• Mucki@feddit.org
    link
    fedilink
    English
    arrow-up
    3
    ·
    1 month ago

    Sounds cool. Naive question: you need many of them. Thousands or more. Is that not going to further slow down the river’s current, which in consequence will provide less for the turbines further down the stream? And so on… There is no comment about that in the article.

    • varyingExpertise@feddit.org
      link
      fedilink
      English
      arrow-up
      5
      ·
      1 month ago

      Lets think about that.

      • The rivers flow rate is the product of its cross section times the flow speed.
      • The flow rate is also the sum of all the runoff and streams that end in the river above any given point.

      So, if what you assume were true, the flow speed would sink. The ingress flow rate would not reduce though, why should it, so the only way to keep the ratio between flow speed and cross section, aka the flow rate constant would be to increase the cross section area. So, the water level would have to rise, no other way to achive that. So the question is: “Will the river in its entire length raise its level when we put these turbines in at any point?” - that would be a great way to get hundres kilometers of deeper shipping lanes for free, but no, of course it won’t.

      • glimse@lemmy.world
        link
        fedilink
        English
        arrow-up
        1
        ·
        1 month ago

        The world is working on another plan to give us deeper shipping lanes and this one will be global!