Sorry, the design procedure is delayed until the next post, because we really should address claims of, “fish friendly.” To be able to compete with accepted vertical slot fish-ways, we need a 100% injury free fish passing rate, so we can call this truly fish friendly. These claims linked below are a very similar design to a fish-friendly GWVPP, so would be easily confused and could give the technology a bad name environmentally.
Hopefully most people are sensible enough that they don’t blindly believe everything that is claimed. These are links to the claims we are referring to, followed by the reasons why they must not be fish-friendly with their existing design.http://turbulent.be/
The linked page above has a claim of fish friendliness in a blue tab lower on the page.http://www.ir3s.u-tokyo.ac.jp/3e-nexus/pdf/011817/session3-2_Bajracharya.pdf
The linked page above has a claim of fish friendliness in the design drawings they have borrowed from the Austrian GWVPP design (very different from their design).
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Both Turbulent.be and the Dhakal conical design are intended to operate at higher flow rates than the 480 l/s compared above, so the unfriendliness for fish would be greater. Neither design would be anywhere near possible for fish travelling against the flow (even salmonids), and only fast fish of small size would have good chance of being unharmed going with the flow direction. Likely better than a modern Alden turbine, because there is not as much pressure variation, but worse in the aspect of turbulence and blade strike risk.https://energy.gov/eere/success-stories/articles/eere-success-story-alden-fish-friendly-turbine-allows-safe-fish
This Alden developed design claims better than 98% success for fish going down through the turbine ONLY WHEN the fish are less than eight inches long (0.2m). Of course, any dam big enough for an Alden turbine would need to have a very expensive and complex fish-way for up-river migrating fish!
Why are we going to so much trouble on this subject now?
This is very important to understand that for safe fish passage in both upstream and downstream directions we must have:
1. A subcritical flow through the rotation chamber (less turbulence)
2. A maximum velocity that local fish can swim against successfully
3. A large enough orifice & big enough blade gap for the largest local fish
4. Low energy remaining so the local fish like to swim through (W/m3)
5. The flow rate tightly controlled so design maximums are not exceeded
6. A slow enough RPM so there is no blade strike risk for fish
7. A resting pool underneath each rotation chamber
These 7 points will help the design procedure (to be posted soon) make more sense.
Please note: We don’t mean to belittle research work in developing countries where the emphasis is on energy production, that the quality of living may be improved. The chart should demonstrate anyway, that while small efficiency gains may be had with higher RPM, because less gearing is required; designed for electricity is not designed for fish.
One more important issue: Anything less than total transparency in a fish-way/pass, is not good enough. An example to make this clearer, is the Murray River in Australia, where some fish migrate upstream and some downstream. For either direction in the 2000km from the Hume Dam to the sea there are a lot of weirs and locks (about 26 major barriers), so let us now follow a migration path using an arbitrary figure of 5,000 fish at 90% success showing how many remain to face the next barrier: 1/4500 2/4050 3/3645 4/3281 5/2953 6/2658 7/2392 8/2153 9/1938 10/1744 11/1570 12/1413 13/1272 14/1145 15/1031 16/928 17/835 18/752 19/677 20/609 21/548 22/493 23/444 24/400 25/360 26/324 So 6.5% made it through 26 barriers at 90% passing rate, not taking any predation or other causes of mortality into the equation. If the pass rate was only 80% then only 0.3% would arrive or 15 fish out of 5000. Many waterways in Australia have more barriers (often for irrigation) per 100km than the Murray. What makes this situation worse is the fact that European Carp and Red-fin fish don’t need to migrate so their population can increase faster than most of our local endemic fish.
First stage of the design procedure next.