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Harnessing Slow Water Currents For Renewable Energy

Posted by Soulskill on from the hydroelectric-for-those-who-won't-give-a-dam dept.

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."

25 of 113 comments (clear)

  1. Harnessing my leaky faucet? by macraig · · Score: 2, Funny

    I wanna harness the slow water current of my leaky faucet to trickle-charge my laptop; can I do that? If that works, I'll move on to trying to harness my *other* leaky faucet.

    1. Re:Harnessing my leaky faucet? by Anonymous Coward · · Score: 2, Funny

      my *other* leaky faucet

      Have you tried this?

  2. Secondary effects? by Vellmont · · Score: 5, Interesting

    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?

    --
    AccountKiller
    1. Re:Secondary effects? by canthusus · · Score: 3, Insightful

      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.

    2. Re:Secondary effects? by Felix+Da+Rat · · Score: 2, Insightful

      From the look of the system, there wouldn't appear to be too much slow down. Probably about on par with tossing a reasonably sized rock into a stream.

      Of course, it's a matter of scale. One rock? not much impact, but throw to many in, and you have a dam. So I think the impact this system would have depends most on how much power it generates and how many can be fit on a given body of water before having a damming effect.

    3. Re:Secondary effects? by sdpuppy · · Score: 4, Interesting
      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.

    4. Re:Secondary effects? by confused+one · · Score: 2, Insightful

      except that it would induce additional vortex currents around the device.

    5. Re:Secondary effects? by pushing-robot · · Score: 3, Funny

      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.

      --
      How can I believe you when you tell me what I don't want to hear?
    6. Re:Secondary effects? by maxume · · Score: 3, Insightful

      "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.

      --
      Nerd rage is the funniest rage.
    7. Re:Secondary effects? by Ex-MislTech · · Score: 3, Informative

      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

      --
      google "32 trillion offshore needs IRS attention"
    8. Re:Secondary effects? by ldbapp · · Score: 2, Informative

      The energy is taken from the vortices, but it's not free or otherwise lost energy. Without the cylinders in the water, the vortices would not exist. The cylinders induce them, thus converting the forward flow of the water into a form that can be harvested.

      So you are not harvesting energy that would be lost energy; you are harvesting the energy of the flow.

    9. Re:Secondary effects? by instarx · · Score: 2, Informative

      The Colorado River at Phantom Ranch averages 80,000 ft3 of water per second, or 2.4 x 10^9 cc. The energy that would have to be extracted to cool that water by 0.001 degrees C would be 2.4 x 10^6 calories.

      2.4 x 10^6 calories = 10^9 joules.

      watts = joules/second, so that would be 10^9 watts, or 1 million kilowatts/second would be extracted. Now that's a lot of power for a 1/1000 degree temperature drop.

      Another way to look at it is that it would take a million kilowatts to heat 80,000 ft3 of water 0.001 degree C.

      We can be pretty darned sure that nowhere near that amount of power would be extracted by these vortex generators, so it is not reasonable to assume that the cooling of water from the extraction of energy using this method could possibly be an environmental hazard to anything. The energy extracted from the moving water would equal to millionths or billionths of a degree.

    10. Re:Secondary effects? by sumdumass · · Score: 2, Insightful

      Are we all forgetting what caused the water to move in the first place? I mean the last couple of comments sort of act like this is a car on flat land coasting and we are talking about hitting the brakes every once in a while or introducing obstacles to slow it down. Imagine the same but with the car constantly coasting down hill.

      Gravity is forcing the waters motion. It is going from one place that is higher to another that is lower in elevation. You have other factors like force and so on to consider but slowing the water down at a specific point would only be a temporary effect that would eventually rejoin the force of gravity and the weight of all the water behind it. Unless you damn the entire river up, your not going to be able to take enough energy out of the system to cause a lasting effect. This is because the momentum and force behind the water will just cause what is moving too fast to penetrate the blockage as efficiently to raise up and over it causing gravity to take hold in original ways again. This is different then say water in a pipe that has no other place to go.

      Look at the spill ways of reservoirs. They line them with concrete spikes and riffraff to control the erosion but the water going into it is still effected by gravity and moves down hill as it normally would. The water will move around the objects or rise over them and create a controlled turbulence but it doesn't stop it. Try this experiment. Take a bowl, turn it upside down, place it in a cake pan or something else to capture the water and pour a glass of water slowly on top of it. Time how long it takes to fall off the bowl. Now have a friend put his fingers all around the bowl as to block portions of it, now poor the water in the same way and it will evacuate just as fast.

      The only real difference between a fast moving river and a slow on is the drop in elevation from the height of the water at the beginning to the end and the carrying capacity of the channel. These generators will basically lower the carrying capacity causing a larger drop in elevation from the top of the water where they are installed to where the river will dump out in.

  3. Doubling the Global Warming Reduction by Doc+Ruby · · Score: 4, Interesting

    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.

    --

    --
    make install -not war

    1. Re:Doubling the Global Warming Reduction by foniksonik · · Score: 2, Informative

      hmm except that I'm reading it now and it says Interesting... so I'd say the moderation system works just fine - only not on a short timeline. It's like looking at an election vote too early... maybe only the no votes happened to be counted first... doesn't mean the voted on item won't pass later.

      --
      A fool throws a stone into a well and a thousand sages can not remove it.
  4. The Æolian Harp by Doc+Ruby · · Score: 3, Interesting

    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 !

    --

    --
    make install -not war

  5. That acronym is so 1980's... by mangu · · Score: 5, Interesting

    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.

    1. Re:That acronym is so 1980's... by owlnation · · Score: 4, Insightful

      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.

    2. Re:That acronym is so 1980's... by xant · · Score: 3, Interesting

      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.

      --
      It's rare that you're presented with a knob whose only two positions are Make History and Flee Your Glorious Destiny.
    3. Re:That acronym is so 1980's... by foniksonik · · Score: 2, Insightful

      Hey I agree with you. I've been trying to get someone to do a weighted search for a long time... no takers... I'll have to do it myself. Works like so:

      Put in two words... tell the search engine that the second word is WAY more important, ie: Bass (+0) + Fish (+10)

      What you should get back is a whole lot of pages about Fish where Bass is the actual keyword within that subset. Almost works like a category. Really it's multiple searches... first a search for the highest rated keyword, then a second search within those results for the next highest rated, and so on until you get to the lowest rated keyword.

      The ideal UI would be to use sliders for each keyword and use an AJAX call to update your results live. This way you could play with the numbers and see immediate results. Then you bookmark it.

      --
      A fool throws a stone into a well and a thousand sages can not remove it.
  6. Headlines. by Anonymous Coward · · Score: 5, Funny

    - 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.

  7. Oceans, Not Rivers by Doc+Ruby · · Score: 5, Insightful

    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.

    --

    --
    make install -not war

    1. Re:Oceans, Not Rivers by lysergic.acid · · Score: 2, Insightful

      while you're probably right in that this technology will be most useful by extracting the vast amounts of energy contained in the ocean (absorbed solar energy) it will likely be deployed in a lot of rivers as well. in fact, the video mentions that the pilot project is being built on the Detroit River. so it's not just coastal cities who are going to benefit from this technology.

      i think it's interesting that this technology is expected to be much more cost-effective than conventional solar power. and the ability to operate efficiently in rivers too slow for hydroelectric dams is another plus. rather than simply being a low-impact replacement for dams, it's more likely that this technology will open up hydroelectric power in a lot of new places with slow-moving currents where hydroelectric dams can't be used.

    2. Re:Oceans, Not Rivers by gyrogeerloose · · Score: 2, Informative

      Most big dams are installed for flood control. That they simplify irrigation is a nice side benefit.

      That may be the case where you live but here in the the western U.S., the majority of dams have been built for water storage purposes, followed in number by dams built for generation of hydropower. Relatively few have been built exclusively for flood control; I can think of a couple in the Los Angeles area and that's about it.

      --
      This ain't rocket surgery.
  8. A few alternatives by ishmaelflood · · Score: 2, Interesting

    Self rectifying water turbine, always turns the same way even if the water flow reverses

    http://www.cetusenergy.com.au/action.php

    and if you really want fishy like motion then

    http://www.biopowersystems.com/biostream.php

    The thing is enormous - 50 feet high, generating 300 hp. Full size proto is under construction.