From the pages of the Ivory Tower: "U-M to tap Detroit River's current to create energy." "This is VIVACE, a device to harness energy in slow-moving water currents across the globe and turn it into electricity. VIVACE, which mimics the way fish swim in currents, is to debut next year in the Detroit River, powering the light for a new wharf between Hart Plaza and the Renaissance Center." "...It's one of a handful of new techniques -- the first in more than 100 years -- to use water to create clean, renewable energy." (emphasis mine)
My take on this: All of these people need to let the public know the truth - "clean" energy is a myth. There is cleaner energy, but nothing is 100% clean (the 2nd Law of Thermodynamics forbids it). As nice as this idea sounds on paper, these devices will have to be manufactured, which itself is inherently non-clean, non-green. So there's that. Why do these reports always ignore the energy and materials it takes to build these devices? Why not look at the big picture - the entire life cycle of the device? How much energy do we get out versus how much energy (and chemicals, materials, waste, etc.) went in? And then look at the ratio.
Now onto the technique here (you can see a picture of the cylinder array here), which is a novel one where upright cylinders in water sway back and forth in a slow-moving current (due to vortex shedding on the sides of the cylinders such as happens in air. You can see a computer-simulated visual here. This shedding induced vibrations, or the swaying back-and-forth of the cylinder). However, when I think of anything swaying back and forth in a repetetive, oscillatory manner, fatigue failure comes to mind. How long will these devices last? They will need maintenance, as the article indicates. Plus there's the biofouling factor in the Detroit river (versus clean laboratory water - albeit I'm sure the researchers took this into account). I doubt the claim in the article that they will be cheaper than wind power (solar maybe). In any case, it will be interesting to see the results from the initial trial, especially on the economic feasibility front.
