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posted by cmn32480 on Wednesday November 25 2015, @06:43PM   Printer-friendly
from the give-a-hoot-don't-pollute dept.

The All Energy Forum at last week's ANS Meeting in Washington D.C. was an eye-opener for many reasons, not the least being my underestimation of the amount of new hydroelectric power that could be installed in America without building a single new dam.

Almost 90% of America's low-carbon energy sources come from hydropower (21%) and nuclear power (67%), which together avoid almost a billion tons of CO2 emissions each year. If we are to achieve any of the low-carbon goals we have set out for 2030 and beyond, hydropower must increase significantly and nuclear has to maintain it's share of power, and even increase slightly by 2030.

David Zayas, Senior Manager at the National Hydropower Association (NHA), says that the goal is to double hydropower over the next few decades, adding 60 GW by 2030, producing an additional 300 billion kWhs of electricity each year.

The premise is that most dams in America don't produce power, and that adding that capability would account for the increase.


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  • (Score: 3, Insightful) by bob_super on Wednesday November 25 2015, @07:46PM

    by bob_super (1357) on Wednesday November 25 2015, @07:46PM (#268109)

    > without building a single new dam.

    I guess there are enough idiots out there to fall for the seemingly innocuous-looking wording...

    Dams are easy, right? drop some rock in a river and there you go, got yourself a dam.
    Oh, you mean you wanted hydro-power from it? Easy, just ask a giant sand worm to dig a hole through the base of the pile of rocks! It's a ten-minute job.
    I'm sure nobody downstream will notice.

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  • (Score: 5, Informative) by Anonymous Coward on Wednesday November 25 2015, @07:55PM

    by Anonymous Coward on Wednesday November 25 2015, @07:55PM (#268113)

    I've been aware of this potential for a while, saw a show on PBS about it a year or two ago.

    When they say that you don't need to build a single dam they aren't trying to minimize the financial costs. It is about minimizing the ecological costs. Building a dam changes the ecosystem of the river that is damed up. But these dams have been in places for decades, most of the damage is already done and it isn't clear if taking the dam down would be enough to let the river recover. So, since the worst has already happened, might as well get the most out of the situation.

  • (Score: 2, Informative) by khallow on Wednesday November 25 2015, @08:09PM

    by khallow (3766) Subscriber Badge on Wednesday November 25 2015, @08:09PM (#268117) Journal

    I'm sure nobody downstream will notice.

    You slide in the power generation infrastructure before they do notice. Magic trick.

    More realistically, you'd have to drain the reservoir, divert water for years, and punch some holes in the dam (unless the dam is shorter than 10m from base, then you could pull water over the top of the dam (vacuum pulls water up to 10 meters up)) in addition to installing the necessary and very expensive gear.

    Really what he's saying here is that you can generate somewhat more hydroelectric power by replacing all the non hydro-power dams with something that generates electricity without changing the surface area of lakes. The problem here is that most such dams just aren't worth the bother. You have to have a good combination of flow rate, height, and "capacity factor" (how much the dam is used). For example, a dam that you have to pump water into (example [wikipedia.org]) in order to use, could have a lot of height and flow rate, but a negative capacity factor. Capacity factor would also be reduced by any need for flood control or water storage since you might not be able to drain the reservoir when you need to and you can lose water to other means than through the generators.

    Really, if those lakes were so awesome for generating hydro power, then they probably would already do that.

    • (Score: 1, Interesting) by Anonymous Coward on Wednesday November 25 2015, @08:33PM

      by Anonymous Coward on Wednesday November 25 2015, @08:33PM (#268128)

      > More realistically, you'd have to drain the reservoir, divert water for years, and punch some holes in the dam (unless the dam is shorter than 10m from base,

      Most of the dams are quite small and out in the middle of nowhere. One of the biggest logistical problems with this proposal is getting the transmission capacity to the dams so that the generated power can be sent somewhere useful.

      • (Score: 2) by frojack on Wednesday November 25 2015, @09:49PM

        by frojack (1554) on Wednesday November 25 2015, @09:49PM (#268149) Journal

        The dams are neither small nor "out in the middle of nowhere".

        They are all up and down the Mississippi, Illinois, and Ohio rivers, and they are huge [army.mil].

        --
        No, you are mistaken. I've always had this sig.
        • (Score: 0) by Anonymous Coward on Wednesday November 25 2015, @10:01PM

          by Anonymous Coward on Wednesday November 25 2015, @10:01PM (#268152)

          There are 54,000 dams in the study. You are only talking about the 100 largest of them.

          • (Score: 1, Informative) by Anonymous Coward on Thursday November 26 2015, @01:22AM

            by Anonymous Coward on Thursday November 26 2015, @01:22AM (#268198)

            The press release says that "the top ten sites alone have the potential to provide approximately 3 GW of generating capacity, while the top 100 sites together could potentially provide 8 GW [...]". For comparison, the Bruce Nuclear Generating Station [wikipedia.org] has 8 reactors with a capacity of 7.3 GW.

            About the cost of retrofitting, the report asserts that "adding power to the existing dam structure can often be achieved at lower cost [...] than development requiring new dam construction."

            • (Score: 0) by Anonymous Coward on Thursday November 26 2015, @06:34AM

              by Anonymous Coward on Thursday November 26 2015, @06:34AM (#268252)

              Thanks for quoting the report. What's your point? Or do you even have one?

    • (Score: 3, Informative) by frojack on Wednesday November 25 2015, @09:58PM

      by frojack (1554) on Wednesday November 25 2015, @09:58PM (#268151) Journal

      You don't have to drain the reservoir. Nor could you. These are RIVER dams.

      You simply build a coffer dam where you will be installing your intake gates, and run your piping (underground) around the existing dam to your turbine house down stream of the existing dam. You never touch the existing dam, and there is no disruption of the shipping channels.

      The problem is most of these dams provide only 15 feet of head, and that requires custom turbines, and maybe more water than would be available while still maintaining navigation levels.

      --
      No, you are mistaken. I've always had this sig.
  • (Score: 1, Funny) by Anonymous Coward on Wednesday November 25 2015, @08:29PM

    by Anonymous Coward on Wednesday November 25 2015, @08:29PM (#268126)

    I'm sure nobody downstream will notice.

    Frankly, I don't give a dam.

  • (Score: 2) by frojack on Wednesday November 25 2015, @09:41PM

    by frojack (1554) on Wednesday November 25 2015, @09:41PM (#268148) Journal

    Did You missed the part of TFS about NOT building and new Dams?

    They expect to some how add power generation to navigational dams on the major rivers, while somehow preserving the shipping locks. These waterways handle a humongous amount of materials shipment, as well as grains, and freight. To do that you need locks, and locks need a differential in river height upstream. See http://energy.gov/articles/powering-america-s-waterways [energy.gov]

    To the extent these dams send excess water over their spillways, they could add power plants. The problem is that these are usually low head dams, which require specialized turbines, and lots of them.

    Example Lock & Dam 24 [army.mil] on the upper Mississippi, near Clarksville Mo. The average lift/head is only 15 feet. It is representative of just about ALL the dams on the rivers, as they were all designed and placed so as to provide a 15 foot differential. Power generation was not a consideration. These were navigational dams with a irrigation option bolted on to a few of them.

    Grand Coulee Dam in eastern Washington has a head of 350 feet by comparison.

    Retrofitting power plants would be hugely expensive, but would probably pay out eventually.

     

    --
    No, you are mistaken. I've always had this sig.
    • (Score: 2) by bob_super on Wednesday November 25 2015, @10:31PM

      by bob_super (1357) on Wednesday November 25 2015, @10:31PM (#268162)

      Which was exactly my point.
      This country has over 50000 "structurally deficient" bridges. Why would anyone think it's even remotely possible to safely modify the existing dam infrastructure to add major elements affecting their very structure? Each dam is unique and needs years of studying and careful upgrading to avoid life or commerce losses.

      • (Score: 2) by frojack on Wednesday November 25 2015, @10:48PM

        by frojack (1554) on Wednesday November 25 2015, @10:48PM (#268167) Journal

        As I pointed out elsewhere, in the vast majority of cases, you don't have to touch the original dam.
        You plum around them.

        --
        No, you are mistaken. I've always had this sig.
        • (Score: 2) by bob_super on Thursday November 26 2015, @02:05AM

          by bob_super (1357) on Thursday November 26 2015, @02:05AM (#268206)

          > You plum around them.

          "around" is the hard part.
            - Above relies on the structure of the dam
            - Under undermines the dam
            - On the left or right side can threaten the river bank/cliff stability or the dam stability, get delayed by the land owners suing, typically will run into roads if not highways, rails and bridges, require an Environmental Impact Study because the blue frog lives there, require studies for he 100 and 1000-year floods...

          Despite the changes in regulations, it's still probably faster to remove a most small dams and build new dams of about the same footprint than it is to figure out how to go around dams that have been there since the Great Depression. Its got to be assessed on a case-by-case basis, which each study probably taking half a dozen years.

  • (Score: 0) by Anonymous Coward on Thursday November 26 2015, @01:26AM

    by Anonymous Coward on Thursday November 26 2015, @01:26AM (#268199)
    The sandworm would die from exposure to water.
  • (Score: 2) by morgauxo on Monday November 30 2015, @07:39PM

    by morgauxo (2082) on Monday November 30 2015, @07:39PM (#269871)

    Everyone knows that water is poisonous to sandworms!

    • (Score: 2) by bob_super on Monday November 30 2015, @08:41PM

      by bob_super (1357) on Monday November 30 2015, @08:41PM (#269898)

      How else do you get the worm out to put the turbine in?