vortex Induced Vibrations for Aquatic Clean Energy"

There was a time when creating an acronym that made a real word was considered cute. Those were the days of the "ESPRIT" (Estimation of Signal Parameters via Rotational Invariance Techniques) and "MUSIC" (MUltiple SIgnal Classification) algorithms.

All that is in the past. These days, acronyms should Google well. Google for VIVACE, MUSIC, or ESPRIT and you'll get page after page of irrelevant sites. Scientists should try to name their projects with unique names, names that will let interested people search the web and *find* their projects.

Re:That acronym is so 1980's...

[owlnation]

These days, acronyms should Google well. Google for VIVACE, MUSIC, or ESPRIT and you'll get page after page of irrelevant sites. Scientists should try to name their projects with unique names, names that will let interested people search the web and *find* their projects.

No. No. No. Scientists, and anyone, should name things what they want, and Google should make a considerably higher effort to make search work MUCH better than it currently does. This just shows you how bad search is, and far it has to go. Google needs more competition.

Re:That acronym is so 1980's...

[xant]

And how is Google going to do a better job of searching? Magically discern your intent from the keywords you typed in? Keywords is all we have. Make your keywords better.

Suppose "what you want" is to name your project "The". Is there some way Google is going to find that when someone wants to learn about "The"? A search for the project's name would be completely useless, and no UI change or smarter algorithm is going to fix that as long as you search by typing into a text field. What a searcher would end up doing is typing in other relevant keywords, and not even including "The" as a keyword because it would serve no purpose. So your project would be indexed on the relevant keywords, which suggests that you should have named it using better keywords in the first place.

Headlines.

[Anonymous Coward]

- for example, groins have been constructed on parts of the Thames to slow the water near the banks, encouraging scour of the main shipping channel

Has there been any ship collisions with those. If so was there a headline like this?

Ship hits Thames in groin.

Oceans, Not Rivers

[Doc Ruby]

This device targets ocean currents, not rivers. Ocean currents already have too much energy (by historical comparison), accumulated in twistier undersea currents from the decades and centuries of escalating Greenhouse effects.

River current power is what is captured by hydroelectric dams. Which have their own problems, but we're already stuck with them. More ocean hydroelectric could allow us to release some dams that have too high a cost (environmentally or operationally) to justify their power output. Though application of these generators in rivers might just be a low-impact replacement for dams. However, the dams also deliver irrigation and drinking water, so we're probably stuck with them for the long haul.