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Comment by nitrogen | Hacker News Reader

Microhydroelectric has come up on HN before: https://news.ycombinator.com/item?id=6895582

This open design looks interesting, but there are a couple oddities in the Wikipedia article I'd appreciate clarification on from a subject matter expert:

>It was first patented by Greek-Australian Lawyer & Inventor Paul Kouris in 1996[1], who was searching for a way to harness the power inherent in a vortex.

What power is inherent in a vortex apart from gravitational potential energy being converted to kinetic energy?

>after a year of use its operation cost was approximately one US dollar per Watt capacity of output.

Shouldn't that be installation cost, not operating cost?

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Fluid dynamicist here. Your understanding is correct. I would not read anything into vague statements like "the power inherent in a vortex". That explanation is basically woo. There's nothing special about vortices. The large vortex used here is sustained by the gravitational potential energy, as you said.

The Wikipedia article read a bit like an advertisement to me.

I don't suspect the Coriolis force of the Earth contributes much to this turbine either, though I admit I don't know much about the Coriolis force in fluid dynamics. For objects of the size shown, Coriolis forces are neglected in my experience.

Edit: Wikipedia backs me up on the Coriolis force being negligible. Aside from starting the rotation in the cited tests (something needs to break the symmetry), the Coriolis force is negligible compared against gravity. In the turbine case I believe turbulence would break the symmetry (the turbulence itself being influenced by imperfections in the flow, surfaces, vibrations, etc.).

https://en.wikipedia.org/wiki/Coriolis_force#Draining_in_bat...

The webpage for one of the companies cited in the Wikipedia article spends a lot of time talking about how their generators are powered not just by gravity but also by the earth's rotation.

My first thought was that didn't sound right so it must just be marketing bs.

Straight up lies.

Couldn't it be simple ignorance? And not intentional deceit?

You're saying the company that built the generators wouldn't know how they work? I don't see how it could be anything else other than intentional.

>"You're saying... Nope, I "asked" a hypothetical question based on this:

>...one of the companies cited in the Wikipedia article..."

And then this:

>liars

If the company in question are saying stuff like "powered by the coriolis effect" then to call them liars, you'd have to actually look at their site and see if they actual sell anything real. Then either do research on the claim, and then come to a judgement, like this:

1. If they are crackpots in their garage and sell hand-made junk from PVC scraps, then yes, it could be ignorance.

2. If they have a real engineer and a marketing department, then it's probably lying.

Which is it? I don't care to look at every site on Wikipedia to figure out which one the comment was about. So instead, I asked the question, maybe someone else has done some research?

Conservation of angular momentum says you can't get energy from the Earth's rotation unless you have a reaction force on something in space.

Indeed. Coriolis force doesn't give any energy since it applies the force perpendicular to the direction of motion.

The symmetry is broken by the direction of the inlet. Point the inlet the other way, the vortex will form in the other direction. Even if you started the vortex the wrong way, the incoming stream would stop and reverse it in short order.

Coriolis Force is meaningless on this length scale.

Still, that doesn’t mean it has to be an ad, it could just be run of the mill arrogance, or the writer drank the Kool Aid. It is funny though, like someone worried about the influence of the cosmological constant on their own body or something.

Would it be viable to create a vortex system that acts as a fluid flywheel?

Yes but centrifugal forces on the simle “rotating fluid” equivalent are too strong and require a costly casing when compared to an equivalent solid flywheel. What they do is they use the rotating part as a pump to push the fluid up a vertical pressurized storage and the pressure there plus the potential energy of the fluid store the energy in a more manageable matter than having it all in the fluid speed

There's a cult of "vortex power" enthusiasts. It's as much bunk as TimeCube, but less obviously disordered.

Ignoring the BS about coriolis, I think there is something legit here.

Of course there isn't any power to be gained from the vortex. What you would gain is a lot of RPMs from very little head. It makes the system be high speed and low torque. The dynamos would be higher voltage (lower amperage), the wiring and inverters are cheaper with lower amperage, and the structure doesn't have to be as strong since the torques are lower. It might even automatically safe during floods, since too much water entering it would distrupt the vortex and halt the wheel.

It is more like a clever hydraulic gearbox that potentially makes all the other components less expensive. Or am I completely off base? The water is spinning around faster than it would be flowing out, correct?

This other company[1] built a prototype of a low-cost vortex in Chile, and claims it produces 15Kw consistently with a drop of 2-3m. If true that's fantastic. As suggested in their video, they could could build several of those in a row because they don't need a massive reservoir.

[1]: https://www.youtube.com/watch?v=gY3p2e1-kN4

Actually I think it is the opposite. This is very low speed at 10-20 rpm. A non-vortex hydro plant runs way faster with 1-2 meters of head, some fast enough that a high-pole-count generator can be directly driven.

To me the fun puzzle is to lift part of the water above the source without moving parts. One can easily do that with a mech. pump but how to make it solidstate?

Well, I suppose you mean: with the only moving part being the water itself. A hydraulic ram can move water uphill easily without any external power, electricity, etc., using basically only simple valves. If I could build a hydraulic ram of ice, does that count?

Re: vortex, reminds me of in "Echopraxia" a bunch of monks powered their monastery with a trapped tornado. No idea how feasible that is but it was badass.

https://www.tor.com/2014/07/29/the-colonel-peter-watts/

> >after a year of use its operation cost was approximately one US dollar per Watt capacity of output.

> Shouldn't that be installation cost, not operating cost?

Since the Wikipedia article does not say, we can not be sure. I interpreted that sentence to intend to describe the long term operating costs without consideration of the up-front installation costs (which obviously will inflate the actual long term operational costs if installation costs were amortized over the lifetime of the unit).

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